View Full Version : Astrophotography Question

2004-Apr-28, 08:54 PM
OK, yesterday morning it was my own fault for not loading film correctly into the camera, while attempting to photograph Bradfield. #-o

But this morning I know the film advanced and several exposures were taken, yet the developed negative strip looked as if absolutely nothing was exposed. I checked the camera and the shutter is working in the manual mode. The lens cap was also removed (it was in my pocket, and I could see the brighter stars in the SLR viewfinder before I "took" the pictures).

To my mind this leads to one conclusion: I severely underexposed the film. I used exposure times on the order of 10 seconds, using fresh Kodak 800 ASA film (C-41 process).

Should the exposure times been minutes instead of seconds?


2004-Apr-28, 10:19 PM
You left out your f-stop & lens details. Those would be relevant; big difference if you're doing f/1.2 or f/22.

2004-Apr-28, 10:32 PM
Right... I just now realized it myself.

35 mm Canon AV-1 camera, manual mode (an oldie, but a goodie).

70-205 mm zoom lens (lens set at 70 mm this morning because I couldn't spot Bradfield in the clouds, but I thought I would "take a chance" anyway)

F/4.5 (as wide open as I could get), focused to infinity (checked with visible stars and distant farmhouse lights).

800 ASA film

7 second exposure (some were 3 seconds, some were 5 seconds)

No discernable density changes on the "white" developed film negative.

NOTE: on spaceweather.com, there are several nice photos, and one of them lists a 30-second exposure time, so... that sort of answers my question (although it doesn't give any other particulars).

Tomorrow, weather permitting (and right now it doesn't look good), I'll try some longer exposure times. At this point I have invested enough time, that I just have to get something.

2004-Apr-28, 10:32 PM
Ouch! Sorry to hear that. I know I've been thinking about trying my hand at some astrophotography in the near future. If nothing else, I now have an idea about what not to do :wink: .

I did a little looking around and found this page (http://voltaire.csun.edu/cometshoot.html) that referenced comets specifically. It doesn't look like it's a completely up-to-date page (it's talking about shooting Hale-Bopp), but should help you out. The bottom of the page has link to the other imaging hints on the site.

The one thing that I looked for and saw on the page was that the author talked about exposure times going from 1 to 20 minutes.

Hope this helps.

Edit: I was responding directly to OP, but a couple of posts snuck in between the time I started and finished (I hate it when work gets in the way of BABB)