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Lack of film flatness or lens separation?

Edward Kang , Aug 25, 2000; 01:08 a.m.

Hi there folks. Included is a test image I took with my rolleiflex TLR. If you notice, the picture has acceptable sharpness for the bottom 60% of the picture, but the sharpness rapidly decreases in the upper 40% of the picture. The picture was taken with a flash, indoors, with a tripod, so camera shake is not an issue. The aperture was set at f/11. The tapestry held up is being held up vertically.

This same blurry top effect has been in all my photographs for the past year, and it is only now that I've realize that something strange is going on with this camera.

The question I have is, after looking at the sample photo, does the problem appear to be one of film plate flatness (or lack thereof) or one of a lens separation?

Thanks for any input you can give me.


sharpness problem. rolleiflex TLR (Fuji Astia)

Responses


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Wayne DeWitt , Aug 25, 2000; 01:50 a.m.

The transition is so abrupt and severe that I vote for a flatness problem - but it's only a guess. When I saw fringing in the background I suspected lens separation, but then I realized that it will occur with film flatness problems also (and the fringing could be a scan artifact also).

David Doyle , Aug 25, 2000; 03:33 a.m.

Edward,

Make sure that you have the pressure plate on the camera back set for the proper film type. The typical Rolleiflex has the capablity to use either 120(or 220) or 35mm film. I would imagine if the pressure plate has been moved to accomodate 35mm film it is not supporting the 120 film size in that area. That would be my guess, not having one in front of me to test this theory but having had them previously (did'nt use the Rolleikin though..). Only other thing not mentioned that might cause such an abberation in my mind would be a sizable gouge in the rear element, and that would be obvious to the eye.

richard oleson , Aug 25, 2000; 09:23 a.m.

I would look at the focusing panel: rack it back to infinity and make sure it is parallel to the body casting and the lenses are tight in their mounts. I assume the camera has not been dropped, but check it anyway - the Rollei focusing panel can get dented out of alignment.

This definitely does not look like lens separation to me - at least not unless the separation was caused by otehr major damage to the lens. Separation itself has little optical effect beyond flare from reflections off the decemented surface - it should not affect focus. Separation is also very easy to spot: just look at your lens (from both front and rear; in the older Tessar and Xenar, separation can only occur in the rear element) - separation will appear as a bright reflective spot in the glass, usually beginning at one edge and extending inward.

Edward Kang , Aug 25, 2000; 10:01 a.m.

Thanks

Well, I have just given my camera a once-over. The lens does not appear to have any separation either from the front or the back, judging from visual examination. The film plate is definitely set to the correct 120 (2 1/4" x 2 1/4" setting). It looks like it's springing back to the right place. The focusing face looks accurate to within a half millimeter. Does anybody else have any input as to why this sort of thing keeps happening?

Christian Deichert , Aug 25, 2000; 12:10 p.m.

I'm willing to bet it's a film flatness problem caused by leaving the film in the camera too long. IIRC, film is positioned in the Rollei with the unexposed spool on the bottom of the camera, pushed towards the front; the film must bend around the bottom edge of the camera in order to come up the back into position in front of the lens. If you leave the film in the camera long enough, the film tends to keep the bent shape despite the pressure plate's efforts to flatten it.

Solution: try to go through one roll at a time quickly enough that the film isn't left in the camera long enough to bend.

It's interesting to note that when Minolta came out with its Autocord, essentially a modified copy of the Rollei, it saw the potential for this exact problem. They modified the design so that the film traveled down the back of the camera, avoiding the bent film problem altogether.

Edward Kang , Aug 25, 2000; 01:36 p.m.

Looking over it again, this might be the problem. But there's another issue - this entire roll was taken with a fresh roll of film, and the roll was finished from putting into the camera to taking out within a matter of twenty minutes. Come to think of it, the same effect came from a bunch of wedding pictures I did - two rolls in twenty five minutes.

Could it be possible that the film coming around the bend at the bottom of the camera from a _fresh_ roll has enough springback to overcome the spring force of the film plate, therefore causing the lack of flatness in the film?

Do most Rollei users let the film "sit" between exposures to ensure film flatness? Is there a fix for this?

On a related note, does the image on the film that comes through lens end up inverted? That is, does the top of my image that I posted actually correspond to an area of the film that is pointed towards the bottom of my camera?

If this is the case, then I'm starting to understand what's going on. But the question is how do I fix it?

Paul Roark , Aug 25, 2000; 01:39 p.m.

I have seen similar results with my Rolleis when the film is left in the camera for a long time. The film "remembers" the last sharp turn. To test the lenses on Rolleis (or any medium format) what eliminates the flatness issue in at least properly working cameras is to wind through a blank frame quickly, then let the film "relax" on the film plane for 2 minutes. Then take your test shot. (Also, avoid frame number 1 for testing.) For example, if you're on frame 3, wind to 4, shoot a blank immediately, and wind to frame 5, wait 2 minutes, and shot the test shot.

Good luck.

Paul Roark, http://www.silcom.com/~proark/photos.html

Doug Paramore , Aug 25, 2000; 06:53 p.m.

Edward, Forgive me for even asking this, and I will accept harsh words, but you going under the film sensing roller? Since the out of focus is at the top of the picture, that would mean the unsharpness is occuring at the bottom of the camera. Even if film buckle or "set" occurs, it would be on only one shot. Are the springs still tight and in the slots that hold the film flatness plate down? Try putting a small ground glass at the film plane and see if it is evenly focused. You can use a plain piece of glass stripped with Scotch Magic Tape to make a temporary ground glass. Put the tape toward the lens.

andrew schank , Aug 25, 2000; 11:41 p.m.

I don't see how it could be a film curl problem if it has been uniformily blurry on top. If you have noted the pressure plate is set right and still seems to have a nice EVEN spring to it, something must be seriously out of allignment--like an element shifted, or the whole front end is cocked at an angle. Have the thing checked out by one of the Rollei specialist, because without putting the camera to the test, we are all just guessing.


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