Introducing Photographer’s Friend for iPhone and iPad (Podcast 592)

Introducing Photographer’s Friend for iPhone and iPad (Podcast 592)

It gives me great pleasure to tell you that I have now released the update to our iPhone app, Photographer’s Friend. We now support iPad in addition to iPhone and iPod touch, as well as landscape and portrait orientations.

As I mentioned in an update a few weeks ago, from the end of August I started studying how to develop for iOS, and following a week going through an online course, I set about the task of rebuilding our old MBP Podcast Companion app, as it was a little too long in the tooth to support iOS 11, which has now been released.

I picked up the Swift programming language relatively quickly with the aid of the online training, augmented by other invaluable resources such as the Hacking with Swift and Stack Overflow websites, I was able to create the app that I’d designed in my mind, and even add a number of features that I didn’t think I’d be able to do at this point.

I submitted Photographer’s Friend for review last Thursday, and it was passed as I got up on Friday morning, and I’ve been delighted to see hundreds of updates from the previous version happening across the planet. Although I put a lot of work into this, I really wanted to make it a free update for all of the users that had been kind enough to buy the original app, so I’m also very pleased that I was able to achieve this.

Anyway, I’ve put together a video to walk you through the features of Photographer’s Friend v2.0 which I’ve embedded below. If you’d prefer to read, scroll down for a summary or visit the product page for more details.

Feature Summary

[custom_font font_family=’Open Sans’ font_size=’19’ line_height=’26’ font_style=’none’ text_align=’left’ font_weight=’500′ color=” background_color=” text_decoration=’none’ text_shadow=’no’ padding=’0px’ margin=’0px’]Photographer’s Friend is the only app on the App Store as of Oct 9, 2017, that has both a Depth of Field calculator and a Neutral Density filter calculator. [/custom_font]

I’ve gone into great detail as I implemented both of these fundamental photography calculators, and I’m very proud of how they’ve turned out. The settings of the Depth of Field calculator can all be adjusted with your thumb while holding the app in one hand because sometimes you only have one hand free.

Depth of Field Calculator

To calculate your depth of field, you just set your Camera Type, which is your film or sensor size, and choose an aperture and focal length, and set the approximate distance to your main subject. So basically everything is set with the four dials across the bottom of the interface. The two blue labels indicate that there is some functionality there. You can toggle between feet and meters by tapping the [Focus ft/m] label.

If you tap on the other blue label which displays the Hyperfocal Distance calculated from your selected settings, that Hyperfocal Distance is transferred to the Focus Distance dial, and the display is updated to show your near focus limit, the actual focus distance, and at Hyperfocal Distance, of course, the far limit is infinity, as you can see in the left of the three screenshots (below). All of these settings are saved, so even if you don’t use the default 35mm Camera Type, your selection will be restored whenever you open the app.

Photographer's Friend DoF Calc and ND Calc

Photographer’s Friend DoF Calc and ND Calc

I even built in a NightView mode for the Depth of Field calculator, so if you are using the DoF Calc at night, and don’t want to lose your night vision, just shake your device to toggle in and out of NightView, which you can see in the center image (above).

Neutral Density Calculator

The Neutral Density calculator, which you can see to the right of the three screenshots (above) takes your base shutter speed and calculates the new shutter speed that you have to set after attaching Neutral Density filters to your lens to slow down your shutter speed. Simple to use, you just dial in your base shutter speed on the left and tap any of the filters on the right, and your newly calculated shutter speed is displayed at the top of the screen. 

If your calculated shutter speed in 5 seconds or longer, the Timer becomes active, and we’ll sound an alarm when it finishes to let you know. The first time you start a Timer running, you will be asked for permission to send you notifications via the Notification Center, and if you grant that, if the app is closed or in the background when the timer ends, you’ll see an alert on your device instead. This works even if you force close the app or restart your device.

Links and Help

There is also a scrolling list of links to articles on Depth of Field and Neutral Density filters, as well as a link to open our podcast in the iOS Podcasts app, which now displays images again as we progress through various topics. There are contact us links and I also added some help screens to walk you through how to use the two calculators, in case some of this theory is new to you. 

Anyway, that’s a quick summary for you. I do hope you’ll check out the video that I put together or have a look at the product page for more details. For the introductory price of just $2.99 for two epic photography calculators, I think Photographer’s Friend is a steal, so I hope you’ll pick up a copy, from the App Store

Download Photographer's Friend from Appstore

Note that if you’ve updated to the latest version of iTunes on your computer, you will not be able to buy iOS apps unless you click through from an iOS device.

Please Rate and Leave a Review

If you find Photographer’s Friend useful, please do consider giving us a rating and leaving a review on the App Store. I’ve reset the reviews for version 2.0 and we need some high ratings and positive reviews to start ranking highly in searches. 

Show Notes

Photographer’s Friend Product Page:

Photographer’s Friend on the App Store (please click on an iOS device):

Music by Martin Bailey


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All About Neutral Density Filters (Podcast 391)

All About Neutral Density Filters (Podcast 391)

Having been asked many times about the Neutral Density filters that I use for my long exposure images, today I’m going to explain what Neutral Density filters are, which one’s I use, and how I use them, along with some ways to easily calculate your new shutter speeds, and some guidelines on how much neutral density to use for various effects.

Before we jump into today’s episode, I’d like to thank our sponsors Squarespace. Squarespace is the all-in-one platform that makes it fast and easy to create your own professional website, portfolio or online store.  For a free trial and 10% off, go to and use offer code MBP10. We’ll hear more from Squarespace later on.

