Astrophotography setup

Hey.

I know this has been covered to death already, but I need some help in choosing a setup for astro-imaging.

I am planning on using my dslr (350d) and regularly use it as a piggyback on some club scopes.
However, I really want to start doing this properly, ie. My own mount, scope and tracking.

I was going to buy a large (8-10") dobsonian, but have thought about it alot and know that I need an EQ mount to get good images as high powers - through the scope itself.

Can someone help me to pick something that I will enjoy.

My budget is roughly £400.

I would ideally want it to be small enough for me to carry by myself and load into the car.

On another point, I am familiar with programs such as registack and would like to know what is the longest exposure I can use at 50mm before I get star streaks? Also, as the camera at the moment is on a normal camera mount which I don't want to rotate during shots, would it be possible for registack to take 100 or more images and stack them even if they have rotated somewhat due to te time difference between each shot?

Thanks a million.

Jay

Hi Jay,

I've been thinking a bit about your post (and the other one about the poncet) mount. The first thing you really needf to appreciate is that astro-imaging is not a hit and miss sport (if you get my drift). The required precision with regards to tracking is rigourous. There is no room for error. For that reason a poncet mount is just not going to cut for you. A Poncet is really only good enough for visual tracking. A barn door mount will give you some leeway when using a camera/short focal lenght lens combo. However even that is not perfect. As the tracking performance degrades as time goes forward.

You asked the question, how long can I get with a 50mm lens with no tracking. The answer to that is 20 seconds (approx) with no detectible trailing. Certainly long enough for basic constellation photos.

If your eventual goal is to use your 8 inch for deep sky photography, then there is no alternative to a german equatorial mount. £400 (stg) will get you something like a celestron CG5 or syntha EQ5. Both mounts will be only capable of doing the job as long as they are guided either manually or automatically. You will be able to get some short exposures from these mounts without guiding. How long depends on a lot of factors, polar alignment and just how good the particular example of the mount is. You're looking at something between 30secs and 2 mins (max). If you want a mount with better performance than this you are going to have to pay a lot more money. e.g; (prices approx) EQ6 £1000stg, losmandy gm8 $1700 losmandy g11 $2200. You can keep going up until the bank manager steps in!!!

I dont want to be discouraging, in fact I would like to encourage you. Astrophotography is one of the most exciting areas of amateur astronomy IMO. However dont underestimate just whats involved. The best way to appreciate this is to get started. One of the basic mounts will allow you to do that, but your gonna be dreaming about better mounts in no time at all!

Hope some of this is helpful.