20 replies to this topic

[vehnae]

Greetings from Finland, it's been a while since I posted images here.

 

For quite a while now I have been thinking about how I want to approach astrophotography, what is my style and what would be the optimal instrument to achieve my artistic goals. After quite a bit of contemplation I decided to build my own telescope from parts to make sure it would meet my (rather high) standards and have all the features I wanted. The project has taken almost two years from the first idea to completion and finally the work seems to be paying off. Of course there are final touches to be done but the scope is already very usable. No glass pushing was involved though as I could obtain most of the parts from commercial sources. 

 

So here is the first image from my new scope, a 10" f/3,8 newtonian. Quick specs: 10" f/4 quartz conical mirror from TS, 4" Antares Optical secondary, ASA Wynne 3" 0,95x corrector, extra-thick foam-core carbon fiber tube and Integra85 focuser/rotator for precise framing. So far the project has exceeded my expectations, and it will only get better once the ASI6200MM gets released :-).

 

I published two images from this FOV, the northeastern part of the wall is very interesting and deserves more attention so I cropped it separately. 

 

 

Full field:

 

 

Thanks for looking!

 

  ++ Jari

 

[jhayes_tucson]

Jari

That's an outstanding image!  The detail is superb and your processing looks excellent.  Very well done!

 

Question:  How did you combine the RGB data with the NB data?

 

John

[Eric H]

Outstanding indeed!

[vehnae]

Question:  How did you combine the RGB data with the NB data?

 

Thanks John!

 

I would love to tell you that I used an arcane PixelMath incantation derived from markings hidden in the margins of Burnham's Celestial Handbook. But in reality I removed all the stars from the NB images using Starnet*, and put the stretched RGB stack on top using the Screen mode in Photoshop :-D. 

 

Sometimes simple solutions work very, very, well.

 

*) and spent quite a few hours cleaning up the result because, well because perfectionism

 

 ++ Jari

[Nikguy]

WOW!!!

THE DETAILS!!! I'm shocked!

[BenKolt]

Outstanding job, Jari!

 

Ben

[ciraxis]

Wow!  Incredible detail. 

[Salacious B Crumb]

Outstanding Jari. Care to share some photos of your homemade scope?

 

 

- Mikko

[lucam]

Jari,

That’s fantastic. Congratulations on both the image and the outstanding optical instrument you put together.


Sent from my iPhone using Tapatalk

[vehnae]

Thank you all for the kind words, I really appreciate it!

 

Outstanding Jari. Care to share some photos of your homemade scope?

Sure, here are a couple.

 

1. Scope mounted on my rig: https://www.dropbox....ounted.jpg?dl=0

2. Backplate and wiring: https://www.dropbox....okouru.jpg?dl=0

 

There is also a build thread with more information and lots of pictures. It's in Finnish though, but I guess you'll (be the only one in this thread to) manage!

 

  ++ Jari

 

[Salacious B Crumb]

Sweet looking thing, I like the carbon fiber.

 

 

- Mikko

[PhotonHunter1]

Superb! I love the FOV sections. I don’t believe I’ve ever seen sections of the Wall, rather the entire wall. Exceptionally done Jari. 

[Seanem44]

 

Sooooo....  WOW!  And this makes me even more confident in my 1600.  Fabulous images!

[fco_star]

WoW… is an amazing image   

[vehnae]

Thanks a lot Mike, Sean and Francisco!

 

Sooooo....  WOW!  And this makes me even more confident in my 1600.  Fabulous images!

No need to doubt it, I think that right now the ASI1600 is the best chip available at amateur prices for narrowband! 

 

  ++ Jari

[Coconuts]

Jari:  Spectacular image and impressive integration time! 

 

On the hardware front, it seems that you and I think very much alike (although you are ahead of me in actualization).  A few years ago, I purchased a 10" f/4 conical mirror from Robert Royce, along with an ASA 3" Wynne corrector; very nearly your exact configuration! 

 

A few years before that, when visiting a carbon fiber supplier for work, I noticed what looked like short thin carbon fiber telescope tubes.  It turns out that he had the Celestron contract, and he gave me a pair of 300 mm diameter x 412 mm long carbon fiber tubes for free.  Back then, I was in the process of making a 10" Lurie-Houghton astrograph.  I had Newport Glass diamond generate the two BK-7 corrector blanks, and had started in on the 11" primary mirror, but kept getting zones from my polishing machine, and then realized how difficult edging the corrector blanks would be, and how heavy the scope would be.  I ended up selling the diamond generated corrector blanks to a talented optical designer in the Netherlands who posts in the CN Optics forum.

