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All about box camera photography with a special emphasis on Ensign Ful-Vue cameras.

Sunday 21 March 2021

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
   

 

   









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