Posts Made By: Ed Blankenship

I concur with Tom: Yikes !!!

This seems very unstable to me !!!

I'd find a way to put the 80mm on the opposite side of the mount (trade for the dual mount).

Jason,

I have a C102HD on the Celestron CG-4. It would work as a teaching tool for learning setting circles, but I also have a C8 on a fork mount. I'd much rather us the larger circles of the C8 if it was my choice. You might want to consider a C8 or an 8" Meade SCT (used on this site are available for a little more than your stated cost). It depends on how much you (or he) will depend on those (smallish) setting circles. The SCT circles can be used with the vernier, but the CG-4 circles are so small, the vernier would probably be questionable. (I confess, I haven't tried using the CG-4's circles yet as it is my newest scope/mount).

Clear skys,

Ed

P.S. Setting circles only work well if one has the patience to level and polar align the mount/ scope really well. I have become spoiled by my telrad books and 1x finder. I just rough align to polaris and start pointing at bright objects. Just an extra $0.02.

Steve,

I share your feelings of loss. I just finished placing an offer for an older Tripod & Mount similar to what you describe: $50 gets me the wooden tripod & GEM (EQ-2 I think, but an older one). I am planning on mounting my Celestron 80mm ST that I bought as a finder for my 8" SCT setup. I will probably never view from my front yard based on your experience: The extra distance to the "back-40" will hopefull give me some sense of "protective buffer" from the "thieves-on-wheels" experience. Sorry to hear your story and hope they get caught soon.

Best regards,

Ed

Hello John,

I have a Celestron C-8 which is on a fork mount. The fork
mount needs a "wedge" to make the forks able to align with
polaris, so the RA motor can make the fork mount move to
counteract the earth's motion (aka "TRACK"). When you
say "wedge" I think you are really meaning "fork mounted" ?

The advantage of the fork mount for the SCT is portability
and ease of use because the fork lets you "point and shoot"
kind of like an alt./azimuth mount, but it can "track" with
one motor. Unless you get a very heavily built fork mount
(like an LX-200 or C-14), the fork mounts are subject to
vibration. Also, on my C-8, the Declination axis can't
easily be motorized because of the design.

I also have several refractors mounted on German Equitorial
Mounts (aka GEM or EQ mounts). The GEM takes a bit of
getting used to for some people, but it sounds like you
already have some experience, so that may be a good choice
for you if you aren't wanting the portability advantages of
a fork mount. The down side to a large GEM is that big
counterweight. The larger GEM designs can have separate
motors on both RA and Declination, so they are good for
"auto-guiding" or using a hand controller. I don't have
any direct experience using an SCT on a GEM, but from what
I have used (EQ-3, CG-4) for a C102 refractor with a bunch
of accessories, I'd think a CG-5 might be a little light
for an 8 inch SCT. Maybe others with more experience on
the larger GEMs can chime in and give us their experince ?

Best regards,

Ed

Hello Cam & everyone,

One possibility is perhaps something like the UTI travel scope that Infinity sells (they are a sponsor, so check their link from the main page of ASTROMART) or just copy the stuff between quotes "www.infinityscopes.com" into your browser. I would like to have a large, light scope too, but wonder if the complexity of putting a truss design onto a GEM is really worth the hassle ?!?!?!?

Cheers,

Ed

Hello Anders,

I have a simmilar SCT telescope: Celestron C-8 (203mm,f/10) and I can get the best views with a 9mm eyepiece for the planets (Mars, Jupiter, Saturn, etc.), but only on a good seeing night. The 2x Barlow is a good way to double your eyepiece collection. With a 26mm eyepiece, you get to change it into a 13mm. You might also want a 2.5 x Barlow which will get you more magnification, but maybe too much unless your seeing (atmospheric conditions) are better than mine.

Cheers,

Ed

Hello again,

Another related question, "If I use a wideband filter for the SCT exit aperature, will that 'stack' O.K. with any or all of the much narrower band filters ? For example, I also have polarizing filters and the Celestron LPR filter.

Thanks in advance,

Ed

Hello John & all,

I recently bought a used Losmandy setup here on ASTROMART, but haven't had time to try it out. Here's a link to the Losmandy site: http://www.losmandy.com/secondary.html#DWS which should give you some ideas.

Ed

P.S. Nice finder scope John.

P.P.S. There's a couple of ads for used balancing systems on the Classifieds that I read (partly for getting ideas). Here's an example: " http://www.astromart.com/viewad.asp?cid=206400 " of one for a 10 inch Meade that might feed your thought process (if you are inclined to "home brew" or "adapt a Ford part onto a Chevy" like I sometimes am tempted to do).

John,

My highest power viewing is often limited by seeing (and it depends on the turbulence of the air that I'm looking thru), but on the better nights I can use my 9mm Vixen LV Lanthanum eyepiece or Barlow up a longer focal length eyepiece to get to 8mm and sometimes even to 7mm. My good friend has a 7mm Nagler Type 1 and plans to sell it because it is just too rare when the seeing allows that high of power in our scopes. He has a Meade 8 inch LX10 and I have a C8 like yours (2003 mm focal length). I usually start with the Vixen 24 to 8 mm Zoom and dial in on the object (usually Saturn, Jupiter or Mars). When I notice the image clarity go beyond the "sweet spot" I read the mm setting of the zoom and pick the 9mm only if the zoom gets past the 12mm marking. The single 9mm LV eyepiece is slightly better than the zoom, so if I get to 10-11 on the zoom, I know if the 9 will work O.K. or not. We have only been able to use his 7mm Nagler in the SCTs about 30% of the time. It does a great job on those occasions when the seeing allows, but he plans to trade it or sell it and get a 9mm Nagler, which I will have trouble using because of my eyeglasses. Someday I want a set of Radians: 8mm, 10mm 12mm so I can pick the best one for a given night, but that's over $600 for three eyepieces. For now, I'm just investing in better quality Barlows to use with my 35mm Celestron Optima (best eyepiece in my case). The eyepieces I own below 10mm, are getting sold with the shorter focal length refractors.

Cheers,

Ed

P.S. Congratulations on the C8 collumation improvements. I will probably need to get those Bob's Knobs and see if I can get more out of my C8. That might be a limiting factor in the high power I can use too.

Hello Luis,

I will begin to share with you what I found on the web a while back when I had some of the same interest in the different types of telescopes. One nice web site I found was Dr. John F. Gills description of the evolution of the modern MAK/CASS which can be found at: " http://www.weasner.com/etx/guests/mak/MAKSTO.HTM " In addition, I started to look at variations of the Cassegrain design and found names like Ritchey-Chretien, Klevtsov, Baker, Wright, Slevogt and Houghton to add to my list of Gregory, Maksutov and Schmidt. I hope that gets you started.

Cheers,

Ed

P.S. One reference that keeps comming up on this and the ATM forum is " TELESCOPE OPTICS:A Comprehensive Manual for Amateur Astronomers by Rutten and van Venrooij "