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BIG TELESCOPE - BIG MISTAKE?

Started by Thomas Dey, 06/06/2016 09:07PM
Posted 06/06/2016 09:07PM Opening Post
I finally got all the parts to build my final biggest telescope: A 36-inch f/3.75 Dob (to replace my ~too-small~ 29-inch). The 36 will just fit my geodesic dome up this dark rural hill from the house. Found a buyer for the 29 and threw in a brand new enclosed deluxe 12x5x5 trailer almost free! Good for him and good for me. Thanx, Kevin! So I am committed to the 36, excited and a bit trepid. I got the excellent journal Amateur Astronomy back issues on DVD and have been reading back from the present to educate myself on the history of Dobs. Tom Clark composed an excellent article 10 years ago (issue 51) wherein he describes the +/- of scopes small to gigantic. He concludes that [scopes around half gigantic (such as half of 36) are generally most staisfying for a variety of reasons that we DS folks are familiar with.] And I gota admit my most satisfying By Far was the trusty 17.5 that I built using a (good!) Coulter mirror and oil drums. It resided in a 12-foot dome behind the house and was pure pleasure exploring the cosmos. Also cheap, easy, reliable = +++. My 29 was expensive and required more TLC to perform. The exceptional nights were indeed wonderful. Now comes the 36! Tom's consul regarding his 36a, 36b and 42 is: [exceptional on rare exceptional nights --- but smaller scopes far more often perform to capability.] And my experience with the 29 bears that out. When it's good, it's GREAT ... but the seeing cooperates far less often. So now I will build the 36, install it in the dome --- and hope for the best. I'm targeting 1st light by Aug 1st - might take longer. All excited and wondering what I have gotten mysely into. I'm actually very happy that I decided to do it. Worst that can happen is I won't like it all that much --- and that would be OK. Tom Dey

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos
Posted 06/06/2016 09:38PM | Edited 06/06/2016 09:44PM #1
Thomas Dey said:

I finally got all the parts to build my final biggest telescope: A 36-inch f/3.75 Dob (to replace my ~too-small~ 29-inch). The 36 will just fit my geodesic dome up this dark rural hill from the house. Found a buyer for the 29 and threw in a brand new enclosed deluxe 12x5x5 trailer almost free! Good for him and good for me. Thanx, Kevin! So I am committed to the 36, excited and a bit trepid. I got the excellent journal Amateur Astronomy back issues on DVD and have been reading back from the present to educate myself on the history of Dobs. Tom Clark composed an excellent article 10 years ago (issue 51) wherein he describes the +/- of scopes small to gigantic. He concludes that [scopes around half gigantic (such as half of 36) are generally most staisfying for a variety of reasons that we DS folks are familiar with.] And I gota admit my most satisfying By Far was the trusty 17.5 that I built using a (good!) Coulter mirror and oil drums. It resided in a 12-foot dome behind the house and was pure pleasure exploring the cosmos. Also cheap, easy, reliable = +++. My 29 was expensive and required more TLC to perform. The exceptional nights were indeed wonderful. Now comes the 36! Tom's consul regarding his 36a, 36b and 42 is: [exceptional on rare exceptional nights --- but smaller scopes far more often perform to capability.] And my experience with the 29 bears that out. When it's good, it's GREAT ... but the seeing cooperates far less often. So now I will build the 36, install it in the dome --- and hope for the best. I'm targeting 1st light by Aug 1st - might take longer. All excited and wondering what I have gotten mysely into. I'm actually very happy that I decided to do it. Worst that can happen is I won't like it all that much --- and that would be OK. Tom Dey

I wouldn't sweat it much....via easily accomplished masking you can beat the seeing restrictions....one way is off axis masking. http://www.bbastrodesigns.com/OffAxisMasks.html and when the seeing co-operates? Forget about it smile

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 06/11/2016 01:10PM #2
Congrats! Way to take the leap. No going back now! I wouldn't sweat the small stuff. Greg and I are both big fans of the telescope design strategies used in "Merope". It would be neat to see some of them scaled up. The collimation method is VERY cool.

http://www.cloudynights.com/topic/490435-merope-engineering-a-low-compromise-compact-16-dob/

Thomas Dey said:

I finally got all the parts to build my final biggest telescope: A 36-inch f/3.75 Dob (to replace my ~too-small~ 29-inch). The 36 will just fit my geodesic dome up this dark rural hill from the house. Found a buyer for the 29 and threw in a brand new enclosed deluxe 12x5x5 trailer almost free! Good for him and good for me. Thanx, Kevin! So I am committed to the 36, excited and a bit trepid. I got the excellent journal Amateur Astronomy back issues on DVD and have been reading back from the present to educate myself on the history of Dobs. Tom Clark composed an excellent article 10 years ago (issue 51) wherein he describes the +/- of scopes small to gigantic. He concludes that [scopes around half gigantic (such as half of 36) are generally most staisfying for a variety of reasons that we DS folks are familiar with.] And I gota admit my most satisfying By Far was the trusty 17.5 that I built using a (good!) Coulter mirror and oil drums. It resided in a 12-foot dome behind the house and was pure pleasure exploring the cosmos. Also cheap, easy, reliable = +++. My 29 was expensive and required more TLC to perform. The exceptional nights were indeed wonderful. Now comes the 36! Tom's consul regarding his 36a, 36b and 42 is: [exceptional on rare exceptional nights --- but smaller scopes far more often perform to capability.] And my experience with the 29 bears that out. When it's good, it's GREAT ... but the seeing cooperates far less often. So now I will build the 36, install it in the dome --- and hope for the best. I'm targeting 1st light by Aug 1st - might take longer. All excited and wondering what I have gotten mysely into. I'm actually very happy that I decided to do it. Worst that can happen is I won't like it all that much --- and that would be OK. Tom Dey

~ Charlie Stevenson

8" f/5.7 String Telescope - 1st Scope Build; 2nd Place Stellafane 2016 Optical Award for Newtonians 12.5" and Smaller
10" f/4.5 Newtonian (June 2015) mirror refigured by Optic Wave Labs P-V WaveFront 1/14.24, Strehl Ratio 0.993 (Aug '15)
Criterion RV-6 seems to be circa 1973 (June 2015) [For Sale]
Celestron C8-A XLT (January 2015) [For Sale]
Celestron PowerSeeker 70AZ (Christmas 2014)
Aldrich Astronomical Society member since 2015
http://astro.charleskelleystevenson.com/