I will keep you updated, and of course I will publish my observing reports with this scope in the next few months (weather permitting). I also will publish some technical details (mount, tube, mirrors) and some test results for the primary by Orion Optics UK.
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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?
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.
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).
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.
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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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!
Tonight I got a chance to test the Zeiss diascope 85 and the Manfrotto tripod astronomically for the first time. The Moon was high in the south, and my first impression was ......wow! Although the seeing was not very good, the Moon was there, crystal clear, in the Zeiss 20-60 eyepiece. What a view. The Alpine Valley was clearly visible at lowest magnification (20x). Beautiful! The contrast between the Mare and highland areas was stunning. My girlfriend also came out to have a look, and her first reaction was: “I never have seen such a clear and sharp image of the Moon through any other instrument we owe”. We also noted another thing with this little instrument. Usually, at first quarter, we see only the half of the Moon that is illuminated. I only have seen earthshine, or any un-illuminated part of the Moon with a crescent Moon or with a lunar eclipse. But with the Zeiss we could see the contours of the whole of the Moon, full circle. This telescope definitely has a lot of contrast. I am very eager to try it on some of my favourite deepsky objects, like the Orion nebula and the Pleiades.
After the first views with the zoom-eyepiece I tried all my other eyepieces. The 25mm TAL plossl, the 32mm Televue plossl and the whole Lanthanum range (25mm-5mm). They all snapped into focus nicely. The 32mm Televue offered even a slightly wider field of view than the 70-degree Zeiss zoom eyepiece at 20x. Next I tried to focus the Zeiss with one of the deepsky filters or the Baader IR/UV cut filter mounted at the base of the eyepiece. With the 32mm Televue Plossl it was no problem.
What I also noticed is that with this Manfrotto tripod and the 45 degree angled telescope it is no problem to observe objects in the zenith, and because of the 45 degree angle, you see everything oriented in the sky as you see it with your naked eyes. I hope to do some serious deepsky observing and shoot some solar and lunar images with the Zeiss in the next few months.
I am excited
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I also hope to show you some more result with the Baader Herschel wedge (white light), but the Sun is going lower and lower in the sky during the coming months. The Sun disappears behind the trees and stays invisible from my backyard for quite some time, so I will have to wait until next spring for more solar observing sessions. But....... when the Sun goes lower in the skies, the Moon rises higher and higher, so this is the season for lunar observing and imaging. I will keep you updated!
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If you want to see the exact setup of my connectors for the Coolpix 4500, the Televue plossl eyepiece and the Vixen Lanthanum eyepieces, follow this link to the equipment section of my website. Here you will find a photo album with images of the complete setup.
About a year ago I decided to get a new mount for my TAL 200K. The main reason was that I wanted a mount that could be equipped with some sort of go-to system or digital setting circles. I had been suffering from serious back-problems for quite some time, and I was fed up with kneeling down and crouching under my telescope to locate my favourite deep sky objects, especially in the cold winter period.
While deciding which new mount to buy, there where a few things that I took into consideration: I wanted a mount that could carry larger and/or heavier OTA's in the future, but still could be transported to a dark sky site. The mount would not be used for long exposure photography and finally, as always, there was the money issue: how much can you spend?
The search for the mount quickly narrowed down to the EQ-6. The Sky-Watcher EQ-6
- could take heavy loads (up to 22 kg) using a standard dovetail;
- should be OK for taking short exposure images of the Sun and Moon;
- could be equipped with several types of digital setting circles;
- could be transported to a dark sky site;
- fitted nicely into my budget;
- seemed to be good value for money.
EQ-6/Argo Navis on "wheels"
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Argo Navis Digital Telescope Computer
Once I decided to go for the EQ-6 I started looking for digital setting circles (the EQ-6 wasn't available with a goto system in may 2004). There where several systems on the market, but there was one that really stood out from the others, the Argo-Navis Digital Telescope Computer from Wildcard Innovations. This computer can be connected to a wide variety of mounts, including dobs mounts, with encoders that are produced by JMI. The Argo Navis can be ordered, completely with encoders, from JMI in the US or from Wild Card Innovations in Australia. The specs of the Argo Navis computer blew away all other systems at that moment (may 2004). You can read all about the Argo Navis by following these links:
JMI NGC Super Max (Argo Navis)
Argo Navis Digital Telescope Computer by Wildcard Innovations
but here are the specs what made me decide for this unit:
- very easy to use out in the field, even when wearing gloves;
- a big rotary dial and two buttons do all the operations;
- the display comes with a dew heater;
- the display is dimmable with 100 settings and has a digitally contrast control;
- its database with more than 29.000 objects
- a wealth of bright stars, variable stars and doubles stars in the database;
- data on most objects: position, size, magnitude, surface brightness, class, star chart cross reference etc,
- the tour mode: let Argo Navis take you on a tour along your favourite objects;
- add 1.100 user-defined objects;
- can be used on many different equatorial mounts but also on dobsonian mounts;
So the combination I went for is the Sky-Watcher EQ-6 and the Argo Navis Digital Telescope Computer. As you will read in the next paragraphs, I don't regret it.
Setting up and using the EQ-6
I have been using the Sky-Watcher EQ-6 mount for more than a year, and I'm very satisfied. The setup is done within minutes. You just have to assemble three parts: tripod, mount and counterweights, connect the battery and the hand-controller, and you're ready to go. The mount itself is the heaviest part, weighing 16 kilograms, but it can definitely be carried around and transported in a small car. Taking the EQ-6 apart also takes only a few minutes.
