Use a Telescope or Spotting Scope for Astrophotography?

If by using a telescope you're talking prime focus (objective lens serves as telephoto) versus spotting scope you will be much better off in terms of sharpness and aperture by using the telescope. For example, a 60mm objective with a 15X to 60X zoom sounds pretty good at first, but the effective aperture will be a slow f16 at 15X to a dismal f64 at 60X. Even a cheap 60mm astro telescope (usually has a 60mm diameter objective with 700mm focal length) would be between f11 and f12 and be sharper at the sacrifice of some magnification. The 700mm focal length would give you 14X magnification. (Divide focal length by 50 to get effective power when using objective as a telephoto lens). Even better: a 90mm diameter, 1,000mm focal length objective lets you have a 20X view at f11. Hope this helps.

Mike

Steve I agree with Mike, the telescope would better.

I have a Celestron CR-150 HD-6 and use it sometimes with my 10D.

For astrophotography a scope would be better. But I have seen some great shots done with a digital camera attached to a spotting scope for terrestrial use. Do a Google search on "digiscoping"

If by astro you are limiting yourself to shots of the moon and/or (maybe) planets, then a spotting scope might work. But for long exposures (over 15 seconds) what will really make or break the shot is the mount, not the optics. But that may be completely off-topic depending on your intentions.

FWIW, a relatively inexpensive Newtonian could offer you the focal length AND the speed you're looking for, with a 500-700mm f/5 a good entry point. Also known as "light buckets".

Thanks for the help. I'll look for a telescope, then. Can someone point me to resources that will explain things such as "Newtonian" (I have no idea) and focal lengths, magnification power, brightness, etc. Also some recommended brands, models, etc.

Thanks again, Steve

Keep in mind that most inexpensive refractor telescopes (e.g., the common 60mm ones) and many reflector scopes do not have sufficient back focus to let you focus at infinity. Also, if you only want to take photos of the moon then the spotting scope should work fine because the exposures are so short. If you are thinking about photographing planets and deep sky objects such as nebulae, you need to mount the telescope on a tracking drive to keep pace with the Earth?s rotation. Suitable telescopes and drives, such as the Meade LX-200, are fairly expensive.

You might find that a better way to get started in astrophotography is begin with wide field images using conventional lenses. You can also build a barn door tracker for about $15 that will allow you to make high quality tracked photographs. The other important aspect is to learn about basic observational astronomy. There are many good basic astronomy books available. I have written a book intended to introduce conventional photographers into astrophotography called Heavenly Bodies: The Photographers Guide to Astrophotography.

Check Orion Telescopes (I don't remember the URL, but a search will reveal it). They have refractors, reflectors, and Maksutov Cassegrains(like big mirror lenses). You will need a prime focus adapter that slips into the eyepiece holder in place of the eyepiece and a T-ring to take pictures with most refractors or reflectors. Orion has those. Cassegrains may have the adapter built in (just need a T-ring then) or if you shop elsewhere for a Meade or Celestron Schmitt Cassegrain you will need the T-ring plus a T-adapter. Many larger camera stores stock those scopes and adapters. The older model Meade ETX 90 with motor drive is still in stock at some dealers and may go for under $200 if you can find it. It has a 1250mm f13.8 objective. The cheaper telescopes, especially the 4.5" reflectors probably won't reach focus. Good luck

Mike

I agree about the mount being the most important thing to consider. It must be perfectly aligned to North and be able to track the apparent motion of the stars (yes, it is really the Earth moving) You really need to do some reading on astronomy and astrophotography... my favorite starter book is Splenders of the Universe by Jack Newton and Terence Dickenson. Also, telescopes (and spotters) are made to work with an eyepiece and our eyes... they are not ideal for a camera because film is sensitive to a wider range of colors (lens needs to be better corrected... usually more complex) and because a flat field is needed (film is flat) Our eyes don't notice the color issues, or the curved field, as much as camera with film does, that's why camera lenses are designed for use with film, not our eyes. Some of the expensive telescopes might work, but they are also heavy and require very expensive mount and motor drive. What do you want to photograph? Unless you need big magnification, you can just use regular camera lenses (non-zoom is best) but you still need a tracking mount. I'm building my own (cross between a barn-door and german equatorial) and starting with hand driven, eventually upgrading to motorized. You also need another small scope to see how well the setup is tracking (I made mine out of bino optics) Hey, seriously, this is not easy to do, requires much patience, and most of all you need to find a place far from city lights with clear dark skies.

check out this info from Sky and Telescope.

A comprehensive guide to what it takes and how to do it, from polar alignment all the way through to PhotoShop techniques, from a long-time expert is to be found at Jerry Lodriguss' AstroPix site.