What features to look for in a motorized DSLR mount for astrophotography?

Question

I'm planning a foray into astrophotography, and am looking for some advice on features to look for in a motorized equatorial DSLR mount. I'm interested in both wide angle and deep field pictures. I use a Nikon d7100, and for lenses a Sigma 10-20mm f/3.5, a Sigma 150-500mm f/5, and a few in between.

There are so many options out there, so I figured I could get some advice here that would steer me in the right direction. Doesn't need to have a really high payload capacity, as it's just holding a D7100. Looking for something under $1000.

Answer 1

Matt,

If you're looking at AP with just your camera and a couple of lenses, you should be able to get buy without a heavy, megabucks mount. For exactly the same purposes as yours, I use an iOptron SkyTracker which sits on a camera tripod, and uses a ballhead to support up to 7.7 lbs of total weight. This runs off 4 AA batteries or an external 12VDC supply.

This won't be a problem at all for the 10-20mm because in actual fact, you could image with this lens even without a tracker, by following the 500-rule (500/35mm-focalLength = slowest exposure) to control star trails. With the 150-500 however, under the assumption that you'd like to shoot at 500mm some of the time, this is equivalent to 750mm which would limit you to 2/3 second exposures, which in turn would probably not give you the details you want.

This is when you need a tracker. Here's a picture taken by a friend using the Tamron 150-600 @ 600mm, on the SkyTracker, of the Orion Nebula

right now, it's selling for $299, so it's well within your price range.

Answer 2

A simple rule is that the longer your focal length, the more precise the Mount has to track.

Also a long exposure is way better than many short exposures, thus a more precise longer tracking will give better results than many short unprecise shots.

It all boils down to what you want to shoot. If you have in mind to shoot the very faint nebulas then you need a very expensive (1500 + $) tracking Mount, possibly with camera that tracks the star on a subpixel level. If you want to shoot the Andromeda galaxy and some field shots like the ones you see usually on the web then even a barndoor tracker will do.