Long exposures in digital?

[keith_anderson7]

I have really enjoyed taking night photos with a film camera, whether it be star

trails, sunsets, or the tide hitting rocks on the shore while the sun is just

about down. Generally exposures are anywhere from 30 sec to 12 minutes. I've

tried to do this in digital but have never been all that happy with the results.

When I use film, I use velvia 50, set the aperature to the smallest the

particular lens will allow, and calculate light with a light meter. Simple

enough. When I try to duplicate this with a digital, I end up with so much

sensor noise and "hot" pixels it more or less is a flop no matter what I've

tried. Has anyone else had any success using digital for these types of photos?

If so, what's the secret?

 

Thanks!

[saskphotog]

One secret is a good camera. What camera were you using when you found the results so bad?

[photobiscuits]

for 'sensor noise and "hot" pixels', what was your ISO?

[keith_anderson7]

It's a Canon 300D, ISO 100, f/22, exposure from 30sec (minimum)

[berg_na]

Can you post a typical example of your results? I took this shot with a D100 at f/5.6 with a 10-min exposure. The bright dot in the center is not a hot pixel but the North star...<br><img src="http://img528.imageshack.us/img528/9171/sky040507al4.jpg" border="1">

[saskphotog]

Maybe you can get some help here:

 

http://www.dcresource.com/reviews/canon/digital_rebel_xt-review/index_pfv.shtml

[phule]

Did you enable noise reduction (which will do a dark frame subtraction after the shot is taken)?

[keith_anderson7]

Rob, I'll try that, I'll have to dig out the manual first though. Actually since I'm male, I'm not supposed to read the directions, am I? ;)

 

Berg, I'll take one and post tonight. I seem to have three hot spots on my sensor which are in the same place for every shot. If only it were just the north star. ;) Usually they look bad enough that I don't bother saving them so I don't have good (bad) examples handy.

[keith_anderson7]

Here's an example. It's not full size, but you can still see plenty of noise if you zoom in over the wood on the deck. The image is f/22 with a 20min exposure.

 

http://i159.photobucket.com/albums/t138/sothoth_forum/photonet/IMG_0094s.jpg

[keith_anderson7]

Oh, and I made a typo in a previous post, the camera I use is a Canon 350D, not a 300D.

[saskphotog]

Keith, a small point about the manual. A friend of mine pointed out that using the manual is sort of like cheating. Cheating is, of course, very manly, so feel free.

[berg_na]

Keith - That's a nice place you live in... Anyway, I don't see anything wrong with your shot, and you'll always get higher noise in areas that are underexposed, there isn't much you can do about it other than to try to reduce the noise through post processing which may also impact the image sharpness.

[keith_anderson7]

Berg,

 

That's not what I wanted to hear. Can you give me an answer that's more pleasant for me to hear (and accept)? Kidding of course.

 

I don't know about the rest of the world, but I personally hate resorting to photoshop. I'm a purist. Also, I'm never happy with the results when I do noise reduction (using the filters). Maybe I just stink at PS.

 

Anyway, thanks for the feedback. Unfortunately if you're correct, it means I will stick with film for my night photos.

[roger_smith4]

What are you using to process these files with? I find Lightroom gets rid of most of the hot pixels without me doing anything. I also do the dark frame subtraction for long exposures.