I think you could however having tested the above method just metering I feel whatever is behind the glass needs to be an even tone i.e pointing to the sky
I think you could however having tested the above method just metering I feel whatever is behind the glass needs to be an even tone i.e pointing to the sky
I haven’t tested this, but why not mount the step wedge to the translucent sheet and focus at 1:1? That would account for lens flare and bellows flare and still be easy to meter, assuming a spot meter. I’ve done btzs tests in the past and find the results are not as close to real world shooting as I would like. Flare is the most likely reason. If I were to test again I’d try for a setup that’s as close to real world conditions as possible. To get closer to normal conditions you might need to mask off the area around the step wedge since the bright area will add more bellows flare than normal.
Regarding the idea to "mount the step wedge to the translucent sheet and focus at 1:1"...
Some people do it that way.
But the image of a step-wedge starting with 1000:1 contrast, after traveling through lens and camera will deliver maybe 100:1 contrast. Flare gives the darkest patches exposure about a stop greater exposure than the amount you want the patch to get in the test. The darkest patches are the ones that tell you the film speed. So flare ruins the speed check.
If it really is that big of a difference I guess it wouldn't work for the standard testing methodologies. But it does seem like a useful starting point for a new testing methodology since the flare is built into the test. Or maybe not...Originally Posted by Bill Burk
The problem with building flare into the test is that under real shooting conditions flare is of course variable (and not under control). It can be a good "supplemental" test to show the general effect on EI and the lower part of the curve relative to a no-flare EI test (although that is generally superfluous anyway), although obviously the flare factor will depend on the test conditions including the type/layout of the step wedge.
I'm convinced it's not that useful of an idea given there are too many variables. Thanks for setting me straight.
excellent, if I think tracing paper is more appropriate.
I will see if the linhof is economical for the chassis.
What I am understanding from the translation of the text is that the stoufer wedge is inserted/glued into the camera plate in such a way as to make several shots without having to sandwich the plate holder.
If I'm wrong, let me know... my English is not so good...
Thanks
is very likely to happen, that
enlarging and achieving 1:1, without losing light, is complicated.
I understand, there is nothing left but trial and error, being tidy
For anyone wanting to work with step wedges, I suggest acquiring a copy of
photography: CONTROL & CREATIVITY
by T.L. Bollman & G.E. DeWolfe
Special Services, Rochester, New York 1972
It's a small paperback that was very popular at the Rochester institute of Technology in the 1970s.
Beware of excess yellowness, potentially added up from the diffusers, plus the yellowing atop most LED fixtures, plus their native spectral discontinuity, plus any distinct yellowness inherent to very old step tablets. The cumulative offset could amount to as much as that between recommended filter factors for daylight vs tungsten light. When in doubt, check the net K temp with a color temp meter. You need you test illumination balanced to that or your intended work illumination.
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