You are right. You do not want to open-close-open the camera with shot n place. Forgot about the vacuum/pressure effect on film flatness. Your proposed sequence is better.
My recommendation for the sequence is not an arbitrary choice for the sake of consistency alone.
- advance film just before picture taking to benefit from the film's natural curvature keeping it flat against the pressure plate (see post #18 by Helge)
- advance film after opening camera to avoid having the film sucked forward by the opening motion of the bellows
what do you do after the second film advance? close the camera? and what is the sequence for the next picture?
Agree with the consistency part. Once habit has become second nature, you won't ask yourself "did I advance the film or not".
i dont see any problems with film flatness, misalignment of the lens, pressure plate etc. in that image.
The image looks perfectly sharp except for the dark edges.
Dan Daniel had it right from the start. This is the bellows intruding into the image.
You can see it easy enough by opening the camera back, setting the camera on bulb, and looking through it.
The Super Ikonta iii is one of the smallest 6x6 folders with a rangefinder, and the bellows is just a bit too narrow.
I have one and love it.
These cameras are called 6x6 but never use the full 6x6 area of the film due to the rails.
Usually 56x56mm is about right but for the Super Ikonta iii you want to crop it down a bit more. 54x54mm should be about right.
Or even 56x54 if you like it a little more rectangular. Just keep that in mind when you are framing, leave a little buffer on the sides.
So now I am confused. Maybe there are two separate issues? If the bellows are shading the edges, focus would not be affected, would it?
The pressure plate *is* thin enough that curvature would be possible but, as you said, that issue would present itself with different symptoms. I think you’re right but I don’t think it’s a lens issue.So somehow you must have a curved pressure plate, one that holds the film flat in the middle and is bent out towards the edges. Easy to measure, but now tell us how that happens? Maybe the pressure plate spring isn't strong enough so any longitudinally curvature in the film's base layer is over-riding the pressure plate spring, but the middle area of the negative would then be OOF and the edges sharper.
Thank you for pointing this out. I’m guessing that a lot of nominally 6x6 cameras actually yield a slightly smaller image. This is something I didn’t think about at all, however, the first thing I thought when I looked at the Ikonta was “wow, those bellows are narrow”.i dont see any problems with film flatness, misalignment of the lens, pressure plate etc. in that image.
The image looks perfectly sharp except for the dark edges.
Dan Daniel had it right from the start. This is the bellows intruding into the image.
You can see it easy enough by opening the camera back, setting the camera on bulb, and looking through it.
The Super Ikonta iii is one of the smallest 6x6 folders with a rangefinder, and the bellows is just a bit too narrow.
I have one and love it.
These cameras are called 6x6 but never use the full 6x6 area of the film due to the rails.
Usually 56x56mm is about right but for the Super Ikonta iii you want to crop it down a bit more. 54x54mm should be about right.
Or even 56x54 if you like it a little more rectangular. Just keep that in mind when you are framing, leave a little buffer on the sides.
Yeah, there is an inner film gate but since it’s quite a bit more deep-set I probably wasn’t tempted to use it for the indoor infinity focus.+1
On my Super Ikonta A (645) there are inner rails (width of film) and outer rails (beyond width of film), raised slightly, definitely more than thickness of film+paper. .
The pressure plate spans the width of the outer rails. Meaning it cannot press the film to the plane defined by the inner rails. I believe the (raised) plate defines the film plane, the film being pushed backwards at both ends of the gate by the rollers, and held at the back by the plate.
So if one adjusts focus with a ground glass sitting on the inner rails, it will be wrong. I used a piece of film+paper with a hole in the backing paper, backlit by the "red window" and applied Oleson's "infinity indoors" method. This simulates closely "natural" operation. Alternatively, one could use a film (no paper) and a transparent backplate substitute (glass, plastic) with the size and position of the actual pressure plate.
Having stated that caveat, my take on the test image submitted by henryvk is : I fail to see unsharp image zones at the left/right, I do see blurred edges, that look like bellows vignetting, as stated by darinwc.
The pressure plate *is* thin enough that curvature would be possible but, as you said, that issue would present itself with different symptoms. I think you’re right but I don’t think it’s a lens issue.
Thank you for pointing this out. I’m guessing that a lot of nominally 6x6 cameras actually yield a slightly smaller image. This is something I didn’t think about at all, however, the first thing I thought when I looked at the Ikonta was “wow, those bellows are narrow”.
