Star photography question

[wchamilton]

I've been in my backyard for the past several nights trying to get some shots of the Milky Way while it's still in its summertime glory. I'm having some problems getting a decent shot, though, and was hoping someone here could point me in the right direction.

I have a Canon Rebel XSI with the standard 18-55mm kit lens with a UV filter on it (not sure if that works against me in trying this). I'm in a dark back yard, I have my camera on a tripod, I have the lens set to 18mm, am pointing it at what looks like a promising point in the sky and taking a 30 second exposure at 100 ISO, F5.6 and a 30 second exposure. So far, I've gotten a few stars but nothing like I would think.

Do I need to be using a higher ISO for this? I was thinking of 800, but I was concerned about noise, especially given the length of the exposure and the amount of black in the shot. Or is this a lost cause with the gear I have? I've only had the camera for about a month and haven't purchased any other lenses yet. I know I probably won't get spectacular shots but I would think showing the Milky Way in a shot wouldn't be out of the question with my setup.

Also, how exactly am I supposed to set this lens to focus at infinity? I wear glasses and am having a heck of a time getting the focus for this correct.

Thanks in advance.

[Trader]

Increasing the ISO will not help what you want to do. First thing I would suggest is to take off that UV filter, it is not helping in any way. Next thing I would try doing is using the 55mm end of your lens. Switch your focus mode into Manual and set it to infinaty. Give that a try and see what you come up with.

[BryanC]

Originally Posted by Trader

Increasing the ISO will not help what you want to do. First thing I would suggest is to take off that UV filter, it is not helping in any way. Next thing I would try doing is using the 55mm end of your lens. Switch your focus mode into Manual and set it to infinaty. Give that a try and see what you come up with.

Higher ISO is exactly what is needed (1600 at least), stay at the 18mm end of your lens, along with widest aperture, long exposure (30 seconds can work), focus at infinity, lose the UV filter, and a tripod. Very dark skies and the brightest area of the Milky Way that you can see are also must haves. I'm not familiar with your camera and it's noise at higher ISO's, but if you have noise reduction in camera, that can help. Try this and let us know the results.

[wchamilton]

Originally Posted by Trader

Increasing the ISO will not help what you want to do. First thing I would suggest is to take off that UV filter, it is not helping in any way. Next thing I would try doing is using the 55mm end of your lens. Switch your focus mode into Manual and set it to infinaty. Give that a try and see what you come up with.

I realized after my second attempt at this that the filter may not be helping matters at all. The other issue is the infinity focus... there's no infinity mark on my lens and I don't have alot of distant objects that time of night to lock focus on, so I assume the best thing is to grab a far away focus while it's still daylight and try it from there.

And aperture always confuses me... for something like this, I want the lower number, correct?

[Gonzo13]

Yes you want a smaller number for a larger aperture. Curiously though are you trying to get a photograph of stars or are you trying to get star trails? If you want trails then you need to get some form of a remote for your camera, turn on your remote shutter setting on the camera, set a low iso, a low f/# and from my experience a wide focal length is better especially if you want some foreground interest.

[wchamilton]

Originally Posted by Gonzo13

Yes you want a smaller number for a larger aperture. Curiously though are you trying to get a photograph of stars or are you trying to get star trails? If you want trails then you need to get some form of a remote for your camera, turn on your remote shutter setting on the camera, set a low iso, a low f/# and from my experience a wide focal length is better especially if you want some foreground interest.

Nope, not star trails. I'm trying for a view that makes it apparent that I'm shooting the Milky Way. So far, even if I open the raw image and am taking the exposure all the way up it just looks like a field of random stars and not the full-out star-speckled field I'm hoping for.

[BryanC]

Here's a link to a photo taken of the Milky Way by someone with a Rebel XTi. It was the closest to your camera I could find at the time.

Sagittarius Milky Way on Flickr - Photo Sharing!

His settings were:
Camera: Canon EOS Digital Rebel XTi
Exposure: 156 sec (156)
Aperture: f/4
Focal Length: 18 mm
ISO Speed: 1600
Exposure Bias: 0/3 EV

I'm not sure what the longest preset shutter time is on your camera. 30 seconds maybe? To get longer you would use bulb mode and a remote. Not too long though, or you will get 'trails' and not a sharp image. I have seen alot at the 30 second range that have come out nice, though.

Do a search on flickr, enter 'Milky Way' in the search. Alot of samples to see, and if you look at the exif info (settings) of them, you'll see that they are usually about the same:

Shorter Focal Length
Larger Aperture
Higher ISO
Longer Exposure
Tripod

Good luck and hope to see some of your shots!

Added: You have the right idea to find infinity on your focus. Do it during the day when you can see and make a note of where that's at.

[Elmo]

U omitted one key a mount for the amera that will allow you to track the star movement. This also assumes a guide scope.

[BryanC]

Originally Posted by Elmo

U omitted one key a mount for the amera that will allow you to track the star movement. This also assumes a guide scope.

Yes, if it's a longer exposure like the example. But, these shots can be achieved with 20-30 second exposures where just a tripod is needed. There's plenty of examples on flickr and on the web in general. Also, if you google 'Milky Way photography', there are hot-to's and tutorials along with more examples of these types of images that are achieved in this way.

[inkista]

Try looking at Samir Kharusi's pbase gallery. He has some helpful tips on astrophotography.