killdabuddha
Pooh-Bah
Reged: 08/26/11
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2 inch EPs for the binoviewer
#5024912 - 01/18/12 02:25 PM
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Lookin for the best 2" 24mm (or longer) UWA (80 degree) EP that we can use side-by-side for our binocular telescope build. We've written to Harry Siebert to see whether he can put some together as he's already makin 34mm and 36mm 70s that work side-by-side. We wanted the ES 24mm 82 but they measure 70mm.
Thanks
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Tamiji Homma
Carpal Tunnel
Reged: 02/24/07
Loc: California, USA
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5025183 - 01/18/12 04:39 PM
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Lookin for the best 2" 24mm (or longer) UWA (80 degree) EP that we can use side-by-side for our binocular telescope build. We've written to Harry Siebert to see whether he can put some together as he's already makin 34mm and 36mm 70s that work side-by-side. We wanted the ES 24mm 82 but they measure 70mm.
Thanks
I would recommend a pair of Nagler 22T4s if you are looking for 24mm-ish 2" eyepiece for binoscope. That's my plan. I already have the pair but I don't have binoscope/binoculars, waiting for it patiently 
Tammy
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: Tamiji Homma]
#5025299 - 01/18/12 05:47 PM
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Think we're gonna go with Siebert's 34mm 70s for super-low power and significant TFOV gain, and Barlow with his 1.5x Telecentric for a 22.3mm EP. (The ES 24-68s we woulda had for each eye were .8" degree TFOV, vs the 1.25" degree TFOV with the 34s.) His 2" Observatory EPs are designed to work with his 2" binoviewers for side-by-side. But thanks for that Tamiji...if we have a chance to get the 22mm Naglers we certainly will as we have the 11mm T6s.
Tamiji...just looked at the 22mm Nagler T4 and that has to be at least 3" in barrel diameter. How will you fit these side-by-side? Actually, depending upon which photo you look at here
http://www.optcorp.com/product.aspx?pid=30-718-68-71-1247&kw=&st=0
guess they can be either 2.5" or 3" diameter. As you have them in hand I'll take it that they're more like 2.5"
Edited by killdabuddha (01/18/12 06:13 PM)
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Tamiji Homma
Carpal Tunnel
Reged: 02/24/07
Loc: California, USA
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5025457 - 01/18/12 07:23 PM
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Nagler 22T4 diameter is about 61.5mm.
It is a little larger than my IPD but I have tried the pair when I had 150mm f/5.6 binoculars with 2" eyepiece holder. It worked OK at least terrestrial viewing.
Unfortunately, the eyepiece didn't come to focus to infinity with the binoculars so I don't know it works well for night sky viewing.
Tammy
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DaveJ
Pooh-Bah
Reged: 01/07/05
Loc: NE Ohio
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5025465 - 01/18/12 07:29 PM
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guess they can be either 2.5" or 3" diameter. As you have them in hand I'll take it that they're more like 2.5"
According to the TeleVue Eyepiece Specification page, it's 2.4"
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: DaveJ]
#5025603 - 01/18/12 08:36 PM
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Thanks DaveJ. Definitely doable then. Thank you Tammy. We'll either go with Harry's 34mm 70 Observatories or the Hyperion Aspherics in 31 or 36mm. The 31 seems to have better edge correction, but dunno whether we can offset that advantage with the f/6 mirrors and have better luck with the 36s. Those would bring us to our 50-year-old 6mm exit pupil threshold and give 1.35* TFOV. Seems the Sieberts and Aspherics stack up comparably, except that the Hypers look a little brighter with better coatings and of course re-sell higher. Really wish we coulda kept the Explore Scientifics in the mix. The 24 68s are 56mm...wattya suppose the 34s are?
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5028894 - 01/20/12 03:27 PM
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Our options are few but promising. We can fit the Siebert Observatory EPs, the Hyperion Aspherics or the Titan II EDs. We like the Aspherics for better coatings, brightness/contrast, and 72* AFOV, but we don't know whether the 36mm (for a 6mm exit pupil and 1.36* TFOV) is definitively worse at the edge of field than the 31mm, or if so whether this would be sufficiently lessened by our f/6 mirrors. (Some faster scopes showed improvement with a Paracorr.)
Anyway, just thought we should share what we've found.
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5034379 - 01/23/12 06:18 PM
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Just an update (because we're too late to edit this)...
We just learned that the ES 28 68 is only 62mm at its widest point and so we'll be able to use these side-by-side as our go to/finder EPs. These will give a full 1 degree TFOV at 4.5mm exit pupil. (We'll probably add the Aspheric 36 72s, or the Titan II ED 35s, or the Siebert 36s, a little later for Milky Way, etc and nearly 1.4 degrees under better skies.)
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Joe Ogiba
Postmaster
Reged: 02/14/02
Loc: NJ USA
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5034551 - 01/23/12 08:21 PM
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Just an update (because we're too late to edit this)...
We just learned that the ES 28 68 is only 62mm at its widest point and so we'll be able to use these side-by-side as our go to/finder EPs. These will give a full 1 degree TFOV at 4.5mm exit pupil. (We'll probably add the Aspheric 36 72s, or the Titan II ED 35s, or the Siebert 36s, a little later for Milky Way, etc and nearly 1.4 degrees under better skies.)
