Toggling Your Box Camera's ISO

Note: May not be a box camera.

 

I get it. 1 aperture and 1 shutter speed. Kind of limiting, I know. While it's definitely worthwhile getting familiar with the various EVs your box camera can shoot in without adjustments, it is undeniable that having a workaround for when the light doesn't suit your settings is a big plus. It makes the camera more versatile, increases your creative options, and removes a lot of the frustration:

 "If only I could take that shot, but it's just too bright!"

Well the good news is there are some tools and techniques that can help, so never again do you need to curse yourself for bringing your beloved box camera instead of your SLR.

Too Much Light

Box cameras have slow shutter speeds. Laughably slow by modern standards. Most people these days don't entertain shooting handheld at 1/30th of a second, or at least not without lenses with image stabilisation or cameras with vibration reduction. Lacking these features on our box cameras we have to resort to things like exhaling after the shot has been taken, or placing the camera on a flat surface. This works for the most part, but the slow shutter speed can cause headaches when there is a lot of light. Simply, they may cause the image to be overexposed. 

If my camera is loaded with ISO 200 film and I am shooting in very bright conditions, my pictures will be overexposed by maybe one or two stops. We can solve this "in camera" (as opposed to when we process the film), with the addition of a neutral density filter. 

If you're not familiar with neutral density filters, put simply they reduce the amount of light entering the lens, without a colour bias (at least the good ones). They come in various strengths, so depending on the one you use could reduce the light by 1 to 10 stops (and further if you have the bank balance of an oil tycoon). These have many creative purposes, such as allowing the deliberate use of slow shutter speeds to capture motion blur, (think dreamy waterfall shots), or allowing a wide open aperture to produce more shallow depth of field.

For our immediate purposes, we just want our shot to expose correctly. So if our light meter determines that we risk an image being 1 stop over exposed, we can place an ND2 filter in front of the lens and then take the shot as normal. If we risk 2 stops of over exposure, we do the same with an ND4 filter. If 3 stops, we use an ND8 filter. Simple. 

Too Little Light

I have a box camera loaded with Ilford Pan F 50 (or worse, Rollei RPX 25) and when I get to my location it has turned overcast, typical. This, and other low speed films like lots of light. So finding myself in lighting conditions such as EV12 or EV11, suddenly my famously slow shutter isn't slow enough thanks to the fixed f/11 aperture. Now, this workaround won't be appropriate for all subject matter, especially if it's moving, but the simple answer to this is to secure the camera so it is absolutely still and then take the shot more than once. Each click of the shutter lets in more light.

Take the photo twice to add one stop of light. Take it four times to add 2 stops of light. Eight times to add 3 stops of light etc.

This will work with mountains, but your dog won't sit there perfectly still while you click the shutter release four times, so choose your subjects carefully. 

Ful-Vue settings:

ND8 @ 1/30 = 3 stops less

ND4 @ 1/30 = 2 stops less

ND2 @ 1/30 = 1 stop less

1 shot = 1/30 of a second

2 shots = 1/15 of a second (1 stop extra)

4 shots =1/8 of a second (2 stops extra)

8 shots - 1/4 of a second (3 stops extra)

A handy way to get the ND range is a small cheap variable ND filter, which will be plenty reliable at these low settings.

There we go, we can now get +/- 3 stops on a box camera with only 1 extra filter in the gear bag. You can take it further, but pressing the shutter 16 times will get tiresome and the good high stop ND filters are pricey.

Development

Both of the approaches outlined so far to either increase or reduce the amount of light entering the lens are approaches that can be done on location, in the moment, in camera. However, there is another approach that can also help keep you snapping away without worry that the pictures will be under- or overexposed. This approach takes place during development, back home, once all the pictures are taken. Or, if you don't develop your own film, a lab will do this for you. Just make sure they know your requirements.

The processes are called push, and pull developing. Basically, you compensate for the under- or overexposed images by toggling their development times. If your images were overexposed, you want to pull the film. If your images were underexposed, you want to push the film. 

It is highly important to note that this only works for the whole roll, not individual shots.

