Advice on adjusting folder lens standard

[cptrios]

I'm continuing to try to get my Super Fujica Six into tip-top shape, because I rather like the camera and would be very happy if it worked out as a long-term user. At the moment, one of the things standing in the way of that is an off-kilter focus plane, which appears to be closer on the left and farther on the right.

An encouraging sign is that there's a "stop" on either side of the standard, as seen in this photo:

Since the lens already appears to be vertically aligned by the time it reaches those stops, it seems like they'd be perfect spots to add shims in order to get it horizontally parallel with the film plane. Of course, I could also bend them in either direction, but I rather obviously don't want to attempt that yet!

My question is really a reflection of my ignorance. Behold this stunning diagram, seen from top down:

So, first of all, I'm assuming that if the focal plane in the final image is represented by the red line, the actual focal plane is the blue line. Hopefully, I understand at least that much.
To the point, though: if my rather tortured conception of this is correct, does that mean I should shim the left side of the lens to bring that side of the plane closer?

In the end, I'm going to have to burn at least one test roll anyway, so I might as well just try it on both sides! And hopefully the final answer is that one of the stops has to be moved farther away, necessitating a bend.

 

[mmerig]

Why not use a subject plane that is parallel to the film plane? Slanted ones make the adjustment process more complicated.

There is probably a slick way to make these adjustments. but if the standard is only slightly off, it may be very hard to see it in pictures or on a ground glass. There are depth-of-focus equations you can use to calculate what tolerances you need to be within.

 

[shutterfinger]

Something is bent. Once identified it needs to be reformed to original position or compensated for.
The pictures of the camera I found on line shows the body, bed, and lens standard to be square to one another.
Use a digital caliper ( https://www.ebay.com/itm/2644945046...sP098L%2BW2i4g%3D%3D|ampid:PL_CLK|clp:2334524 ) and measure from the body to the edge of the bed on both sides, they should be the same, if not the hinge is bent or worn. Next measure from the body or film plane to the standard mounts on the shutter, then measure from the body to the standard stops. Measure on both sides. The measurements should match exactly.

 

[Helge]

First establish that it is actually off.
There will always be some amount of play in the standard of a folder. It's just the way that particular type of pantograph works (or any known to me really).
That's why open full aperture should only be used when necessary and not with subjects that need a dead flat DoF.
Left/right differences are rarely the fault of the standard though. Check the bed, the front and rear lens elements for alignment (signs of a tool having screwed the retaining ring is a start) and maybe even the pressure plate and the rollers.

 

[shutterfinger]

If the lens cells have been removed for cleaning ensure they have been reinstalled properly also.

 

[cptrios]

Thanks for the responses all. I think anything to do with lens elements is going to be beyond me, especially since I have no way of knowing what they should actually look like. I'm also reluctant to mess around with any sort of disassembly at the moment, since I have a trip coming up in two weeks and don't want to screw the camera up and wind up not bringing it. The misalignment isn't bad enough to take that sort of risk, methinks.

Film flatness is definitely a possibility, as is the pressure plate. I have some digital calipers (the shape of which makes it really hard to measure many aspects of the camera), and though it's not easy to get an accurate measurement on the pressure plate thanks to its springy nature, it does seem to be slightly out of whack. Possibly as much as 1mm shallower on the right side than the left. I would have figured, though, that this wouldn't really matter since the springs would force it to conform to the film rails anyway?

 

[Helge]

Thanks for the responses all. I think anything to do with lens elements is going to be beyond me, especially since I have no way of knowing what they should actually look like. I'm also reluctant to mess around with any sort of disassembly at the moment, since I have a trip coming up in two weeks and don't want to screw the camera up and wind up not bringing it. The misalignment isn't bad enough to take that sort of risk, methinks.

Film flatness is definitely a possibility, as is the pressure plate. I have some digital calipers (the shape of which makes it really hard to measure many aspects of the camera), and though it's not easy to get an accurate measurement on the pressure plate thanks to its springy nature, it does seem to be slightly out of whack. Possibly as much as 1mm shallower on the right side than the left. I would have figured, though, that this wouldn't really matter since the springs would force it to conform to the film rails anyway?

Yeah, film transport in folders is a thorny topic.
It's never going to be perfect. The control mechanisms to achieve that simply isn't there. In some ways even a good box camera is better equipped for perfect film flatness.

Beginning to bend things, is really drastic and should be avoided, unless you are absolutely sure what you are doing and are ready to lose the camera.
It's very hard to reverse bending and easy to overdo. And it might turn out to not have been the problem at all.