 

That's when I settled on buying premium parts from Royce and ASA.  The two CF tubes are still very relevant.  I plan to hard mount the primary using the ground flat at the back of the conical Royce mirror, attaching and preloading it against a surface ground rear plate using the spring loaded central threaded insert that Royce provides and recommends.  No adjustment, permanent collimation.  I will use an electronic indicator around the 10" rim to confirm that the conical mirror's rear flat is perpendicular to the optical axis.  I will also CNC machine a large aluminum ring with flat that will mount to the Losmandy dovetail plate, and it turn be fastened to each of the two CF tubes (one sticking rearward with the primary; the other forward towards the corrector and camera).  A buddy at work has started modeling all of this in SolidWorks.  I plan no secondary, but rather four sturdy plates that will bolt to the front aluminum tube ring and support the 3" Wynne corrector and camera directly on axis. I too am awaiting the launch of the QHY600 "Photographic" OSC and the ASI6200MC.  My no secondary approach will only work with OSC, but I'm a bit lazy, plus the new dual, triad, and quad-band filters close the gap.  And the collimation should all be hard and permanent.  Finally, I am in line for one of the first of the AP Mach2GTO's from Tolga once they start shipping in a couple of months.  The combo should be awesome!  But I still have some work to do...

 

All the best,

 

Kevin

Edited by Coconuts, 20 September 2019 - 10:27 AM.

[SANDRO78]

Wahoo ...very very nice , thank you .

 

alex.

[vehnae]

Thanks for the kind words Kevin and Alex!

 

On the hardware front, it seems that you and I think very much alike (although you are ahead of me in actualization).  A few years ago, I purchased a 10" f/4 conical mirror from Robert Royce, along with an ASA 3" Wynne corrector; very nearly your exact configuration! 

Yes! I thought about the optimal instrument for my goals quite a long time. I wanted something that could provide wide enough field for large nebulae, be mechanically stable and have fast optics but not too fast so that resolution would be significantly compromised. It seems that I have hit quite a sweet spot here. Scaling the scope to 12" would have cost less than 10% more, but since our seeing is rather average I chose the 10" for a larger field since the 0.83"/px is already quite enough. The ASA corrector should handle a full frame camera nicely, so when the ASI6200 comes out it's going to be 2.2 x 1.5 degree field at sky-limited resolution, can't wait!

 

What comes to stability, I run the scope unguided on a 10Micron GM1000HPS with under 3" RMS pointing error in the sky model (after removing some outlier points). I haven't tried how long it can go, but 10 minutes doesn't break a sweat.

 

 

No adjustment, permanent collimation.

How do you intend to make the corrector/camera axis and mirror axis coaxial? If the primary is completely fixed, you will need a mechanism to translate the corrector/camera assembly.

 

re: camera at prime focus, someone should build a filter changer for these applications. I drew up a concept (picture 1, picture 2) some time ago to see that mechanically it should be possible to house four filters without any additional obstruction (this was for 31mm filters).

 

  ++ Jari

[Coconuts]

Jari:  LRGB or Ha-Hb-Si-O3 in a compact package; brilliant!  I would never have thought of that elegant mechanical solution.  Rushing to a movie; will chime in tomorrow.

 

All the best,

 

Kevin

[kyle528]

Absolutely incredible image! Congrats on the IOTD!

[Coconuts]

Jari: "How do you intend to make the corrector/camera axis and mirror axis coaxial? If the primary is completely fixed, you will need a mechanism to translate the corrector/camera assembly".

 

My plan is to use precision machining, with the tube parts fit and epoxied in place (with small fasteners as backup) on a granite surface plate with a tall electronic indicator to confirm no tip or tilt between the mirror rim and the corrector/camera axes.  The focuser will be custom, basically a Crawford design with bearings at each end of the 137 mm long Wynne corrector.  The actuation along the axis will be a Thor Labs 80 tpi screw with strong magnetic preload.  I will only need a few mm of stroke.  The cylindrical symmetry will permit rotation for image framing. This may all seem a bit pie in the sky, but this sort of thing is what I do for a living.  I recently designed (although it took a talented team to get it to market) a 5 mm stroke microscope objective focusing stage (Dover Motion's DOF-5) with 1.25 nm resolution; it was an SPIE Prism Awards finalist.

 

This project will take well into next year to complete, but I will post more about it as I near completion.  Your excellent work has helped kick me into gear, so thanks!  I will be starting out with QHY600 or ASI6200 OSC, but if you don't mind, I would love to use your very clever compact filter switcher concept should I ever go mono.

 

Oh, and two last bits.  The ASA 3" corrector that we both have is now a bit of a collector's item; ASA has stopped serving the amateur community, and is now only building systems for research and the military.  I'm glad I bought it when I did, and for that matter the lead time from OPT was really long, over six months.  Also, Robert Royce,  the talented CT/USA optical fabricator who made my conical 10" f/4, has since retired.  His site is still up, here:

http://www.rfroyce.com/conical

 

All the best,

 

Kevin