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I have a new lucky number...

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#1 CharlieInDayton

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Posted 19 June 2006 - 12:03 AM

6653184...that $20 for raffle tickets was the best double sawbuck I ever spent...ask Tom about the enthusiasm at the Apollo Rendezvous...

Posted Image

I'm checking on a mount for this now...

For the moment, I'm thinking of sticking back a few bucks for the great and grand experiment.

What would the reasons be for or against buying a (relatively) matched pair of zoom eyepieces to stick in this beastie? That would give me a pair of zoom monster binos that range from 21 to 65 power. They're currently available from Seben (down Australia way) on eBay for about $50 each...of course, I could sell a close relative for that matched set of Nagler 8-24 zooms I heard of on a particular unnamed board...

Anyway...what are the pros and cons about using zoom eyepieces in a bino like this?

#2 Bob W6PU

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Posted 19 June 2006 - 01:26 AM

That sure is a beauty Charlie! I can't make out the name, what kind is it?

Bob in NM

#3 Joad

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Posted 19 June 2006 - 01:58 AM

That's the Oberwerk BT: the 80mm doublet, yes? What a great prize!

I have the 100mm version and I am also thinking about a variable power set of EPs. I say "variable" power rather than "zoom" because I gather that zooms do not work well on binoculars, but a high quality click stop eye piece, like the Tele Vue, would work. Pricey, of course, to buy a pair, but I think that that's what one needs to do.

#4 CharlieInDayton

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Posted 19 June 2006 - 06:25 PM

Yes, it's the BT-80-45 -- 80mm aperture, 45 degree eyeball holders...

It comes with a pair of 26mm (aka 20X) eyepieces...I've always wondered, though...variables?

Help me out on this one, troops...I have the money available (it will probably need to be surgically removed from my wallet, but I've got it), and TeleVues do have that superior reputation...

I'd almost swear I've seen this done/talked about here before...checking closer into the archives...

Is this worth at least seriously considering, or is it a bad idea that doesn't deserve pursuing?

#5 Joad

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Posted 19 June 2006 - 06:44 PM

Tele Vue click stops HAVE been discussed before here. At least one active and one vanished member on CN have gotten them to use on the Oberwerk 45° BT. My impression is that they work. I'm mostly concerned about eye relief, though, on the tele Vue vari-power eps and am searching for information myself.

#6 ZX12

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Posted 19 June 2006 - 06:58 PM

I have been using the TV 8-24 zooms in both my Oberwerk BT100/45 and my BT125 Vixen. They work superbly and have become my mainstay for all types of observation, day or night. The only other e.p.'s that get used in the Oberwerk are stock 24mm's for wide field views.
One slight drawback is that you must hold on to the barrel of the zoom e.p. while varying the power to prevent it from rotating. My Vixen has a lock ring to prevent this, while the Obie relies on a slip fit.

Mike

#7 btschumy

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Posted 19 June 2006 - 09:26 PM

The Televue zooms have a pretty narrow AFOV (40º) near the longer focal lengths. I would think that would be a problem. 40º feels pretty claustrophobic to me.

#8 CharlieInDayton

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Posted 22 June 2006 - 02:14 AM

I've located a pair of 8-24 TeleVues for The Beasts...ya know, I've got three scopes at home and I can't remember the last time I got any of 'em out...it's all been binos...I think the 3" Tasco and the 130mm Orion are gonna get advertised...but I'll keep the Bushnell bowling ball with a smokestack Astroscan clone, just 'cause it's simple...

I think I may have found my niche...

#9 EdZ

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Posted 22 June 2006 - 04:49 AM

Charlie.

Those TV clickstop zooms sure sound convienient,and I'm sure they'll work, But I'd be searching out some wider field eyepieces. Even plossls. For the convienience of click stop, you are giving up an awful lot of FOV.

TV plossls 52° - 25mm, 20mm
Orion Stratus 68° - 21mm, 17mm, 13mm, 8mm.
TV Radians 60° - 18mm, 14mm, 12mm, 10mm.
Burgess TMB planetary 60° - 9mm.
Meade 5000 superwides 68° - 24mm, 20mm 16mm,
William Optic SWANs 70° - 25mm, 20mm 15mm, 9mm

A number of the above also have 30mm to 35mm, but in general that would give very low power. With the exception of the Meaded SW and the Radians, all the rest above sell for $120 or less.

Then there is the much more pricy Pentax XW or TV Panoptics

The TV 8-24 zoom goes from Afov 55 to 40. So at low power 24mm, you'd have 22x80 with a Tfov of only 1.8°. At high power 8mm you'd have 65x80 at 0.8°.

My most used eyepieces in my BT100
26mm TV plossls = 24x100 at 2.2°
20mm TV plossls 31x100 at 1.7°
14mm Radians 44x100 at 1.4°

edz

#10 Joad

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Posted 22 June 2006 - 10:43 AM

Thanks for the succinct summary for us of information that I know that you have shared with us many times before, EdZ. I will study your list carefully as I consider any future BT100 ep purchases.


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