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01/18/2006 08:52:25 PM · #1
I'm still thinking of getting one of those, but I'll have to save up a ton or two. I'd love to get those cameras that have really slow shutter speeds. Something slow enough to catch star trails. Anything? I mean is 30 seconds good enough? I've seen some say 45 minute exposure of something, that's the shutter speed right?
01/18/2006 08:53:53 PM · #2
Anything longer than 30 seconds is in Bulb Mode where the shutter is open for as long as you want. I did star trails once in the desert where I loaded a fresh new battery and it stayed open for about 2 hours ;) Kinda fun stuff.

01/18/2006 08:54:08 PM · #3
haven't done it, but you might look through the Astrophotography Gallery.
01/18/2006 10:28:42 PM · #4
With a wide angle lens, you'll just begin to see trails at 30 seconds; you need exposures of many minutes to really get good trails. It's usually a good idea to break up your exposure into several shorter exposures, and combine them later in post processing. This works great, as long as the next exposure always starts immediatley after the last one ends (no time gaps).
01/18/2006 10:35:18 PM · #5
Most of the DSLR's have a bulb mode that will go 8 to 10 minutes in one exposure.
But I have seen some beautiful star trails that were 5 1/2 hour exposures!
01/18/2006 10:55:29 PM · #6
I have a magazine here where the guy taking pix of the stars had a 10 hour exposure.. it was unreal
01/19/2006 05:26:48 AM · #7
DSLRs are good, but it wouldn't be my first choice for star trails because of the battery drain and the constraints that would put you under (unless you can find a location where you can run it off mains power without getting light pollution ruining your shots). It's still good having a bulb setting and I could see myself using it for exposures as long as a few minutes.

If you want to do star trails, I'd suggest getting an old manual camera - SLR, TLR or rangefinder - that has a bulb setting. Because it all works mechanically, it's not using the battery, hence no battery drain so you can keep the shutter open for as long as you like. Use a slow film, around ISO 100, and a narrow aperture (around f-16), so that the sky remains black instead of a murky blue-grey.

Message edited by author 2006-01-19 05:27:50.
01/19/2006 06:28:28 AM · #8
If you intend on driving out to a remote location, you could always buy one of those DC to AC converters that you plug into your auxillary power adapter on your automobile.

You could roll the window down a little in order to keep the door shut to avoid unneeded light pollution from the vehicle. A 10 hour exposure might not be enough to completely drain a car battery that is in good shape with a full charge. Just in case, bring a friend with their own car...
01/19/2006 08:17:00 AM · #9
Originally posted by Ombra_foto:

Most of the DSLR's have a bulb mode that will go 8 to 10 minutes in one exposure.
But I have seen some beautiful star trails that were 5 1/2 hour exposures!


Actually, bulb (at least on the 10D) will allow the exposure to last as long as the camera has power, some number of hours if using batteries, indefinitely if you can externally power the camera.

You will have noise problems with exposures that long. It's better to make a series of images and "stack" them.
09/29/2006 09:40:52 AM · #10
Originally posted by Spazmo99:

You will have noise problems with exposures that long. It's better to make a series of images and "stack" them.


The problem with stacking exposures is that many P&S camera have automatic long exposure noise reduction (at least mine does), that will cause a gap in the trails.
09/29/2006 11:44:55 AM · #11
Originally posted by Raziel:

Originally posted by Spazmo99:

You will have noise problems with exposures that long. It's better to make a series of images and "stack" them.


The problem with stacking exposures is that many P&S camera have automatic long exposure noise reduction (at least mine does), that will cause a gap in the trails.


My Panasonic doesn't do noise reduction most of the time, but it still takes forever to process the image and display it on the screen. That's what really kills me. That and the longest shutter speed being 8s. I have automatic noise reduction disabled on mine, I'm sure you can do that on most cameras.
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