Final double stack set up for our 102mm refractor

[Averton]

We started this project some months back. It was inspired by the set up that Derek had made. Initially the performance was disappointing using our ASI178MM camera. With its 2.4um pixels it was way over sampled and we had hoped that by running binning it would be successful. No matter what we tried it still gave disappointing results.
After the suggestion of Martin, we finally decided to buy an ASI174MM camera and it has been a resounding success. Much better results.
The final setup looks like this.

P1100257 small.JPG (185.33 KiB) Viewed 2105 times

So working from the objective to the camera we have a UV/IR cut filter as an ERF, then a Solar Scout 60 Quark attached by a 3D printed adapter, followed by a Lunt 40mm etalon in a 3D printed housing (very similar to Derek's), then a modified ZWO tilt adapter. In the picture there is a flats screen attached to the front of the scope.

We have also tried the set up with our 72ED, also with good results. This makes it flexible as we can get different FOV.

[marktownley]

Very nice!

[Oak]

It's a great looking piece of gear. Have you tried it visually? Made a big difference for me. Would you be willing to share some of the 3D designs?

-Derek

[OlegLviv]

Cool but dont see result photos?

[Averton]

It's a great looking piece of gear. Have you tried it visually? Made a big difference for me. Would you be willing to share some of the 3D designs?

-Derek

Thanks Derek. We have to admit that we have never actually used any of our solar scopes visually. We very rarely use an eyepiece for any astronomy. We have our scopes set up outside and we are inside viewing remotely.
We often provide our 3D design files on a site called GrabCAD. It's just getting around to doing it. We intend to do so at some point.

[Averton]

Cool but dont see result photos?

Thanks Oleg. Some images from the set up are posted here viewtopic.php?t=38950

[Averton]

Very nice!

Thanks Mark

[thesmiths]

Which refractor is this exactly? The f6 or f7? I think it's a doublet. Do you know which kind of glass it uses? It looks like a very nice scope for solar, and I think it is sold under a few different brand names around the world. Any specs you have for the telescope would be helpful.

[Averton]

Which refractor is this exactly? The f6 or f7? I think it's a doublet. Do you know which kind of glass it uses? It looks like a very nice scope for solar, and I think it is sold under a few different brand names around the world. Any specs you have for the telescope would be helpful.

The refractor is a Kson A102G F7. It is an air spaced doublet. The glass specification is difficult to determine. We did find a site that quoted two types of glass, presumably one for each element, but they are Chinese specifications. At least one of them appears to be just basic BK7 glass. Specs below are from an Australian supplier. Hope this helps.

Description 102mm Achromatic Air Spaced Doublet Refractor
Coating Type Broadband Multi-coating
Glass Specifications K9/QK3 High Grade Optical Glass
Item Number ASKSA102GR
Aperture 102mm
Focal Length 700mm
Focal Ratio f/6.8
Limiting Magnitude 12.5
Resolution 1.14 arcsec
Dew Shield Type Metal
Finish Pearl White
Diameter 102mm
Weight 3.4kg
Dovetail Vixen Style

[thesmiths]

Thanks for that. It does seem it really is very basic glass. I guess it's not necessary to use fancy low dispersion glass for this application. I have seen similar looking telescopes that use FPL53 ED glass and Lanthanum glass lenses to give very low chromatic aberration. Your fine results confirm that expensive glass is not so critical for H-alpha.

[Averton]

Thanks for that. It does seem it really is very basic glass. I guess it's not necessary to use fancy low dispersion glass for this application. I have seen similar looking telescopes that use FPL53 ED glass and Lanthanum glass lenses to give very low chromatic aberration. Your fine results confirm that expensive glass is not so critical for H-alpha.

No problems. As far as we can determine, there is no theoretical reason to have specialist glass for narrow band imaging. We have also been recommended by far more experienced and competent people than us that a budget refractor will do the job for Ha imaging. As you are only focusing on a single wavelength of light, chromatic aberration cannot be an issue. The lens will be figured most likely for green light and definitely not red, but that would be the case for any scope so the resultant spherical aberration should not be any better or worse.