90mm Schneider 4x5 lens problem?

[Paul Ron]

extend the bellows all the way, put a bright light inside. in a dark room, look over the entire camera for light leaking out from the mounted lens, the filmback, and bellows.

[Jerry Bodine]

Colonel, you may get a response from someone suggesting use of a torch rather than a flashlight to look for light leaks ... don't do it, as the flames would probably do more damage than good.

[Robert Opheim]

I have had light leaks from sunlight directly coming through the dark-slide opening when the sun was in alignment with the film holder opening. Years ago a photographer that actively shot 8x10, and 11x14 in Seattle told me that you need to cover the rear of the film holder when you pull out the dark-slide. He used his dark cloth. Recently I have had a reminder of this with a 3/4 inch light leak on two exact shots.

[Bob Salomon]

I have had light leaks from sunlight directly coming through the dark-slide opening when the sun was in alignment with the film holder opening. Years ago a photographer that actively shot 8x10, and 11x14 in Seattle told me that you need to cover the rear of the film holder when you pull out the dark-slide. He used his dark cloth. Recently I have had a reminder of this with a 3/4 inch light leak on two exact shots.

You should also pull the dark slide out only as far as needed to uncover the film and not out of the slot to minimize the chance of fogging.
But did the op look at his diaphragm and make sure that all the leaves are in proper position?

[ColonelKurtz]

Thanks, Doremus. I did all checks, and the only thing I can think of is improper darkslide removal or re-insertion, which I very likely could have done. Will have to make sure I pinch the back to the camera body from here on out.

[ColonelKurtz]

@Jerry Bodine LOL. Its a brand new Chamonix view camera that I did check for light leaks on, and there are none...

[ColonelKurtz]

Got a pretty much identical light leak on black and white film, so I'm thinking its the film holder. Since I didn't keep notes, I'm going to have to make the mistake at least one more time, before I find the suspect film holder, but the process of elimination will narrow this down.

[Mark Woods]

Well, the problem is now known.

[ColonelKurtz]

Yep, the big auction site is a gamble, as ever. Although I do pull my dark slides all the way out, when making a photo. I'm going to not pull the dark slide completely out on these next 10 exposures (I've only got 5 film holders), and see if that makes a difference.

[Mark Woods]

Have you thought about putting the film holders in the camera without the dark slides and putting a flashlight over the opening to see if you can see any light? Might be a short cut to finding the culprit.