Slashdot Mirror
Equatorial Mounts For Budget Astrophotography?
Timoris writes "With the Perseids approaching rapidly, I am looking for a good beginner's motorized equatorial mount for astrophotography. I have seen a few for $150 to $200, but apparently the motor vibrations make for poor photographs. Orion makes good mounts, but are out of my price range ($350) and the motor is sold separately, adding to the price half over again. Does anyone have any good experience with any low- or mid-priced mounts?"
It depends on how you are wanting to do your astrophotography. If it is a camera alone then you might consider making and/or getting a barn door mount.
http://en.wikipedia.org/wiki/Barn_door_tracker
They are simple and work well.
If you are considering astrophotography through a telescope then you'll have to have some sort of eq mount for the scope and then the prices do rise. But since you seem to be interested in photographing the Perseids then I doubt this is the case. The wide field available with just a camera would be the way to go.
I hope you are not intending on photographing a meteor from a telescope.
The most common thing to when photographing meteor showers is to point to the pole star and set your SLR (hopefully manual, film based on a tripod with a cable for the shutter) to a B setting and take a shot for a couple of hours. This produces really nice star trails and the occasional meteor.
If you are piggybacking the camera to a telescope you should not have any issues with the motor vibration, but you will need to beware of wind.
Save up your money and buy a Meade LX200, you can now get the older models (I personally think are better) for around 2000$US, combine that with a wedge and reticle eyepiece and you are ready to go. The thing really is a light bucket and something you will be happy with, with a little training you can even work out the periodic error correction with the scope so you can do astrophotography with the camera for the eyepiece.
If that is not satisfactory, build an adjustable wedge and buy a motor that rotates at 15 deg/hour and attach the motor to the top of the wedge with a camera on it.
GO BLUE!
Check this out:
http://members.cox.net/tfangrow/hissdrive.html
Otherwise, barn door mounts:
http://www.mikeoates.org/mas/projects/scotch/
http://www.astunit.com/tonkinsastro/atm/projects/scotch.htm
http://www.davetrott.com/DoubleArmBarnDoor.html
Equatorial platforms:
http://tech.groups.yahoo.com/group/eqplatforms/
Lots of other links:
http://members.ziggo.nl/jhm.vangastel/Astronomy/links.htm
>like the free Deep Sky Stacker to align them into a final image with total exposure time equal to all the shots combines
This is excellent advice on getting a much improved image quality but do note that stacking images will not give you the same results as a single image using the combined stack times.
In other words, if each image in the stack is 20 seconds then 10 stacked images will not give you an equivalent of a 200 second exposure.
Stacking 10 images simply improves the image quality by removing hot pixels. The result, however, is still a 20 second exposure.
The single 200 second exposure image will contain fainter objects (and more noise) when compared to the stacked 20 second image.
an equatorial mount will give you photos of meteor showers like this:
http://www.medanku.com/wp-content/uploads/2009/08/perseid-meteor-shower.jpg
instead of this:
http://celeb-news.net/wp-content/uploads/2009/08/meteor_shower_san_diego-8369.jpg
Except that you would see the earth rotation a lot quicker than you apparently expect -- depending on where you are.
At 50mm, depending on your earth location, you would see star trails after 8.5 seconds (equator), or 25 seconds (30 degrees from celestial pole).
The rule of thumb is this:
Around 30 degrees from celestial pole: 1200 / focal length = max exposure time.
Around the equator: 400 / focal length = max exposure time.
I use 600, because that's what I found yielded the best "rule of thumb" for me, as compared to my location.