W7MEV

I took this on 4 Dec 21 with my Celestron C-11 using the Hyperstar with the ZWO ASI178. Exposure was 16 frames totaling 41.7 seconds, binning =1, camera gain= 510. Assembly was with Registax 6 with clean-up in Photoshop.

I am quite happy with this and am certainly enjoying the capability the Hyperstar adds to my scope.

Any and all comments are welcome. Suggestions are always welcome since that is one way I learn how to improve!

Sidwalkastronomy Loc: New Jersey Shore

With the hyperspace doesn't it change the C 11 f10 to f 2? I often wonder taking the secondary out and replacing it the camera and the putting the secondary does it mess with the columination even if slightly?

W7MEV

The secondary is firmly fixed to its mount and there is a keyway on the on the secondary mirror mounting bezel attached to the corrector lens and a key on the secondary mirror assembly. When the mirror is removed and then replaced the key-keyway combination insures the mirror returns to its previous position exactly. The collimation screws on the secondary are locked down and are not disturbed by the mirror being removed and reinstalled.

I find no collimation problems when I remove the Hyperstar and reinstall the mirror.

Yes, the scope does go from f-11 to about f-2 and the field of view increases greatly allowing me to get pictures of my targets in the context of the surrounding sky, which I cannot do otherwise. For example if I had taken the crab with the normal secondary installed and the camera on the visual back I would have had a huge (and probably highly detailed) crab, but few, if any, of the background stars.

Using the scope as an F-2 lens allows VERY short exposure times. This also largely reduces the need for a guide camera since the exposures are so short there is not time for much movement. This picture took total of 41 seconds to shoot. As an F-11 it would have taken several minutes - and needed guiding.

This, too, introduces its own set of problems. If I need an exposure time of several minutes, it is easy to adjust the camera gain and exposure time for the best picture. LONG range of adjustment possible. But, with an F-2 lens, the camera gain and exposure times have a VERY short adjustment range and it becomes very tedious to get the gain and exposure just right. I have considered, and may well try, using a neutral density filter on the camera to cut down on the light getting to the sensor to give a little more adjustment range for the exposure.

All that said, I have always wanted a way to get a wider field of view, and now I have it! In the past, using Sharp Cap I have sometimes stopped guiding and switched the guide camera to be the imaging camera. My QHY guide camera is mounted on an Orion ST-80 refractor, so I get lots of field, but lose the guiding ability.

Nothing's perfect!

Thanks for your comments. I always welcome a response and will always try to address questions.

Sidwalkastronomy Loc: New Jersey Shore

I have a C 8 for years (1983) and with my film cameras I could get the complete full moon with a small nice border. When I changed to digital I was having issues then realized it was a crop censor camera. So I dug out my focal reducer which changed my f10 to a f 6.3 and bingo full size moon returned. My C 8 after all these years still gives excellent views. I also have a CPC 11 on my ROR backyard observatory. And a Meade 10. With my last stimulus check I bought a nice explorer scientific 102 APO, which stimulated me and the economy. The 102 refractor gives great contrast and easy to overcome around. I place it on an AVX mount and great travel scope. Excellent images you post here and astrophotography with tracking and stacking is extremely difficult so I can see you going to the f2. My brother has same setup as you and his collumination stays accurate also.

Ballard Loc: Grass Valley, California

Neat shot. Particularly for such short exposures.