Fog on polaroid 405 film back - any advice?

[Andy M]

Hi All

Can anyone offer some advice as to the fog off my Polaroid 405 film back? This is a pinhole front (shop bought 0.1mm and properly lens mounted) on a Sinar f1.

The exposure is long (about 2 hours) and the film is Fuji fp100c. I'm tracking the sun (heavily Nd filtered).

The fog is coming from the 'dark slider' end and not the 'roller' end off the back. I think it is the seal on the slider? I only get it with long exposures of 20 seconds plus.

Anyone had similar issues? Or can offer advice? I'm looking for a replacement back, but can't find one anywhere...

Much appreciated

Andy M

[Jim Noel]

apparently you have a leak where the dark slide goes. keep the camera covered with dark cloth during exposure.

[Joseph Dickerson]

Are you removing the dark slide completely? If so, you might try just pulling it out as far as the (blue) line on the slide. At least mine had a blue line. If yours lacks the line it's an easy matter to add one.

As Jim says, keeping the camera covered with the dark cloth is also good advice.

JD

[Andy M]

Thanks Joseph/Jim - Appreicated - I will give that a try.

[Louie Powell]

Andy -

I have a 405 that delivered similar results. Here's what I concluded:

The tab at the end of the darkslide is fairly small. And because the holder is relatively small compared with the full 4x5 frame, that tab often ends up in a position where is separated from the camera back by only a fraction of an inch. As a result, it is easy to inadvertently pull the holder away from the camera back when pulling or reinserting the camera back, especially if you are like me and have fat fingers. That may not be an issue when pulling out the darkslide, but it can cause fogging when reinserting it. Once I became aware of that problem and started being more careful about how I maniulated the darkslide and the problem went away.

The darkslide in a 405 was not designed to be removed entirely. There is a red line on the slide that indicates how far it should extend.