Basically, neutral density or ND filters, stop a given amount of light from passing through your lens to your sensor, making it necessary to increase the length of the shutter speed to achieve the same exposure. There are applications when you might use an ND to shoot say portraits in bright light when you still want to use a wide aperture for a shallow depth of field. There are also times when NDs are used for video, because video usually looks best when shot at 1/50 or 1/60 of a second, and I’ve used both of these techniques, but today, we’re going to concentrate on the use of ND filters used to achieve longer shutter speeds to capture movement in our subjects, such as to make waterfalls look silky smooth, or to capture movement in clouds etc.

Are They Really Neutral?

The idea behind the ND is that they are supposed to be totally neutral in color, cutting down the amount of light passing through the lens without changing the color of the resulting photographs. The filters that I use pretty much are neutral and have never been a problem, though I have heard of people getting a magenta cast on their images. My friend David duChemin for example says that he gets a magenta cast sometimes when stacking two of his square resin filters. The type that attach to the front of your lens using a screw in filter holder.

I used to use these, and I think they’re useful especially if you want to use graduated neutral density filters, which are dark on one half and clear on the other, with a graduation between the two. These are used to darken the sky for example, when you have a light sky and a much darker foreground. You’d use a graduated neutral density filter here to even out the light in the scene.

I personally stopped using graduated ND filters a few years ago, as I simply haven’t found them necessary since the dynamic range in our cameras became so much greater. I keep in mind that I might sometimes have to shoot multiple images to merge together in Photoshop later, but we can bring so much detail out from the shadow areas in Lightroom or Nik Software’s Silver Efex and Color Efex Pro now, that I haven’t merged images like this in years either. The result is that my main use of NDs now is in the form of circular screw-in solid neutral density filters. I use a mixture of Kenko, Hakuba and Hoya filters, though mainly Kenko. I have also heard good things about B+W filters, though I have never used them myself.

Neutral Density Ratings

Neutral Density filters are often rated with a number so that we can understand how much light they will stop from entering our camera. An ND2 will block out one stop of light, so if for example we use this with a base shutter speed of 1/250 of a second, with a one stop ND2 filter fitted, we’d need to adjust the shutter speed to 1/125 of a second, twice as long as the original shutter speed, because we need to let in one stop more light, and that always require us to double one of our exposure settings, such as ISO, Aperture or Shutter Speed, but as I say, because most of the time we use NDs to increase the shutter speed, that’s what we’ll concentrate on here.

The next rating you’ll see is an ND4, which blocks out two stops of light, and then an ND8, which blocks out three stops of light. I know these numbers might seem counter-intuitive, but if you think of these numbers, 2, 4 and 8 as the denominator in fractions, it gets easier to understand. An ND2 cuts the light entering the camera by 1/2, an ND4 cuts the light to 1/4 and an ND8 cuts the light down to just an 1/8 of the original amount of light that would have entered the camera without the filter fitted.

So, because an ND2 cuts the light entering our camera to 1/2, we have to double the shutter speed to compensate for this, and I’m sure you already know that if we double the shutter speed, we are increasing it by one stop. This is why an ND2 gives us one stop of darkness, and an ND4 gives us two stops, and an ND8 gives us three stops of darkness, or longer exposure.

This calculation is continued, with the not so commonly seen values ND16, ND32 and ND64 and so on. Each consecutive rating halving the amount of light is passes through compared to the previous value filter. The next value filter I own is an ND400, which of course is not a fraction. The natural progression would be ND128, ND256 then ND512, as we keep halving, but the manufacturers decided that ND400 would be a good value to add to the range too. This does still cut the light down by 1/400 though, so if we do the math, we find that this is an 8 and 2/3 stop filter.

The absolute darkest ND filter I own, which is actually made for directly photographing the sun, is an ND100000, which cuts the light down to 1/100000 of it’s original brightness. This filter can give me multiple hour exposures if I want to, or still take me down to multiple minutes in very bright conditions, like when you are shooting towards the sun over the sea, for example, when there is a lot of reflectivity going on.

Optical Density

OK, so I know I’m geeking out here, but before we move on, I’d just like to cover the other neutral density number system that you might see quoted on ND filters, and that’s the Optical Density. Now, although I’ve figured out how to do these calculations in Excel using a logarithmic formula, Wikipedia says, and I quote “For an ND filter with optical density, the amount of optical power transmitted through the filter can be calculated from the logarithm of the ratio of the measurable intensity after the filter to the incident intensity.” That helped me to develop my Excel spreadsheet, but I’ve never really felt there is any benefit in trying to figure out what the hell that means, so let’s just look at a table of the values as a reference.

ND Rating
Optical Density
F-Stop Reduction
% of Transmission
No Filter 0.0 0 100%
ND2 0.3 1 50%
ND4 0.6 2 25%
ND8 0.9 3 12.5%
ND16 1.2 4 6.25%
ND32 1.5 5 3.13%
ND64 1.8 6 1.56%
ND128 2.1 7 0.78%
ND256 2.4 8 0.39%
ND400 2.6 8.64 0.25%
ND512 2.7 9 0.20%
ND1024 3.0 10 0.10%
ND2048 3.3 11 0.05%
ND4096 3.6 12 0.02%
ND8192 3.9 13 0.01%
ND100000 5.0 16.6 0.001%

You’ll also see that I included F-Stop reduction and the % of Transmission here too. The percentage of Transmission is the amount of light that gets through, starting at 100% with no filter, 50% for a one stop filter, and 25% for a two stop filter, and so on. This isn’t used to rate ND filters for photograph use though, so you don’t need to be too concerned with this. The F-Stop reduction for each filter is useful though, so do take a look at the chart though, especially if you have a filter with a known optical density, but you aren’t sure of its ND rating or how many stops it reduces the light by.

What Do I Use?

