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Seeing "Focus-drift" with Oberwerk 15x70mm LWs

binoculars observing
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#1 randy_1701

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Posted 17 May 2019 - 12:28 PM

Greetings All, and Happy Friday!!

 

I got some nice used Oberwerk 15x70mm LWs here on CN Classifieds for a great deal, a while back, and they are an awesome addition to my equitpment.  They were off a bit in collimation, but the great support link on the Oberwerk website helped me correct this very easily with a jeweler's screwdriver, and they are nearly perfect for me, now.

 

Only drawback is that the focus wheel seems to "drift" away from sharp focus whenever I am using them; it is not so noticeable when holding them horizontally or mounting them on a tripod/mount to view during the day, but if I turn them skyward, as I did with the almost Full Moon, last night, the focus just won't "hold."  The view of the Moon through these at 15x is awesome, as are Milky Way sweeps or open Clusters, or planetary conjunctions, or spotting the brighter asteroids...by the way... *grin*

 

Anybody else experience this with either Oberwerk brand or other larger binos of this type??…

 

I'm thinking that I need to perhaps service and grease them with a "thicker" grease, or see if there is anything "loose" in the focus wheel or elsewhere on the crossbar..or is there some way of adjusting the tension a bit tighter...

 

Any advise or common experience would be appreciated!

 

Regards and Clear Skies,

Randy in South Carolina

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#2 Bill Barlow

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Posted 17 May 2019 - 02:55 PM

I would probably call Oberwerk and speak to Kevin.  

 

Bill


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#3 randy_1701

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Posted 17 May 2019 - 04:01 PM

Thank you, Bill I will give that a try.  Still curious to find out what is going on with these otherwise great binos...

 

Clear Skies,

Randy



#4 SMark

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Posted 17 May 2019 - 08:58 PM

The info below may assist you... waytogo.gif

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#5 Binojunky

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Posted 18 May 2019 - 09:49 AM

I had a pair of these, a good value but still a low cost instrument, mine too went out of alignment but was able to do a conditional alignment with the tutorial on the web site, one thing to look for in the bridge that connects the two eyepieces is any rocking or movement, when you press the rubber eyecups agains your eye sockets it can move slightly and put things a touch off focus. Also as the day or night progresses your eye vision can change and often needs a touch up focus wise via the wheel or right diopter adjustment.D.


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#6 StarBurger

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Posted 18 May 2019 - 10:45 AM

SMark and Binojunky +1.

I have used many brands of bins and always have to continually re-focus. It's the eyes!


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#7 randy_1701

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Posted 18 May 2019 - 12:12 PM

Thanks for the responses, but these are acting totally differently than with my other binoculars, such as my Celestron Classic 10x50mm and Minolta 8x40mm pairs, and even my vintage Celestron 11x80mm, that I don't use that much, ALL hold their focus just fine, horizontal daytime or skyward usage...

 

I will check out the bridge for any looseness in the 15x70mm Obies, but to describe the way it seems to work, I can lock down my left eye just fine in focus but when I touch the diopter focus on my right eye, which has a bit of astigmatism, the left side has already started to drift away from good focus, and I have to start all over again... I can hold the focus wheel with m finger and it does seem to lock down the left eye focus, but if I let go then it does seem to drift away again.

 

I appreciate the responses, keep them coming!

Regards and Clear Skies,

Randy



#8 Jon Isaacs

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Posted 18 May 2019 - 01:19 PM

I will check out the bridge for any looseness in the 15x70mm Obies, but to describe the way it seems to work, I can lock down my left eye just fine in focus but when I touch the diopter focus on my right eye, which has a bit of astigmatism, the left side has already started to drift away from good focus, and I have to start all over again... I can hold the focus wheel with m finger and it does seem to lock down the left eye focus, but if I let go then it does seem to drift away again.

 

I think this is what Bill Cook's "thumb test" is all about.   Pinch the bridge end and the far end of the hinge between your thumb and forefinger and see if the focus shifts.  

 

Some threads are "self-locking", some are not.  Binoculars that shift focus when you push them against your eye sockets, are not self locking.. 

 

https://en.wikipedia...ocking_property

 

Jon


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#9 Mark9473

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Posted 18 May 2019 - 05:00 PM

Congrats, Randy, you're one of the few to completely fill my laptop screen with just your signature. ;-)


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#10 randy_1701

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Posted 18 May 2019 - 08:44 PM

Lol, sorry for the long Sig. I actually had shaved it down a bit...;-)


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