Problems with long exposures

Hi everyone.

I've been recently doing some extended exposures at night with my 4x5 camera. It's a challenge of course to focus and compose and all that with the relatively slow lenses I have, but unfortunately by the time I get back from work, it's dark, and I don't want shooting to be something relegated to teh weekends. So I've been getting the hang of it, but I seem to have some kind of problem with vibration or something.

It doesn't seem to happen on every negative, but it happens more often on the exposures that are on the long side, from tens of minutes to hours (the longest so far is 2hr). There will be 2 images, on a mm or two out of registration with the first. Both images are "sharp" I suppose, but the sheet is of course ruined by this problem.

This suggests to me that the camera is moving once, because if it were a vibration or movement that happened continuously the whole thing would just be a blur. Or if it happened once every few minutes I'd see several distinct exposures.

So... I don't know what to do. Try to plant the tripod in softer ground? Maybe the film is shifting in the holder, can I ... tape it to the holder?? (this sounds like a bad idea though...)

well anyone who has figured this out, let me know.

Thanks!

-Tadge

tadge.net

Tadge,

Film: It sounds like the film may be shifting in the holder. If temperatures or humidity are changing during a 2 hour exposure, this could affect it. Try tapping the film holder gently against the bottom edge before putting it in place in the camera.

Tripod: Is it completely tight? Is it heavy enough? Is there wind?

Camera: Are all movements completely tight and locked down well? Is the lens board well seated in the camera so it cannot shift if the wind blows on the cable release?

Tadge -

I suspect film movement, and Tim's suggestion about tapping the holder is a very good idea. Keep in mind that "bottom" refers to the orientation of the holder in the back of the camera - one common risk with long exposures is for the film to slide downward during the exposure.

A variation on this theme is for the film to "pop" in the holder during the exposure. This can happen because pulling the darkslide exposes the film to air. It's particularly a risk going into the Fall when the nights are cooler. A potantial solution to this is to pull the slide and then pause for a few seconds to allow the film to acclimate to the environment before opening the shutter.

Louie

Nothing really to add to the excellent responses above, except to underline the likelihood of film shift/movement being the problem. It's something that bedeviled me for many months before I realised what was happening and I can't tell you how many shots were ruined because of it. Take the already listed precautions and I bet you'll never get another double image.

Film movement in the film holder is probably correct. I shot some interiors in an old train station once that had that double image. I thought at the time that it was caused by the 5 o'clock rush hour traffic on the freeway near the building. I returned at a different time and did not have a problem leading me to believe I was correct. Now I am not so sure.

leec

Thanks everyone. Good to know that it's a problem other people have had, so it's not just me.

I will try letting the film settle for a few minues before exposing... after all, if I'm waiting around for an hour, an extra few minutes to save the image is certainly worth it.

Also now that I look, it is only in photos that were in the vertical orientation. Well, and one horizontal one, but I think I actually bumped the camera at some point during that one (doh!) so I wasn't expecting that to come out.

Well there's more and more darkness every day to shoot in, so I'm off to go expose more film! Thanks!

-Tadge

Pop a little bit of double sided tape to the center of the septum on your holder.

CP Goerz

The other responses are probably right about likely causes of the problem. But you might also consider the possibility that the front is shifting. With my camera, if I don't tighten down sufficiently, the front can shift its position unexpectedly.

I had this exact problem at night, and I think film shift was a problem for me. After I pull the darkslide, I will tap the holder a couple of times and this has helped with my 'double' exposure problems.





I think the slider was occasionally catching the film and pulling it up when I had the back in vertical composition. Never had the problem in horizontal...