Anyone interested in longer exposures of the night sky with your camera and landscapes?
Hi All, I recently received my AstroTrac for taking long exposures of the night sky. It is a great device and it is not too terribly expensive. I recently got my D800E as well and that is a GREAT camera for astrophotography. Tons of detail of the sky. For info on the astrotrac, go here www.astrotrac.com to get the details. I have the Really Right Stuff BH-40 mid sized ball head (awesome quality) for my camera since I have the "L" bracket on it. The AstroTrac is mounted on a Monfrotto 410 Jr gear head for fine tuning to get the AstrTrac polar aligned. I use the tripod with the legs spread one notch out for more stability. I also use the MC-36 remote to take the long exposures on the camera. It's a great device if you are interested in longer exposures of the night sky and get some land/sky scapes. Here are some photos:
killersnowman wrote:
i dont get it... how does that crazy contraption help you take star images?
Once the AstroTrac is polar aligned (with the north star), it requires a 12v battery (not shown in photos) to power the AstroTrac and it tracks the stars (actually it moves in the opposite direction of the Earths rotation to give you pinpoint stars) without getting those star trails.
remember, we are rotating about the axis, this will help eliminate the star trails we see. Looking at the Pic #4 we see its a 10 mins exposure, on a normal tripod you will start to see star trails because the earth is rotating. Its that simple, this will counter the displacement, it has to be equal and opposite to stay in the exact position the entire time the shutter is open regardless of the rotation of the earth (which we know is constant).
@ TODD so jealous of the setup, where did you take this photos? I live in the worst possible location in the country to do this kinda stuff. I live in Seattle! We see clouds and we just assume there are stars behind those clouds
ahmedumair wrote:
@ TODD so jealous of the setup, where did you take this photos? I live in the worst possible location in the country to do this kinda stuff. I live in Seattle! We see clouds and we just assume there are stars behind those clouds
Oh wow, I guess that is a bad place to be to try and photograph the sky if there are clouds and rain all of the time. I took these photos in Far West Texas, a town called Fort Davis. It was during the Texas star party last year and this year. That is the area of Texas where the McDonald Observatory is located. Those are pretty much the darkest skies in the United States. Next year that Texas star party starts on May 4 I believe. You can look it up online just do a search for the Texas star party. And if you do not want to go to the star party, then you can just visit out there when there is no moon in the sky. The sky there is amazing and the Milky Way and bright stars will blow your mind. Thank you for your comments.
Better seeing conditions are not all that far from Seattle, so it is not quite as bad here as it may seem. And you sure do not need to go all the way to Texas for a star party. Here is a link to one close to Seattle: http://www.tmspa.com/index.html
The photo with the camera mounted also shows the small polar alignment scope, which mounts on that small accessory arm. With it and with the right technique you can align fairly fast. The polar alignment scope is mounted on that arm with small magnets, and has been know to get knocked off now and then, so watch out for that.
The AstroTrac gives up to 2 hours of tracking before you need to "rewind" the drive system of the tangent arm. And the tracking accuracy is very good on this system, because it makes use of a computer calculation and a precision drive shaft and stepper motor, so it corrects for "tangent error" and is nearly dead on for a full 2 hours.
There is no photo that shows the whole AstroTrac system all folded up, but it does stow very nicely compared to most equatorial tracking mounts. It is considered very good for travel or portable use, and ends up at about the size of your forearm when detached from the ball head and support wedge.
The Manfrotto 410 gear head can work out for an equatorial wedge and alignment system, but AstroTrac sells a nice (and expensive) adjustable wedge that is more rigid than the 410. You can use most any ball head on the top to actually aim and frame your subject, but I would generally recomend something bigger than the BH-40 except for fairly small camera loads. I use the BH-55, and its low profile seems to work out well for this use.
As a final note, I would not recomend putting a layer of rubber between the ball head and the AstroTrac like the original poster shows. A metal to metal contact there is going to give you the most rigid connection. Any possible benifit of rubber to dampen vibrations is minimal at this location, and the much lower stiffness of the rubber will have bad effects for longer lenses. Using a carbon fiber or wooden tripod may help for dampening if they are also stiff enough. The special dampening pads that fit under the feet of the tripod are another way to help dampen vibration caused by wind.