You might find 40mm eyepieces with 70° AFOV.
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: Joe Ogiba]
#5034674 - 01/23/12 10:17 PM
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Are those William Optics? Thanks. Dunno how those escaped me.
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EdZ
Professor EdZ
Reged: 02/15/02
Loc: Cumberland, R I , USA42N71.4W
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5035019 - 01/24/12 07:36 AM
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one of the issues you may still have with very wide-bodied eyepieces is that there may be no room at all for your nose between the eyepieces when you have your face right up against them. I've taken the outer shroud off of my Meade 5k 24mm and got the diameter down to 50mm and they are still pretty tight to fit up against them. My IPD is 61mm.
At 62mm diameter, there won't be any room at all. As you can see in Joe's picture, stuff like that looks cool, but it might not be practical. There are lot's of guys in the binocular forum who have decided against various wide-bodied eyepieces for exactly this reason. They simply do not fit their face.
edz
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: EdZ]
#5035238 - 01/24/12 10:17 AM
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Thanks Ed,
Yes, I've considered this from others mentioning the same, but either I don't sufficiently judge just how much my nose is actually intruding into the interocular space of my current binos, or I'm hoping that the long eye relief is enough to let us have as much focal length as our exit pupils will allow. No doubt the 56mm width of the 24s is an easier fit for the face, but then we may as well resign ourselves to only 1.25" EPs, a 28mm field stop, and .86 degrees TFOV. For 317mm binoculars this just seems absurd, even obscenely so, especially when for a mono we would be enjoyin a 46mm field stop and nearly 1.4 degrees TFOV (with 36mm EPs that we'll get later), and especially when we have to use a 2.6" secondary anyway, one which will give .8" full illumination and 1.8" 75% illumination. How can we just throw away those photons? There's also sumthin I think I remember from one of your reports way back when I got my binoculars, that the optimum magnification (don't remember for what) seemed around 49x (don't remember for which), and how counter-intuitive this seemed to me at the time. But yes, now we're chasin the low magnification capabilities too. I guess we won't know until we try, and as there are other advantages to using 2" focusers there's no reason to not at least try?
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EdZ
Professor EdZ
Reged: 02/15/02
Loc: Cumberland, R I , USA42N71.4W
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5035284 - 01/24/12 10:56 AM
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long eye relief helps. You won't need to be so close up to the eyepieces.
edz
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EdZ
Professor EdZ
Reged: 02/15/02
Loc: Cumberland, R I , USA42N71.4W
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Re: 2 inch EPs for the binoviewer
[Re: EdZ]
#5035490 - 01/24/12 01:12 PM
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No doubt the 56mm width of the 24s is an easier fit for the face, but then we may as well resign ourselves to only 1.25" EPs, a 28mm field stop, and .86 degrees TFOV. For 317mm binoculars this just seems absurd,
Not sure what you mean here. My Binocular telescope is 620mm and using the 24SWA I get 26x with a 2.5° field of view
I guess your referring to what you would get in your scope.
edz
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: EdZ]
#5035706 - 01/24/12 03:07 PM
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Yes Ed,
The numbers I referred to are for 12.5" f/6 mirrors with at least a 5" focuser height due to the additional star diagonal required. The best we can get is around 50x at a 6mm exit pupil, and we're 50-years-old so we're not goin above that. But 1.4 degrees (per eye), as compared with .86 degrees, is considerable, and we don't just want the wide field option for ourselves. The scope will be used for outreach and we feel that there'd be some additional "wow factor" at 1.4 degrees TFOV as there was, and still is, for us when we drool through other people's WF EPs.
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GlennLeDrew
Postmaster
Reged: 06/18/08
Loc: Ottawa, Ontario, Canada
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Re: 2 inch EPs for the binoviewer
[Re: killdabuddha]
#5036023 - 01/24/12 06:38 PM
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I use 30mm, 70* AFoV Meade QX eyepieces on my home-made right-angle bino. The fairly generous tapering on the upper barrels, in addition to the good eye relief, should allow the nose on most folks to fit in between...
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killdabuddha
Pooh-Bah
Reged: 08/26/11
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Re: 2 inch EPs for the binoviewer
[Re: GlennLeDrew]
#5036122 - 01/24/12 07:58 PM
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Thank You Glenn,
I went to the Meade site and I see exactly what you mean. Putting together EdZ's point and your solution has given us another option. Yes, it's as though, with the tapered tops and cups, they've made a space exactly for our nose.
Just realized the confusion, and between your example and Ed's question I understand better the mistake I made. The reason that Joe's 40mm EPs can work, and our 36mm Aspherics, is because these barrel diameters are narrow and still nose-manageable, whereas the ES 28mms will have no wiggle room. Therefore, jumpin after the 28s over the 24s may be a mistake. Stayin with the ES 24s and adding the Aspheric 36s later will leave us nose room in both cases. Thanks Ed and Glenn.
Edited by killdabuddha (01/25/12 10:46 AM)
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