Although I own a couple of ND4 two stop filters, I actually don’t carry them with me any more. I mainly carry my ND8 and ND400 filters, in both the 77mm and 82mm filter sizes. I also have a circular polarizer in each filter size, and all six of these filters live in an envelope style filter case from a company called Marumi, that is really slim and slips nicely into my vest pocket. I basically lives there the whole time while I’m out shooting. I also often carry the ND100000 in my camera bag, just in case I need it.

Filters and Filter Case

Filters and Filter Case

Stacking Filters

I should mention too that it’s OK to stack ND fitlers, and the calculation for your new ND Value when doing this is really easy. You literally just add together the stops for each filter. For example, when I only owned an ND4 and ND8 filter, I would sometimes stack them for 5 stops of darkness. Nowadays, the ND8 and ND400 give me a hair under 12 stops of darkness, and this is enough to get me down to between 10 seconds and a couple of minutes in the middle of the day, depending on how much light I have to start with.

Stacked ND400 and ND8 Filters

Stacked ND400 and ND8 Filters

Remove the Protector

I know that there is a lot of polarity out there surrounding whether or not you should use a protector filter, and if you don’t use them, that’s fine. It’s your decision, but I do use them, and intend to continue to use them for a number of reasons that we don’t need to go into today. The reason I mention this now though, is because if you do use a protector filter, you will often need to remove them when you stack multiple neutral density filters.

I try to buy the narrow framed filters when available, so I can usually get away with one ND on top of a protector filter, but using two causes vignetting, which is where the corners of the image goes dark, on my 16-35 and 24-70mm lenses when used at the wide end, so whenever I’m stacking filters, I take my protector filter of first.

Another way to avoid vignetting of course is to use the large square filters like the LEE system, but I’m not a fan of square filters. They have their benefits, like only having to buy one system that you can easily use with many filter thread sizes, but I can use step down filters with my circular filters if I wanted to as well. I choose not to for the same reason that I choose not to use the large square filter systems, which is because there is no easy way to use a lens hood with either solution. LEE apparently do an absolutely awful lens hood for their system that very few people like, and once you start using a larger screw in filter with a step-down adapter, your lens hoods can’t be attached either.

Not a Fan of Vari-ND

And while we’re on the subject of systems that I don’t personally like, I’m not a fan of the variable neutral density filters that change in density as you rotate the front element either. These are basically two polarizing filters that create a varying amount of darkness depending on their rotational relationship to each other, but because they are using polarization to create the effect, the results can be pretty nasty when used on wide angle lenses, with some parts of the scene much darker than others. I bought a Singh-Ray Vari-ND, and although it worked well with longer focal length lenses, and I found it useful for video, it was pretty much useless on my 16-35mm lens, so I stopped taking it out with me.

Here are two images both shot with the Vari-ND at 20mm, but with the ND rotated slightly differently. The first image (left) was shot at 1.6 seconds, with a bit of the effect showing, but the second image (right) was a 4 second exposure, and I tried to get a longer exposure, but also in an attempt to get rid of the patchy darkness that can be clearly seen in these images. In the end I gave up, and this was pretty much the end of the Vari-ND for me. If you click on the images to view them larger in your browser, then use your mouse or keyboard arrow keys to jump back and forth between them, the effect I’m talking about is very easy to see.

Winter Scene with Vari-ND - 1.6 seconds

Winter Scene with Vari-ND – 1.6 seconds

Winter Scene with Vari-ND - 4 seconds

Winter Scene with Vari-ND – 4 seconds

Another reason that I don’t like variable ND filters, is because they don’t give you a definitive indication of the levels of density. All of the variable NDs I’ve seen, have a series of notches or marks without any numbers, so you can’t easily just set them at exactly 7 stops for example. You can take a good guess, but then you may end up basing a two minute exposure on that, only to find that it’s under or over exposed, and I don’t want to mess around with exposures that long.

The fact that they give a smooth transition between often 2 and 8 to 10 stops of density can be a benefit of course and is workable if you are using Aperture Priority or otherwise allowing the camera to control the exposure, because you just rotate the filter and let the camera do the math. I rarely use Aperture Priority though, as many of my longer exposures are more than 30 seconds anyway, which is the longest exposure my camera will do before I have to jump into Bulb mode and do my own exposure calculations anyhow.

Calculating the New Shutter Speed

So, let’s look at how I do my exposure calculations in the field. For exposures up to a few seconds, I generally just use Live View on my camera with Exposure Simulation turned on, so I can see on the live histogram exactly where my exposure is, and don’t really need to do any difficult mental calculations. If you don’t have Live View or a live histogram, you can just shoot a test frame, then check your histogram in image playback mode, and adjust as necessary.

Remember, you generally want the brightest part of your image, which is the right side of the graph, to be just touching the right shoulder of the histogram box. These days there is usually a line around the box, so it’s easy to see, but if your camera is getting a little long in the tooth, you may need to be careful with this, as many didn’t have the box. See the episode of Exposing to the Right (ETTR) if you want more information on why it’s better to expose this way.

One thing to note too is that when you use a heavy ND filter, like the ND8, or even darker, like the ND400 or ND8 and ND400, it starts to get very difficult, if not impossible to see through the viewfinder to compose your shot. What I sometimes do is set up my shot, deciding on my composition and get it focused etc. then find my ideal exposure without the neutral density filter on, and then screw the filter or filters on to the front of the lens and mentally calculate my new exposure.

For example, in this shot (below) I was photographing a waterfall in the daytime, and without an neutral density, the shutter speed was 1/20 of a second at f/16, with ISO 100. In this case, I only intended to use an ND8, so all I needed to do was put the filter on, and check the exposure in Live View, but what I generally find myself doing is counting out in clicks from my base exposure. I have my cameras set up to adjust exposure in 1/3 stop increments, as most Digital SLRs do, and this means that all I need to do is increase the shutter speed by nine clicks on the main dial. Three clicks per stop, multiplied by three.

