16 inch f4.5 mirrors from Telescope & Astronomy

FredSnerd (Claude) · #1 09-06-2009, 03:43 PM

I'm looking at building a 16 inch classic Obsession Dob from David Krieg's book (It will be my first telescope). I also want to add tracking and Argo Navis.

I have 2 issues to start with (I'm sure there will be many more to come).

(i) The mirror

Telescope & Astronomy are selling 16 inch f4.5 mirrors they're getting from China for $1800 plus postage. They say the mirrors are the same that they put in GSO scopes and even the meade dobs.

I would be grateful for anyones views on the quality of such mirrors. Being a newbie to this game I figure once my standards get more exacting i can always change the mirror or if I get appeture fever I can build a bigger dob.

(ii) Tracking - I'm looking at the servo cat but is there anyone in australia that makes a drive system suitable for a obsession DOB

Gratful for your views

Regards

Claude

Paddy (Patrick) · #2 09-06-2009, 03:50 PM

A 16" home built for a first telescope? Wow, you like jumping in at the deep end don't you!

CoombellKid · #3 09-06-2009, 04:09 PM

I built exactly what you are intending to build. Save yourself up to
$700.00 or there abouts and buy the mirror directly from GSO. I
landed mine here for around $1100.00 including freight.

The views a fantastic for what they are and well worth the price IMO.

regards,CS

AstroJunk (Jonathan) · #4 09-06-2009, 04:15 PM

Great project Claude. The classic Obsession design is rock solid and never bettered on performance (it can be beaten on portability!)

The GSO mirrors are good. It is amazing that large mirrors of reasonable quality should be available at such a low price. But seeing you are thinking of going that extra few yards by fitting Goto, you may wish to consider top quality optics from Mark Suchting (Satchmo on this forum). A little bit more $, but a lot more bang.

On the subject of Goto. The ArgoNavis / Secvocat combination is very nice indeed. If you go down that route I have a couple of installation tips ...

FredSnerd (Claude) · #5 09-06-2009, 04:32 PM

Gee thanks for the tips guys

CS I just went on the GSO site and like you said there are the mirrors. I will send them an e-mail for their latest prices.

AstroJunk. It was music to my ears when you said you would have some installation tips for the go to. Ive been worrying about that (along with other things) and will be keen to pic your brains when the time comes. I'll also contact Mark S before I make a final decision about the mirror but at this stage I think money;s and issues (aint it always)

Regards

Claude

CoombellKid · #6 09-06-2009, 04:35 PM

A little bit more $, but a lot more bang.... try $2400.00 more than what
I paid for my GSO above, well from that last quote I got from Mark. And
although you'll be getting better optics, at your stage of the game you
probably would not be able to tell the difference unless perhaps it was
pointed out to you. I've looked throught both types at 16" but not side
by side but a year or 2 apart. From what I've heard you get more
contrast in the view... how much more... you'd have to do a side by
side.

In the end it is a lot of $'s spent on something you want to be sure
about as you might find in 12 months time your not as keen on
astronomy as you thought you were.

regards,CS

CoombellKid · #7 09-06-2009, 04:41 PM

Servo-Cat comes with a DVD showing you how to do the install. I never
bothered with my 16" as I see no need for it at that size. But that is
just me, others will say different.

regards,CS

Satchmo · #8 09-06-2009, 05:35 PM

Quote:

Originally Posted by CoombellKid

A little bit more $, but a lot more bang.... try $2400.00 more than what
I paid for my GSO above.

Oh , really ??

Haven't had a request for a current quotation from you lately..you speak with great authority...

CoombellKid · #9 10-06-2009, 05:46 AM

Quote:

Originally Posted by Satchmo

Oh , really ??

Haven't had a request for a current quotation from you lately..you speak with great authority...

So what

your so sacred we aren't allowed to talk about you and
prices that you have quoted in the past??? I never claimed to be
speaking authority... just experience. Of course it doesn't appear we're
allowed to do that.

Cheers,CS

Satchmo · #10 10-06-2009, 09:22 AM

CS

I've just lost a long detailed reply to this

when I tried to do a message preview , so I'll have another go later if I can summon the time.

The general tone of your post was the old chessnut about `little apparent bang for buck' with premium optics . Well I guess the concept of `bang for buck' applies more appropriately to budget telescopes. It was quite reasonable for Astroron to at least mention my service as the original poster didn't say anything about a preference for budget optics or otherwise. Its not common for beginning ATMeres to build a premium scope as their first project, but It does happen.

I can currently do a fast cooling 16" Conical mirror for significantly less than the cost of importing from a US specialist in them and am not in the business of competing with mass production optics using cheap materials. I exist because I can offer something specific to a project, with guaranteed quality and highest quality materials. When people want something very specific , like a 32mm thick 18" hyperboloid at F3.66 it is a custom optician that they come to. Its only when cottage industry specialists are gone that anyone will really miss the service that they do.
Mark

sally1jack (Phil) · #11 10-06-2009, 01:19 PM

I think it depends on what you want fredsnerd in the end if you want a top class telescope then get a top class mirror & use top class eyepieces vs Gso mirror & med grade eyepieces , IMO there will be a difference, is it worth the extra $ that only you can answer , I believe it is.

Sure mass produce mirrors are cheaper & maybe great value, but i have first hand experience in seeing the Chinese companies entering a market with very cheap product only to drive out competitors then turn around charge very high prices for a less quality product once they have cornered a market, I wouldn't like to see that happen here,But thats the way it will probably go & premium mirror making will be another lost art.

Cheers Phil

bmitchell82 (Brendan) · #12 12-06-2009, 02:21 PM

I will have to agree with Mark on this one. its like expecting the proformance of a BMW M5 out of a hyundai excel... sure the excel will smoke the wheels speed around corners and get to 180km/h, but hell youll be holding on for grim death.
Press the M button in a BMW and youll be saying woohooo.... You get what you pay for its upto you not to get ripped off from somebody who claims to be somebody better than they are and in marks case well, the truth is in the pudding! let the drag strip have the last say. you get my drift.