Pulling Film

I've discussed pulling film here before, but to pull film you need to reduce the development time by about 10% for every stop pulled. My husband has a neat calculator for this on his own website, which can help you determine the correct development times. If you are loaded with ISO 100 film, and decide a reduction of 1 stop to ISO 50 would better suit the lighting conditions, then you pull by 1 stop. If you are loaded with ISO 200 film, then you'd need to pull by 2 stops etc. 

What this means on the actual shoot is that you just take your pictures as normal (no neutral density filters) resulting in a roll of overexposed images. The shorter development time then compensates for this and should result in developed images that look correct and not overexposed. 

Pushing Film

We do this for the opposite scenario. For example, you are loaded with ISO 50 film and an increase of 1 stop to ISO 100 would better suit the lighting conditions. In this instance you push 1 stop. If you need ISO 200, you push 2 stops and so on. Predictably, when pushing, you want to increase the development times. Use Nicky's clever calculator to work out the necessary timings for your own film development.

Again, during the shoot, just take the pictures as normal. No taking multiple exposures. You will end up with a roll of underexposed images and the push processing should correct this. I've got a few posts on this blog where I experiment with this method using Catlabs X Film 80, which produced some good results. By pulling and pushing I was able to treat it anywhere from ISO 50 to 640 without any problems. 

Pros of this Method

1) Nice and flexible. You can basically load up your film, make a mental note of the EV at your shooting location, then work out which ISO would have been best suited to those lighting conditions and push/pull accordingly.

2) Less limiting. You can still shoot your camera even if the box speed of your film isn't ideal and still get good results.

Cons of this Method

1) All or nothing. You can't push/pull just a few frames. It affects the whole roll.

2) Not all films are created equal. You can push and pull some no bother. Others within reason, and others should be left well alone. You'll have a lot more wiggle room with black and white film than colour. Make sure you do your research first.

3) Just like with digital photos, if you toggle the ISO this way you increase the noise. The more stops you push, the more grainy the images. The more stops you pull the more contrast you lose.

Things to Consider

1) Is the roll already part shot with correctly exposed images? Then you probably don't want to shoot the rest of the roll with a view to push/pull processing. You'll ruin the first images.

2) Are the lighting conditions really changeable? Then you probably want to correct the exposures in camera with filters or multiple exposures, or you will get inconsistent results.

3) Do you know that the lighting will stay consistently too high or too low? Then correcting the exposures in development is the best option if the camera is loaded, or the film cupboard was sparse.

Some Results

Catlabs X Film 80 pushed to 640

Catlabs X Film 80 pulled to 50

   

 

   

Using Filters

There are so many filters out there this could be an incredibly long post.

However, some are considered more "essential" than others. For most photographers, instances where the polarising filter will come in useful will far outweigh the number of times they wished they had their trusty Cokin "Mirage" special effect filter handy.

Now, box cameras can take filters too. Usually the push-on type, although the Fulvueflex has a 37mm filter thread for screw-on types. Realistically, the filters that would be most useful for helping you achieve your creative vision would be the following:

Linear Polariser, neutral density, close-up, yellow, orange, red, and green.

Ensign Ful-Vue model 1 with its orange filter. This is a 25mm filter, but it's a little roomy, so a 24mm would be better.

Why a linear polariser? Because they are cheaper than circular polarisers. A circular polariser is made from a linear polariser with a randomiser stuck to the back of it which increases the cost. In any case, circular polarisers are only essential for cameras with through-the-lens metering or autofocus as the polarised light can cause them to give false readings, and our box cameras do neither. Polarisers filter out scattered light which can help produce darker, more dramatic skies; can reduce the shine on surfaces; and can remove the reflections from water. The only caveat is that the viewing lens and taking lens on box cameras are different so you'll have to hold the filter to your eye, rotate it until you achieve the desired effect on your subject, then attach it to the taking lens in that precise position.

The chances of finding tiny push-on neutral density filters are pretty slim, however they can still be used on box cameras. Firstly, they can be simply held in front of the lens. Secondly, if the lens mount has a filter thread, either buy the screw on filter to fit, or buy a step up adapter and use a larger filter. If it is a variable ND filter you'll have the same problem where you have to adjust it to just the right setting and then attach it to the taking lens in that precise position. However, it is well worth the hassle as the limitations of the box camera can put certain subjects in bright light conditions out of bounds, unless of course you have an ND filter. These filters can also give some excellent motion blur on moving water, to the point where waves on the sea look smooth and calm. This would be a nice creative use of the box camera's Time setting.

