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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 1971
Loc: Florida
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I've been assisting a neighbor that had severe double images in his 60's vintage Tasco bino's. Using the prism adjusting screws he's got them nicely aligned. They focus fine inside infinity but at infinity he and I cannot get a sharp focus. It's got me miffed and I'm not sure what would cause that. It's close to sharp focus but just slightly off. Any suggestions?? Thanks, Bill N.
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
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astrokido
sage
Reged: 06/09/08
Posts: 248
Loc: Phoenix, AZ
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Bill,
The eyepieces don't have enough travel inwards, towards the objectives, where the infinity focus is. You'll need to look at the focusing axle that moves the eyepieces, and modify it where it contacts the eyepieces in order to allow the eyepieces to reach further inwards.
There are usually a few thin washers between the axle and the first eyepiece, removing one or two of the washers should allow reaching focus at infinity. It's also possible that different observers may experience different focus limits due to different eyesight.
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- Gill C. - All opinions subject to a speed limit of 299,792,458 m/s unless noted otherwise.
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12513
Loc: Cumberland, R I , USA42N71.4W
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Quote:
You'll need to look at the focusing axle that moves the eyepieces, and modify it where it contacts the eyepieces in order to allow the eyepieces to reach further inwards.
There are usually a few thin washers between the axle and the first eyepiece, removing one or two of the washers should allow reaching focus at infinity.
That's not how you correct the infinity focus adjustment. There should be only one thin brass washer between the two eyepiece arms. It should stay.
The entire focus assembly screws into the center axle. These are connected several different ways, so there is no way for me to tell you how to remove the focus shaft from the axle. It could unscrew at the focus knob. It could be held in place by a brass screw, accessed thru the L bracket hole.
I agree, it sounds like the focus screw needs one turn more towards the "IN" position to get closer to infinity focus. You would do that by twisting the focus screw inside the disassembeled focus shaft. Then the entire focus shaft should be reinserted into the axle and retightened.
edz
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
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Bonco
Carpal Tunnel
Reged: 04/17/06
Posts: 1971
Loc: Florida
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Gil, Edz,
Thanks for the advice I'll investigate the inward focus.
Cheers, Bill N.
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RV6
Meade 2045
6 inch f/4 RFT R. Fagin Optics
TV Genesis
2.4 inch Lafayette Equitorial
3 inch Polarex/Unitron Equitorial
10 inch Zhumell
PST 40mm Solar scope
4 inch F/15 Antares
2.4 inch Unitron Equitorial
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DJB
Pooh-Bah
Reged: 02/23/05
Posts: 1259
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I have done exactly what EdZ has alluded to. You can achieve infinite focus, or any other you wish for an eye condition, precisely in the manner which Ed has described.
Unless, you run out of screw travel, that is.
Best regards,
Dave.
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Simon S
super member
Reged: 01/07/07
Posts: 100
Loc: Crawley West Sussex UK
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Remove the worm from the focus wheel and wind just the focus wheel in a few turns. Then resemble. That should do it.
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