Starting deep sky astrophotography...pls help

[davidscanlan]

Hi All,

I want to attempt to take some decent images of M13 tonight using my canon eos 450D and 12" Lx200

Can anyone advise me on what I should take

What exposure?

What ISO?

ONe shot or a series of shots?

Do you know of any free image processing sofware I could use to touch up the photos afterwards?

Thanks

Dave

[xboxdevil]

Do a Google search for Registax, it can stack loads of images together. I use the movie mode on my camera and get Registax to convert it to a single picture with much more detail than a single snap.

[blinky]

Assuming you dont have a focal reducer I would try for as long an exposure as you can get without star trailing. Something like 3-5 mins should give something decent, or even a little longer if you can. Take as many shots as you can, also at the end cover the front of the tube and take around 10-15 shots at the same ISO and exposure as your main ones. Download DeepSkyStacker (it's free) and add the shots to that - the light frames are ones taken without the tube covered, dark frames are what you take with the front covered. Once added just let it stack using the defaults. As for editing try something like PaintShopPro, I think that may be free/trialware/shareware and should offer some decent options for editing.

[Bizibilder]

As above but use GIMP to process - its free and opensource software (gimp.org - I think!)

[ollypenrice]

3 to 5 minutes with a focal length of an almighty three metres is incredibly optimistic. Even with a focal length reduced to about 70 percent of that it is still wildly optimistic in my view. But of course do try it! I would have thought that you'd be trailing within 30 seconds even on a well aligned wedge. I have assumed you are talking about unguided imaging here.

The thing is to give it a go.The alignment of your wedge, the balance, the quality of your drives and PEC will all play a big role. My own feeling is that at that focal length 30 seconds will be tops.

Olly

[blinky]

Good point Olly - I was thinking this was guided!

[RichieJarvis]

Definitely go for multiple shots - I wouldn't use Registax to stack though - its really meant for Planetary images. I would recommend Deep Sky Stacker instead (also free) which is designed for stacking DSO's

Exposure - as said above - the longest you can get away with without trailing.

ISO - As you are unguided, its probably best to go for the highest your camera will support. The higher the ISO, the noisier the images though, so you'll need to stack more to remove the noise. If you were guiding, then I'd recommend 800 ISO.

Good luck - I look forward to seeing your results!

Cheers,

Richie