My Equipment, and a Few Things I've Learned
At right is my Traveler / ST-4 / Guidescope (80 f/11 Celestron 'Firstscope') / Pentax 6 X 7 / G11 setup. For film imaging, of course.
For CCD imaging, just imagine the Traveler replaced by a Celestron C-8, thanks to Losmandy's 'DSBS' dual-platform dovetail plate. Of course, the C-8 would have a SBIG ST-237 attached to the front, too (see my "1st CCD's" page for pics of this setup.
Everything works very smoothly now, but I DID have some frustrating nights!
The biggest help I had was to be around an experienced imager--I cannot recommend this more highly if you are just starting out in an 'imaging endeavor.' Ken Sablinsky helped me immensely, especially in figuring out the nuances of, and proper settings for, the ST-4.
It is not my purpose here to add another tutorial on imaging: I am just a beginner, after all. There are many excellent Webpages--and even a few good books--that cover the essentials:
|If you are only going to stop at one
site to learn about film imaging and image processing, go to: Jerry
Lodriguss'--you won't regret any time spent there... But there are
other excellent sites out there: I think of Chris Cook's and Wil Milan's...
Check my links page.
For CCD imaging--techniques and processing--there are even more excellent sites out there: Robert Gendler, Ron Wodaski, John A. McCubbin, and Christopher Anderson come to mind...
Nuances I've Learned (the hard way) About My Setup
The Losmandy G11 mount / ST-4 setup is very capable, and probably the 'best buy' in imaging setups out there (the ST-4 is no longer made, but can be found used). What do I not like about this setup?
The G11 can be sticky when slewing around by hand (I'll throw my 'two cents' in about GOTO capabilities later), but it is an easy matter to re-lube the bearing surfaces once a year--in fact, there is a Webpage or two devoted to this... There are no fine adjustments by hand--you must pick up the hand-controller. Though Losmandy machining is very beautiful and tactile to the touch, their cast-iron counterweights leave something to be desired in the 'fit and finish' department. Likewise, their polar alignment scope--though quite accurate in my experience--has a funky 9-volt battery dangling in the wind (in fact, a wire is broken in mine which I now must fix!). I've heard that periodic error can be significant in G11's--this has not been the case with mine, judging by the average corrections of the ST-4 when I am polar aligned properly (usually '1' or '2' over a cycle).
The ST-4: Read the directions and practice in your backyard (if you have one--I don't) before you go to your dark sky site! Print the 'ST-4 tips page' (which can be found on several websites, including Chuck Vaughn's) and bring them with you. Have an experienced partner nearby the first few times you attempt to use the ST-4! I had a 'flip mirror' device (from a now-bankrupt company <hmmm?>) that came with my used ST-4; I no longer use it--it was NOT parfocal, and the center of the reticle was NOT the center of the chip! My procedure now is as follows: Find a guide star, center it in a Celestron reticle eyepiece--pushing down a little bit to compensate for the added weight of the ST-4 head... Replace reticle eyepiece with parfocal eyepiece (be sure I am wearing my glasses!); focus; replace this eyepiece with the ST-4. This procedure usually works like a charm, after I take a dark frame, of course, and proceed to the 'find and focus' mode... But before I go to the 'calibrate drive' mode, I make sure my "TVC" (backlash compensation) is on the third or fourth LED from the left. Also--and equally important--I make sure the drive corrections (the speed of the slew) on the G11 control panel is on .5x or 2x (if .5x gives an error message in calibration mode). Occasionally--if I still have errors (watch the readout when calibrating)-- I will have to fiddle with the "CA" mode--this adjusts the time (independently) each axis is receiving commands to move... This often happens if I am shooting low in the East or South-east.
GOTO or no GOTO? I have nothing against this technology, in fact, I have my 17.5-incher sometimes equipped with DSC's, which ain't exactly GOTO, but very closely related. For $1500 I could outfit my G11 with GOTO. But for me: it is not necessary or desired when imaging. First of all, I like to star hop. And being an old deep-sky observer turned imager, I don't get enough of it (star-hopping, that is): While the ST-4 and G11 are ticking away for an hour or more, I can't look through any telescopes! (Unless, that is, I cram another scope in my little car, or there are other observers at my site--where I go, usually this is one night in three)... So my star hopping is just like when I "observed": get out the maps, or boot up MegaStar, look naked-eye at the sky and try to make sense of the map/territory... When I've done that, point the scope, look through the finder; try to make more sense out of the map/territory thing... "Go to" the depth of perception a little further and do the same thing through the eyepiece/telescope combination (can't do this with the Fastar setup though). It ain't that hard or time consuming: in fact, it is a lot of fun!