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Posts Made By: Sean Cunneen

July 20, 2007 05:50 PM Forum: Telescope Making

spider defraction spikes

Posted By Sean Cunneen

I am new to reflectors, I've had refractors all my life. I've just purchased a 6" f/8 I'd like to use just for planetary. I have been reading about spiders and 3 vane vs 4, curved vs straight. My question; does the thickness of the vanes affect the quality of the diffraction spikes? My telescope comes with threaded rod vanes about 3/32"dia, what if I replaced those with rods 1/16"dia, or take it to an extreme, suspending the secondary with music wire under tension. If the diffraction spikes are ot all that effected by thickness of the vane, it may not be worth the effort. Anyone have any experience? Thanks in advance,

October 31, 2007 01:29 PM Forum: Telescope Making

Build your own motor drive?

Posted By Sean Cunneen

I am collecting parts for a motor drive, any one else try this? What problems did you not expect? I plan to run a 1rpm or so timing motor and gear it down with a worm drive and several belt drives. Any thoughts on steppers vs/ servos/vs timing motors? How did your drive do in cold temps? Anyone?
Thanks,
Sean

November 16, 2007 08:27 AM Forum: Refractors

C4-R Limiting Magnitude

Posted By Sean Cunneen

Last night I split my first"real double", actually the triple of Zeta in Orion. I saw(with Averted Vision) the 10th mag third star, even better, I did not know it was there until I kept looking and looking. 10th magnitude isn't bad considering I live 3 blocks outside of Chicago! So I'm asking, what's the dimmest magnitude you've seen in your scopes compared to what they were rated for? According to Celestron, this scope is limited to 12mag, but what do those mathematicians know anyways!

December 13, 2007 09:16 AM Forum: Eyepieces

19mm Pan vs 18mm Radian

Posted By Sean Cunneen

I'd like to take advantage of the sale before x-mas and I cannot decide between these two. Is the only difference eye relief/field of view? I am mostly concerned with sharp flat fields and bright/high contrast images, I am leaning towards the Radian. I like mostly bright Messier Objects and planets, as I live in the City. I have a 4"f/10 refractor and an 8" f6 reflector, any help would be appreciated!

June 11, 2008 02:32 PM Forum: Pictures of Me and My Telescope and........

8" f/8 Newtonian on a CG5 Pier...

Posted By Sean Cunneen

I've just finished it, the mirror is a discovery mirror, the spider is a curved 3-vane. The mirror cell is adjustable in depth for future additions. The project has taken me 3 months start to finish!

October 24, 2007 01:15 PM Forum: Equipment Talk

Making a Binocular Mount

Posted By Sean Cunneen

It is probably the same, 1/4-20, some professional tripods use a 3/8"dia post, but you'd be able to tell the difference pretty easily. Take a trip to your local hardware store and try some in the screw aisle, sometimes there are different threads, but in your case, it should be 1/4-20.

November 3, 2007 07:26 PM Forum: Beginning Astronomy?

Focal ratio

Posted By Sean Cunneen

I am speaking from my own personal experience only, but I do a lot of planetary viewing and I love my Celestron c4r/c102hd. Cheap "fast" scopes just don't do it for me! For under $1000, I would stick to an f/10. I'm convinced that owners of 5" and 6" f/8 achromats don't complain about all that color because they don't want to feel bad about all that money they just spent wink you would have to spend a heck of a lot of money to get a fast scope that can handle that high of magnification and be steady enough to pick out details. For a telescope under $1000, the mount is almost more important than the optics, ESPECIALLY for planetary use! I had a 10" f/5 Dob before my little refractor and it almost drove me out of the hobby all together! I know you said you wanted a refractor, but again, for planetary use, I would keep an eye out for a used high quality 6"f10 newt on a decent GEM, No CA and a very comfortable viewing position. My 2 cents!
P.S. check out the C4R thread in the refractor group!

November 3, 2007 07:30 PM Forum: Equipment Talk

Re: Celestron C-9.25

Posted By Sean Cunneen

Just don't eat one and you'll be fine smile

December 1, 2007 05:19 PM Forum: Equipment Talk

Whats the worst scope you had?

Posted By Sean Cunneen

I had a Celestron C-90, I bought it as a Camera lens and it got me into the whole Astronomy hobby, in a bad way... when it got cold, the lens barrel would refuse to turn. When it got warm the image would shift so bad during focusing there was no hope for high mag viewing at all. Add into the fact that it cost as much as a MUCH larger newt, but accepted .965 eyepieces...
SHEESH, What was I thinking?

December 1, 2007 05:26 PM Forum: Pictures of Me and My Telescope and........

Henry's 42" er

Posted By Sean Cunneen

Did he have to pick between the scope and college?


Smart kid wink