6x17 negatives have curved edge on one end

[Shaps]

I have a 3D 6x17 camera made by Custom Camera Builders. It came.with a mounted 90mm Super Angulon f/8 lens. I have noticed that on some, not all, of my frames one end sometimes is not a clean verticle edge but slightly concave. It is always on the same side. could this be a misalignment on centering the lens in the cone? The lens is very sharp and works well.

 

[MattKing]

That sounds like an issue with the film transport.

 

[Shaps]

Here is an example of the fall off. The fall off amount varies and this is one of the most pronounced. Some frames have no fall of at all. I’m am usually at f/45 on the lens.

 

[MattKing]

Ah, that is different.
It isn't that the end is concave. It is that a whole chunk of the end of what should have been imaged is vignetted.
Is the plane of focus parallel to the film, or is it skewed at an angle?

 

[OAPOli]

That looks like mechanical vignetting. Were the images showing this effect taken with the lens extended to focus on a close subject? Maybe the helicoid is causing the vignetting...

 

[Shaps]

That sounds like an issue with the film transport.

Looking through several rolls of negatives It looks like the fall is more on frame 1 and lessens as I go through the roll. Advancing the film is very easy with no drag. Perhaps holding the feed knob, on the left, and back winding the supply knob a bit afte I get to the frame I want might work?

 

[Shaps]

Ah, that is different.
It isn't that the end is concave. It is that a whole chunk of the end of what should have been imaged is vignetted.
Is the plane of focus parallel to the film, or is it skewed at an angle?

At an angle, with focus set for the near branches about 3 1/2 meters.

 

[Shaps]

That looks like mechanical vignetting. Were the images showing this effect taken with the lens extended to focus on a close subject? Maybe the helicoid is causing the vignetting...

most photographs I’ve taken with this camera I’m focusing on something near from 1 to 4 meters away. On the example I uploaded I’m focuse at 5 meters (using a lazer to determine focus), f/45, and infinity is sharp. This was the first of 4 exposure made of this scene. The fall off is most on this frame but still there for the other 3 on this roll. This is the last roll I have made with this camera.

 

[OAPOli]

most photographs I’ve taken with this camera I’m focusing on something near from 1 to 4 meters away. On the example I uploaded I’m focuse at 5 meters (using a lazer to determine focus), f/45, and infinity is sharp. This was the first of 4 exposure made of this scene. The fall off is most on this frame but still there for the other 3 on this roll. This is the last roll I have made with this camera.

Does the vignetting correlate with focused distance? I.e. closer focus --> more vignetting or distant focus --> less vignetting?

 

[Shaps]

Does the vignetting correlate with focused distance? I.e. closer focus --> more vignetting or distant focus --> less vignetting?

No, actually this example has the focus set the farthest so far. And the first one where I can see if infinity is sharp. In PS enlarging the image both the foreground and that triangle island are both very sharp.

 

[mshchem]

Call the seller

 

[Shaps]

Call the seller

I emailed him this morning. If it is something that needs to go back for adjustment I will just live with it. Mail going through US Customs in Chicago can be very slow. Right now waiting for something there (Chicago customs office) for 8 days without movement.

 

[OAPOli]

Did you use filters on the lens?

Edit. In addition, maybe you can comment on any difference in camera settings between the pictures where vignetting was present and absent?

 

[Shaps]

I have been reviewing all my negatives with this camera, and dates I bought the filter I’m using. My first roll before any filter is fine, no cut off. Dates on my notes taken when I used the camera show the filter going on for roll #2. That roll had two frames testing the rubber shade and show cut off with the shade extended. All the later rolls show some degree of cut off.
next step is to 1-not use any filter,and then 2-use Tiffen slim uv alone. On checking the specs on the Tiffen Slim filter is is not clear how thich the frame is. Hoya makes one that claims to be 3mm thick, so that’s a possible choice.
for many years I avoided any filter on my lens unless I needed to correct something. As time went on and my professional photography went towards news work I began to use protection filters. So now that I’m older and working slower I will not use filters. But my Super Angulon is in such new looking shape I want to protect it.

 

[blee1996]

@OAPOli has a good point about filters. Also do you use lens shade on top of filters? To protect your lens, you can use oversized filters with step-up ring or go for the bigger square filters systems (like Lee, Formatt/HiTech 4x4).

