Nice RB67, but there's this one little thing

[Maris]

I shoot mainly with view cameras and if I think I see a defect in image quality across the frame I repeat the shot with the camera upside down. If the defect swaps sides it's a camera/lens/film problem. If the defect stays in the same place it's a subject/lighting/flare problem. I guess a mamiya RB67 could be checked in the same way and the scanner as well.

 

[yessammassey]

Good to know the bent shutter tips are a feature. I was wondering how it could possibly have happened like that accidentally.

its not easy isolating a problem if your equipment isnt up to par to begin with. you will fix one thing n still have tge same problem n then fix something else n something else till you totally rehabed the entire camera. so one thing at a time?

one blade has a bent edge, thats normal.

its just a pita process of elimination piece by piece.

then after all that... you'll find out it happens no matter what you fixed because it was the scanner all along. try scaning using different orientations n see if it moves consistantly with the negative anyway? i know you say its in the neg.. but humor me?

scaners do weird things.
.

Yep, guess that's where I'm at. It's not looking like it's going to be open & shut case as to the cause, unless someone else who had the exact same problem happens across this thread, I guess. The discoloration is so subtle, I guess it's really hard to diagnose.

Thought I might save myself some trouble, but a step by step testing process is looking like the only way to resolve it.

And you're right about digital repro. Unless it's like one of those Hasselblad flex tension things, or a drum scanner, I've found that imperfectly flat film usually leads to some kind of aberration in the scan, other factors notwithstanding. I've switched the negatives from the first two example images around vertically & horizontally, flipped them over, used different parts of the glass. I get the sense the aberration would show up on an optical enlargement, but I don't have any color paper or chems at hand, and neither of the two photography stores in my metro area do prints from optical film enlargements.

EDIT:

i shoot with an RB67 both negative and positive film. Contact print your negatives or try using a chrome film to test the camera. Or you can look at chrome film directly and see exactly how the camera is performing. Running negative film thru a scanner leaves too much up to other issues. Good luck..

This is good advice. It's very strange; the one roll of Velvia I've shot so far wth this camera hasn't turned up any of the same problems, as far as I can tell. (Velvia is the only chrome I've got on hand, but it should be ideal for this purpose since the colors come out so saturated)

In fact the results from that roll had assuaged my trepidation about using the RB (I've been seeing the issue with the color negatives for some time), but it was back in my next roll of Portra.

I was also pretty careful with my light source placement using the Velvia. If the cause of the color shift is related to lens flare, it would make sense if it didn't show up.

This is the only frame out of the roll that showed any kind of aberration. Kind of orange on the bottom right. But I think it's just flare from the light source.



Also the Velvia was professionally developed & scanned. All the C41 stuff I do at home.

 

[wombat2go]

I can see the problems in your o/p
I hunted around for a C 41 photo with
Pro-S, with 90mm f/3.8 C which has reasonably constant colors on both sides ( taken in Oct 2015):
https://app.box.com/s/yxzg6ak5axfbi4m0mfwtpll3ygviki3z

 

[shutterfinger]

Around 1996/1997 I bought a Pro with 127mm lens and 120 roll film holder that was locked up and half exposed roll of Kodacolor in the holder. Pro SD bodies and K/L lens were available new so no repair manuals were available outside certified repair shops. I started dismantling the body and figured out how to release the lens so it could be removed, bottom plate, cocking shaft and gears. I reassembled it as was but without the lens, the body worked. Next I disassembled the lens and opened the shutter to find the main spring mounting shaft worn and not repairable. I found a newer 127mm lens on ebay that I could afford. I trashed the Kodacolor as it was 10 to 12 years beyond expiration. When the replacement lens arrived I loaded it with fresh film and went for a shoot. The roll film holder had multiple light leaks ans seal kits were not common. I went through 4 rolls of film before I got the leak around the wind lever solved.
I was able to sell it for what I had invested (cost) and the repair experience was my profit.

You have enough tips of what to look for and how to test from many sources in this thread so you should not have to solve it with a blindfold on as I did.
1. Verify the body is light tight. Fix any light leaks.
2. Test each lens/shutter on the same subject/lighting/exposure by swapping lens. Use a tripod if possible.
3. do not go to the local hardware store and get a sledge hammer then take your frustrations out on the camera.

P.S.
I like ISO 400 B&W for testing as it will show any irregularity in exposure or faint light leaks quickly. Irregularities are easy to see on the negative.

Your Velvia is much slower so it will not show the 1/4 stop or less exposure differences/faint light leaks like Portra 400 will.

