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Zeiss Diascope and Coolpix 4500 for Birding and Lunar Imaging

During the last few months I have frequently been asked about the new setup that I use for birding and for imaging the Moon: what setup do you use for birding and for imaging the Moon, and why do you image the Moon with the Zeiss Diascope anyway. Why not use the TAL 200K or the TAL 100RS?

I will start with answering the last question first, why do you image the Moon with the Zeiss 85mm, why not use you’re 8-inch TAL Klevtzov or 4-inch TAL reflector. In the second part of the article I will tell you more about the setup I use for both imaging the Moon and for birding.

Why use the Zeiss for lunar imaging anyway?

TAL 200K
My 8-inch TAL 200K is an f/10 (2000mm focal length) telescope, and is only fit for use with 1.25 eyepieces. I achieve the lowest possible magnification using the 32mm Televue plossl. This eyepiece gives me a magnification of 62.5x, and with a 50-degree apparent field of view, this results in a true field of view of 0.8 degrees or 48’. The Moon has an apparent diameter of 30’, so visually the full Moon fits nicely into the field of view, but it fills the view almost completely. There is not much “space” left around the lunar disk.

However, shooting a picture of the full Moon (or nearly full Moon) with this setup is impossible. When the camera is connected to the 32mm eyepiece and the TAL 200K, the view will suffer from severe vignetting (a kind of tunnel-view). I can get rid of this problem by zooming in on the Moon using the camera’s optical zoom, but then I cannot fit the lunar disk completely into the field of view of the camera. At the bottom and the top, a part of the lunar disk is “cut off”. So the TAL 200K is excellent for shooting detailed images of the Moon, better than all other telescopes I own, but for imaging a (nearly) full Moon, I need another telescope.

TAL 100RS
Since two years I have been using the TAL 100RS, a 4-inch f/10 (1000 mm focal lenght) achromatic refractor, to shoot my overall lunar images. With the 32mm eyepiece I get a true field of view of of 1.6 degrees or 90'. Using this telescope got me some satisfying results, but the problem with achromatic refractors is that you get a more or less bright, somewhat colored circle around bright objects like the Sun, the Moon and the Planets. When processing the images I shot with the TAL 100RS, the bright fringe around the Moon becomes even more apparent. I simply need yet another telescope for shooting the overall lunar images. The solution to the problem came from a totally different instrument, a birding scope.

ZEISS DIASCOPE 85MM
During the last few years my girlfriend and I have gradually taken on the hobby of birding, not only during vacations, but also throughout the year, around our home and in our backyard. In 2005 we decided it was time for a birding scope. The choice was rather easy. There are three different top-class birding scopes available, Zeiss, Leica and Swarovski. These have all been tested many times, and you can find enough test reports on the Internet.

We chose the Zeiss because we simply liked the views we got from it, and we liked the professional finish of this wonderful instrument. Because of the high quality and the short focal lenght, this little scope is not only perfect for birding, but also for imaging the full Moon. The Zeiss Diascope 85 is an f/5.5 (focal lenght of 500mm) apochromatic refractor. With the 32mm Plossl eyepiece, the true field of view is almost 3 degrees, or 180'. So there's lot's of space around the Moon, and no colour fringe! However, for shooting detailed lunar images I will allways use the TAL 200K (shows much more detail on the surface because of higher resolution).

The eyepieces
For birding we only use the Zeiss 20-60 Zoom eyepiece. You cannot change eyepieces when you've got a bird in focus, because birds have the strange habit of moving around, especially when you want to shoot an image! Sometimes it seems like they don’t like being photographed.
grin

Luckily the Moon moves a bit slower across the sky (and not in all different directions like those.... birds). Using an adaptor enables me to connect all astronomy eyepieces I currently own to the Zeiss. The 32mm Televue Plossl and the whole range of Vixen Lanthanum eyepieces, they all come into focus, even the 2.5mm Lanthanum, which results in a magnification of 200x. I am convinced that there are a lot of astronomy eyepieces on the market, that will not come into focus with the Zeiss Diascope, but that’s no wonder. The Zeiss Diascope is a birding scope, not an astronomical instrument. So be careful when considering this instrument for backyard-astronomy!

The setup for birding and for imaging the Moon
Shooting images of birds or the Moon has two problems in common: how do I get the object into focus, and how do I shoot the images without touching the camera, resulting in vibrations and .......blurred images. To make life a little easier I chose for a complete adaptor-set from Eagle Eye OpticZooms in the UK:

1. A digimount adaptor for connecting the camera to the eyepiece;
2. A Shutter-release arm and wing 4500 bracket;
3. A 10-inch shutter-release cable;
4. A micro fiber lens cleaning cloth.

On the images below (click on the images to enlarge them) you can see how everything is connected to each other. The shutter release cable works mechanically. You do not have to touch the camera to shoot your images. The X-tend-a-View Pro is just great. It magnifies the 1.5-inch TFT color monitor on the backside of the camera with factor 2. The view is so detailed you can even see the different colors of the individual pixels. It is a great help for focusing the camera/telescope on a bird, the Moon, or whatever other object. With the shutter release arm and the wing 4500 bracket, both the shutter release cable and the X-tend-a View Pro are connected to the coolpix 4500.


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Click on images to enlarge


So this is the setup I use for birding. The setup I use for imaging the Moon is basically the same, only the eyepiece and the eyepiece adaptor are different. You find more info on how the Televue Plossl and Vixen Lanthanum’s are connected to my camera on my old website, backyard-astro.com. Just follow this link to get there. The shutter release cable and the X-tend-a-View Pro are used for shooting the lunar images as well.

Anyway, I want to finish this article with a close-up (award-winning) shot of a sparrow, shot with the birding set-up. In a contest from the Dutch Bird Protection (Vogelbescherming Nederland) my girlfriend was one of the ten prize winners with this image. Not bad for a beginner . I hope that in the next months these everlasting clouds will disappear over the city of Landgraaf, and I will be able to shoot a few lunar images with the Zeiss to present them to you in this blog.

Clear Skies to all of you! wink


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Posted by Math on 03/03 at 07:45 AM
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