This may seem redundant.. but if the filter is a -2 or -3 stop change to the exposure for middle grey, just how much correction can be made, if you are shooting above f/5.6?
This may seem redundant.. but if the filter is a -2 or -3 stop change to the exposure for middle grey, just how much correction can be made, if you are shooting above f/5.6?
I'm not sure i understand the question, but when you say 'shooting above f/5.6' are you concerned about reciprocity failure ?
If you mean you are shooting near wide open, then make your exposure adjustment with the shutter speed.
I have no idea what the question is actually asking.
General info here:
Do all your exposure calculations and find the aperture/shutter-speed combination you want to use before worrying about filter factors.
Then, decide which filter to use and find the right factor in stops for it.
Change either the shutter speed or the aperture (or a combination of both) to give the additional exposure required for the filter. (We do know that changing one shutter-speed number is the same as changing one f-stop on the aperture, right?)
Usually, when working with large-format cameras, a small aperture is required and finding the optimum aperture is a priority. If this is the case, make your adjustment with the shutter speed (one shutter-speed number change is one stop). Remember, shutter speeds are fractions of a second, so seemingly higher numbers (e.g., 60 vs 30) are faster speeds and less exposure. When applying filter factors, you want slower shutter speeds, so make sure to go the right direction
For filters with factors in fractions of a stop, e.g., 1 2/3 stop, then get as close as you can with the shutter speed then adjust the 1/3-stop remainder with the aperture. In the example given, you'd open the shutter two stops (1/3-stop too much), then close the aperture a third of a stop to get back to the exact spot you want.
Sometimes, when subject movement requires a faster shutter speed and the desired depth of field requires a small aperture, and we want to use a filter, we find ourselves in a tough spot: if we use the filter, we get a too-slow shutter speed or a too-large aperture or both. In this case, it's time to rethink the choices. When confronted with this, I often make an exposure with no filter and one with at the best compromise I can arrange.
Hope this helps,
Doremus
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