BillC
on a new path
Reged: 06/04/04
Posts: 2109
Loc: Washington, USA
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Wes, I was juggling my Granddaughter and son at the time. HOWEVER, I DID respond; to you, and EVERYONE that asked about them. I may be a curmudgeon, but I try to be a polite one.
Cheers,
Bill
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William J. Cook, Chief Opticalman, USNR-Ret.
Founding Editor, Amateur Telescope Making Journal
20-year vet. of Captain's Nautical Supplies, Optics Dept. Mgr.
Optics Machanic, WG11-3306, Ft. Lewis, Tacoma,WA
Yata, Yata, Yata . . .
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Wes James
Carpal Tunnel
Reged: 04/12/06
Posts: 2457
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Hi, Bill-
Sorry, never got your reply. I trust that things are better by now? Know that a lot of people were remembering you in their thoughts and prayers.
Wes
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Well, they are sure off to a Nagler-like performance... start
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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ausastronomer
scholastic sledgehammer
Reged: 06/30/03
Posts: 771
Loc: NSW Central Coast (Australia)
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Quote:
Ed,
Of all the other binoculars that I've tried one other that stands out for the quality of its edge performance is the Zeiss 15x60 B/GATs.
John Finnan
John,
Without a doubt these are the best medium/large astronomy binoculars I have used, which includes almost all of the premium contenders previously mentioned. These have outstanding unsurpassed performance in every criteria and it's unfortunate they took them out of production a few years ago, when at the time they were clearly the best medium/large astronomy binocular money could buy. Notwithstanding the high price tag, there was still a market for them at the top of the tree.
Second hand these would be a great buy, but I doubt you will see them offered. Whilst there are quite a few pair of these out there, except for deceased estate sales, no one that owns them will ever sell them.
Cheers
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John Bambury
AS of NSW
AS of Hunter Valley
18"/F4.5 Obsession with Argo Navis and Servocat, 10"/F5 Newtonian with Argo Navis
Lots of Pentax XW's. Plus 12mm & 17mm Nagler T4's, 31mm Nagler T5 & 13mm ETHOS. TV Paracorr and 2.5X Powermate
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Joe Ogiba
Post Laureate
Reged: 02/14/02
Posts: 3361
Loc: NJ USA
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Many Naglers require the use of a Paracorr in fast F3.5-F8 scopes and 99.9% of binoculars are in that range. I would prefer binoculars with 70° AFOV and 20mm eye relief like the Pentax XW's than the Naglers that have about half the eye relief.
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Pentax PF-80ED
Meade 102ED APO
Orion EON 72
120ST
Apex 127
C6 XLT
CR150
C9.25
XT10
Zeiss 7x42 FL
Canon 10x42L IS WP
15x50 IS
12x36 IS II
Garrett Optical 28x110 HD-WP Signature Series
Oberwerk BT-80 45
Apogee RA-88-SA
Denk II Power x Switch binoviewer w/13mm Ethos, 20mm Pentax XW's, 20mm Widescan III's.
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ronharper
Pooh-Bah
Reged: 02/14/06
Posts: 1006
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Thanks for a very interesting thread. I like 7x50s and have always been curious about the Prostar.
Since somebody asked, the Fujinon 7x50 is no great shakes in this department. The field is rather curved, about 2 diopters from center to edge. Despite it's narrower apparent field, the edge is quite a bit softer than the 10x50.
Henry Link has reported in other forums that the optical train of the Prostar (and its 10x70 sibling) and FMT are very similar except the Prostar has an extra convex lens cemented to the output end of the prisms. Very interesting! Comments, BillC or Henry?
While the Prostar is apparently supreme for edge correction, it's apparent field is only 53 degrees. Several of the second-place binos provide 60-67 degrees. If these were field-stopped to 53 degrees, Ed, would it be a different story?
