Originally posted by photoptimist NOTE: a properly exposed ISO 100 image will have the highest IQ (unless there's clipping) but that might require too slow a shutter speed or too wide an aperture. Thus "ISO invariant" does not mean "use base ISO and whatever shutter and aperture you like." The more underexposed the image at base ISO, the lower the IQ. Thus, the photographer still must think about the exposure triangle and the trade-offs between image noise (due to high ISO or post-processing EV boost), motion blur due to too slow a shutter speed, or image softness/defocus due to too wide an aperture.
Or in other words, there's no free lunch.....
You want, the lowest ISO, at the slowest effective shutter (without incurring motion blur) with the appropriate aperture setting (often ƒ5.6 for APS-c or ƒ8 for FF.)
If you can't get to 100 ISO, ƒ8, 1/100s everything after that is likely a compromise. It's always your choice as to what you'll sacrifice in your image but whatever it is, it won't be ideal once you vary from optimum settings.
But there's a lot of leeway between "ideal" and "good enough." Almost any camera will produce great results with ideal settings, it's how much of the less than ideal is still useable that defines how good the camera is.
The fact that some prefer to shoot at 2.8 or 1.4 doesn't change that. There is a technically definable ideal setting for each camera at every f-stop. Most are impractical.
I'd love to be able to look at the charts and decide for what I want to do 100 ISO, ƒ11, and 1/2000s would be the best solution. But the practical problems with using such a setting on a regular basis are obvious to anyone with experience in the field.
Deciding where to put your compromises, a bit of noise weighed against a bit of motion blur, a wider depth of field weighed against better subject sharpness, that's why photography is an art, not a science. Even with sharpness, an ƒ11 which is well past the diffraction limit can look sharper than an ƒ4 image, because the whole subject is in focus. The science can't predict how pleasing the combination of variables will be based on what looks good to a human. Only on how it looks to a test chart.
It is our individual biases as to how to compromise that in most cases sets us apart from other photographers and gives us a unique style. It also means 20 photographers shooting the same scene will likely produce 20 different images. None of them are "wrong". But some may be found more pleasing by a large part of the population.
Even then, you may not be in agreement with what the majority of the population thinks looks good. Using a good camera, which for digital I would define as anything form 4/3 to 645, gives you more chance of producing images you like, as more deviation from the standard "everything in focus shot in broad daylight" is possible.
Last edited by normhead; 03-25-2020 at 08:34 AM.