Skógafoss (Falls)

Skógafoss (Falls)

Clicking and Counting on One Hand

If necessary, you can use this technique for heavier ND filter combinations. If I use the 8 and 2/3 stop ND400, I can literally just count in sets of three clicks, folding a finger for each three, which is one stop, until I get to 8 stops, and then add two more clicks for the last 2/3. The Japanese way of counting to ten on one hand is useful here too, because I’m using my second hand to rotate the main dial.

I start with an open hand, with all five fingers extended for zero, then fold the thumb in for one, while counting three clicks, then the index finger for two stops, counting another three clicks off on the main dial, and son on. Once I fold my little finger or pinky for five stops, I then re-extend the little finger for six stops, still counting three clicks per stop on the main dial, and work my way back, until I extend my middle finger for eight stops, then count off two more clicks for the final two thirds of a stop.

If I’m using my ND400 with my ND8 for 11 2/3 of a stop, I’d keep going until I had all my fingers extended again for ten, then I simply start again folding the thumb back in for my eleventh stop, then rotate the main dial twice more for my final two thirds. One problem with counting and clicking with this much neutral density of course, is that if you aren’t working in quite bright conditions, you will go past 30 seconds, and the camera won’t go past 30 seconds just by rotating the main dial, so you have to use Bulb mode and a timer or cable release, which we’ll get to in a moment.

For me, I know that 1/125 of a second is the slowest base shutter speed that I can be using before I will go past 30 seconds when using my ND8 and ND400 together. So, if my shutter speed is is lower than 1/125 a second, I start with two clicks on the main dial, as 2/3 of a stop is more difficult to calculate in my head later, so I like to get that out of the way.

As an example, let’s say, we just we have a base shutter speed of 1/100 of a second. From there I count my first two clicks, for 2/3 of a stop, taking me down to 1/60 of a second. Now I have 11 full stops to count to get my new exposure. That will take me through 1/30, 1/15, 1/8, 1/4, 0.5 and I get to 1 second after 6 stops. Once you get to full seconds, I stop clicking the main dial and start doubling the seconds, so 2, 4, 8, 16 to 32 seconds, which is the time I have to program into my Remote Timer.

Note too that if I want to go even longer than 32 using this same example, I’ll start looking at my aperture and ISO again. Generally, I’ll also be using ISO100, but changing that to ISO50 would take me to 64 seconds. If I was already at f/16, I might consider going to f/22, although I don’t like to because diffraction can start to make the image softer, but if that will take me from 64 seconds to 128 seconds or 2 minutes 8 seconds, then I might go for that, and deal with the diffraction later, using Canon Digital Lens Optimizer, although I rarely find I have to with my current lenses.

Anyway, this may not be a very scientific way of doing these calculations, but it works for me. Remember that a lot of the time I’m all togged up and often even have gloves on, so getting my phone out and using an ND Calculator can take me longer, plus, most of the ND Calculators available don’t give you the ability to stack filters, or they don’t have the ND400 in the list, or they use the optical density instead of the ND number, so I generally find them quite frustrating to use. When we get around to adding the functionality to my iPhone app, it will be a very different story.

Bulb + Remote Switch

Canon Timer Remote Controller TC-80N3

Canon Timer Remote Controller TC-80N3

So, as I said, you will run into problems, especially on Canon cameras, if your exposure goes past 30 seconds, because most of them only go to 30 seconds as their longest camera timed exposure. After that you have to start using the Bulb mode. In Bulb, you have to use a cable or remote release, and time the exposure yourself, or use a Remote Timer, and program the exposure time in, then press the button, and it will start and stop the exposure automatically.

If you have a basic cable release, you need to start the exposure, then time it and release the button to stop the exposure. Most cable releases have a locking mechanism so you don’t actually have to hold the button down the entire time, but I think I’d find it a pain having to sit over a stop watch or count out seconds on my watch while the exposure is made.

Another quick tip here on the use of the Remote Timer–I generally also use a 2 second timer before I start my exposure, so that the camera is totally free of any vibration that I might have caused by touching the camera, by the time the exposure starts. Because of this, I just add two seconds to the exposure time that I set with the Remote Timer. This way the Remote Timer starts the two second timer on the camera initially, and then the real exposure starts two seconds later, and I get the exposure time that I want.

Also, if it’s windy, I tie the remote timer around the tripod head so that it doesn’t dangle and bang on the tripod legs, vibrating my setup. If it’s really windy, I hold the remote timer ensuring that I don’t pull on the cable, which would again wiggle the camera, messing up my shot. I’ve often thought that it would also be a good idea to put some Velcro or magic tape on the back of the timer and another piece on one of my tripod legs, so I could just stick the timer on there while the exposure is running.

Don’t Bother with Mirror Lockup Any More

Note too that I haven’t mentioned Mirror Lockup, basically because I don’t use it any more. Some of the early DSLR cameras with Live View used to jiggle the mirror around before they started the exposure, even when shooting in Live View, so mirror lockup was necessary for a while, but now, if your shooting in Live View the mirror is already up, and doesn’t move when the exposure starts, so mirror lockup isn’t necessary when shooting in Live View, which I use pretty much exclusively when I’m shooting long exposures.

I’m able to do this, even in Bulb Mode, because the Live View on Canon cameras actually still give you a pretty good idea of what you are shooting, with an ND8 and even my ND400 sometimes, depending on how light the scene is before I apply the filters.

ISO Shift Compose Technique

This brings me to another useful technique that I sometimes use when applying a lot of neutral density. Although Live View can give me a pretty good idea of what my image will look like even when I have a certain amount of neutral density applied, once the available light drops or you start to really go heavy on the NDs, even Live View goes dark, and you can’t see to compose your image or focus.

