Focal Reducer for 8 & 9.25" EDGE HD scopes - WHEN?
Posted 09 November 2012 - 02:35 PM
And there's never an answer that's in the least reassuring... Had there ever been anything like a positive answer, I'd have already bought one of these scopes...
It seems like a great fumble on Celestron's part, sort of like the lack of a 6" EDGE HD... Is there anyone awake at Celestron?
Posted 09 November 2012 - 08:23 PM
Posted 09 November 2012 - 08:35 PM
Posted 10 November 2012 - 10:37 PM
I don't know what adapters will be necessary to adapt the A-P reducer to an 8" EDGE HD scope for visual use (but I see you have an 8" EDGE, and likely know the answer to my question from personal experience, and probably have already answered my question, directly, or indirectly)...
Posted 10 November 2012 - 11:16 PM
I used it in front of the diagonal on a Meade 12" and got a 1.3 degree FOV, measured by fitting alpha and beta Muscae in the field of a ES30mm 82 degree eyepiece.
If I get a clear night I'll try the CCDT67 attached to the eyepiece with the 8"Edge and let you know how much extra field there is.
Posted 11 November 2012 - 08:27 AM
Putting the reducer in front of the diagonal gives a larger increase in FOV but stars become aberrated in the outer field.
Personally I don't see any advantage using a reducer on an 8" visually since a 35 Panoptic or 30mm UWA gives a low power ~1.2 degree FOV anyway.
Posted 11 November 2012 - 04:46 PM
And you're right; my 35 mm Panoptic should deliver just about 1.2 degrees, and the 41 mm Pan will stretch that a little further, to almost 1.4 degrees. I'd been hoping to get into the range of 1.5 degrees, but 1.4 is probably *close enough*.
So I probably CAN live without a reducer, using a 41 mm Panoptic as the last step. And it's simpler to just keep on feeding it eyepieces, without having to add intermediate optics...
Posted 11 November 2012 - 07:24 PM
1.2 degrees is about the limit with the C8 since the 38mm clear aperture at the rear cell will noticeably vignette the 41mm Panoptic field stop of 46mm. The 35 Pan or 30mm UWA variants are the best low power eyepieces for the C8.
I tried another reducer combination today: the CCDT67 can be screwed directly to the body of a WO diagonal, replacing the nosepiece, but at the expense of almost 3/8" of aperture due to vignetting inside the OTA. I'll see how it looks at night when I get the chance - it should give a much wider FOV.
Some SCT's are better suited than others for use with a reducer and the 8" is one of the worst for vignetting.
Posted 12 November 2012 - 10:26 AM
Truth is, my 8" Newtonian, with superb Mike Spooner optics can do everything as well or better, other than the compactness of the SCT design, and I already have the Newtonian... Heheheh!!!
Posted 12 November 2012 - 11:26 AM
Posted 12 November 2012 - 04:44 PM
Posted 12 November 2012 - 05:43 PM
Thanks for prying out data on BOTH subjects (reducer & 6" EDGE - both are items I've given more than a small amount of thought to...)... It's greatly appreciated!!!