Ron
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BillC
on a new path
Reged: 06/04/04
Posts: 2109
Loc: Washington, USA
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I have owned 4 Prostars . . . AND WILL AGAIN. But, I have never noticed this extra lens. I treat my binos well, so I doubt I will ever have a reason to go inside. But, I have repaired them for others and still don't recall it. But then, my memory . . .
The only one I can remember with a separate field-flattener was the old Swift Commodore. This was a good bino--for the money--but Swift's lack of ability to really promote it killed it off.
Cheers,
Bill
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William J. Cook, Chief Opticalman, USNR-Ret.
Founding Editor, Amateur Telescope Making Journal
20-year vet. of Captain's Nautical Supplies, Optics Dept. Mgr.
Optics Machanic, WG11-3306, Ft. Lewis, Tacoma,WA
Yata, Yata, Yata . . .
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Rich N
Post Laureate
Reged: 09/22/04
Posts: 5312
Loc: San Francisco Bay Area, Calif...
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The Zeiss 7x42FL has a 450 foot true field at 1000 yards.
The Nikon 7x50 ProStar has a 383 foot true field at 1000 yards.
It would be interesting to see how sharp the Zeiss is at the true field of the Nikon.
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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I've now have test data on 7 different 7x50s. The Prostar has an Afov of 53°. None of the other 7x50s are wider than that. Most of the others are between 52° and 49° and this is normal for a 7x50. One of them has a 45° Afov.
The Prostar 7x50 also has the widest Tfov of all 7x50s tested. It's not until you get into 8x binoculars that you start seeing wider Afov eyepieces and Tfov wider than 7.0° to 7.5°. But even with that, in fact only 3 out of 11 of the 8x binoculars that I've measured have a wider Tfov than the Prostar 7x50.
FWIW, I just checked my data files. 19 out of 36 small binoculars tested have Afov 54° or smaller. 14 of them have a narrower Afov than the Prostar. Prostar is just about right in the middle of Afov and is near the top in Tfov of 36 different binoculars tested.
So as it turns out, in the grand scheme of things, the Prostar Afov of 53° is NOT really all that narrow compared to many other binoculars ranging from 7x to 12x, and as far as comparison to 7x and 8x binoculars, it has a wider Tfov than 3/4ths of all 7s or 8s I've measured.
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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Rich N
Post Laureate
Reged: 09/22/04
Posts: 5312
Loc: San Francisco Bay Area, Calif...
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The older classic Zeiss 7x42 also had a 450 foot true field at 1000 yards.
It would be interesting to set out two small lights separated by 383 feet and get back 1000 yards to see how sharp they are in the Zeiss.
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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a far better test than that would be
take the closest observable double star pair that can be seen at the edge of the Prostar and try to observe it in the other binocs. Starting with the double placed on the extreme edge, slowly move it inward until it can be seen and record the position. Try Alya, theta Serpens; an even magnitude 22" pair. I saw theta Serpens all the way out at 90%+ of fov in the Prostar.
FWIW, there are some 8x binoculars I've tested in which I cannot even see theta Serpens beyond dead center.
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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Neil Weiner
member
Reged: 08/29/04
Posts: 98
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Advertised TFOV: Prostar 7.3, Fujinon 7.5.
A few years ago I won a perfect Prostar on auction at a very fair price. I took my time comparing it to my Fujinon Meibo for Terrestrial (yes) viewing. I sold the Prostar and kept the Meibo.
The Prostar felt somewhat tunnel-view , the Fujinon felt natural. The Prostar was especially clunky to hold steady, the Fujinon (rubber armored), easier to hold steady--though still a big, heavy 7x50.
So despite the technical, optical excellence of the Prostar, I was seeing and enjoying more, Terrestrially, with the Fujinon.
Of course this is off topic regarding Nagler, but yet another reminder that bino "better" and "best" are not absolute, but relative to for-what and to-whom.
Edited by Neil Weiner (05/08/08 01:39 PM)
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Quote:
Advertised TFOV: Prostar 7.3, Fujinon 7.5.
