how to calculate low light gear requirement

Started Dec 26, 2013 | Discussions thread
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calterg Regular Member • Posts: 499
how to calculate low light gear requirement

For shooting in low light without using flash and low noise results.

Sunny 16 rule is:

F16 iso100 ss1/100 will give you perfect exposure in bright sunshine.

Indoor light depending on the type of lights used is minimum 7 stops from this rule, typically you will encounter 9 stops if you like warm soft lighting in your home.

So, to avoid shake and be able to freeze general subject movement, set the ss at 1/100.

You will then be able to see exactly what kind of lenses and noise performance you need for low light indoor photography without flash.

Typical light level in a home with warm lights is 9 stops from sunny 16 rule.

F4 is four stops below f16, so if you can only afford a f4 lens, you will need to get the other 5 stops from increased iso, meaning you will need to set your iso at 3200 which is 5 stops above iso100.

I think most cameras suck at iso3200, if you are noise sensitive as most geeks are, you would not go above iso800, but at this iso you need to gain back another 2 stops, which would then need to come from better lenses.

To get the 2 stops from f4, you need a f2.0 lens which you cant get at some focal lengths, especially zooms, even if you could engineer one , I couldnt afford it.

So calculate your own compromise from this. Eg, to stick with f4 lenses you will need to shoot in better indoor lighting thats only 7 stops below sunny 16, typically found in homes with florescent lighting and many of them switched on.

Point is, you need to know how many stops below sunny 16 rule your indoor lighting is, from there you will know exactly what equipment you need to get a good exposure without camera shake and missed shots.

Eg of a cheap low light setup, a 35mm f2.0 prime lens will enable you to shoot 9 stop indoor light conditions typically found in warm incandescent light homes.

F2.0 gives you 6 stops from f16, the other three stops you get by setting setting iso to 800 to get the total 9 stops for a proper exposure and acceptable noise performance.

Want to shoot your cousin kissing your sister under the staircase? Too bad, thats 12 to 13 stops below sunny 16, I couldnt afford that kind of gear.

Some could say you can gain 2 to 3 stops from image stabilisers, im saying, IS is pretty unreliable for party shots.

People always say they want the best low light performance, now you know how to calculate that low light performance and whether you are willing to pay for it.

What else? Group photos of say 5 persons standing two rows front to back, to get the depth of field you will need to shoot at f5.6 minimum depending how close you are focussing, how much is that 3 stops going to cost? You get the idea.

Cheap solution? Learn to like flash pictures.

What other places are typically 9 to 12 stops below sunny 16 rule?

Romantic restaurants, clubs and pubs.

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