In these situations, you can remove the filters, and check the composition and focus through the lens if there is enough available light, but another trick you can try is to just crank your ISO way up. For example, if you have an ND400 on for just under nine stops of neutral density, and you are shooting at ISO 100, you can crank your ISO up as high as it goes, which will usually give you about eight or nine stops more sensitivity. The image on the LCD gets very grainy when you go this high, but you can at least see to compose your image and usually see well enough to know when your focus peaks, even if it’s not totally sharp.

This is often easier than removing the filters, and is especially useful if the front of your lens rotates when you focus, as you can shift your focus when you screw the filters back on otherwise.

When to Go Heavy?

OK, so earlier we looked at a waterfall photograph, that I shot with a 0.4 second exposure. Waterfalls will smooth over like that from around a quarter of a second, while maintaining a little bit of texture. They really start to smooth over from 1/2 a second or more. I shoot waterfalls with two or three second exposures too, if I want to really smooth the water over. It really depends on the effect you are looking for. I rarely shoot waterfalls in direct sunlight, as they just look terrible with all the contrast. It’s usually either cloudy or I visit them at a time of day that I know they’ll be in the shade due to the position of the sun. This means that you can usually get down to around half a second quite easily with a three stop ND8 filter.

Falling water is moving quite fast though. If you want to smooth over the sea, which moves slower and doesn’t smooth over as easily, or even clouds, that move slower still, you have to use more neutral density. Coincidentally, if we continue using the 1/20 of a second starting exposure that I had before adding the ND8 for the photo we viewed earlier, I would get a 20 second exposure if I used the ND400 instead.

20 seconds will smooth over a relatively rough sea, but won’t give you much cloud movement. Of course, it depends on how quickly the clouds are moving, but generally, if you want cloud movement, you’ll want to get down to at least 30 seconds, and if possible, go down to more than a minute. This photo from the Falklands a few years ago was a 2 minute 30 second exposure, so the clouds have moved significantly. You can also see that the relatively rough sea has smoothed over, but leaving some texture, which I quite like in this shot.

Wrecked Minesweeper

Wrecked Minesweeper

There’s also a seagull in the bottom left of the frame that stayed very still for me during the exposure. There were also some gulls on the boat that moved, leaving a ghostly outline, which I also generally like. Notice too that I more often than not convert my long exposure images to black and white in Silver Efex Pro. Sometimes the color works, but I generally just think long exposures look better in black and white.

Use a Good Sturdy Tripod

One last thing that I want to touch on before we finish, is that once you slow your shutter speed down with neutral density filters, you’re not only going to need a tripod, you’re going need a good sturdy tripod. Don’t think that just because you are going to have to carry it for a while that you can get away with a flimsy little thing. Also, don’t fall into the trap that all Gitzo tripods are good either. Gitzo make a whole range of tripods, and even their smaller carbon fiber tripods don’t cut it for long exposures with heavy gear, especially when the wind gets up. For long exposures you just have to bight the bullet and use a big sturdy tripod. See my episode on what tripods I use and when for more information on this.

So, I hope that was useful for you. As you know, I love long exposures, and try to make time to do them whenever possible. It does take more time, literally, but you really find yourself in a location for a while if you make a couple of exposures, but watch what the clouds are doing, try a few different shutter speeds, try to shoot a few frames, and enjoy the process. Of course, long exposures also work with people on a busy street in the middle of the day, and you maybe get one person that stands still for you. The possibilities are endless once you get into this, so I hope you give it a try if you don’t already do long exposures.

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Show Notes

Why Expose to the Right (ETTR)

What Tripods I use and When I Use Them

Music by UniqueTracks


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A Few Filter Tips (Podcast 36)

A Few Filter Tips (Podcast 36)

Welcome to episode 36 of the Martin Bailey Photography Podcast. I was recently asked by a listener to do a Podcast on filters. In recent years, digital photography has done away with the necessity for some filters, such as daylight filters, warmup filters etc. as most colour correction is now taken care of, and I must say, much more easily, by the White Balance feature on our cameras. There are still certain filters that I still use today, and some that I am now shying away from in favour of Photoshop. Listen on for details, along with some real-world examples, as usual…

In my film SLR days, which started really back in 1991, I used the A system filter system from Cokin. The A system holder and filters are quite small and are only compatible with lenses of a filter diameter up to 62mm. In my film days I didn’t own any lenses with a filter size larger than 58mm, so it was fine for me back then. On moving to a Digital SLR some five years ago and buying my first 77mm lens, I bought into the P series, with a holder and a number of filters. The P system is good up to 82mm lenses, and apart from my 600mm F4 lens, that does not accept screw in filters, I don’t own anything winder than 77mm, so this still does me fine. I’m doubt though that the P system would work well with ultra wide focal lengths, say at 16mm now that I have a full-sized sensor camera. I might find some serious vignetting there now, so if you’re about to buy into a system and use wide angle lenses with 35mm film or sensors, you’d be wise to check this out fully first. The Cokin Web site does state that in 35mm terms, for focal lengths as wide as 28mm the P System is OK. For up to 20mm the Z-Pro system is recommended, and for 14mm the X-Pro System is recommended. There is actually a little contradiction between the information on the and the sites. The site says that for shorter focal lengths 20-24 or 28mm as well as for wide angle zooms (24-50mm / 28-85mm or 35-135mm the P system is strongly recommended. I suggest taking your camera with a few different lenses to the store and asking to try numerous manufacturers filter systems before buying if possible.