After assembling the Sky-Watcher EQ-6 I usually align the mount with the celestial pole, using the built-in Polar Scope. This only takes about five minutes. Once the EQ 6 is polar aligned, it keeps all stars and deepsky objects right in the centre of the field of view. I have been indoors once for more than two hours, leaving my telescope centred on M 37. When I returned, M 37 was still visible right in the middle of the eyepiece. When using digital setting circles, it also pays of to align exactly on the pole (see next paragraph). The EQ-6 has no different speeds for stars, moon and sun, but I never experienced any problems with that. The Sun and Moon are kept in the eyepiece nicely. Every now and again you need to perform minor adjustments.
I mounted different telescopes on the EQ6, my 8-inch TAL 200-K Klevtzov-Cassegrain (12 KG), the TAL 100RS 4-inch refractor (6 KG) and the 40mm Coronado PST (2-3KG). I also mounted the TAL 100RS and the Coronado PST together using a Duo-Mount bracket from Teleskop-service in Germany. The mount proved to be very stable on all occasions and changing telescopes was very easy using the standard EQ-6 dovetails.
In the period I've been using the EQ-6, it always worked correctly. The hand-controller though looks a bit cheap and has a bright green LED in the middle. A little sturdier box and control buttons, and a red LED would be great improvements for the future, but then again everything worked just fine until now. I also have used the EQ-6 for short-exposure photography with the Coolpix 4500 connected to the eyepiece (Scopetronix / Vixen adaptors). The images of the Moon and Sun I got were just perfect. I am not interested in deep sky photography, so I can't tell you what the EQ-6 is like, when using it for long-exposure imaging.
After using the EQ-6 for more than I year I can say that I'm very satisfied with this mount. I paid 999 Euros but it is worth every penny, a fantastic mount for a very down-to-earth price. What other mount can carry 22 KG in this price range? I couldn't find it, so the choice was very simple, and I do not regret it for a moment! This is definitely value for money.
Setting up and using the Argo Navis Digital Telescope Computer
I ordered the Argo Navis and a set of encoders (8192 steps) for the EQ 6 from JMI. The package arrived in good order, and the installation of the encoders took me about 15 minutes. The only piece of equipment I used was a screwdriver (on the images below you see the RA and DEC encoders mounted on the EQ6). After the installation of the encoders I installed 4 AA 1.5V batteries to provide the internal power for the computer (at the moment I use an external DC power cable to connect the Argo Navis to 12V power pack). Finally, I connected the computer to the encoders using the encoder cables. After printing out the manual, I was ready to do the initial setup.
After going through the initial setup (which you only have to do once and takes about half an hour) I started the alignment procedure. This procedure has to be done every time you setup your telescope. The alignment procedure is very simple for the EQ6. Connect the Argo Navis to the encoders (and to the external power source). Be sure that the telescope is polar-aligned exactly. Power up the Argo Navis and align the telescope on a star that you select from the alignment star list and you are ready to go.
You can also use the "rough align" mode, but you have to align on two stars. I have not used this mode, because I always had Polaris available to align the EQ-6 mount. However, when you cannot see Polaris from your observing site, you can use the rough-align mode from the Argo Navis. What I've heard from other users, this works fine.
After using the Argo Navis for more than a year I can only say that I am impressed with this great piece of equipment. If the mount is exactly aligned to the pole, you can align the Argo Navis within one or two minutes, and from there it will take along any number of objects. One night I just tested the Argo Navis for locating different targets. I let the computer take me to 40 different targets: double stars, open clusters, planetary nebula's, planets and globular clusters. They all ended up in my 45' field of view the first time. The Argo Navis did not miss one! And then the wealth of details you get on all the objects is fantastic. Here's an example (M 31):
M31, also known as NGC 224, Galaxy in Andromeda, _size=3.18 degrees x 1.03 degrees, mag=3.3, SB = 14.5 _morph=SA(s)b, Andromeda Galaxy M31, very bright, _RA= 00:43:00, DEC = +41deg 17’35” above horizon, _SA=4
(The last data “SA=4” means that you find M31 in the SkyAtlas 2000 on map 4. You can change this into the Millennium Star Atlas or the Uranometria edition 1 chart numbers)
Another great feature of the Argo Navis is the Tour mode. One night, when I came home from work the sky was covered in clouds, but later that night suddenly the clouds disappeared, so I could observe for an hour or two. I had nothing like an observing list or program ready, but the Argo Navis has a "Tour Mode". In this mode I simply chose a constellation and objects I would like to see, and let the computer do the rest. I let him take me along all different kind of objects within Orion, brighter than the 10th magnitude. I had a great time and I really felt like an astronomical tourist. Clusters, asterisms, double stars, nebulae, they all came along. This option is fun!
In the end I can say that the Argo Navis amazes me every time I use it. This unit proves not only to be very reliable and accurate, it also is very easy to use. The whole unit is controlled with two buttons and a big rotary dial, very basic and simple. You don't have to take of your gloves to use the controls. I never had any dew problems or technical failure due to outdoor conditions. Uploading a list with user data is a piece of cake with the software that accompanies the Argo Navis. The wealth of detail that is displayed on the adjustable two-line LCD screen is just another great bonus you get from the Argo Navis. The tour-mode is wonderful, and the manual that is supplied on a CD-rom is very accurate and detailed.
If it comes to navigating the night sky, the Sky-Watcher EQ-6 and the Argo Navis Digital Telescope Computer form a great team. If you have any questions or remarks, please feel free to post a comment.
Clear skies to all of you!