Looking down the bellows through the open lens I can see the fuzzy edge of the second to last fold before the edge of the film gate comes into view. I guess that solves the mystery… I would have thought what with these being such popular cameras this quirk would be common knowledge. Oh well.
Yeah, there is an inner film gate but since it’s quite a bit more deep-set I probably wasn’t tempted to use it for the indoor infinity focus.
Btw am I the only one that uses hair for this? It’s very convenient if you have access to it. I’m very much balding and rely on my wife for the hair.
That is the other possible explanation. The lines seems too well defined and straight for that to be the case.
I always give my bellows a very light brush with bees wax oil to protect and moisturize them. That might also help keep the bellows straight and not bow inwards due to drying leather over the fabric substrate.
One of the pluses for folders over box and other rigid cameras is that the bellows actually works as very effective light baffling, raising overall contrast.
Maybe it depends on the hair? My wife’s hair is not too curly and long enough to be easy to handle; to tape it to the rails I use the kind of packing tape with the paper surface that is at the same time sticky and easy to remove without leaving traces. That way it’s not too hard to make it quite taut.Isn’t hair very hard to keep taut?
I’d say the old hole punch through the frame number of a of a sacrificial roll of film (and paper) and then light from the back with open red window, is the best possible way to determine exact focus.
Of course as with any measurement you need to have few samples to be sure.
This means that the inner part of the bellows is not unfolded as much as intended, and is perhaps even pushed back by the front part.
This creates the apparent inward curvature.
My standard treatment of folders is always lubrication with silicone oil of all the folding parts, and as described above, a light brushing of the bellows with bees wax oil. Especially the folds.
This is probably what has helped me avoid the problem so far.
Any thoughts?
my specimen having sat around for a long time in a potentially dry environment. It at the very least makes for an argument to keep all folders well moisturized e.g. with beeswax or similar.
The inside of the bellows is felt. And there is a seam where the bellows are folded over. It will match up exactly the pattern on the edges.
I did som further research and It turns out you two guys are exactly right.
I was wrong and you where right! Sorry.
It is exactly the bellows bowing/curving into the lens projection frustum. With most of the curve lying nearest the film plane.
This is very interesting and noteworthy for all folder users, because it's something that could potentially affect all leather bellow cameras.
And strangely, not something very well described or even noted anywhere on the web, other than here.
Which makes this thread rather important on a global folder camera scale!
Especially in not having people attempt stupid fixes to an imagined origin of the problem.
Anyhow, It appears that the problem is that the outer "pointier" part of the bellows becomes stiffer, (or is it the inner part that becomes softer?) when the folder is folded over long periods, or just due to ageing of the leather.
This means that the inner part of the bellows is not unfolded as much as intended, and is perhaps even pushed back by the front part.
This creates the apparent inward curvature.
My standard treatment of folders is always lubrication with silicone oil of all the folding parts, and as described above, a light brushing of the bellows with bees wax oil. Especially the folds.
This is probably what has helped me avoid the problem so far.
Any thoughts?
What part do you suppose is the seam intruding?
We could ask the OP to check.
It probably is, but it’s not often that cut and dry.
It’s a diffuse shadow.
You want something that won’t rot, and encourage mold growth, even when between folds for years and years, bees wax checks that.Probably good advice that. I don’t use oil myself but a more solid wax-like stuff originally meant for furniture which is very easy to apply thinly and evenly. Excess is carefully buffed off with a cloth and a-tips.
But, yeah, like you said: just imagine how thin of a coat of shoe polish you need for your boots and then scale that down to the thin leather of the bellows.
You want something that won’t rot, and encourage mold growth, even when between folds for years and years, bees wax checks that.
And you want something that doesn’t necessitate applying pressure to apply.
Again, this is a very this easily destroyed structure.
A solid wax sounds daunting.
You want something that won’t rot, and encourage mold growth, even when between folds for years and years, bees wax checks that.
And you want something that doesn’t necessitate applying pressure to apply.
Again, this is a very this easily destroyed structure.
A solid wax sounds daunting.
It’s more of a soft paste like shoe-polish.
Lexol leather conditioner (in the US) is a liquid so can be wiped on in very thin coats. I imagine that there are dozens of similar products used by horse people and shoe makers.
Lexol Leather Conditioner Review - BestLeather.org
You can see Obenauf’s and Chamberlain’s leather conditions in action. There are a lot of options in leather conditioning but Lexol is very good at a very good price. The reason you should condition your leather is because leather is made of microscopic strands of fibers that rub on each other...bestleather.org
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