 

[Light Capture]

I have been reviewing all my negatives with this camera, and dates I bought the filter I’m using. My first roll before any filter is fine, no cut off. Dates on my notes taken when I used the camera show the filter going on for roll #2. That roll had two frames testing the rubber shade and show cut off with the shade extended. All the later rolls show some degree of cut off.
next step is to 1-not use any filter,and then 2-use Tiffen slim uv alone. On checking the specs on the Tiffen Slim filter is is not clear how thich the frame is. Hoya makes one that claims to be 3mm thick, so that’s a possible choice.
for many years I avoided any filter on my lens unless I needed to correct something. As time went on and my professional photography went towards news work I began to use protection filters. So now that I’m older and working slower I will not use filters. But my Super Angulon is in such new looking shape I want to protect it.

While 90mm f8 Super Angulon covers 617 easily, there's only 17.5mm to the edge of the image circle on the edges.
I would say this is caused by rubber shade or by filters in some way.
If the lens was misaligned, it would have to be misaligned quite a bit to reach mechanical vignetting on this lens.
In other words, misalignment would be readily visible.

Rubber shade would be quite hard to use as they usually don't hold the shape very well.
Double filter on this lens will almost certainly cause mechanical vignetting.

This is easy to check by looking through the camera with lens open and looking from the corners through the lens.
If you can see the filter or the shade, they're most likely going to shade the image.
Shade on 617 can be in the view in this case from the top and the bottom as the image circle is mostly unused there and it would be beneficial there. Shouldn't cause any issues unless positioned too far.
I'm usually using a sheet of some kind or simply cover it with hand when shooting outdoors. This will eliminate flare from sun and won't cause any vignetting.
As long as the reflections or light aren't hitting front glass at sharp angles images will be fine.

Even without any shading the design of the camera will shade the lens without using the shade. The purpose of the shade with LF lenses is to limit the image circle to the image area so the light doesn't bounce around the camera and cause reflections. Design of the cone on the 617 prevents that as the cone itself will cut off vast majority of reflections. I would say it's more effective than standard shades.
I have yet to see flare in any of my images with this camera and wouldn't recommend using any standard lens shades as they're going to be ineffective and likely cause vignetting while not providing any shading where it's actually needed.

I can't find the datasheet for center filter for this lens at the moment. Here's some information on center filters - it should be correct:

6x9 lens by Dan Fromm (1)

6x9 lens for speed graphic, by Dan Fromm

www.galerie-photo.com

If you look at the recommended IIIa center filter, it goes from M67 to M86 thread. That really shows how quickly image circle becomes limited with mechanical vignetting.

Other than this, it could be caused by issues on the lens but likely wouldn't be as sharp.
Stuck or out of place aperture or shutter blade could also affect things.
Can be checked by looking through lens and releasing it a number of times.
Recently I had a lens that had one shutter blade that was staying in the frame randomly every few releases.
Considering there's also some vignetting in corners on the left side, this is very unlikely.

Lastly, I don't stop the lens on 617 beyond f22 very often. f22 is more than enough for any distances beyond 4-5 meters.

 

[Shaps]

While 90mm f8 Super Angulon covers 617 easily, there's only 17.5mm to the edge of the image circle on the edges.
I would say this is caused by rubber shade or by filters in some way.
If the lens was misaligned, it would have to be misaligned quite a bit to reach mechanical vignetting on this lens.
In other words, misalignment would be readily visible.

Rubber shade would be quite hard to use as they usually don't hold the shape very well.
Double filter on this lens will almost certainly cause mechanical vignetting.

This is easy to check by looking through the camera with lens open and looking from the corners through the lens.
If you can see the filter or the shade, they're most likely going to shade the image.
Shade on 617 can be in the view in this case from the top and the bottom as the image circle is mostly unused there and it would be beneficial there. Shouldn't cause any issues unless positioned too far.
I'm usually using a sheet of some kind or simply cover it with hand when shooting outdoors. This will eliminate flare from sun and won't cause any vignetting.
As long as the reflections or light aren't hitting front glass at sharp angles images will be fine.

Even without any shading the design of the camera will shade the lens without using the shade. The purpose of the shade with LF lenses is to limit the image circle to the image area so the light doesn't bounce around the camera and cause reflections. Design of the cone on the 617 prevents that as the cone itself will cut off vast majority of reflections. I would say it's more effective than standard shades.
I have yet to see flare in any of my images with this camera and wouldn't recommend using any standard lens shades as they're going to be ineffective and likely cause vignetting while not providing any shading where it's actually needed.

