Sevo,
I have friends coming over this afternoon : will ask both of them to focus for me (with the "bare" no-fresnel back) and then will check with my own eyes. Will repeat several times with 55mm, 300mm, long-distance, close-distance etc.
Now, if their focus corresponds to mine every time... it must mean something happened to my Sinar and not my eyes, right ? (??)
ax.
Test done with other people focusing for me and nothing here : I focus exactly where they do, no difference.
So there must "something" between GG and Norma back(s) ; will go tomorrow morning to the only LF shop in Paris, Norma in hand, to see and hear if they have a clue.
Thank you all for your patience and input.
ax.
Axel, if I may muddy the waters a bit more. My late 60s 4x5 Norma back has no fresnel on the lens side and has the clips to attach the removable fresnel to the eye-side and has never exhibited any problems. These uploaded images show a configuration which employs a fresnel on the lens side AND the clips for the removable eye-side fresnel. Since one would never use BOTH fresnels at the same time, it seems odd that a full-factory back would be supplied this way. So I would ask whether this back was in fact supplied by the factory, or whether it was purchased "new" from another outlet and assumed it was a factory configuration?Originally Posted by Axel
Actually a Sinar user (F1) for twenty years. The OP mentioned sample images from Horseman and Dayi roll film backs, and multiple lenses. Ergo my suggestion that multiple backs and lenses indicated a camera problem.
Maybe it would be less confusing if he had referred to them as roll film holders. Either way, it's a puzzlement, and I feel his pain.
JD
As roll film holders do not come with a variety of fresnels, I assumed that backs meant backs - and the photographs posted later on confirm that. Now, I can believe in grown variations across different backs, but there is no place where a uniform focus error on all of them could have grown by mere old age on Sinar type backs, as the register distance is permanently milled into them, and not subject to shims or adjustment screws. It must either be an issue with the holders, or the Dayi holder (after whose purchase the troubles apparently started) damaged all backs the same way - but I am absolutely stumped as to how it could have done that.
Sevo...you made the right assumption, I didn't! Sure hope he sorts it out, a lot of us will be losing sleep over this one.
"Curiouser and curiouser"!
JD
I agree, it is hard to imagine this stemming from the camera itself. It should be repeatable with the Sinar P he mentions owning, ruling out the camera.
Perhaps it an Absinthe problem?
Well, weirdness continues :
I show the LF shop owner both my Norma backs and right off the bat he points one out and says "That is not right."
One very american acronym is creeping up in my head, WTF ?, because "that" is the one I've been using since 1990 with no focus problems whatsoever, whether studio, lifestyle, portrait, close, far, up, down and diagonals ! The one with the fresnel sandwiched under the ground glass !
Then he points to the other back and says "But THIS is right" - "this" being the one I bought recently with only the ground glass and removable framed fresnel...
So I guess I'll be making (another set of) tests this weekend on 4x5" and 6x7 and 6x9 with THIS back, the one that's RIGHT, in hope of getting all this right AGAIN.
The P2 is in Lyon and I'm in Paris ; I don't know when I'll go get it back but since I don't do studio anymore, I'd rather stick to the simple and somewhat more lightweight Norma. And if THIS back is RIGHT, then I really don't need to go get my P2 for a simple test... right ?
Come to think of it, I also have the 8x10" Polaroid developing machine - no use for that anymore either :(
Anyway - I never did drink absinth :)
(or maybe I did ?)
(but maybe I should ?)
A poster here on the thread already pointed out that this at the very least suspicious, as that is a frame with the recess for a rear fresnel, which is quite unlikely to be factory made with a front side fresnel. Sinar components are milled to fit and the ground glass is placed on forward rests, so there is no way to place a fresnel between the original rests and ground glass without screwing up focusing. You'd have to grind down the frame to make room for the fresnel - impossible at least on my Norma frames, as the ridge forward of the rests is not strong enough to cut away the about 3mm taken up by the fresnel and air space on my front-fresnel cameras.
Did you perhaps in the past use only a holder that came with that camera and back (at least for your positively in-focus results)? If so, it might be worth checking whether the film plane on that holder has not been modified to match that apparent fresnel hack on the frame.
Sevo,
The only rollfilm holder I used with the Norma is the old Calumet C2 - in focus.
What I mostly used this Norma with were and still are my three dozen 4x5" chassis - in focus.
... that is probably why I should start drinking absinth :)
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