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View Full Version : What would be a good starter scope for Astrophotography?



AutoBoof
2011-Sep-07, 08:52 PM
I currently own an 8 inch dobsonian and love it, but I would like to take photos of planets and deep space objects and I don't think the dobsonian is good for that.

I was wondering if someone could recommend a good "getting into astrophotography" website with a rundown of what types of scopes/mounts are best to hook up to a SLR camera to get some long exposures.

Assuming I have a camera, can all the rest of the equipment be purchased for under $1,000?


Thanks,
Chris

RickJ
2011-Sep-08, 03:50 AM
The needs for the two types are so different it's best to pick one.

Planetary work needs aperture but mount need is simple and camera rather inexpensive compared to what is needed for deep sky so the cheaper place to start.

An equatorial platform such as a Poncet system is all that is needed to turn the Dob into a planetary scope if the optics are up to it. This is doable for your $1000. Both a Flea3 video camera and a equatorial platform will fit within the budget with room to spare. You want a rapid imaging camera for planetary work so you can take several thousand images in a couple minutes. Software, some like Registax is free, will pick out and stack the usable frames which will have, after stacking, very high signal to noise ratio. This allows aggressive processing without introducing artifacts. Best imagers use a mono camera with filter wheel. That adds cost to above your budget and adds processing complexity. A color camera will suffice. You'll need somewhat longer exposures which will reduce the percentage of good frames but shouldn't hurt significantly. You'd want to run at f/25 to f/30 so add a good three element barlow if you don't own one plus adapters.

Deep sky through a scope is well above your price range however. Here the mount is by far the most important factor. These start above your price range and go way up from there. Bottom range mounts can handle small APO refractors. Orion's 80mm ED 3 element APO with a field flattener is a good inexpensive scope for this that a bottom level mount can handle. You will need a second camera to act as a guide scope and a second scope or better yet an off axis guider for the guide camera. The mount must accept the guider inputs from the guide camera. Not something that is inexpensive to assemble.

A basic DSLR camera such as a Canon 350 can take reasonable wide field deep sky images in 30 seconds with a wide angle lens. Only a tripod needed. If you want to go deeper take several images and use processing software to align the stars and stack the 30 second images. These are lower noise than a single exposure of the same duration needing a drive. Though if you want to go that route the equatorial platform for the Dob will also work for a simple drive for a camera and allow longer focal length lenses to be used.

For examples of planetary images with a Flea3 camera see Jaicoa's posts. For what can be done with a basic DSLR see Bloodhound's posts of late. Taking very distant, tiny galaxies like I normally post is far beyond your budget. It took me a lifetime to save for it. The learning curve very steep.

A book like Covington's "Astrophotography for the Amateur" will give you a lot more detail. For DSLR info see http://www.astropix.com/

Some DSLR's can take video but it is lower quality than the Flea3 I mentioned. Still I've seen a couple folks make it work -- sort of anyway. Many start with a modified DSLR for deep sky through a scope but again it is a compromise situation. To me it is harder to get a good long exposure through the scope deep sky image using one than a dedicated astro CCD. Like with planetary work a color CCD works but most serious imagers use mono cameras and filters as they have far fewer limitations, especially if you live in an area of some to major light pollution. This, of course, raises the cost even further.

No matter how good your deep sky imaging equipment you can't image a black hole but it sure will turn your bank account into one.

Rick