Light leak diagnosis issues

[Josh Harmon]

Hello!

Long time APUG user/lurker but haven't posted in quite a while and I apologize if this is a redundant post; I don't know who else to ask or where else to post.

Recently I purchased a Crown Graphic along with 17 holders from a retired high school photo professor as a foray into true 4x5 large format. Doing my do diligence, I asked about issues with light leaks as well as if the shutter worked properly. According to the the seller everything was working completely and I believed him based upon the pretty good (to very good) condition of the camera and holders (several of the holders were/are new in their originally Linhof packaging).

Still, being skeptical, I shot a few throwaway sheets to test the abilities of the camera and for light leaks. These few sheets didn't reveal any major leaks, aside from a few small streaks I attributed to my processing methods. I processed those sheets using the 'taco' method in a Patterson knockoff brand tank where the inner post somehow let light creep in. Overall I felt quite confident in the camera so I bought equipment to tray develop and figured I was all set.

I went on a trip last week up to Highway 395 and the Eastern Sierras as both a break from life but also become familiar with this new camera and expand my large format technique and eye. I also brought with me my Pentax 6x7 system. To make a long story short(er) all my sheets (20 of them, Ilford Delta 100) have light streaks and of those I've developed so far most are unusable. I'm not terribly put out since I still have 12 rolls of 120 from my Pentax and it was great LF practice but I would like to diagnose where the leaks are to fix them or my technique.

What I am wondering specifically is if it's user error, bad bellows, bad holders, or a bad lens board. Attached is a scanned sheet that shows the leaks prevalent in all the sheets I've processed so far.


Tech notes:
Crown Graphic w/ Kodak Optar 135mm f/4.7
Holders range from never before used Linhof's to battered old Fidelity's. I marked each holder and have notes regarded which shots come from which one.
Ilford Delta 100 film processed in trays in complete darkness with d76 1:1
The bottom two horizontal streaks are on all the sheets so far. The top leak is only visible in some sheets (about 2/3rds of them)

Note:
I have been shooting and processing film for six years and this is not my first time using a large format camera. In college I shot with a Calumet Monorail and processed sheets with a Jobo system and never experienced these issues before. By no means am I an expert but neither am I a complete novice.

Thanks!

Josh Harmon
joshharmonimages.com


Mild front rise to bring the sky in. 1/10sec f/22 w/ orange filter

 

[Jim Jones]

You've eliminated the film holders. The common way to check for a bellows leak is to insert a light bulb into the bellows through the lens board frame in a dark room and look for light coming out anywhere. Then do the same through the rear with the ground glass removed. The seam for the bellows is on the bottom, and occasionally they do open up. There is also the possibility of a hole on the lens board that once was used to mount a solenoid.

 

[John Koehrer]

The "image" at top looks like a pinhole image. Is there anything at the front of the camera that's got a similar form.
I kinda like Jim's suggestion of a hole in the lens board.

 

[canuhead]

possible that the bellows were more extended during your trip = light leaks ? did you fully extend them during your quick test ? if the folds were tighter, that might mask any issues.

 

[shutterfinger]

A common fault is the light trap slot in the film holder seat of the back has dirt in it and or the left end corners of the film holder seat have dirt/debris built up preventing the film holder from seating properly. The top of the image has a pattern I have never seen before, looks like a double pin hole exposure, streaks on the bottom may be due to improper film holder seating in the camera.

I'm across the bay from you if you want/need to bring it over.

 

[Doremus Scudder]

It's not the holder light trap because the light-struck areas are along the longitudinal sides of the film, not at either end. Besides, with all those holders being used, you'd expect most of them to be light-tight (and certainly not all have the same problem).

It looks more light the camera back is not seated properly or a light seal is missing along those sides.

When you do your test for pinholes, do it again with the back on and insert the light source through the lens opening (with the lensboard removed) and check the back and where it seats for leaks as well. Do this with a filmholder inserted too and check how it seats, especially on the long sides.

I'll bet you'll find your problem soon.

Best,

Doremus

 

[Josh Harmon]

Thanks everyone for the recommendations and ideas!

I agree with Jim and Doremus that it isn't a holder issue given that the leaks are not near the light traps of the holder.

As for John's suggestion that it might be an unwanted pinhole image, that got me thinking a bit harder. With that idea in mind I did take Jim's idea and performed a 'lightbulb test'. At first I could not find anything, but after extending the bellows out a bit I angled my phone's flashlight all the way back, inside the body but outside the bellows, finding that the first bellows fold has a slight tear. Looking at the ground glass I could see a double pinhole image of the single light source. Moving the light around where the bellows connects to the body I found a few other places that light was getting through. So that settles that mystery!

Next question, does anyone know of a source to find replacement bellows? Or would it be worth saving for a more featured field camera (I've seen old Tachiharas for ~$600)? I'm going to temporarily tape things up with gaff tape but wouldn't mind fully solving the problem.

Thanks again!

Josh

Shutterfinger, I work in Redwood City am actually moving to that area very soon. I'd love to meet up and talk shop with another analog user!

 

[shutterfinger]

Do Not use tape to patch light leaks in bellows. Gaffers will dry out in a few months and leave a non removable white residue.
PM sent.

 

[Jim Jones]

For small pinholes, I scrub artist's black liquid acrylic paint thoroughly into the fabric bellows liner with an old soft toothbrush. Let it thoroughly dry before compressing the bellows. It would be worth a try, even on a small tear.

 

[John Koehrer]

I've used Jim's method in the past & it worked out OK.

There are a couple of bellows makers around. For first hand recommendations
Here at APUG(of course) and LFPF(large format photographeers forum)

 

[RobC]

looks like some heavenly body or alien spaceship in your image. Very cool. On the other hand it is more likely a good capture of your camera focus rail and internal bellows

 

[adelorenzo]

For a temporary "fix" just throw your dark cloth over the top of the bellows before you pull the dark slide. Even with a light-tight camera I normally do this just to reduce any chance of a light leak.

eBay should have replacement bellows for your camera.