What is a star tracker?

12 years 6 months ago #156958 by motol66
I've been getting interested in shooting pictures of the moon and stars. Anyway, as we all know, the earth revolves and therefore, subjects such as the moon are forever moving out of the viewfinder and in turn, out of focus. I've heard of these "tracker" devices which your camera mounts to and move in synch to the earth's rotation. So..

1. What is the actual terminology for this type of hardware? I've been unable to produce any Google searches thus far.

2. Can one of these units be had for a decent price?

3. Can anyone recommend a place where I might be able to buy one of these from?

4. I've read about people making their own "tracker" using an old clock. Is it worth the effort?


,
12 years 6 months ago #156971 by Be Mine 4ever
To counteract the Earth's rotattion and keep a star in the viewfinder, requires either an equitorial mount (having a single motor because it only moves in 1 axis), or an alt-azimuth mount that has 2 motors that moves the mount in 2 axis at the same time, which requires computer controls.

The mount must be accurately orientated to be parallel to the Earth's rotation axis. Variations in the accuracy of that alignment cause the star to drift in the viewfinder. A good mount usually has controls that can correct that drift as it happens.

The stars move at a different rate than does the Moon and the planets, so a good mount will have 3 speeds.

Since the Earth rotates through 360° in 24 hrs, :

24 hrs x 60 minutes/hr = 1440 minutes per 24 hrs.
360° / 1440 minutes (1 day) = 36 minutes per degree, well short of 60 minutes/°.


,
12 years 6 months ago #156974 by effron
Some possibilities.....
www.astronomyboy.com/barndoor/links.shtml
veiks.com/hiking/report/barndoortracker.html
I've seen some fine results with these, and for little money, too. Astrophotography can be as expensive as you allow it to become. Find a star party or astronomy club in your area, and spend some time BEFORE you start spending cash.........;)

Why so serious?
Photo Comments
,
12 years 6 months ago #157001 by motol66
BeMine, thanks for the math. I really didn't think about how to figure it out.

Effron, thanks for the links. I'll check them out. I'm a member to meetup.com, maybe there is a astronomy meetup on there. :) I can't wait to check it out, I'm getting excited!!!! :woohoo:


,
12 years 6 months ago #157009 by Cappy
The device you are alluding to is a 'barn door tracker'. In it's simplest form it is simply a camera mounted unto two pieces of plywood hinged together and a thumb screw to change the angle of the hinge in incremental amounts. The idea is to align the camera to the rotation axis of the earth and then change the angle of the hinge incrementally to offset the rotation of the earth. Google will lead you to lots of sites explaining how they work and how to build one with some plywood and a few pieces from the hardware store.

Don't scoff at the simplicity of the device, it really works. Invest a couple of hundred dollars to add a clock drive and some gears. But it's not a necessity in order to get started. You don't even need expensive camera gear. Point a 50 mm lens at the milky way for 10 to 20 minutes while keeping the camera aligned with your barn door tracker and be prepared to be amazed at the imagery.

Check out the CloudyNights astronomy site. They have a good beginner section as well as a section on astrophotography.


,

817.3K

241K

  • Facebook

    817,251 / Likes

  • Twitter

    241,000 / Followers

  • Google+

    1,620,816 / Followers

Latest Reviews

The Panasonic G9 II is a 25.2-megapixel micro four thirds camera with numerous features that make it punch out of its weight class, like 779 AF points, 5.8K video, and weather sealing.

May 10, 2024

The Fujifilm XT5 is a 40MP mirrorless camera capable of 6.2K video at 30p. With those specs, it’s an ideal choice for photographers needing a camera to pull double duty for imaging and video.

Apr 25, 2024

The Canon EOS R100 is an entry-level mirrorless camera introduced in 2023. But just because it’s an entry-level camera doesn’t mean it’s a bare-bones camera. Find out why in this review!

Apr 22, 2024

Nikon’s retro-looking Nikon Zfc is anything but retro. Under its classic body is a host of features and amenities that make it a worthwhile compact mirrorless camera for 2024.

Apr 15, 2024

Forum Top Posters

Latest Articles

The Panasonic G9 II is a 25.2-megapixel micro four thirds camera with numerous features that make it punch out of its weight class, like 779 AF points, 5.8K video, and weather sealing.

May 10, 2024

Cinematic photography is an interesting genre that combines photographic and videographic skills along with effective storytelling techniques. The result? Highly impactful images!

May 09, 2024

Newborn photography requires skill, the right gear, and a lot of patience. This beginner’s guide discusses critical topics that will help you be more prepared for before, during, and after the shoot.

May 08, 2024

To fill the frame means to expand the footprint of the subject in your shot. Get in close, zoom in, crop the image, or use other techniques to bring the subject to the forefront.

May 06, 2024

With these simple yet effective beginner photography tips, you can avoid some of the common mistakes beginners make and get improved results with your images.

May 06, 2024

Urban photography is a genre showcasing features in urban settings. You can photograph people, architecture, mass transit, and many other subjects. Learn how to do so in this guide!

Apr 30, 2024

The Nikon D850 might be an older DSLR, but it was ahead of its time when it debuted in 2017. That means it still has plenty of firepower to compete with today’s powerful mirrorless cameras.

Apr 30, 2024

The best beginner camera isn’t the same for everyone. That means having choice is of the utmost importance. In this guide, explore five excellent beginner camera options for 2024 and beyond.

Apr 25, 2024