Does the film have slackness issues when the roll is finished? Some folders seem to have been designed with slightly larger spool diameters in mind. Using the spool ends as break discs.
Slack film and possibly a slightly too loose a pressure plate could leave to a wavy film plane.

How sure are you that the ailment is reoccurring?

Under any circumstance, don't rush anything to get the camera to a deadline. It's never coming back if you break it. And you'll kick yourself in the butt forever.
Stop down on the trip, use a flash and/or fast film indoors. You'll get sharper photos and plenty shallow DoF even at f8 (if that's what you're after).

 

[cptrios]

Yeah, film transport in folders is a thorny topic.
Beginning to bend things, is really drastic and should be avoided, unless you are absolutely sure what you are doing and are ready to lose the camera.
It's very hard to reverse bending and easy to overdo. And it might turn out to not have been the problem at all.

Under any circumstance, don't rush anything to get the camera to a deadline. It's never coming back if you break it. And you'll kick yourself in the butt forever.
Stop down on the trip, use a flash and/or fast film indoors. You'll get sharper photos and plenty shallow DoF even at f8 (if that's what you're after).

Yup, not touching anything at the moment, and probably ever. I am going to try a little plastic shim and set up a big sheet parallel to the camera for some test shots. By the way, how does one go about diagnosing and fixing a pressure plate issue?

How sure are you that the ailment is reoccurring?

Hmm...somewhat. I'm fairly sure that the ailment exists, but I'm not sure how consistently serious it is. If you take a look at some of these test-ish shots, it ranges from fairly extreme: https://www.flickr.com/photos/12802682@N00/51329272576/sizes/o/ , https://www.flickr.com/photos/12802682@N00/51538676667/sizes/o/

To "not too bad" : https://www.flickr.com/photos/12802682@N00/51540388420/sizes/o/ , https://www.flickr.com/photos/12802682@N00/51540399080/sizes/o/

To "there, but not particularly noticeable" : https://www.flickr.com/photos/12802682@N00/51539472241/sizes/o/ , https://www.flickr.com/photos/12802682@N00/51538696217/sizes/o/

Interesting, right?

 

[Helge]

Yup, not touching anything at the moment, and probably ever. I am going to try a little plastic shim and set up a big sheet parallel to the camera for some test shots. By the way, how does one go about diagnosing and fixing a pressure plate issue?



Hmm...somewhat. I'm fairly sure that the ailment exists, but I'm not sure how consistently serious it is. If you take a look at some of these test-ish shots, it ranges from fairly extreme: https://www.flickr.com/photos/12802682@N00/51329272576/sizes/o/ , https://www.flickr.com/photos/12802682@N00/51538676667/sizes/o/

To "not too bad" : https://www.flickr.com/photos/12802682@N00/51540388420/sizes/o/ , https://www.flickr.com/photos/12802682@N00/51540399080/sizes/o/

To "there, but not particularly noticeable" : https://www.flickr.com/photos/12802682@N00/51539472241/sizes/o/ , https://www.flickr.com/photos/12802682@N00/51538696217/sizes/o/

Interesting, right?

Frankly I don’t see what you are talking about.

The railroad fence photo with the wire fence dead on is an ok test.
The wire appears to be an equal amount out of focus.
The same with the detail seen through the fence. It’s equally in focus all over the image plane.

All the other photos have too much going on topographically to say anything for certain. But I don’t see any problems with them either.

Most of these triplets and Tessars has quite a curved DoF, especially at close ranges and at low (open) apertures. That might be what is tricking you?
Quite normal and even modern lenses has the problem to a lesser degree.

You need to take the classic image of a brick wall on high resolution film to say anything for certain.

The light leaks might be due to modern film not being wound tightly enough, and getting leaks during unloading and storage until development. You can fix that in a number of ways with pads and bushings in the right places.

 

[cptrios]

I think they're all a bit topographically hard to figure out! The railroad fence is definitely the obvious candidate, though.

Focus was on the bush in the center of the shot. Either f/5.6 or f/8, I don't remember. The tree on the left is quite a bit closer than the cars on the right, but the cars on the right are in nearly perfect focus and the tree is way out.

And the light leaks are actually reflections! The inner frame of the film gate is painted a not-matte-enough black, which I'm attempting to remedy.

 

[Nicholas Lindan]

You need to take the classic image of a brick wall on high resolution film to say anything for certain.

Agreed. Try it at full open (shallowest DOF) and 3 stops down (highest resolution).

Franky I can't see a whole lot wrong in the sample photos, things are just too ambiguous.

