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mooreorless
Carpal Tunnel
Reged: 07/05/05
Posts: 1547
Loc: Cornpropst Mills,Huntingdon,Pa
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Quote:
I think I can shed some light on how Stephen Ingraham's resolution figure was measured. At the time he tested the Ultralites (1993) he was using the Edmund poster of the USAF 1951 pattern combined with a 5x telescope behind the binocular eyepiece, so the 4.5 arcsecond figure is the actual resolution of the binocular optics rather than the visible resolution at 8x. He used the formula on the poster to convert line pairs per mm to arcseconds so the resolution represents the distance between the peaks of two bars. Later in the same issue of BVD he mentions that "the resolution of the unaided eye is about 60 arcseconds" , so like everyone else he was unaware of the alternative method of measuring bar chart resolution in ophthalmology.
Thanks Henry,that is kind of what I was trying to say in my feeble attempt at this stuff.I know you do a lot of "optics" tests along with a lot of others on here.I'm grateful for any information I can get here.
Steve M
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Regards,Steve M
"the eights are better" Jim Carmichel of Outdoor Life magazine
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brocknroller
Carpal Tunnel
Reged: 10/16/03
Posts: 1517
Loc: Liberal, Kansas
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Very few binocular retailers list arc second resolution for their binoculars. Kalinka Optics, which sells Russian binoculars, lists resoultion numbers for most of the binoculars they sell. For example, they list the resolution of the BPOC 10x42 Military Commander's Binoculars as 4.3 arc seconds:
http://www.kalinkaoptics.com/cgi-bin/kowstore.cgi?user_action=detail&catalogno=BBPOC1042
ITE, which also sells Russian bins, lists the resolution of the Kronos EWA 8x40 as 5 arc seconds. http://www.ITEastronomy.com/products/binoculars/specifications.php?p=EWA8X40
Given the differences in power between the two binoculars above, the relative numbers appear to be consistent.
It would be very helpful if the binocular industry would chose a single method of measuring binocular resolution and then reference that standard in their ads so buyers know they are comparing apples with apples.
In any case, the non-WP 8x42 Ultralites are quite sharp by any standard, as Edz mentioned, and a real bargain for the price. Hopefully, the newer version matches the optical quality of its predecessor and is as easy to use, with the added feature of waterproofing.
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Oscar Zoroaster Diggs
"O.Z."
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"And remember, my sentimental friend....a heart is not judged by how much you love,
but by how much you are loved by others."
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Swedpat
Pooh-Bah
Reged: 02/18/05
Posts: 1033
Loc: Boden, Sweden, Scandinavia
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In another thread I mentioned the lack of 10x42 binos with good ER, and got to know that Nikon 10x42 HG has ER of 19mm which is good. But the Kalinka 10x42 has 21mm. Here we can really talk about "built like a tank" binoculars. 1,5kg for 10x42 and 1,1kg for the 7x30...
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*2,3x40 Constellation View Wide-Bino
*Leupold 6x30 Yosemite
*Leupold Katmai 6x32
*Swarovski SLCNew 7x42B
*Bresser (Lidl) 10x50
*Oberwerk 11x70
*No name (Kunming) 15x70
*Scopos ED APO 66
*Meade 5000 26mm Plössl, Vixen LV 10/5mm
Psalm 19:2
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brocknroller
Carpal Tunnel
Reged: 10/16/03
Posts: 1517
Loc: Liberal, Kansas
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Most Russian military bins have reticles, which I think would be distracting for birding, not sure how much it shows up at night. The other complaint I've heard about Russian mil spec bins is their strong yellow bias. A problem for birding but perhaps not so much for astronomy. Holger could probably comment on this.
Somewhere (on this site? or elsewhere on the Web) is an article explaining how to remove the reticles.
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Oscar Zoroaster Diggs
"O.Z."
#########################################
"And remember, my sentimental friend....a heart is not judged by how much you love,
but by how much you are loved by others."
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