morris
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vbnut wrote:
I sounds like Frank (based on his response to you) is already using manual exposure, but (despite photographing wildlife quite a bit longer him as well as some sports) I haven't gotten to that level (I can't imagine doing it for BIF), so I would be grateful if you could explain more.
Hi Frank and VBnut,
When you set your camera for auto ISO, you are still using auto exposure as the camera varies the ISO rather than the shutter speed or aperture. The effect on exposure is the same, the camera uses it's sensor(s) to measure the light striking them and adjust accordingly. You are probably set up for matrix metering and what this means is the camera looks at the center of the frame and also the edges of the frame and estimates settings that will produce a neutral gray exposure for the entire frame. This works unless:
- the entire frame is very bright
- the entire frame is very dark
- your subject is very bright for example white
- your subject is very dark for example black
The ISO or ASA standard is based on a principle called "Sunny 16" and it states a proper exposure will result when the camera's shutter speed is 1/ISO at f16 on a sunny day. Go out and try it, you will like the results. Any sunny 16 equivalent will work, for example 1/100, ISO 100 at f16 is sunny 16 at ISO 100. 1/200, ISO 100, f11 is a sunny 16 equivalent. Other than DOF, the two photo will look the same as the exposure is the same.
Suppose it's cloudy, your exposure needs to be -set for 1/2 the amount of light. If you don't like log math and have not memorized the f-stop table (which is log based) then adjust the ISO or shutter speed by doubling the ISO or halving the shutter speed.
Shade, also 1/2 sinny 16 equivalent
Deep shade 1/4 sinny 16 equivalent
very dark clouds 1/4 sinny 16 equivalent
What matters is the amount of light on your subject.
Now I think about this situation: It's bright sun out and your subject is between you and the sun (shooting into the sun). Do you want the background exposure correctly or the subject?
If you want the background exposed correctly use a sunny 16 equivalent exposure. Note that your subject will be dark.
If you want you subject exposed correctly use 1/2 the sunny 16 exposure. Note that the background will be very bright.
It's all based on this. When I'm shooting flight I set my camera for the sunny 16 equivalent that I like to use to have a fast enough shutter speed. Nomatter what happens to the background as long as the bird is in the sun the exposure of the bird is perfect. If the bird flies into the shade or a cloud blocks the sun I role the shutter selector to halve the divisor (the bottom number in the exposure fraction) thus doubling the amount of light allowed into the camera.
For a white subject one needs less exposure so double the divisor which is 3 clicks if your camera is set for the usual default of 1/3 EV per click. I actually prefer 2 clicks which produces brighter whites at New York City's latitude. Further south you will need the full 3 clicks. I like using the clicks rather than looking at the shutter speed int he view finder as I can keep my eye on the subject and compostion.
I hope this helps,
Morris
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, yeah I'm still working on that too!
I'm glad you have found a passionate hobby to pursue. I imagine this is a great mental washing of the mind for you, nothing easy about your previous job in today's environment.
The whites can be tricky, sometimes reducing contrast in PP can yield more relaxed whites. When the sun is full on and there is no shadows it is difficult to see detail in whites. 