DSLR Another stupid question

[Guest Madatter]

I have been taking a few dso photographs with my 40d connected straight to my scope, the results are ok but as i don't know what they should look like, Ive been exploring the internet and have found quite a few that are using the same setup to me.

The problem is where does the magnification come from if your not using EPs? some of these photographs look like they used the Hubble to take them.

[Guest Kheldar]

The magnification (or better described as the field of view) comes from the telescope itself (focal length) and the size of the sensor you are using. The telescope is effectively a lens ... if you wanted to get a much smaller field of view (say a bird on the horizon) you would use a long lens

Believe it or not, for most things, you don't want magnification!

Maybe some specific examples might help of what you're trying to do?

Edited October 9, 2012 by Kheldar

[Guest Steve]

Hi Steve, (we need to stick together),

Are you taking multiple images and stacking? This makes a huge difference to what you see in your images. I've just started down this road connecting my Canon 450D to my laptop and using BackyardEOS to control the camera and Deep Sky Stacker to process - and I've just got the bits to start Autoguiding so I can take longer exposures without star trails.

There's lots of info on these in the Imaging sections on the forum.

[Sheila]

Hi

I have a modded 40D canon camera and if you look in DSO's in imaging on the forum you will see the first image I took of M31 (first attempt at DSO's) this was taken straight from the camera with normal lens on. I took bout 200 subs and then stacked and got quite pleasing image. There are other examples in there of what you can expect when attached to the scope as well.

Unfortunately now i am going down this route I find that the bank balance dwindles significantly with all the stuff, software, guiding etc etc.

Be aware if you move to the dark side you have to have deeper pockets LOL

Sheila

[Guest Madatter]

The magnification (or better described as the field of view) comes from the telescope itself (focal length) and the size of the sensor you are using. The telescope is effectively a lens ... if you wanted to get a much smaller field of view (say a bird on the horizon) you would use a long lens

Believe it or not, for most things, you don't want magnification!

Maybe some specific examples might help of what you're trying to do?

Thanks, I think that answers my question, I thought they might be using digital zoom by cropping the image.

Hi Steve, (we need to stick together),

Are you taking multiple images and stacking? This makes a huge difference to what you see in your images. I've just started down this road connecting my Canon 450D to my laptop and using BackyardEOS to control the camera and Deep Sky Stacker to process - and I've just got the bits to start Autoguiding so I can take longer exposures without star trails.

There's lots of info on these in the Imaging sections on the forum.

looks like we are doing the same thing, I'm using the software and a 40d I haven't go to Autoguiding yet, just sticking to short exposures.

I have a really bad street light problem and I find using less than 15s exposures helps to keep it under control.

[Perkil8r]

I don't use any digital zooms or lenses, just straight on the scope. I do crop nearly all of my images due to bad bits around the edges. This is caused by the optics not being great right to the edge. Better scopes, field flatteners etc will help a lot with that, but I guess most folks still crop a bit off even then. There is a way of increasing the size of the image which is using drizzle techniques in the stacking process, I've tried it, but it doesn't really help much.

Always make sure you shoot in "RAW" format, Jpegs lose detail, RAW don't. And as above, take lots and stack them. You'd be suprised how big the images are at 100% size. And as Stephen will tell you, there are three very important things..... Focus, Focus, Focus.