When you shoot film on a fully manual film camera, it is very important to know which settings to set. Fret not, exposure triangle is very simple. When I first started photography in 2011 with a dSLR, I didn’t bother learning because they looked very complicated. Plus, dSLR has ‘auto’ mode. So, why bother? Wrong mindset I know.

Now that I am serious about photography, and I want to have full control of my camera instead of letting it decides for me. Furthermore, I am shooting film with manual Nikon FM2! So, I started reading up about the exposure triangle and find it really simple! Trust me, you will feel more satisfied to have control over everything to achieve a shot!

In this post, I am going to share what I learnt about this exposure triangle and you should take it as a pinch of salt.

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ISO/ASA

In film photography, sometimes you see ‘ASA (American Standards Association)’ instead of ‘ISO’. These two terms mean the same thing and they are used interchangeably. ISO is an indication of the film speed and how sensitive your film is to light. The ISO value can be found on all the film name, box and cassette you got. For example, a Kodak Portra 400 film has an ISO of 400, a Kodak Ektar 100 has an ISO of 100.

Film with ISO 200 and below is a slow film and require a lot of light for exposure. People normally use ISO 100-200 in sunny condition. If you follow the sunny 16 rule with an ISO 100, your shutter speed should be 1/125, aperture f/16 at noon. With a ISO 400 at noon, setting would be 1/400, f/16. You see, at ISO 100, your shutter speed is slower compared to 1/500.

A higher ISO film speed will give more grains on your image. However, the grains on film is somewhat aesthetic compared to digital ‘noise’. In digital, ‘noise’ is really an unwanted stuff because noisy digital image just look crap.

For digital, ISO indicates how sensitive your sensor is to light. The ‘noise’ created by the high ISO (eg. ISO 3200) in digital camera is due to the heat created by the machine. Hence ‘legends’ has it that the grain might be lesser if you shoot in a cold country.

Aperture

After telling your camera the film speed, next is to deal with aperture. Aperture is a measurement of how wide your lens open, or the diameter of your lens opening. It determines how much light is allow to hit your film. In another word, aperture is the light intensity.

I always wonder why aperture is marked by ‘f’ and a lot of guides only state ‘aperture is a fraction of focal length’. I don’t understand it at all! After reading up and thinking a lot, I figured out:

Aperture means diameter right? So, an f/22 is focal length divide by 22. Let’s say if my focal length is 50mm, my lens opening diameter (aperture) is 50mm/22= 2.27mm. If you use a ruler to measure the diameter of the lens opening, it should be approx. 0.0227cm.  For f/11, is 50mm/11=4.5mm. So, f/11 is wider twice of f/22.

Anyway, there’s so much complicated theory about aperture. If you don’t understand, doesn’t matter. No one cares. If you would like to find out more, read ‘The Camera by Ansel Adams‘. So, just remember, one-stop up the aperture, eg f/5.6 to f/4 allows twice as much light to hit the film. From f/8 to f/4 doubles the diameter opening but allows 4X more light to enter. A confusing concept to digest is: the higher the aperture number, the smaller the aperture diameter, the lesser light intensity, and vice versa.

Depth of Field

Aperture also determines ‘Depth of Field’. When I first started, I don’t understand this term at all and what shallow and deep depth of field meant. In my term, depth of field is how blurry the background is. Or how deep the focus is. A shallow depth of field means the the focus is very shallow in the picture, anything that is too far (deep) in the picture gets blurry. A nice term for very smooth creamy blur is ‘bokeh’. A low aperture number (eg f/1.8 and f/2.8) gives a very shallow depth of field and very creamy bokeh. Example in the photo below, shot at f2.8, notice the subject is sharp but the background is blurry.

On the other hand, a wide/deep depth of field means the focus is very deep in to the picture where anything behind your subject of focus is still sharp and focused. Wide  depth of field is achievable by setting higher aperture number, for example, street photographers like to shoot with aperture f/8 or f/16 because these apertures can give deeper depth of field and allow enough light to enter. A deeper depth of field is desirable such that viewers get a sense of the background story of a picture. Furthermore, deeper depth of field (f/8-f/16) allows street photographers to do zone focusing without the risk of blurry subject compared to shooting at f/2.8.

Another factor that determines depth of field is the focal length. If you want deeper depth of field, use shorter focal length. For eg, use 28mm instead of 85mm.

Shutter Speed

Shutter speed is the duration you allow light to pass through the lens whereas aperture is the measurement of amount of light. Mechanical shutter was only introduced in the 19th century and before that, photographers had to personally and manually remove and replace lens caps. As such, all their exposure time was always more than 1 seconds, so they compensate by increasing aperture (higher number). That is to say, if you decrease the intensity of light to enter, you need to expand the time the light enters (slow shutter speed). Likewise, if you increase the intensity, you need to shorten the time (fast shutter speed).

You might notice some film camera also have this ‘B’ on the shutter speed dial. I was so silly at the beginning to think that I only needed to press once to open the shutter, and click again when my iPhone timer rang to close the shutter. Wrong. For Bulb (B) mode, you need a shutter release cable or else you have to press the shutter with your hand for the amount of time you want to expose your film (eg. 30 seconds). The problem with using hand is that you risk camera shake introduced by unstable hand.

Anyway, shutter can control precise exposure time from the slowest 1 second to the fastest 1/4000th or 1/8000th second. If you want to freeze your subject, it’s recommended to use shutter speed of at least 1/125. Or if you are using long lens and hand-held, fast shutter speed is also needed to prevent image blur.

Exposure triangle

In conclusion, the reason it is named ‘exposure triangle’ is the direct relationship between the three:

1. If you are shooting in low light condition, increase your ISO (>800). Then you can have a faster shutter speed to prevent image blurriness. Since the shutter speed is fast, you need to compensate by opening your aperture (low f-number) to get the exposure.
2. If you are shooting in the day, lower your ISO (100-400). You can also use shutter speed faster than 1/125 to prevent image blurriness. Then, since it is so sunny, you can increase your aperture to f/8-16, or even f/22.
3. If you want cotton effect: shutter speed 1/4 is the slowest speed for hand-held without blurriness. Since it is so slow, we need to reduce the intensity by decreasing the aperture to f/22 and ISO 200.
4. If you want to freeze a subject, e.g jump shot or water splash, you need a super fast shutter speed of 1/1600, then you also want deeper depth of field but still allow ample light, so f/5.6 and ISO 3200.
5. Lastly, if you want to do those light trail shot at night, the rough setting is f/18, shutter speed 30 seconds and ISO 200.

I hope I have simplified the theory of exposure triangle. Otherwise you can always email me and we can discuss about it. Have fun experimenting!