Rebel XTi for sky shooting, some questions?

I have been using my 30D for a year now, but have continued doing my

astrophotography with my Canon film cameras. I have not thought too much about

doing this with my 30D as I have other uses for it and still felt my film

cameras had some good uses still left in them. However, I find the convienence

of the digital world overtaking my photographic life.

 

So, I bought an XTi for the purpose of replacing these final tasks of my film

cameras and putting them away, more or less, for good. Why not use the 30D for

this, because I just don't want to, I have uses for it, I felt I needed a

digital backup or secondary camera anyway. I am no good with one camera, I

feel, and having only one digital camera when I shoot mostly digital seemed too

limiting.

 

However, I have not read or seen a whole lot on using Canon digital cameras such

as the XTi for shooting very long exposures. Is it reasonable to shoot say a

30min to hour long exposure with digital? I have seen some long exposure

digital shots with these cameras but I am confused as to whether they came out

as one frame that long or whether they are layered multiple shorter length

frames or something.

 

I love shooting star trails, and am intrigued by the possibility of doing this

with digital but wonder about the battery, image noise, and camera wear. Does

doing very long digital exposure degrade the sensor or electronics faster than

if you didn't shoot many long exposure shots? I must confess I am a little

ignorant or misinformed in this area of digital photography, as all I know is

what films to use and how to do long exposure shots with film cameras. I feel

like I have the rest of the digital world under control, though, this is the one

area I feel completely lacking in, and it is something I do a good bit just wish

it was with digital. I want to know more before I start doing this with my XTi.

 

Anyone else do very long exposures with their digital Canons? Suggestions?

Thanks, J.D.

I felt I must clarify...I know there are some advantages with digital and astrophotography, in that you can remove the low-pass filter, I've even read the sites on how to do it. This does not interest me at all. All I do is wide angle stuff, no telescopes, nothing really beyond what my Canon lenses cover about 20 to 400mm.

You are more experienced than I am with astrophotography but you might get some answers here: http://www.canon.co.jp/Imaging/astro/index-e.html

Here's another insightful article on shooting a star trail exposure with a 1Ds II and the Canon

timer remote:

http://www.naturephotographers.net/articles0407/ab0407-1.html

 

The article suggests that the batteries of some DSLRs might be the limiting factor in long

exposures.

I don't do a lot of such shooting. The linked articles cover most of the basics. I would add to

them the idea of looking at a program like Noise Ninja to get the final bits of noise out of the

images if and when you need that. The warmer that is mentioned is really quite useful and in

fact necessary in some circumstances when the temps and humidity dictate dew. Not much

else to add.

<p>I have now done a grand total of two star trails photos with my 300D but the second one did come out pretty well. <a href="http://www.photo.net/photo/5568246">This one</a> was about a 2.5h exposure, I started with a fresh battery and was still shooting with it the next day. I haven't done anything longer than 1-2 min with my 30D.</p>

 

<p>Now the other issue, noise! Even on this small image the noise is visable, I've had it printed as an 8x10" and it is ok from a distance. I haven't used noise ninja but I would be interested to hear if anyone thinks I'd get good results on something that bad.</p>

 

<p>The third issue is that there was red hilight down the right side of the photo, I have cropped most of it off but it is still a bit visable. I'm not sure what caused it but I'd be guessing at heat or something like that.</p>

 

<p>Anyway that's about all I know, I'd say it would definately be worth trying a 1 hour exposure or even longer (it's not going to cost you anything) but be aware of the limitations beyond that.</p>

Will, which ISO setting was that shot at? Still, I imagine you'd end up with a much less noisy

image by using Noise Ninja or Noiseware (which I find a little easier to use). Both have free

demo versions available so you might just want to download either of them and run the

image through it.

 

I ran the fairly small image you linked to through Noiseware and it come out much better.

Obviously, you need to fine tune the filter a little to not get rid of some of the star trail you

actually *want* in the image. But noise on the left side of the frame and right above the

mountain shades is almost totally gone.

<p>Thanks for that Patrick, I've been thinking about investing in some sort of noise reduction software for a while though mainly for indoor volleyball and swing dancing events (ISO 1600 - 3200 most of the time).</p>

 

<p>The star trails photo was shot at ISO 200, my understanding is that it would make the trails a bit wider/thicker since I was shooting at about 10 or 12 mm. I've taken a few other star photos now but they are only short exposures.</p>

 

<p><a href=" star photo</a></p>