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WO binoviewer on TV-85?

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#1 gecko64

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Posted 12 April 2013 - 12:49 PM

I just got a Williams Optics binoviewer for my TV-85. I did some googling beforehand for any reports that it wasn't compatible, but found nothing, so I went ahead and purchased it. But turns out there's not enough in-focus on the TV-85 (with or without the diagonal). Or maybe I'm missing a step? Anyone have any suggestions or insights?

thanks!

#2 Mark9473

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Posted 12 April 2013 - 12:51 PM

The WO normally comes with an 1.6x corrector lens; are you using this?

#3 gecko64

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Posted 12 April 2013 - 01:18 PM

Yes, I screwed that in right away. (And I did try without it -- much worse!)

#4 Mark9473

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Posted 12 April 2013 - 01:20 PM

Well the usual next recommendation would be to use a 1.25" diagonal instead of 2" but since you report not reaching focus even without diagonal, I have no more ideas.

#5 DaveJ

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Posted 12 April 2013 - 03:22 PM

Yes, I screwed that in right away. (And I did try without it -- much worse!)


Do you have a 1.25" diagonal? If so, screw the corrector into the front of the diagonal, put the diagonal into the focuser and put the binoviewers into the diagonal. If you've already tried that, please let us know. That really should bring them to focus at infinity.

#6 Jim7728

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Posted 12 April 2013 - 03:45 PM

I recall having to use a 1.25" diagonal for my Denk Standard with the part s ocs mounted in front of diagonal when used with my TV-85.

#7 gecko64

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Posted 12 April 2013 - 04:32 PM

Thanks for all the tips. I don't have a 1.25" diagonal, but will try to get ahold of one and see if that does the trick.

#8 johnnyha

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Posted 12 April 2013 - 09:04 PM

If you have a regular barlow you can put the WO in that without the OCS.

#9 Mark9473

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Posted 13 April 2013 - 02:52 AM

I don't have a 1.25" diagonal, but will try to get ahold of one and see if that does the trick.

That can only work if you mis-diagnosed not reaching focus without a diagonal in place.

#10 daniel_h

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Posted 13 April 2013 - 06:16 AM

still not enough in focus without any diagonal & the 1.6x corrector in place..ouch tube cutting may remedy it but who could cut thru a TV85?

#11 REC

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Posted 13 April 2013 - 08:26 AM

I have no problem using the 1.6x in front of the 1 1/4" diagonal in my 80mm.

#12 gecko64

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Posted 13 April 2013 - 10:05 AM

I don't have a 1.25" diagonal, but will try to get ahold of one and see if that does the trick.

That can only work if you mis-diagnosed not reaching focus without a diagonal in place.


I was wondering that too...so I tried it again without the diagonal, and in fact I can reach focus no problem at all. Dunno why I got that wrong yesterday (except that I was doing it hurriedly at lunchtime, with the scope in my lap).

In fact, without a diagonal, it only reaches focus withOUT the corrector lens. With it, there's not enough out-focus (which is also true for a single eyepiece without the diagonal. I never knew that!)

So I'll order a 1.25" diagonal. Any thoughts on that? I should get a mirror, not prism, right? Like this?

http://www.telescope...-Diagonal/p/...

EDIT: Actually, that's why I mis-diagnosed it yesterday: I had the corrector lens in and didn't think to try without it.

#13 johnnyha

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Posted 13 April 2013 - 12:06 PM

You can get a similar 99% diagonal from our sponsor Astronomics for the same price but with a CN discount. ;)

#14 Mark9473

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Posted 13 April 2013 - 02:38 PM

In fact, without a diagonal, it only reaches focus withOUT the corrector lens. With it, there's not enough out-focus


I figured you had to be at the wrong end of the focusing range.
So yes, a 1.25" diagonal will help. But as to which model is best, I can't help you. Prism diagonals have a shorter light path than mirrors, but it's difficult to know if those few mm will make a difference in your case.

#15 gecko64

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Posted 13 April 2013 - 03:20 PM

Thanks for all the info, much appreciated! And I'll place my order with Astronomics!

#16 gecko64

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Posted 22 April 2013 - 09:12 PM

I got the 1.25" diagonal, put the barlow in front of it, and the binoviewers focus without a problem. Thanks for the help!






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