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Equipment Discussions >> Binoviewers

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Reged: 02/01/06

Re: Binoviewers for a C8 HD [Re: coutleef]
      #5849736 - 05/09/13 10:41 AM

Ah, well that explains the difference as to why you did not see the same amount of apterure loss that I did.

For some reason, I missed that you were using a standard C8. I guess because this was a thread about binoviewing the EdgeHD 8", I must have jumped to the conclusion that you were also using an EdgeHD.

And that figure (7.6) is about exactly right for the standard C8.

Assuming 230mm of back focus (just a guess) your apeture would indeed be 7.6" or so.

My apologies for my confusion.

If you are using a standerd C8, assuming that the light path would be Clicklock (38mm of back focus) Siebert Diagonal (about 45mm of back focus) and WO binos (about 110mm of back focus, the would put you at about 190mm to 200mm of back focus.

With 200mm of back focus, you should be working at about 7.9", but you would also reduce your focal lenght quite a bit as well.

Again, forgime my confusion.

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Reged: 12/22/08

Loc: Straight of Gibraltar
Re: Binoviewers for a C8 HD new [Re: coutleef]
      #5911789 - 06/09/13 06:35 PM Attachment (9 downloads)

I have the recommended Eddgie setup for my c8 hd (with Maxbright binoviewer) and two Baader hyperion 17mm eyepieces.
My question is: should I also use the 1.25x Glass Path Corrector?
Will I lose aperture/brightness?
Also where should it be positioned (position A or B?).
I did read somewhere that it might be better positioned nearest the optical tube (position B in the picture)

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Reged: 02/01/06

Re: Binoviewers for a C8 HD new [Re: beammeup]
      #5912007 - 06/09/13 08:42 PM

There would not be that much benefit in the GPC for general viewing, but for planets where you want as much aperture as possible, I would put the GPC in between the nose and the front of the diagonal. This will give you about 1.5x but it will increase the aperture by maybe 2 tenths of an inch.

What visual back are you using?

if you are using the Televue Shorty/T2/Maxbrights, you are probably already working at 7.7" and the 1.25" GPC will be like shortening the light path about 20mm, and this will give you very close to full aperture.

For general viewing though, it restricts your exit pupil to much. It is better to have the much lower power vs the slightly larger aperture because for most deep sky observing, you want the ability get as low a power as possible.

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