Originally posted by Marc Sabatella True, but the downside is that the viewfinder dims as a result. So if you want to shoot stopped down, you either live with much harder focusing, or else you manually turn the aperture ring every time you want to refocus. I don't see that as easier than hitting the Green button, particularly given that in many cases, light doesn't change all that often, so I can Green button once and make a lot of different shots on that same exposure. I tend to finesse the shutter speed as I move from light to shadow without bother to Green button again; really, the exact same produce I use with my DA lenses. I'd find the M42 procedure a *lot* more work.
You are arguably right on both counts...Button or preset is mostly a toss-up I think....neither is a *lot* more work...I probably push the preset method because I've got quite a few preset-only lenses (m42's, modified nikons, etc...)
Focusing with a stopped down lens is harder, especially when using a split prism.
The way split prism focusing (and phase detect focusing) works relies on off-axis rays, and when the lens is stopped down the off-axis rays go away (and half the prism goes black). That's why such focusing is f-stop limited more than it is brightness limited.
I think most of us don't pay enough attention to your technique of just setting the exposure and tweaking it as lighting varies. Lighting doesn't vary much in most venues - the wide swings in exposure we often see are due to our metering systems seeing a white shirt here, or maybe a black shirt there & overcompensating.
I recall you pointing out that the lighting at a basketball game doesn't change from minute to minute and one is best to shoot for the average lighting - that will result in consistent exposures.
Dave in Iowa
PS in addition to all the above, in practice I find that I only use the fast primes wide open (or close to it) so the method really doesn't matter much. If the scene only needs a modest f-stop, I'll typically use an auto lens.