How to Photograph In Low Light

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Light levels may be too low for your meter to cope with and if you try to take an exposure reading,  by applying the halving and doubling principle (using shutter and aperture together), there are a number of things that you can do.

Basically, the meter will indicate shutter and aperture settings for correct exposures. With the halving and doubling principle, each shutter speed and f number either doubles or halves the light reaching the film - so you can alter one as long as you compensate exposure with the other.

Each of the following exposure pairs will produce the same exposure:

f16 1/30; f11 1/60; f8 1/125; f5.6 1/250; f4 1/500

You can pick f16 1/30 for maximum depth of field, or f4 1/500 to stop fast motion or to have shallow depth of field to blur cluttered backgrounds.

Applying this principle when shooting in a low light situation, if you are using slow film and you want to use a small lens aperture such as f16 to maximise depth of field and your meter's sensitivity has been reduced, simply take a reading with your lens set to it's maximum aperture then back track to find the shutter speed required for the aperture you want to use.

eg. if your meter suggests 4 secs at f2.8, to recalculate your exposures, the following combinations could be used:

• 4 secs at f2.8
• 8 secs at f4
• 16 secs at f5.6
• 32 secs at f8
• 64 secs at f11
• 128 secs at f16

If you still can't get a reading with your lens set to it's maximum aperture, set the camera's film speed dial to ISO 1600 or ISO 3200 then take a meter reading. To find the exposure time required, follow the procedure outlined above then do the same for the film speed; doubling the exposure each time you halve the film speed.  

If your meter suggests an exposure of 2 seconds at f4 with ISO 1600 film, but you are using ISO 100 film and you need to work at f11, the exposure of 2 seconds at f4 is the equivalent of 16 seconds at f11.

The exposure combinations would be as follows:

• 16 secs at f11 for IS0 1600 film
• 32 secs at f11 for IS0 800 film
• 64 secs at f11 for IS0 400 film
• 128 secs at f11 for IS0 200 film
• 256 secs at f11 for IS0 100 film
  

Don't forget to then allow for RECIPROCITY. When using very long exposures as indicated above, the film speed no longer applies and the exposure suggested by your meter must be increased to prevent error. This is known as reciprocity failure. Each type of film is affected differently, so there's no magic formula to overcoming it.

As a rough guide, if your meter suggests 1 sec, increase it by 1/2 a stop, if 10 secs is suggested increase it by 1 stop and if 100 secs is suggested increase it by 2+ stops.

Reciprocity law failure can also cause colour shifts with some films. This can be prevented by using filters, but shooting unfiltered can actually enhance your photographs.

It's a good idea to keep detailed notes on what you are doing, so if something dosn't work out, you have the details and you can keep refining your technique until you determine what combination works best for the camera and film stock that you use and the quality of the light in the environment that you are shooting in and allowing for the reciprocity characteristics for the film stock that's being used.