astroimages
Darin E. Fields' Astrophotography Pages
 

Telescopes and Equipment

Optics:

The Newest scope is the TEC-140 Apochromatic Refractor!

TEC-140-E:

Takahashi CN-212 Newtonian/Cassegrain
My second Takahashi is really two telescopes: an F/12.4 (2630mm) focal length classical cassegrain and an F/3.9 (200mm) newtonian. Switching between the two modes is achieved by swapping out the secondary assemblies. Additionally, I purchased the focal reducer for the cassegrain focus enabling imaging at f/9.9. A corrector is included for the newtonian focus as well as the necessary collimation tools. The scope includes a magnificent 7x50 finder scope and is constructed beautifullly like any Takahashi. Focus is achieved in both modes by adjusting the primary mirror, but with the correct adapter (Tak WU adapter) my Optec TCF Focuser attaches directly to the back.

cn212a: cn212:

cn212train:

With the Optec unit in place, the f/9.9 adapter cannot be used, but I can use my Astrophysics 0.67 reducer that attaches directly to the nose of the SBIG camera, enabling imaging at f/8.3 (1762mm).

tak:

Takahashi FS-78 Apo Refractor (f/8, f/6 with focal reducer)
What words of praise can be said about Takahashi scopes that haven't been said? I can say that I often attributed those words of praise partly to the effusions of people who had dumped a big chunk of change on a piece of equipment--of course its great! Until you own one (or have spent a lot of time at the eyepiece) you can't really appreciate those seemingly overblown words of praise. The acuity and contrast of this scope are like nothing I've seen. The quality of its craftsmanship is superb. I have taken my best images with this scope, and I have enjoyed amazing views through it.

c-11: The Present

Celestron C11 SCT (f/10)
This scope saw first light on June 27, 2001. After weeks of trying to decide on the C9.25 or the C11 SCT, I finally opted for the larger aperture of the C11 over the much touted optics of the 9.25. While visiting my hometown of Tucson, AZ, I happened into a scope shop that had both 9.25" and a C11 used on the floor. The 9.25 was the older style with the digital focus counter. Both scopes were in excellent shape, and the right price. After much discussion and contemplation, I settled on the C11. My first view through the scope was of the moon late in the afternoon (yeah, I confess that as soon as it was locked in place I had to look at something!). Later, M13 was a delight and reminded me of the great views I've had of it throught my friend's 12" Meade LX200 and 14.5" Starsplitter DOB. I knew then that for whatever visual use I would put the scope to, the C11 was the right choice.



Sigma 400mm Apo MF(f/5.6) Apochromatic telephoto Camera lens
Sigma 70/300mm Apo Zoom Apochromatic telephoto Camera lens
I bought both of these lenses for wide field imaging with the CCD cameras. In preliminary trials with the ST-237 I was pleased with the tack sharp stars across the color filters. Of course, as soon as I get my camera lens adapter for the ST-2000XM, I'm going hunting for some big objects--like the Rosette Nebula!



Mounts:

Losmandy G11 German Equatorial Mountwith Gemini GOTO System
A well-crafted precision device, the G11 is used by many amateur astronomers. Go here for my thoughts and comments on the Gemini System.

Vixen Great Polaris EQ Mount
I acquired this mount with the Takahashi FS-78. Since constructing the observatory and fixing everything in it, I have thought about having a smaller, simpler, travelling setup to venture out to dark sites (ironic, isn't it?). While the Gemini is not battery friendly, the Vixen runs on a D battery pack. The previous owner added an autoguider port to the handcontroller, and took several outstanding images with his ST-2000 and this setup. I hope to do the same.

Imaging Equipment:

The C11 imaging train with Optec TCF-S, ST-2000XM with CFW8a
c11-image-train:
SBIG ST-2000XM CCD Imaging Camera with Color Filter Wheel
The SBIG ST-2000XM is a 2 megapixel ABG camera with the same 7.4 micron pixels as the ST-237. Constructed in the ST-7,8,9,10 chassis, the camera has a 1x frame size of 1600x 1200. The USB connection provides for 4.5 second downloads of the 3.7 mb 1x image. Compare that rate to the 2 minute download time for a full frame on a non-usb ST-8 and you can quickly see the allure of the USB option--on an image run of 50 images its a savings of more than 90 minutes in download time! The CFW allows RGB integrations and has a vacant filter slot for a specialized filter.

Optec TCF-S Temperature Compensating Focuser
The Optec focuser sits in the image train as a crayford style focuser. A Temperature probe monitors the optical tube temperature, tracks the relationship between temperature and precise focus over time, and retains said data for subsequent use. The Optec focuser integrates with Maxim DL/CCD.

Astrophysics CCD Telecompressor for SBIG Cameras
The new AP focal reducer threads into the SBIG nosepiece and provides a clear aperture of 1.75" and a compression ratio of 0.67x with the SBIG ST-2000XM and CFW8a with 99% light transmission.

SBIG ST-237 CCD Imaging Camera.
The SBIG ST-237's 7.4 micron pixels were an excellent match for the fast f/4 newtonian, and I took A LOT of images with this camera with the color internal filter wheel. But the ST-2000XM has many, many more 7.4 micron pixels. My first ST-237 found a new home where I hope it provides as much excellent use as I received from it. In 2005, I purchased another ST-237 without a color filter wheel to use as a secondary guider.

Minolta SRT-100 35mm
A solid, fully manual, workhorse camera. It lacks some of the preferred features for astrophotography like removable focus screen and mirror lockup, but for the $50 I paid for it, it works beautifully.
Mamiya C3 Twin Lens Reflex Medium Format Camera
This camera belonged to my father who used it for portraits and some nature photography. The 80mm f2.8 lens captures approximately a 40 degree square image field. Thus its a great camera for wide field shots.

Image Acquisition and Telescope Control Software
I use Maxim DL/CCD 4.01 for camera, telescope, and focuser control. Though the Gemini system has its own control software, Maxim DL/CCD is a single program solution for everything.



Old Stuff that I no longer own or rarely use anymore:

Apogee 8" Newtonian (f/4)
This scope saw first light on September 30, 1999. Overall, I have been happy with its optical performance, which I would rate as fair to good. The mirror has a slight turned edge, but no apparent astigmatism. Collimation is, of course, critical, but a laser collimator has solved this problem. For the $600 dollars I spent, I feel I have received pretty good value. By that I mean one must match expectations to price. I haven't had it off the shelf in several months.

Meade 90 mm achromat refractor(f/11)
This was purchased as a guidescope. However, since acquiring the ST-2000, it hasn't seen much use and is now on the shelf as well.
Celestron 80 mm Short Tube (f/5)
I have nothing but praise for this little scope.  For a small Chinese-built achromat for $200, it can't be beat.  I performed some minor upgrades to the scope, most of which involved blackening shiny interior parts, that significantly reduced the chromatic aberration.  Also, I purchased a quality star diagonal which also improved performance significantly.

Lumicon Giant Easy Guider
An essential tool for astrophotgraphy with an SCT like the C11, the Lumicon GEG allows the autguider to utilize the same optical path as the image train and, therefore, reduces or eliminates problems with mirror flop so common with SCT telescopes. The Lumicon GEG utilizes an 80mm focal reducing lens that can be repositioned in the guider to allow for imaging at four different f ratios: f/10 (no focal reducer), f6.5, f/5.5, and f/4. It is a precision-built, very rugged device with many features. An excellent tutorial/overview of its features by Philip Perkins can be found here. Since acquiring the ST-2000XM and other equipment, I have not used the GEG.