 

[Helge]

I think they're all a bit topographically hard to figure out! The railroad fence is definitely the obvious candidate, though.
View attachment 286799
Focus was on the bush in the center of the shot. Either f/5.6 or f/8, I don't remember. The tree on the left is quite a bit closer than the cars on the right, but the cars on the right are in nearly perfect focus and the tree is way out.
View attachment 286797

View attachment 286798

And the light leaks are actually reflections! The inner frame of the film gate is painted a not-matte-enough black, which I'm attempting to remedy.

The left example is from the extreme edge of the film plane and the other a bit further in. Grass and leaves are also a bit more ambiguous too WRT contrast. Both due to the diffuse lighting and the colours that are quite close.

I was referring however to this photo:
https://www.flickr.com/photos/12802682@N00/51540388420/sizes/k/

The light leaks looks very much like a film edge leak. Not like something that happened in camera.
The edge of the film gate would not really have a chance of creating that kind of pattern.
The anti halation dye of the film would take care of that kind of reflection from anything parallel to the film plane.
And a shiny surface parallel to the projected light would not create that kind of wavy, peaky pattern.

 

[shutterfinger]

Put the camera on a tripod. Focus on a test target that fills the frame. Ensure the film plane is parallel to the test target. Lock the shutter open. Place a ground glass on the film guides at the film plane (not the backing paper guides). Check focus with a loupe. A piece of plain glass or clear acrylic plastic cut to fit the film plane with strips of transparent tape next to each other without overlapping works for a test ground glass. Place tape side toward the lens.
Shooting hand held can introduce camera shake, composition can favor one side or the other.
I printed out 1951USAF test targets on glossy photo paper at the printer's highest resolution, cut them out on a rotary cutter, taped them to a 24x36 inch foam core with double sided tape. 1/32 difference between one side of the film plane to the test target and the other will produce focus test errors at 6 feet, lens wide open. The side of a building with textured wall or a brick wall will work also.
https://www.google.com/search?sa=X&source=univ&tbm=isch&q=Free+lens+test+chart&client=firefox-b-1-d&fir=raoopdv1WNUHLM%2CwmfjYu_6CAvH9M%2C_%3BdPzVxo_Z8OrfCM%2C4OXAR9tHJ-XdAM%2C_%3BezGj4I0Rcz8n_M%2CFkU0UraGqm0__M%2C_%3B7Liw5Q1YBw1XCM%2Cx52YmnNKndewmM%2C_%3B-djWHRq18MbEtM%2CSVPh-__0C9RdiM%2C_%3Bh99HpaGKDOlsGM%2CiJ0067lWJeghyM%2C_%3B2megYMjOLeCeKM%2CFkU0UraGqm0__M%2C_%3B9irFJIoKTP_0-M%2CARSoDpI6xSX_BM%2C_%3B5ojbE9vfqztMfM%2CFkU0UraGqm0__M%2C_%3BMxVZeifD9Te5mM%2CfIJMKXTI5ZGg8M%2C_&usg=AI4_-kQ6MII3ld1Lb1JRwz3urTH4xvRzwQ&ved=2ahUKEwiFiO7FrKrzAhWDNX0KHbkuC1UQjJkEegQIBxAC&biw=1920&bih=955&dpr=2

Pressure plates are often spring loaded. Pulling out on the low edge can correct compressed springs.

 

[cptrios]

Franky I can't see a whole lot wrong in the sample photos, things are just too ambiguous.

Well I'm glad people don't see much issue. I think even with its issues it's a great camera for the very small amount of money I paid. Not a Planar, obviously, but definitely the sharpest folder I've tried so far.

I was referring however to this photo:
https://www.flickr.com/photos/12802682@N00/51540388420/sizes/k/

The light leaks looks very much like a film edge leak. Not like something that happened in camera.
The edge of the film gate would not really have a chance of creating that kind of pattern.
The anti halation dye of the film would take care of that kind of reflection from anything parallel to the film plane.
And a shiny surface parallel to the projected light would not create that kind of wavy, peaky pattern.

Light leak is what I thought in the beginning, too, but I 'tested' that on a few frames by covering the lens and leaving the shutter open while I shined a flashlight everywhere I figured a leak could be. Nothing! However, when I put Shurtape around the edges of the gate, those bright spots disappeared. I even left one border untaped as a control, and that side still had issues. The 'phenomenon' is most pronounced and readable in this shot, where all of the leakish looking flares at the top of the frame correspond with highlights right up against the gate. I swear I'm not crazy!

 

[shutterfinger]

I was referring however to this photo:
https://www.flickr.com/photos/12802682@N00/51540388420/sizes/k/

Another possibility uneven development. The left edge is lighter in tone than the center or right.
A picture of the negative will reveal more than the print/scan from it.