Periscope Image

[dgc]

I have attached a photo of one of my first LF negatives, which has the appearance of looking through a periscope. I have attempted a search online to determine what has caused this with no luck - not even sure what the correct term is.

I know I should take more notes about each photograph but at the moment I am just enjoying the process, however, I do recall that I was using the B setting and the cable released slipped. I recocked the shutter then continued with the long exposure. I have 2 periscope negatives from the 6 images I have taken, using two different lenses but the periscope look has only occurred on the wide angle Fujinon lens; the fujinon has also produced a 'normal' looking negative. Both negatives show a continuation of the image from the periscope circle suggesting a very short exposure for the whole negative on the first attempt.

Is this a case that the lens did not open fully on the 2nd firing (a sticky lens opening problem) or is it simply operator error ?

Many thanks, David

[Lachlan 717]

What are the lenses? Specifically, please.

[koraks]

The odd thing is that the area outside the circle seems fully exposed instead of blank, which suggests that it is not a matter of the shutter opening (which wouldn't have resulted in this kind of effect in any case, due to the location of the shutter in-between the front and rear cells of the lens). If I were to hazard guess, it would be light leaking long the sides of the lens, but I'm not sure how one could manage that without also fogging the center of the image. What kind of camera did you use? Have you checked that the bellows and front standard are well connected, that the lens is properly mounted on its board and that the lens board is properly seated in the front standard?

[dgc]

The camera is a Linhoff Technika III (the early one with the older type of lens board and the lens is the Fujinon 90mm f5.6 and Schneider Symmar 150mm f5.6).
The lens board used was a homemade bit of ply with a hole not quite as snug as it should have been for the lens fitting (I am now hanging my head in shame for this obvious omission from the above).
However, this does not explain why two of the negatives are normal, though these were taken at night with exposures +20minutes ...

[koraks]

Night time = less stray light. I think you need to take that camera setup into a darkroom and do some checking with a flashlight, as it seems you have a rather massive light leak to deal with. The lens board is the first suspect.

[dgc]

Thanks Koraks. It is a perfect light leak though !

[koraks]

If light leaks around the lens, the perfect circle is just the rear lens group blocking some of the stray light. Although I'm not sure if that hypothesis holds much water.