Actual measured TFOV: Prostar 7.5
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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Henry Link
sage
Reged: 03/31/04
Posts: 316
Loc: Greensboro, NC
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You can see the extra element in this internal view supplied by jrweisner in a thread last year:
http://rchamon.iies.es/nikon/7x50sp.jpg
Notice that it's placed in front of the objective focal plane and does not move with the eyepiece elements, so I think it should be considered a third objective element. My guess is that it's designed to correct field curvature by making the field curvatures of the objective and the eyepiece nearly complimentary. I agree with Ron that other so called "field flatteners" (Fujinon FMT-SX, Nikon SE, Pentax PIF) appear to correct astigmatism, but not field curvature.
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Rich N
Post Laureate
Reged: 09/22/04
Posts: 5312
Loc: San Francisco Bay Area, Calif...
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From the Zeiss UK site...
http://www.zeiss.co.uk/c12567a80033f8e4/Contents-Frame/9a7c62f395e8b0dcc1256f27003e957a
Zeiss 7x42 T FL has a 60 deg APOV
Zeiss 8x42 T FL has a 61.8 deg APOV
Zeiss 10x42 T FL has a 63 deg APOV
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Rich N
Post Laureate
Reged: 09/22/04
Posts: 5312
Loc: San Francisco Bay Area, Calif...
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Here is a link showing the internal view of the Zeiss Victory series.
http://www.zeiss.co.uk/C12567A80033F8E4/ContentsWWWIntern/D8E14B4A5A4B8EB3C1256F27003F46D2
No. I don't work for Zeiss. 
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Quote:
I agree with Ron that other so called "field flatteners" (Fujinon FMT-SX, Nikon SE, Pentax PIF) appear to correct astigmatism, but not field curvature.
Seems to agree with what I've found. Examples:
Fujinon FMT-SX 10x50, all or nearly all of the outer field aberration is field curvature.
Nikon SE 10x42, approx 80% of all outer field aberration is due to field curvature.
Nikon SE 12x50, approx 75% of all outer field aberration is due to field curvature.
Note, these binoculars outer filed total aberration is very well controlled, it's just being pointed out here how much of what is there is due to curvature.
Nikon Prostar 7x50, close to zero.
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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Rick
Carpal Tunnel
Reged: 04/12/05
Posts: 2574
Loc: Tokyo, Japan
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The term "Nagler-like" generally means a WIDE AFOV in additon to edge sharpness. Most OEMs consider their binos to be WIDE if the AFOV > 65°. So I am suprised no one has mention the Nikon 8x30 E2 with its 70° AFOV (8.8° TFOV). Generally still available in most of the world ex USA for some silly reason. 
clear skies,
Rick
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www.japanastro.com
Edited by Rick (05/08/08 05:52 PM)
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BillC
on a new path
Reged: 06/04/04
Posts: 2109
Loc: Washington, USA
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Thanks for the drawing, Henry. You saved me 20 minutes of work, and possibly a scratched screw head or two.
Cheers,
Bill
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William J. Cook, Chief Opticalman, USNR-Ret.
Founding Editor, Amateur Telescope Making Journal
20-year vet. of Captain's Nautical Supplies, Optics Dept. Mgr.
Optics Machanic, WG11-3306, Ft. Lewis, Tacoma,WA
Yata, Yata, Yata . . .
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StarStuff1
sage
Reged: 04/01/07
Posts: 437
Loc: East Tennessee
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This afternoon, by sheer coincidence, I was shown a nearly 40 year old Nikon 9x35 porro with an afov of 66°, tfov of 7.3°. While not "Nagler like" in fov this rather small and light bino was remarkably sharp across the field. It was owned by a birder (naturally)who had ordered it from Europe since that model was not sold here. He said it cost about $135 in 1970 and the import duties was almost that, too. A well worn but very nice and compact instrument that was still in decent collimation.
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Two dozen eyepieces, a dozen binoculars, a half dozen refractors, two reflectors and a homemade Image Intensifier Eyepiece (IIE). All products subject to change by the owner at any time.
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