Amateur astronomer beginners and astrophotography
7/27/2012 3:28 PM
I read a lot in the Beginner sections on Astronomy forums. One of my main goals with the "Eyes on the Sky" videos is to help beginners learn the sky, and find things easily. Of course, it's not a simple task - learning the sky takes time. And learning about telescopes is even more daunting, given the myriad choices out there. So when I see a beginner say, "I've enjoyed the stars for a long time - I'd like to buy a telescope, and even do astrophotography. What scope should I get?" I want to cringe a little. Okay, more than a little. I want to cringe A LOT. And usually I do.
Why, you ask? Good question.
First off, as I said before, just learning the sky can be challenging. There are 88 constellations up there, and tens of thousands of stars within the grasp of simple binoculars. (Even if you use a GOTO telescope with a computer, you still need to learn enough stars to align the telescope properly... AND learn how to use the computer!) Add a telescope to what you can see naked eye, and you're now in the hundreds of thousand of stars range. But finding interesting objects in the sky isn't easy - no thanks to light pollution. The problem is this: Many of the objects in the sky are small. And not just small, but VERY small. Planetary nebula are usually not much more than several arc seconds across. That's 1/10th of 1/60th of ONE degree. And some objects are dim - you may not even be able to see them with a telescope - the North America Nebula is a good example - but it's comparatively large too - probably larger than the field of view of your telescope. If you're looking for a softball and the view of your telescope is only the size of a baseball, you won't be able to see the whole thing!
But the real problem is that astrophotography - despite sharing many similar things with visual amateur astronomy - is different. Oh sure, they all use telescope and mounts and tripods and lenses and things. But just as using a pickup truck to do the job of a sports car isn't a great choice, neither is using a visual telescope for astrophotography - and vice versa. That's not to say it can't be done - it can. But to do that right means spending $1,000 to $3,000 on JUST the telescope, because you're probably talking about needing a 100mm aperture apochromatic refractor for that (or a $500 to $1000 dedicated astrophotography-only, fast-focal length reflector). And with that kind of refractor / reflector, and at the likely size required for both decent visual and astrophotography, a mount capable of of holding that scope is going to start at $1,000. By the way, that's JUST the mount. If you need a tripod too, plan on another $500, at least.
Because the mount is the single most important part of astrophotography. With visual, you can get away with a less than solid mount, because if the telescope vibrates while you're viewing, your eye compensates. A camera takes a picture of the wiggle, and you get wiggly star trails. Hit the "delete" button and start again.
And it's not just the scope and mount: You need a camera. And not just any camera; you'll either need a DSLR that is capable of doing astrophotography and capturing small images with the smallest pixel sizes (starting at $600 to $800 or so new), or you'll need a dedicated astrophotography camera, starting at $1,000. Did I mention you'll need to focus that camera accurately? You DO have a laptop for that, yes? A Bakhtinov mask? What about the accessories to attach the camera to the telescope?
See how overwhelming this is getting?
That's not to say you can't do any astrophotography when starting out as a beginner. After all, with social media like Facebook, Twitter, Pinterest and Google Plus, we'll want to share our hobby with others, and perhaps get them excited about it too. So what to do? Try these instead:
This is where the viewer holds a camera or cell phone (with camera) to the eyepiece of a telescope, and takes a picture of the object in the field of view. This is usually limted to bright objects like the Moon, planets, or a few of the brighter stars (first through third magnitude). The image of Venus transiting the Sun (right) was taken using afocal photography.
This is where the photographer places a camera - DSLR or consumer grade point and shoot - on top of an equatorial mount or barn-door style mount, opens the shutter for a long period of time (15 seconds or longer), and takes a "tracked" picture of the stars, usually in a wider field of view, capturing all or part of a constellation. Note that it usually requires a bit more substantial equatorial mount (that funny looking thing most telescope sit on) to do it well, and many beginner scopes are on marginally-large-enough mounts - adding a camera may overload them.
The nice thing about this is that the cost to get into is fairly low - $100 or $200 ($20 if you find the right webcam to modify yourself!)- and you can use standard equipment on an equatorial mount. It is still limited to brighter objects like the Moon and planets, but it is a good way to get started in the basics of astrophotography without spending a lot upfront.
Afocal is easier than piggyback which is easier than webcam shots, but all three are FAR easier to get into than DSLR / dedicated astrocam 'through the telescope" astrophotography. And both can be done with much lower cost equipment - which is a good thing if you decide you lose interest after 6 or 12 months. Take your time. Learn the sky. Do some afocal photography of the Moon. When I do this, I take A MINIMUM of 30 shots of the Moon. Same with planets. I'm lucky if I get 2 or 3 that are acceptable. Use a webcam style camera if you really want to "learn the ropes," because that alone will be difficult and require a lot of time and dedication to get right. Try the barn door tracker - you'll be amazed at what you can get with such a simple-to-build mount.
Already have a camera, but not the right mount or scope? No problem! For about $10 - $20 in materials, you can purchase the materials to build a simple, manually-turned tracking mount called a "barn door tracker" (because it kind of looks like a barn door, I guess?) that will allow you to take wide-field photos of the night sky - no motor, tracking mount or telescope required! Simple to build, simple to use, and you can take great astrophotos with one.
See, I want people to have fun while viewing or photographing the night sky. The more people do that, the more people will be looking at what light pollution does to destroy it, and take the simple steps required to change their own lights. So start small - no one becomes a par golfer on their first time out on the course. It requires an enormous amount of practice, coaching, determination, persistence, and the right equipment - which is going to cost more than the average golf clubs and balls too.
Start slow, and SUCCEED. Then build your way up. That photo of Saturn at the top of this page? Also afocal photography. In fact, EVERY shot on this page was taken with afocal photography techniques, using an HTC Inspire smartphone through the eyepiece of either a 90mm f/10 refractor or a 6" f/5 reflector. You can get great images with simple equipment.
Here's how to build a telescope bracket to hold your smartphone steady at the eyepiece for afocal photos.
Don't frustrate yourself on the leading edge of amateur astronomy and astrophotography. Get past the steep learning curve first, and above all, HAVE FUN! For more information on how to get started, check out the guides to astrophotography at astropix.com.
Wishing you clear and dark skies - and in-focus photos.