In addition to the holder you need an adapter ring for each filter size of the lenses you want to use the system with. You only need to buy one filter for use with all your lenses as long as it’s in the range of the system you choose. Reading from the Cokin Web site, the A system has adapter rings from 36 to 62mm. The P System goes from 48 to 82mm. The next size up is the Z-Pro series, which goes from 49mm to 96mm and then there’s the X-Pro series that ranges from 62 to 112mm, and there are a few other options for each system. You can find a chart on the Cokin web site. I’ll drop the Web site links into the show notes.

The range of filters from Cokin is pretty extensive, and I’m sure there are other manufacturers that make similar products. Although I do use circular screw in filters from other manufacturers that I’ll get to later, I’ve never used a square drop-in filter system from another manufacturer, and as I don’t like to tell you stuff I don’t have first hand experience with, I’m not going to search around the Web and provide second hand information to you on other manufacturers products. If any of you do use another system that you can vouch for, please post comments and links to the manufacturer’s Web site to the forum at I’m sure it will help other listeners to get a more all-round, un-biased view of what is available.

Cokin do filters for different applications, such as those that produce stars and other special effects, and I’ve experimented with some of these too, but the type of filters I continue to use today are Graduated Grey, and Solid Neutral Density filters. Graduated filters are what they say. The grey part of the filter that will cut down the light that gets to the film or sensor without modifying its colour gets gradually weaker around the center of the filter until it becomes totally transparent. The other type, the solid type has uniform grey density across it’s surface, and so will reduce your exposure by a certain number of stops across the entire image, and not just part of it as do the gradual neutral density filters.

Flowing Stream

Flowing Stream

Firstly, let’s look at a very old photo of mine, shot way back in 1993, which is image number 26. You can see here that the water has a flowing feel to it caused by the long exposure. You can also see that apart from the shadow areas of the shot, it’s a relatively bright day, so even stopping the lenses aperture down to say F22 may well not give you a slow enough shutter speed to obtain this flowing effect in the water. Now I have no idea what settings I shot this image at. EXIF data attached to every image is a luxury of the digital age, and I was not very good at documenting my shooting data in my film days. I would image though looking at detail in the trees in the distance that I was shooting at around F16 or F22. Although my Web site states that I used the new P series ND4, or Cokin P153 filter, for this shot, it was actually using my old A Series Neutral Grey ND4 filter. ND stands for Neutral Density, and 4 is the opacity of the filter. An ND4 filter will cost you two stops of exposure. So you will either need to make your open up your aperture by two stops to keep the same exposure, or make your shutter speed slower by two stops. Of course, you could do one stop of each or any other combinations of thirds or half stops and obtain the same exposure too. But the main reason I use an ND filter is to enable me to make a longer exposure.

As I say, I don’t have the shooting data for this particular shot, but I’d estimate that I was using around F16 for half a second. If I had not used the ND4 filter my shutter speed would have been an eighth of a second at the same aperture. That’s basically just halving half a second to one quarter for one stop, then halving that again to one eighth for the second stop that this filter costs me. Now one eighth of a second would probably not be enough to make this water look like flowing silk, and so the only way to get this shot would be to stop down to a very small aperture.

Sometimes stopping down to a very small aperture may not be possible. For example, one shot that I’m planning right now, sparked by the Contrasting Colour assignment, is shooting a set of traffic lights when all three lights are illuminated. I’ve uploaded my attempt, which is number 984, to my example photos album, but I’m now waiting for a rainy evening so that I can get more reflections hopefully adding enough interest to the shot to make it worthy of my main albums.

Three Coloured Traffic Lights

Three Coloured Traffic Lights

Anyway, I went out with my camera a week or so ago, and shot this image. I always have a small notepad with me and in it noted the times of the light changes. I found that the amber or yellow light was illuminated for about 4 seconds, which means I needed to get the last 4 second of the green light, then the first 4 seconds of the red light. So to achieve an even exposure for all three I would need an exposure of 12 or 13 seconds. If I stopped down to F16 without a filter, I was getting a meter reading of around 3.2 seconds at night, which wasn’t long enough. Remember though I had planned this and I had taken a Circular Kenko PRO1 Digital ND8(W) filter to increase the time needed for the exposure. ND8 filters will cost us 3 stops of exposure, so the 3.2 seconds I was getting at F16 would increase to 25 seconds. To halve this to 13 seconds, which is what I needed to get equal exposure of all three traffic lights, I opened up the aperture by one stop to F11 and set the shutter speed to 13 seconds in manual mode. I timed when the lights would change and then tripped the shutter 4 seconds before the green went off and the amber or yellow light was illuminated. Eight seconds into the exposure and the amber light went out and the red light came on for the last four seconds before the shutter closed again. I’d then got a shot with all three lights in the same shot with equal exposure.

This would not have been possible without a neutral density filter. Even stopping down my lenses aperture to F22, it’s smallest aperture, without the ND filter would have only given me an eight second or so exposure, which was still not enough. By the way, I was using ISO 50 for the shot, so lowering the ISO any more was not an option. I needed at least two less stops to make this shot.

Now this is quite a strange plan that I had, but my point is that creative thinking puts us in situations that we cannot get around without physically reducing the amount of light that hits our camera’s sensor or film, and that’s where neutral density filters come in.

Going back to the P System filters from Cokin; something I should note is that the filter holder takes up to three filters. Let’s look at an example, which is image number 62 that I shot some four years ago with my trusty old EOS D30. For this shot I doubled up a Graduated Grey G2 ND8 filter, the Cokin P121 that reduces the light by four stops, and a Gradual Grey G2 ND2 P121L filter. The L in the code P121L stands for light. This filter only reduces the light entering the camera by one stop. There is also a P121M which stands for Medium, and this is rated at ND4 so reducing light by two stops, but I don’t own one of these filters. Anyway, together the P121 ND8 and the P121L ND2 gave me four stops less light, and I needed it because Mount Fuji in the background here was so bright that without balancing the exposure, that is, say if I’d exposed for Mount Fuji and the sky, the please boat and the red Shinto Shrine gate in the foreground very, very dark.