 

[Alan Klein]

quote: It's very strange; the one roll of Velvia I've shot so far with this camera hasn't turned up any of the same problems, as far as I can tell.....Also the Velvia was professionally developed & scanned. All the C41 stuff I do at home.
==========================================================
Sounds like you found the answer. Not the camera. Either your processing or scanning.

 

[Alan Klein]

Have you scanned the Velvia?

 

[yessammassey]

I haven't. It was scanned by the lab. It's possible that they 'fixed' the scans any of the problems that came out in the negatives. But as shutterfinger says, the issue is so subtle, maybe the slow film isn't picking it up... that's assuming it's a light leak, though.

 

[itsdoable]

I'll mention 2 things.

Some lenses to have a colour cast change as you move away from center, more often with wide angles. I am not away that either of your lenses have that behaviour, but it's a relatively easy test by exposing a uniform white field.

Did you mask the negative when scanning (I know the scanning discussion is not really appropriate here, but we do it to post and discuss after all...). If the rebate, or cut end of the film is exposed to the scanning light, the film can act like a light pipe, and light entering the end of the film will travel along the length inside the acetate, and color cast the sides of the frame. This is particularly bad with the cut end of the film exposed with certain scanner light sources (try it sometime). It is also the reason negative carriers mask off the rebate when printing. Many medium format film holders mask to top and bottom of the film strip, but leave inter-frame space exposed, which often adds a color cast to that edge of the frame. Negative film has a magenta substrate, which leaves a blueish cast at the edge of the frame.

Re: Blue crop lines: I crop right to the edge of the frame, sometimes leaving a rebate - but that's me. I don't think there is such thing as a "correct" crop. And why would they make a film gate that had to be cropped to keep film flat and sharp - a lot of engineering went into keeping film flat...

 

[yessammassey]

I'm going to update this thread when I have the results from my next test. Beyond the concern of even having a fully workable camera, I just want to get down to the bottom of it at this point. It's weird, though; I see a lot more that I'd like to shoot with this camera when it's lying in pieces on my desk than I normally do when I take it out in the field. Funny how that works.

I went through 4 rolls of film before I got the leak around the wind lever solved.

So I've sealed up the camera; replaced all of the foam pieces around all of the mating surfaces. If there's still an issue, I don't think it'll be from a light leak.. but can you say a little more about this? Was it the wind lever on the film back? I don't see any foam around it. If it was the source of your leak, could you fix it or did you just have to get a new back?

I'll mention 2 things.
Some lenses to have a colour cast change as you move away from center, more often with wide angles. I am not away that either of your lenses have that behaviour, but it's a relatively easy test by exposing a uniform white field.

This will be the next test. Portra 400 on an evenly lit wall. I hate to waste Portra but since the problem includes color shifts I feel like it may reveal more than B&W. I'll have it processed at the lab.

Did you mask the negative when scanning (I know the scanning discussion is not really appropriate here, but we do it to post and discuss after all...). If the rebate, or cut end of the film is exposed to the scanning light, the film can act like a light pipe, and light entering the end of the film will travel along the length inside the acetate, and color cast the sides of the frame. This is particularly bad with the cut end of the film exposed with certain scanner light sources (try it sometime). It is also the reason negative carriers mask off the rebate when printing. Many medium format film holders mask to top and bottom of the film strip, but leave inter-frame space exposed, which often adds a color cast to that edge of the frame. Negative film has a magenta substrate, which leaves a blueish cast at the edge of the frame.

I didn't mask when photographing the negatives with my DSLR, but I did when I scanned them. That's interesting, though. Kind of like fiber optics.

Re: Blue crop lines: I crop right to the edge of the frame, sometimes leaving a rebate - but that's me. I don't think there is such thing as a "correct" crop. And why would they make a film gate that had to be cropped to keep film flat and sharp - a lot of engineering went into keeping film flat...

I just got caught up in fitting an actual '67' crop out of the negative. I thought that the reason I should crop the sides was because they didn't fit into a 7x6 rectangle. But I guess there's more to it than that.

 

[shutterfinger]

So I've sealed up the camera; replaced all of the foam pieces around all of the mating surfaces. If there's still an issue, I don't think it'll be from a light leak.. but can you say a little more about this? Was it the wind lever on the film back? I don't see any foam around it. If it was the source of your leak, could you fix it or did you just have to get a new back?

