Long Exposures: Starting Point

[Alex Hawley]

I'm going to try some long exposures; basicaly, still lifes in a darkened room that will take several minutes.

Anyone have a good idea on a time to start with? 10 minutes, 15 minutes, 30 minutes? I'm using 100 or 200 speed B&W film.

 

[glbeas]

A lot depends on the room illumination and type of film used and aperture and bellows factor (if needed) on top of the reciprocity corrections for the particular film used. Do some measuring and get back to us.
Reciprocity failure will increase the contrast so I would think about fill reflectors to lower the scene contrast to compensate.

 

[Donald Miller]

Alex,

Since you said that you were doing still lifes, I would imagine that you may be into bellows extension compensation territory. I have had that screw up more then a few exposures.

Additionally the fstop will need to be considered. As degree of magnification increases the need for smaller fstops (to hold depth of field) increases as well.

What I would do in this situation would be to set up the camera and using a strong light be sure that my subject was in focus. Next I would measure bellows extension. Next I would measure ambient light at the subject level. Next I would calculate my exposure. Next I would add my bellows extension factor. Then I would calculate reciprocity for that exposure. That would then be my exposure. Good luck.

 

[Alex Hawley]

That's essentially what I'm doing Don, except I don't have a meter sensitive enough to make a measurement with. What I'm doing is similar to making star trails except its indoors with a still subject. My hope is to expose long enough so that enough light registars on the film to make a normal image. The advantage is there's no directional light on the subject. So its illumination should be very even.

A long time ago, back in the juvenile years, we shot a landscape like this with kodachrome. Just opened the lens for 30 minutes and it worked. Got the real colors of the vegetation without any sunlight on it.

Maybe I should just go and start with a 20 minute exposure and see what happens. If I'm half-way successful, I'll post in in the Gallery.
Cheers to All,
Alex

 

[Donald Miller]

Alex,

At the length of exposures that you are dealing with even 5 or 10 minutes will only amount to a fraction of a stop. As you know black and white has a lot more latitude then Kodachrome. I would expose for a half hour and process the film. Since you develop by inspection it should be fairly straightforward. Good luck...look forward to seeing your results.

 

[Alex Hawley]

Quick report on the first trial. It failed. I exposed one for 20 minutes and another for 30 minutes. Both were too much but there was just a faint bit of image on the 20 minute neg. More R&D ahead. Thanks for all the suggestions!