Mamiya Super 23 Exposure Trouble

Ohio Sean · Sep 29, 2020

Hi, everyone,

I have a Mamiya super 23 that I shoot with the standard 100 mm 3.5 lens. I’m using a 6 x 9 K back film holder and having problems getting the top and bottom of my negatives to be completely exposed. For some reason a small band at the top and bottom of each shot comes out lighter than the rest of the image. I’ve taken the film back off, inspected it for any sort of obstructions, I’ve looked inside the camera for anything there, I’ve made sure that the adjustable bellows is completely compressed and flat at both ends and made sure the lens is properly mounted. Everything looks fine! Any ideas what the problem might be? Here’s an example of a print I made on Ilford multigrade RC paper with the trouble I’m talking about.
https://www.flickr.com/photos/184817499@N08/50288107978/in/dateposted-friend/
I’m shooting in the full 6x9 format with no mask etc. What would be the most likely problem?

Any help is greatly appreciated!

shutterfinger · Sep 29, 2020

Any troubleshooting of this type of a problem is best done with a picture/scan of the entire negative including the rebate/edges of the film.
Light edges in a print is due to high density in the negative edges, high density in the negative edges suggest a light leak. Seeing the edges of the negative will help determine if there is a light leak or not.
Being your sample is in portrait orientation I would look closely at the hinge and latch seals on the film holder/back.

gordrob · Sep 29, 2020

shutterfinger said:
Being your sample is in portrait orientation I would look closely at the hinge and latch seals on the film holder/back.

+1
I would expect that your seals on the back have deteriorated. Have a close look at all the foam seals on the back. If they appear to be the problem then replace them all. It is not a difficult project to replace the seals and are available on line.

ic-racer · Sep 29, 2020

Under exposure you show at the top and bottom of the print is consistent with mixing box not big enough for 6x9cm. Which enlarger? However, as mentioned, need to see the negative to know for sure.

Donald Qualls · Sep 29, 2020

Also, what lens on the enlarger? Seems like it gets soft at the ends, too. Looks a lot like you might have an 80mm or 90mm that almost covers the 6x9 frame on your enlarger.

Ohio Sean · Sep 29, 2020

Hi Again,

I bet this is an issue with a light leak the more I think about it. I'm sort of embarrassed now to have even asked. There's just so many opportunities for this with the Super 23 with the door to the film back, the mating seam between body and film back, and all the potential issues the bellows might present.

I apologize for sharing the picture I did. It was not the best option because it actually IS shot in landscape, but cropped (so no longer the full 6x9 or even a 6X6 square). So the light areas ARE at the top and bottom of the negative if the camera is held right-side-up.

Ic-Racer--anything is possible, but I doubt that is the issue due to the cropping I'm talking about above. My enlarger is an Omega B22 so my largest negative should be a 6x6. With the 6x9 format, I just lay the negative in the carrier and move it until I get something I can use for composition in the 6x6 format.

Donald Qualls--I'm using an 80mm for this, but as I said I'm never using more than the 6x6 area of any given negative. The light areas in these photos, being at the top and bottom of the negative as it sits in the carrier, are well within what the enlarger can handle. In addition--I don't have these same issues with my TLR or Holga--both 6x6.

Thanks everyone. I'll have a look at the light seals and let you know if that winds up being the issue!

Sean

shutterfinger · Sep 29, 2020

Ohio Sean said:
I just lay the negative in the carrier and move it until I get something I can use for composition in the 6x6 format.

Well you opened the door to more possibilities.
How was the film developed?

Ohio Sean said:
I'm sort of embarrassed now to have even asked.

Don't be, you can't learn without asking questions.

reddesert · Sep 29, 2020

Don't be embarrassed, light leaks are hard to track down. But it really helps to see the whole negative and rebate (unexposed edge). Even laying it on an evenly lit surface (light box, ipad screen, etc) and taking a cell phone photo will help.