Depending on the box camera, it may already have a close-up feature. For those that don't a close up lens, or portrait attachment as they were commonly known can help. Many makers specify a particular attachment. The one intended for the Fulvueflex, for example, allowed the camera to focus as close as 3 feet. As a guide, since most box camera lenses are set to infinite focus, a +1 close-up lens will allow the camera to focus at 1 metre (40 inches), and a +2 close-up lens will focus at half a metre (20 inches).

When shooting in black and white, colour filters are useful tools to render certain grey shades lighter or darker. The yellow filter is probably the most commonly used to emphasise the contrast of clouds against a blue sky, but it also helps reduce blemishes in skin tones. The orange and red filters provide more dramatic results, with blue skies rendered very dark indeed with the red filter. Green filters are handy when shooting foliage as they lighten greens and therefore help retain detail in the darker leaves.

These filters will see the cameras through most situations, and will broaden the lighting conditions in which the cameras can shoot. The most useful when shooting box cameras is undoubtedly the neutral density filter. The increased scope for shooting when conditions are too bright for your film is very useful. The next most useful is probably the yellow filter (assuming you shoot black and white). Any additional filters in your toolkit will be all down to creative preferences. If you want multi-images for that abstract art look, or crazy rainbow effects around all light sources then by all means check out those creative filters.

Who wouldn't want this?

Additional filters that could be worth consideration are the R72 filter for infrared photography; the blue filter (when shooting black and white) for moody shots of fog; and a cross-screen filter for nice star patterns on street lamps etc.  

Filter Factors

In most cases you can't just apply filter and shoot. Colour filters, polarisers, and neutral density filters all darken the scene through the taking lens, so you need to adjust your exposure times to prevent your image from being underexposed. Now, adjusting shutter speed is easier said than done. At a standard speed of 1/30, adjusting by one stop would mean a speed of 1/15. 2 stops would be 1/8, and 3 stops would be 1/4. I don't know about you but my judgement of speed is not that precise. But we can't adjust the aperture either? No, but you can take the shot twice, or even 3 times.  Obviously this has implications for your subject matter. If it is stationary it's no big deal, but if it includes moving elements there may be some ghosts in your final image.

Many box cameras came with pale yellow filters built in, and these could be used at the standard shutter speed without issues. A deeper yellow filter may have a filter factor of 2. An orange filter typically has a filter factor of 4, and a red filter typically has a filter factor of 4-5. These figures are not exact as they vary from each maker, but as a very rough guideline: when using a yellow filter take the shot as normal; with an orange filter take the shot twice; with a red filter take the shot 2-3 times. Depending on the linear polariser you may need to take the shot twice. The strength of your neutral density filter will determine the number of shots needed. If the EV value of your subject is one stop too high, applying an ND2 filter will mean you only need to take the shot once. If you have an ND4 filter, you'll need to take the shot twice.

If you are shooting with an R72 filter, this has a filter factor of 16, which means 4 stops of compensation. For this I'd probably put the camera in Time setting and count half a second by saying "one and" and releasing on the "and". Or, take the picture four times and see which approach turns out best. The resulting images will show you which setting gives the best results so make sure you take notes.

Needless to say, when accounting for filter factor on a box camera, the camera either needs to be firmly secured on a tripod, or sitting firmly on an even surface.

Yes using filters would be a hell of a lot easier on a more versatile SLR that lets you look through the taking lens and then works out the filter factor itself with its metering system. The point of this post is just to show filters are still accessible to box cameras. They just need a different approach.

Ways to work out exposure settings with filters:


Divide the film ISO by the filter factor. The number gives you the modified ISO number by which to meter the scene. Eg: ISO 50 divided by a filter factor of 2 gives a new ISO of 25. Set your light meter to read for ISO 25 and apply its suggested settings. 


Another useful method that I found online in a forum, though it was a long time ago and I don't remember the source, is to count on your fingers using the following sequence: 2, 4, 8, 16, 32. If your filter has a factor of 4, that equals two fingers, which represents two stops of exposure compensation. 8 would be three stops etc.