Also note that the good thing about a using gradual filters is that you can turn the holder to any angle. In this particular image I had the filters tilted so that the gradual line from grey to full transparency ran along the diagonal line of the tree from top right to about a third of the way up from the bottom left corner. I haven’t touched this photo in Photoshop other than playing with the tone curves a little, so you can probably appreciate that the graduation is not visible if lined up correctly when shooting. Also note that to see the effect of the filter more easily, it helps to press your camera’s depth-of-field preview button to stop down the aperture.

So moving on to two more images and I’m going to talk about the only other type of filter that I really use nowadays, and that’s the old faithful polarizer, or PL filter. You can get PL filters for the Cokin system, but I always use a circular polarizer that screws straight into my filter thread on the front of my lenses. The draw back of this is that you need to buy a PL filter for each filter size. As the last PL filter I bought was one of the Kenko PRO1 Digital range, this set me back around US$130 for one filter. If you are on a tight budget it might be worth considering buying just the one PL filter for a system like Cokin, or you could buy one PL filter for your largest lens then buy step-down rings for your smaller filters sizes. The problem here is that the PL filter might end up wider than your lens hood, making it impossible to use both together. Note that you can buy a lens hood to fit on the holder in the Cokin system, but I’ve never bought this either.

Anyway, first, let’s look at image number 154. This is a shot of the Kushiro Marsh made in August 2003 during my first trip to Hokkaido, the island at the northern most point of Japan that I visited in February this year and spoke about in depth in episodes 25 to 28 of this Podcast. Now before we talk about this shot, I want you to try to open two windows and in the second look at shot number 185. Also, as I explain about the shots to make my point, note that the first image was taken just 31 seconds after the second.

Kushiro Marsh

Kushiro Marsh


Kushiro Marsh

Kushiro Marsh

If you are viewing the images on my Web site on the Podcast page, just right-click the two images and select to open them in a new browser window. If you are viewing in iTunes, you should be able to just click the little right arrow above the thumbnail them click the next image to open a new viewer window. Now that you can see both images next to each other, you should be able to notice a number of things. The most striking will be that the water in the first image, number 154 is dark, and in the second image, number 185 it is bright. Another difference, though not as noticeable, is that the sky is darker in the image with the darker water. Another big difference is that the greens and the tree stump in the foreground of the image with darker water and bluer sky are much more vivid. The image with lighter water actually has a deeper, perhaps more saturated green area and the tree stump is much darker, so I’m not really sure which I prefer in this respect.

There is actually one difference in the shooting information, and that is that the first shot with darker water was shot at 1/10 of a second, and the second shot with bright water was made at 1/13 of a second. This will possibly help the brighter greens and tree stump to become a little brighter, but the main reason, and this is the reason that I am showing these two images today, is that although for both shots I had a circular polarizer filter attached to the front of my lens, for the first shot I adjusted the polarizer filter for maximum effect. In the second image I turned the filter around 90 degrees so that it was giving the minimum effect. As you turn a PL filter on your lens you can see the difference in the effect, so I want to say that just dropping a PL filter on your lens and shooting will not give you the effect you require, unless you are lucky enough to stop screwing it on at exactly the spot. This is something that also came up in the forum in the last week, but when using a Polarizer remember that the effect is strongest when you point it at something at a 90 degree angle to the sun. The sun was almost directly overhead when I shot these two images, so conditions were not ideal, but under the right conditions you should be able to see a clear sky turn do a very dark blue while rotating the filter. In fact, you can easily overdue the PL effect on days with a very clear sky, as the sky can be rendered very deep blue indeed. In these conditions it’s wise to not go for the strongest effect possible.

There has also been a discussion in the forum recently about this, started by Landon, one of the major contributors on the site. Landon mentioned when adjusting the effect of the filter, make sure you turn the polarizer in the same direction that it screws on to your lens. This is basically to stop it from becoming loose and possibly falling off while you rotate it. Landon also suggests using gaffer tape to tape the polarizer to the front of the lens, also to stop it rotating and falling off, especially in high vibration situations like when sitting on a helicopter. Landon assures us that gaffer tape can be removed very easily after shooting without leaving any stick mess on your lens. Great tips Landon! Thanks very much as usual. The ensuing discussion is quite interesting too, so I’ll drop a link to this discussion into the show notes.

So, I mentioned in the introduction that there are some filters that I’m now shying away from in favour of Photoshop. Basically, I’m finding more and more that I don’t carry my Cokin gradual grey filters around with me. When I think I might need them I still carry them, but now find that I’m shooting with them to prove a point to myself. I shoot a scene in the traditional way using the grad filters, and then I shoot two shots without the filters, one exposing for bright areas, then one exposing for the shadows, and then merge them in Photoshop to emulate the results of using gradual grey filters. More and more I find that I’m using the Photoshop merge rather than the gradual grey filters.

Oshinkoshin Falls

Oshinkoshin Falls

Take a look at the last image for today, number 935. I briefly mentioned this in episode 28 too, but this shot of the Oshin Koshin Falls in Hokkaido is actually two shots merged to emulate a gradual grey filter.


The challenge here is that the bottom of the falls was in shadow heavy as the sun had not yet rose high enough in the sky to light the whole area. This does of course have the benefit of a much more saturation blue sky, and before you say it, that dark blue sky is natural, caused by the contrast between the sky and the bright snow and the angle of the sun, and not overdone PL. I wasn’t using a PL here because I didn’t want to reduce the sparkle in the water. Remember that if I use a PL I will make water transparent, though probably only to a certain extent for a waterfall.

