Re: B+W 77mm UV/IR Cut (486M) MRC Filter
Re: B+W 77mm UV/IR Cut (486M) MRC Filter
- Subject: Re: B+W 77mm UV/IR Cut (486M) MRC Filter
- From: Ben Goren <email@hidden>
- Date: Sun, 26 May 2013 15:19:44 -0700
On May 26, 2013, at 2:14 PM, José Ángel Bueno García <email@hidden> wrote:
> But if you measure your working area with your photometer/flash meter with 1/10 stop accuracy and test with Imatest you will note that isn't enought accuracy.
1/10 stop works out to about 2 DE in the midtones, roughly. Significant, yes, but only barely.
The thing is, even the best lenses have much more than 1/10 stop differential across the frame.
1/10 stop is more than plenty for the capture phase of things. You'll of course, no matter what, want to take a picture of a white field in the exact same setup and use that to take care of any and all residual unevenness in illumination. But trying to get your lighting more even than even a third of a stop is probably a waste of time, as even that's better than your lens.
If it's inter-shot repeatability you're worried about, my experience with the Einsteins is that, shot-to-shot, there's less than 1/100 stop variability. No human is going to be able to spot the difference...but, if you're still worried, you can take multiple exposures and blend them in a stack in Photoshop with the blend mode set to median. It'll reduce noise, too...not that noise is a factor with proper exposures on modern cameras in studio settings. But it'll also protect you against one of the units not getting the signal to fire, which does happen every few hundred shots or so (depending on how noisy your RF environment is). Still, considering how cheap it is to fire off a few shots instead of a single one, it's good insurance.
Cheers,
b&
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