Astrophotography

[Paul.L]

Hello people, I was wondering if anyone would be so kind as to help me a little getting my camera and telescope set up. I've been interested in photography and astronomy for most my life, sadly i don't get much opportunities to use telescope though so only have a 'Bresser Skylux 70/700' with very little experience, I will not give up on it though. I've been trying to take photos, again not much experience on this but I know how to work it and have tried all types of settings to fix my problem: I have my telescope, t-adapter, t-ring and Nikon D40. On very close objects I can get it into focus perfectly but if I look further away than probably 20 feet it's just blurred in the camera eyepiece and photos. I don't really understand ISO, shutter time or white balance but I have tried on pretty much every setting I could(300 blurred photos of trees and sky),I've tried all ISO settings with lowest to highest shutter speed and different white balance, none of which made much difference, I can just about make out the color of sky or distant trees but that's it. It seems to be most focused as closely focused as the telescope will go and the further out I shift it the worse it gets. Can anyone help please? I can post photos etc if needed. Many thanks in advance, Paul

[Ant]

Hi Paul and Welcome to SGL.

It sounds like you have all you need to get started.

1. Make sure you have removed the Eyepeice.

2. The scope you have has a 1.25" focuser, so you will end up with vignettin (dark corners). This is due to the camera having such a large chip and the hole in the scope being small.

3. You may need to use the diagonal that came with the scope - maybe you won't but you need to try with and without.

4. Start without the diagonal, put in the camera and make sure everything is tight. Then make sure that the focuser is fully wound in. Start turning the focuser (while looking through the camera) and see what happens. If you reach the fully wound out position add the diagonal in and start again from fully wound in...

Let us know what you see as you do this. If you start to see something and you can't quite get where you need to be - make a note of what you've got attached, is the focuser fully in or out and etc...

Then let us know.

Ant

[EA2007]

Hello.

I take it your doing 'prime focus' imaging? i.e. connecting the D40 to the eyepiece holder of the telescope via the removal of the lens and replacing it with the t-ring & t-mount?

If so then you need to ideally find a bringht star (Vega, Arcturus, Deneb, Altair, for example) and see if you can focus with it. The D40 doesn't have LiveView so you will have to use the Viewfinder, this is somewhat of a pain at times as it gives you a ver small area to look through. Try getting your scope on one of these stars to get the focussing right. Then your onto your next area.....exposing!

This is dependant on the object your after, your scopes focal ratio and the camera itself. Here's a 'rought' guide:

Moon: 1/10th sec. exposure (depening on size of cresent). The ISO will be upto you, as a base stick it at 800 then work form there, 800 may be too much so lower it to 600 then 400 etc til you get the correct image.

Planets: Similar to the Moon, short exposure around 1/2 sec. and gain tinker with the ISO level

Bright DSO's (Deep Sky Objects): Usually clusters (open and closed, M13, M92, M71 for example), longer exposure of 30 secs+ on an ISO of 800+, again this is rough.

Mid DSO's (i.e. bright nebulae, nearby galaxies, M31, M27, M51): Longer exposure anywhere upwards of 1 minute and an ISO to suit.

You will find that perhaps the 'noise' will increase with higher ISO levels, this isn't too much of a problem with Canon's and Nikons but the Olympus range are really bad.

Its all a matter of testing until you find a suitable combination.

Please note, this guide is rough, perhaps some other forum people will advise better and more accuratly.

[Paul.L]

Yay I got it sorted, I just needed to take off the diagonal part of the telescope, it's perfect without it. Thanks alot and I'll be back with some photos if that's okay