Image of the day

From the
ATWB Customer Gallery

Northern Cardinal

My Account

New to Astromart?

Register an account...

Need Help?

An Order of Magnitude

Started by RobertHowe, 08/15/2018 02:36PM
Posted 08/15/2018 02:36PM Opening Post
TEC is now making a run of 200 mm f/8 apos.  These retail for $29,600
D&G offers a 200 mm f/12 achromat for $3695.

I understand the need for more expensive glasses in the TEC; I have one of their 180s and it is an awesome scope.
But how can the price difference between an achromat and an apochromat be $25,905?  That's six and a half times the cost of the entire D&G telescope!  Is the apo's glass really THAT expensive, or is the time required to make an apo 100 fold that needed for an achromat, or what?

Enlightenment will be appreciated.  Thanks.

Robert Howe
Wilbraham MA


TeleVue 85 f/7 // Astro-Physics Traveler 105 f/6 // Astro-Physics 130 f/8.35 // TEC 180 f/7
Coronado 60 DS
"Scopes, Brains and Wisdom--but no Beauty"
Posted 08/20/2018 11:59PM | Edited 08/21/2018 12:01AM #1
I would think one factor would be managing to stay in business when you might only sell one or two a year when you get into dollar figures like that......

That train of thought may also explain why D&G has become ghostware.....its been a WHILE since I have heard of anyone getting anything from them......

20" MidnighTelescopes f/5
8" f/16 Muffoletto Achro
Meade 6" AR6 f/8.0 Achro
Celestron C11
Parallax PI250 10" F/5 Newt
Vixen FL102S,NA140SS,R200SS
80mm Stellarvue Nighthawk with WO APOupgrade lens, 90mm f/16.67 Parallax Achro
LXD75/LX200, Mini-tower, GP-DX, CG5 ASGT, LXD650, GM-8, G11, GM-100, GM-150EX, GM-200 and a Gemini G40
4" portable AP convertable 44" or 70" pier
Stellarvue M7 Alt-Az, TSL7 Pier/Tripod
12.5" f/5 MidnighTelescopes DOB Swayze optics
Statham GA
Posted 09/03/2018 12:38AM | Edited 09/03/2018 12:47AM #2
It's possible the price on a vanilla 8-inch f/12 achromat might actually be higher today. It has been a long time since their web page has been updated. 

I don't know about CaF2, but Ohara S-FPL53 is 18 times as expensive as their S-BSL7 (BK-7 equivalent). We don't know what matching glasses TEC is using. They may well be more than BK-7/F2.

Six surfaces, with internal surfaces having to match very closely, and stronger curves and higher internal powers, likely translating to stricter tolerances.

I'll also note that while the D&G instruments are fine scopes, the mechanics are more basic than the TEC OTAs.

Clear skies, Alan