Anyway, what I did here was make a number of different exposures, including a few with a gradual neutral density filter, and I aligned it across the top of the frame to reduce the contrast between the top of the falls and the sky, and the lower, heavily shadowed area of the falls. These shots came out OK, but again I decided to go with a Photoshop shop merge.

Both shots used for the merge were at ISO 100 at F20 shot with the 16-35mm F2.8 lens. The top of this image had a shutter speed of 1/13 of a second. The bottom image was shot at 1/6 of a second. I copied the image with a blown out top, but brighter shadow area that I used for the bottom of the new image to the clipboard in Photoshop and then pasted it over the second image and converted it to a mask. I then painted over the bottom part or the shadow area until I had revealed all of the brighter shadow areas that I wanted yet still had created an image that still had a visible shadow across the bottom. There was only one stop more brightness in the bottom shadowed area compared to a straight shot, as I didn’t want to over do it. I do have a shot with the bottom much brighter, but decided to go with these two as I didn’t want to deny the fact that there was ever a shadow there. Also the texture of the light would have been considerably different in the original shadow area.

I’m not going to go into lots of details about exactly what to select in Photoshop to use this technique, because I use a Japanese version of Photoshop, and it takes too a while to figure out what the precise translations of all the menu item and button names are. If you need more help with masks, take a listen to episode 85 of Chris Marquardt’s Digital Photography Tips from the Top Floor. In this episode Chris gives some great examples of how to use Layer Masks.

There are of course also protector filters, or UV filters that are colourless, and can be used on your lens pretty much all the time. There’s not real artistic and few technical implications with regards to these filters. The debate goes on as to whether or not to buy the best protector filter you can, especially if you are going to put it on the front of some expensive glass. I personally do try to pick up the best quality filters I can and pretty much consistently now use the Kenko PRO1 Digital Series, as they have special coating to reduce ghosting etc. but some say there’s no real difference. Of course, going for the cheapest you can get has it’s advantages as well, no only financially, but as these are sometimes a throw away items, so it really does come down to personal taste. One last thing, there are problems with vignetting when fitting two filters to some wide angle lenses, especially when using a 35mm film or full-size sensor camera, so you may have to remove the protector or UV filter when you want to use a polarizer or other filter. I’ll post a link to a topic on this in the forum in to the show notes too.

So, I hope that has been of some help. I have only touched on my own uses of filters, and not tried to be comprehensive and cover all possibilities. To recap, I’ve totally stopped using my old warm up filters etc. now depending on White Balance. Although I was reluctant initially to do very much in Photoshop, including merging two images, I’m slowly coming around to this idea and employing this technique more and more in my work. I really now only use two types of physical filter, and that the solid neutral density and polarizer filters.

Once again, today’s episode is going to be a few days late. I’m still pretty busy, and finding it difficult to prepare for each week’s episode in time to swing back to my old schedule of releasing on Monday or Tuesday. I am going to try my best to get next Monday’s episode out on time though, as it will be the next episode in which I announce the winner of the Contrasting Colours Photography assignment. Thanks very much to all of you that have voted for one of the images in the assignment album at If you haven’t already voted, remember voting is still open until the end of Sunday the 14th or May. The vote button is visible above each image when viewed at full size having clicked the thumbnail. You can only vote for one image per assignment, but you can change your vote as many times as you want until the voting closes on the 14th.

I’m also happy to say that it looks like I’m not going to have to exercise the right I gave myself to override the vote. Looking at the votes so far, it seems that you guys have exactly the right idea about what I was hoping for with this assignment.

One last thing that I’d like to mention too is that I am now considering accumulating votes from this and future assignment for a yearly Grand Prize. Maybe I can get some sponsor to give a prize or two, and if not, I might spring for something that people want more than one of my original prints for a prize. This way people that aren’t lucky enough to take first prize, but that consistently do great work and gain a steady flow of votes throughout the year, will also have a chance of winning the grand prize. It will also be an incentive for members to participate in the assignment every month. The member’s that have participated to the first assignment are pretty much all saying that they thoroughly enjoyed shooting for the assignment and that it made them think in totally different ways. The traffic lights shot that I made and discussed earlier was planned purely through thinking about colours, and starting to think it would be cool to get all three traffic lights in the same shot. Remember, that one of my personal goals and one of the rules of the assignment is that no cloning in of objects in Photoshop is allowed, so I couldn’t simply shot the same traffic lights three times and clone all the lights into one image.

Anyway, before I go off on a tangent again, please come along and vote by May 14th if you haven’t already. And also listen out for next weeks episode, to hear the winner of the Contrasting Colours assignment and also I’ll give details of the next assignment so that you can start shooting for that too.

One more thing before we finish. On request from a listener, I’ve created a Podcast “Light” page, for people that use small form factor computers such as Pocket PCs. The page will load a shorter toolbar at the top and less sections before the Podcast archive table. Also, only the latest 4 episodes will be displayed in the index by default, not 12 as in the main page. Also, if you jump to the full size images from this page the filmstrip will not be displayed below the full size image, so again, less images to download. If you use a small form factor computer to view the page, please try it out. There’s a link near the top of the current Podcast page, and also I’ll put a link in today’s show notes.

Finally, thank very much to all of those that have completed the Listeners Survery, and I’d like to mention that we’re still short of around 80 survey completions. I can’t start advertising for a sponsor until we make the numbers, so please click on the Listeners Survery icon on the top page of, or the larger image of the guy with the headphones on on the Podcasts page. I’ll also put a link in the show notes to a forum post in which I give more details. It only takes five minutes and will really help me out if you could spare time to complete this survey.

So have a great rest of the week, and a great weekend. Bye bye.

Show Notes
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