I can't find the datasheet for center filter for this lens at the moment. Here's some information on center filters - it should be correct:

6x9 lens by Dan Fromm (1)

6x9 lens for speed graphic, by Dan Fromm

www.galerie-photo.com

If you look at the recommended IIIa center filter, it goes from M67 to M86 thread. That really shows how quickly image circle becomes limited with mechanical vignetting.

Other than this, it could be caused by issues on the lens but likely wouldn't be as sharp.
Stuck or out of place aperture or shutter blade could also affect things.
Can be checked by looking through lens and releasing it a number of times.
Recently I had a lens that had one shutter blade that was staying in the frame randomly every few releases.
Considering there's also some vignetting in corners on the left side, this is very unlikely.

Lastly, I don't stop the lens on 617 beyond f22 very often. f22 is more than enough for any distances beyond 4-5 meters.

Thanks for this. I’m going to stop using any filter or ring on the lens. Also most likely try f/22 i less I’m close to something.

 

[mshchem]

Oh yeah, I have a Fujica G617, rubber hood is not a workable option. I finally found a Fuji rectangular hood, IIRC has a slot for acetate filters. I would bet it's the hood.

 

[Light Capture]

Thanks for this. I’m going to stop using any filter or ring on the lens. Also most likely try f/22 i less I’m close to something.

Using filters is fine as long as they're larger than needed. It's hard to know exactly what's shaded or not when you're using almost full image circle of the lens without some testing.

With these, I hold Cokin P or Z filter in front or use slim 1 filter holder for wide angle lenses. Also have a bunch of step up rings when needed to use circular filters.
Step up rings can be bought cheaply in the full sets.

 

[OAPOli]

Yes, this was caused by filters and/or hood. 90mm on 617 is very wide. I tried a double filter on a G617 (105mm) which caused vignetting.

 

[djdister]

If the vignetting was caused by filters or a lens hood, shouldn't the vignetting effect show equally on both sides? Since it does affect one side more than the other, it seems that the lens is not exactly centered.

 

[Light Capture]

If the vignetting was caused by filters or a lens hood, shouldn't the vignetting effect show equally on both sides? Since it does affect one side more than the other, it seems that the lens is not exactly centered.

The camera was calibrated by me together with the lens before shipping. It was also collimated on collimator and parallelism was checked to be within plus minus 0.08mm for the whole assembly before lens.
I would say that rubber hood is probably the culprit. If you look at the image closely, there's also the edge of the negative on the right side even though it's not that visible. At first look it seems that is off center a lot and that's what I thought at first. There might be a couple of mm's of difference.

Of course, it could have been bumped somewhere along the way but that amount of decentering would mean that lens is of axis and would show up in lack of sharpness. As it doesn't happen on every image the culprit is likely with the filters.
The front cone has a clearance of around 0.25mm and that's the maximum theoretical amount of lateral movement off center when the cone screws are removed.

 

[djdister]

The camera was calibrated by me together with the lens before shipping. It was also collimated on collimator and parallelism was checked to be within plus minus 0.08mm for the whole assembly before lens.
I would say that rubber hood is probably the culprit. If you look at the image closely, there's also the edge of the negative on the right side even though it's not that visible. At first look it seems that is off center a lot and that's what I thought at first. There might be a couple of mm's of difference.

Of course, it could have been bumped somewhere along the way but that amount of decentering would mean that lens is of axis and would show up in lack of sharpness. As it doesn't happen on every image the culprit is likely with the filters.
The front cone has a clearance of around 0.25mm and that's the maximum theoretical amount of lateral movement off center when the cone screws are removed.

Appreciate the response. Looking forward to the OP posting some new shots taken without filters or a lens hood. I have a 90mm Super Angulon and would not even try to use a lens hood with it - just block any light that hits the lens by holding my hat or something similar about a foot or more away from the lens.

 

[Light Capture]

Appreciate the response. Looking forward to the OP posting some new shots taken without filters or a lens hood. I have a 90mm Super Angulon and would not even try to use a lens hood with it - just block any light that hits the lens by holding my hat or something similar about a foot or more away from the lens.

That's exactly what I do when there's a strong light hitting the lens at sharp angle.
In the beginning I was planning to make a lens hood specific for 617 but the cone geometry cuts it down to negligible amount. Shielding it with a hat, hand or something else worked great for me so far (although it might have been completely unnecessary on the 617).

OP shared with me some really nice initial results.
I have quite a few examples from different light conditions shown on the website.

 

[Shaps]

I will test the camera without the filter+empty filter ring in a couple of days and post results.
but I have looked at the filter combo and I’m surprised how thick it is, around 1/2”.
after all my years doing photography I should have realized that this is too much for this lens.