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What's the proper way to focus binoviewers??

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#1 Joe Lalumia

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Posted 27 February 2007 - 04:03 PM

Don't be a dummy like me HA! The first time I put the binos on the SCT I carefully focused the eyepieces BUT IT WOULD NOT come to focus! HUH? WHAT? Took them out looked at them made sure the lenses were all the way in, put them back in...........still out of focus!! OH! I FORGOT to focus the telescope! HA! For a minute there I thought I had a UNIQUE SCT.

Which brings me to the question.........how are you suppose to focus binoviewers? Lenses first? Telescope first? Views were sharp and clear........but I dont believe I actually focused the binos correctly??? :question:

#2 Ken....

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Posted 27 February 2007 - 05:58 PM

There's a procedure for focusing the binos with separately focusing EP holders (I think it was posted here or is available on the Web, maybe by Don Hole), and once that's done you shouldn't need to touch it. The scope should do the overall focusing.

#3 johnnyha

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Posted 27 February 2007 - 08:51 PM

I rough focus with the telescope first. Then I fine tune the focus on one eye (in my case the left) with the telescope. Then I fine tune the other eye (the right side) with the bino EP diopter. Now both eyes should be in focus, and the telescope will do the rest of the focusing. Unless I change out the eyepieces, then I start all over again. Sometimes when I change the Power X switch I have to refocus the right diopter again as well.

#4 Joe Lalumia

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Posted 27 February 2007 - 08:53 PM

Johnnyha, thanks.

#5 johnnyha

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Posted 27 February 2007 - 08:59 PM

Johnnyha, thanks.


Glad to help, Joe. Just remember to occasionally look through one eye at a time and see if they match focus. If not fine tune the diopter.

#6 b1gred

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Posted 27 February 2007 - 11:06 PM

With my DenkII, I bottom out both EP holders, then back them out all the way, counting turns, then turn them back in exactly half tne number of turns it took to back them out.

I then consider the LEFT side to be "fixed", that is I never adjust it. Why left? No reason except that it's my dominant eye, so that's the one I use for focus.

When focusing the scope, I do it with the left eye, then adjust the right side diopter adjustment for fine tuning...

My eyes are close enough to the same focus and my EPs are matched well enough that it rarely takes more than just a slight turn on the right side to match things up.

I don't think there IS a "correct" way to do this, it's just what works for me...

#7 Joe Lalumia

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Posted 28 February 2007 - 09:41 AM

Randy, thanks for your "centering" the eyepiece suggestion.

#8 johnnyha

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Posted 28 February 2007 - 02:12 PM

Joe - another way to do it is, determine which eye diopter is unscrewed the most. In my case the right is screwed out about a turn more than the left. So I screw the left diopter in all the way so it is locked down, rather than centering it.

#9 David E

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Posted 01 March 2007 - 07:46 PM

Binoculars have a diopter adjustment in the right eye only. So I learned to focus the binoviewers the same way as I do binoculars. Most of my eyepieces are not exactly parfocal so I have to make minor adjustments to the right diopter. Everyone's eyes are of course different. I once took my 102ABV to a club public observing set up in bino mode. One person, inspite of the fact that he wore glasses, insisted that the binos were in focus with the right diopter turned nearly 180ยบ clockwise from the left diopter. It would take me quite a while to figure out what he had done to get them back into focus for me.
David E


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