I took the top plate (cover) of the roll film holder off. There is a card stock thick seal under the cover. It was compressed and dried out. I ended up putting a thin coat of black RTV sealant on both sides of the gasket/seal and reattached the cover. If I remember correctly the section around the wind lever is very thin and tricky to get correct. The leak was a flare about 1/2 inch wide 1/4 inch in from the edge that tapered to a point 1/3 to 1/2 down the negative with the holder in landscape position.

 

[paul ron]

there arent any seals in the top section of an rb film insert. the plate all the mechanisms are on seals the light out. you must be confusing the rb with another back.

 

[shutterfinger]

you must be confusing the rb with another back.

NO, I'm not. It's like this one

copied off google.

The leak

The film is PMC 5059 Portra 160.

 

[Alan Klein]

Is there a "ding" or a warp in the back from it having been dropped at one point that's preventing the sealing stuff to actually seal there?

 

[shutterfinger]

I sold it in 1998 or 1999, don't remember. No dings, just in direct sun on a shelf or in a warm/hot closet for several years.

 

[shutterfinger]

RHS6636 sealing strip. You can not see them until the covers are removed.

 

[paul ron]

Sorry the seals you are refering to in the diagram are door seals n have nothing to do with under the top or bottom covers.... or any lever seals. OTOH its much easier to replace these seals if you take the top plate off to do them.

the internal seals in the body are to prevent light leaks in the left compartment, focusing knob side, where the mirror levers enter the inside dark space.

 

[shutterfinger]

Then don't believe me. The one I had definitely had a gasket/seal under the top cover and it definitely caused the problem.
P.S.
the body/back I had was a Pro not the ProS. The manual is for the Pro S not the Pro so older version parts will not be shown. There are two seals-light block shown, one in front of the wind lever and the other to the left of the wind lever that I do not remember seeing in the Pro holder I had.

 

[yessammassey]

I put a bright LED keychain in the mirror box, film back and lens attached, dark slide out, and waited in the darkroom for my eyes to adjust. No perceptible light leaks. To make doubly sure, I'll advance the film and replace the dark slide before lowering the mirror after every shot of this test roll. Will also use MLU + cable release and tripod.

I think this is how I'm going to use the frames:
1. 65mm, wide open, grey wall @ evenly lit ~2 meters
2. 90mm, same
3. 90mm, wide open, grey wall @ ~2 meters with lamp light just outside of frame on the right
4. 65mm, same
5. 65mm, wide open, outdoor sky with sun just outside of frame on the left
6. 90mm, same
7. 65mm, wide open, outdoor brick wall in diffuse/non-directional light
8. 90mm, same

Still trying to think of some good tests for frames 9 & 10

I will be trying to determine if:

• Any kind of color shift appears in the negatives. If exposure & color are even, then it was probably a light leak.
• The aberrations manifest in one lens or the other, or both
• The aberrations are caused by directional light sources. In which case maybe a hood is all that's needed.

Any suggestions for tests to perform with the last two frames? I was thinking of maybe attaching my polarizing filter and shooting the brick wall with a nearby incandescent light source just out of frame. I do sometimes use a polarizer. Can't remember if it was on or off for many of the frames that show the color aberration. I know that's a potentially big deal, but I didn't think a CPL would cause color shift...?

 

[MattKing]

A polarizer would be more likely to prevent an apparent colour shift.
Your change in colour is most likely to be due to the fact that the light at the edge of the scene is reflecting off the subject at a different angle than the light which reflecting off the subject closer to the centre. In addition, there might be a modest difference in the light transmission of the lens near the edge of the frame as compared to the centre.
Your lenses are high in quality. They are not, however, designed like process lenses, where evenness of illumination and flatness of field are emphasized at the expense of other factors.

 

[shutterfinger]

Frames 9 and 10 repeat frames 5 and 6 but with the sun on the right.

 

[paul ron]

Then don't believe me. The one I had definitely had a gasket/seal under the top cover and it definitely caused the problem.
P.S.
the body/back I had was a Pro not the ProS. The manual is for the Pro S not the Pro so older version parts will not be shown. There are two seals-light block shown, one in front of the wind lever and the other to the left of the wind lever that I do not remember seeing in the Pro holder I had.

I don't.

 

[yessammassey]

Yesterday I shot a test roll, and today I got it back from the lab. Let's see what we've got...

First, the interior wall pics. Please note that the orange glow along the bottom of some frames is an artifact from digital reproduction and not an element of the negatives themselves.

65mm KL @ f/4, 1/4sec (DSLR 'Scan')

65mm KL @ f/4, 1/4sec (Same frame, flatbed scanner output)

90mm C @ f/4, 1/4 sec (DSLR 'Scan')

For reference, here's the same scene from a digital Micro 4/3 camera, set atop the RB67 (which dwarfs it).

