The last few Q&A forums have had discussions on groung glass/frenel screen focus ing accuracy, with the comments indicating that this is a VERY tricky matter. N ow I wonder about a couple of things:
1) Why haven't film holders been standardized to the point where, for cut sheet film holders at least, we'd have a uniform one-size-fits-all exact degree of to lerance in terms of how they seat in the camera? This way camera makers could m ake their designs more precise. We have a standard film size, standard ISO meas urements, etc. From what I've read, I wonder if you can even trust the focus of a new camera straight out of the box!
2) So let's say that I'm way off base and there are legitimate reasons for the disparity of holder dimensions, my dumb question is what is the proper way to te st if your focus is "on?" I ask because the camera I have came with the corners cut out of the GG (as if the corners of the picture are somehow unimportant - c hecking for vingetting? I don't think it's quite that simple). My idea was to replace the GG glass, but now I'm wondering if this will only cause more problem s.
One test I thought of is to use my 210mm and focus it at about 2' from a newspap er hung on the wall and shoot at F5.6. If everything is sharp,my focus is OK (s houldn't be that much DoF at 5.6). Any Ideas?
THX in advance
Todd
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