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Thread: 8" Edge or non-Edge for video?

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    Default 8" Edge or non-Edge for video?



    My main question is whether there is an affordable reducer available for the Edge. I've heard that reducers are a problem for the Edges for some reason, but I'm trying to verify that. If I can't easily reduce it, I'll opt for the non-Edge, but otherwise I like it. Mounted on an AVX, it's only a couple hundred more right now on sale.

    Any other thoughts on the Edge/non Edge debate would be appreciated as well. I do want it to be a good visual scope as well.

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    Default Re: 8" Edge or non-Edge for video?

    Without regard to your personal definition of 'affordable', the Celestron 0.7x reducer is about $300, and the Optec Lepus 0.63x is about $200.

    Reducers are not a problem, other than using the wrong type - a standard SCT reducer/flattener combines two optical functions, a field flattener (already designed into the EdgeHD series), and a focal reducer. Using one of these creates optical aberration.

    If you are doing this purely for video astronomy and visual use, you can save money by going with one of the standard SCT's - the integrated field flattener in the EdgeHD is optimized for still astrophotography with a DSLR or CCD - there is some, but minimal benefit for video astronomy, and almost no additional benefit for visual.
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    I agree with Austin. The CCD chips in most current astro video cameras is 1/3 - 1/2 inch, so it would not take advantage of of the wide field flatness of the edge HD. Save yourself some money and stick with the standard SCTs
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    Default Re: 8" Edge or non-Edge for video?

    Okay, thanks guys. I have heard reports that the Edge is helpful for visual, but maybe only if one is quite critical.

    Obviously I need to learn a lot more about SCT optics and reducers, not to mention video imaging. I just looked at Astronomic's website and see that the reducers for Edges are a lot more expensive than conventional. No idea why, but that alone pretty much precludes an Edge for me...

    So I think I'm looking at a C8 on a AVX. But Mike, I see that you have a 9.25 on an AVX. How much weight do you have on the mount and how well does is handle that 9.25? Not sure if I want to spend that much, but could you give me a comparison between and 8 and 9.25 for video/visual use?

    Ron

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    Default Re: 8" Edge or non-Edge for video?

    The human eye is optically very different from an imager at the Cassegrain focus - the eye can't visualize the entire image field simultaneously, and it can correct for spherical defects at the edge of the field. So there is no 'penalty', with respect to optical aberration related to field curvature for a standard SCT vs. the EdgeHD optical system. The 'reports' of visual difference between the EdgeHD and a standard SCT would be myth...

    The cost of an EdgeHD reducer as opposed to a standard SCT reducer/flattener stem from two sources; the lower volume associated with the former, along with optical complexity. These two factor together to increase the cost of the EdgeHD reducer, and combine with market-driven 'hype' to define its retail price.

    Quote Originally Posted by spirit View Post
    Okay, thanks guys. I have heard reports that the Edge is helpful for visual, but maybe only if one is quite critical.

    Obviously I need to learn a lot more about SCT optics and reducers, not to mention video imaging. I just looked at Astronomic's website and see that the reducers for Edges are a lot more expensive than conventional. No idea why, but that alone pretty much precludes an Edge for me...

    So I think I'm looking at a C8 on a AVX. But Mike, I see that you have a 9.25 on an AVX. How much weight do you have on the mount and how well does is handle that 9.25? Not sure if I want to spend that much, but could you give me a comparison between and 8 and 9.25 for video/visual use?

    Ron
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    I am running about 25-27 pounds on my AVX and it does great. Just have to keep it balanced. Gotos and tracking are very accurate. May be a little to much weight for same AP, but fine for video astronomy. The C8 would be great weight on this mount even if you wanted to do AP
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    Default Re: 8" Edge or non-Edge for video?

    Ron,

    I'm leaning towards the same setup Mike has and I have read a lot about it. The AVX mount should be just fine for visual and video, but I wouldn't think you could do AP with this setup. You all have me scared about the reducers now. I know I will have to purchase a couple of reducers to be able to do decent video with it, but I didn't know there were good ones and not-so-good ones and the price of $200-300 is scary. If that is so I may have to go with the C8 also. Are there specific reducers for the C9.25 or will any reducer for SCTs fit and how much are they?

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    Default Re: 8" Edge or non-Edge for video?

    As was mentioned earlier in this thread, only the Celestron EdgeHD series require a specific reducer:

    8" Edge or non-Edge for video?

    The generic Celestron reducer/flattener (about $145) as well as many other 0.63x reducer/flatteners will work with the standard SCT. A generic 0.63x reducer/flattener can be had for about $90 if you shop for it.

    The focal reducer is of dubious value for planetary video-based astronomy, as in this case the SCT's long native focal length combined with small detector of the video imager is desired for image scale (apparent magnification) purposes. With something like a Mallincam, the reducer might be of some value for extended objects.
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    Default Re: 8" Edge or non-Edge for video?

    Thanks Austin, that is the answer I was looking for. I guess I was being last also but I wanted to make sure before I pull the plug.

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    Default Re: 8" Edge or non-Edge for video?

    The high cost of the Edge reducers is what turned me away from the Edge line. This Astronomics page shows various reducers. I sure wouldn't want to be buying one for a 11" Edge!

    https://www.astronomics.com/vsearch....hTerm=reducers

 

 
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