This is not related to the issue at hand, but note that the light transmission between these two lenses is dramatically different. The 65mm has more vignetting, which is to be expected, but the 'hot spot' in the middle of the frame is much brighter than the 90mm, too. So illumination change across the frame is much broader on the 65mm. In the middle, the 90mm looks underexposed by comparison. I'd expect that stopping down reduces the difference.

[The shots with an incandescent lamp placed on the edge of the frame showed nothing significantly different.]

I realize now that settling for the most evenly-lit wall in my house at the time may not have been enough to get a scene that I could draw unassailable conclusions from. There is a very obvious color shift from magenta/blue on the left to yellow/green on the right, but let's take it outside for something with no chance of mixed lighting.

Exterior brick wall. (All DSLR scans from here on. The flatbed scans showed pretty much the same things, just with slightly bluer cast. I think the relative color changes within individual frames are preserved in both scan types.)

65mm KL @ f/4, 1/125 sec

90mm C @ f/4, 1/125 sec (If there is color shift anywhere in these two pics, it is perceptible in the difference between the rightmost and leftmost groups of four square bricks along the masonry embellishment.

The day was very overcast. I wasn't able to use the sun to induce flare. This wall was close to evenly lit by the diffuse outdoor light. I thought red brick would be a good choice for testing color shift, even though it's not solid, as I first noticed the issue in the red curbs of parking lots.

I didn't have a clear sky, but I turned the camera to face the sun and shot four exposures. Only one is reproduced here, as the other three were effectively the same. Changing lenses obviously changed the field of view, but adding the CPL didn't make any difference except in the appearance of the reflections on the window and leaves. All four images were slightly darker and warmer on the left.

65mm KL @ f/8, 1/400 sec

I took 5x5 point samples with the eyedropper tool along the blue eave from three spots on each side of the frame and placed swatches side-by-side for comparison. In real life, the blue eave was continuous in tone, with no real perceptible change in hue or illumination. Same with the sky. Change in the color/luminance of the brickwork present in this last image is apparent without any swatch comparison, I think.

...

So, here's what I think I can declare now:

1. The color shift is not due to any specific characteristic of an individual lens.
2. The color shift is not due to the addition of a polarizing filter.
3. The color shift does not appear solely in negatives developed in my haphazard home wet lab.

Given statements one and two, it's not likely that the color shift is due to an optical effect from either lens, nor is it due to the addition of a CPL. It is unlikely that both lenses suffer from the same optical flaw.

Given statement three, the color shift is not a result of old/contaminated development chemicals, bad temperature control during development, or incorrect development times. Except for the color shifts, everything appears to be even.

The only thing I can image causing this is some kind of very small light leak. But I'm evidently failing to see where the leak is. Maybe I need to buy a new film back... maybe I need a new body.

Any ideas, anyone?

 

[shutterfinger]

Your eyes need calibration.
Ones eyes compensate for minor differences in tone via perception as one knows or assumes the color should not change even though it appears different in different lighting.
Film does not compensate for anything, it only records what it sees. Blue flowers often come out purple tint, pink comes out with a redish tint. The cream centers of the gladiolas in the flare samples are color correct but the edges are reder.

A center filter for the 65mm lens should help even out the exposure if one exists. Center filters can cost as much as the lens.

Your image, eyedropper center of the marked area starting on the far left R-76, G-106,B-132; R-122, G-151, B-185; left center just above the top of the marked area which is more in line with the other two areas R-102, G-133, B-164; R-89, G-118, B-150. Converting to grayscale block 1-46%, block 2-46%, block 2a-46%, block 3-49%. PS7 used as that is what I have on this computer. Right side not checked.

 

[Theo Sulphate]

Ask yourself whether these differences you perceive are important to you.

If so, perhaps these lenses, or even film photography, will not be satisfactory for you because there are so many factors that make the image imperfect.

I do not think you have a light leak; the color shift effect is too subtle.

 

[paul ron]

I don't see any light leaks in your pix. but if you still suspect that to be the cause, then take one more test frame.

the back loaded with film n ready to shoot. expose one frame as such....

with the lens off n front body cap on. extend the bellows all the way out. fire the camera so the mirror is up. from the outside, either shine a bright light or take it outside n completely bath the camera in the sun.

now drop the mirror n finish your roll. if there are any light leaks the unexposed frame you just made will reveal it as plain as day.