The Super 23 Mamiya-type film backs (the S-shaped ones) have a light trap that is yarn or foam in a rectangular channel around the mating surface. This could go bad, and is not hard to replace, but it is already in a channel (like a labyrinth seal). There is also a strip of felt at the back hinge.

Another thing to look for is damaged blacking on either the film back or inside the camera that could be reflecting light from outside the film area onto the edges of the film.

Ohio Sean · Sep 29, 2020

Shutterfinger--Thanks for the encouragement. I've become a creature of habit at this point and always use Xtol. This is Fomapan 200 developed in Xtol 1+1 for 9:00. A single reel in a Patterson tank which I agitate for the entire first minute, then every 30 seconds. Bang it a couple time to dislodge bubbles etc. I wash for 4 minutes, use a Photographer's Formulary fixer for 4 minutes, wash for 10 minutes, then wash with distilled water for two with some stuff from Ilford (can't remember the name) that improves sheeting and prevents water spots. Hang to dry, cut and store. That's the process.

Reddesert--I know what you mean about the backs. This is a K back that is setup for 6x9 but originally came with masks for 6x6 and 6x4.5 (which I do not have). Therefore, it also has ruby windows for the smaller than 6x9 formats. My back has yarn as light seals--which usually last longer. It "looks" to be in great shape as does the back overall. I've looked everywhere inside the camera and the film back for damage or anything missing, but it all looks good. I wonder if I might just "fluff" the yearn seals a bit.

I see foam kits for this film back on the internet. Anyone know if regular black yarn will work or is that a bad idea? The foam gets sticky when it breaks down.

Thanks!

shutterfinger · Sep 29, 2020

Ohio Sean said:
A single reel in a Patterson tank which I agitate for the entire first minute, then every 30 seconds. Bang it a couple time to dislodge bubbles etc

Does the reel stay in position in the tank during agitation? Do you fill the tank with developer or do you just cover the reel?
+1 for Xtol 1:1
With 1 reel and just enough chemicals to cover the reel the reel goes out of and into solution on each inversion giving extra development at the edges of the film closest to the edges of the reel. Extra development = extra density = more exposure time under the enlarger.
I use stainless steel reels and tanks and put an empty reel on top if only developing one roll.
If you do not have a light box or tablet open a blank text document on your monitor/laptop screen, attach the film to the edges, take a picture of the negatives including edges of the film then post the image.

Ohio Sean · Sep 30, 2020

Hi, Again!
Yes--I'm sure the development process is going as intended and the film is completely immersed in the developer. I do not invert when developing. I use the little stick the tank came with and rotate. Additionally, I develop 120 film the same way for two other cameras without incident. The issue I'm having only involves the Super 23 camera.

These are all great ideas and areas to look for problems! Thank you!

Donald Qualls · Sep 30, 2020

If it happens only in the one camera, it's either a light leak or "bellows flare" (which can happen even in a camera with no bellows).

shutterfinger · Sep 30, 2020

Donald Qualls said:
it happens only in the one camera, it's either a light leak or "bellows flare" (which can happen even in a camera with no bellows).

make that When and +1.

MattKing · Sep 30, 2020

Ohio Sean said:
do not invert when developing. I use the little stick the tank came with and rotate.

If this is in a Paterson tank, this may be your problem.
Paterson specifically recommends against using that stick for any more than the first short portion of development, because using it more leads to uneven development.

reddesert · Sep 30, 2020

The OP should post a picture of the full negative including the rebate, otherwise suggestions and remedies are simply going to be speculation.

TwiggerS · Oct 8, 2020

recall the shooting condition of your photos, if some of them outdoor under straight light while others not, and the "high density" pattern are similar across all frames, it's more likely due to developing or scanning processes

John Koehrer · Oct 10, 2020

What's the diameter of the condenser? it is a 6X6 enlarger.

Mamiya Super 23 Exposure Trouble

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