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patter1
professor emeritus
Reged: 01/19/05
Posts: 597
Loc: Canada
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I've noticed that my newer, long eye relief binocs generally have noticeable or even objectionable amounts of chromatic aberration on-center (day and night), while in my older and cheaper binocs with short or regular eye relief, there is little or none.
On the ones that do have it, if I look through one half, and position my eye in just the right position, the color fringing is reduced or eliminated. But with both halves held up to my eyes, it's difficult or impossible to position my eyes or interpupillary distance so that it's eliminated in both sides.
-How common/acceptable is it to have signficant amounts of chromatic aberration (daytime and night) on-center based on the eyes' position?
-Could it be that the additional lenses of the long eye relief binocs has something to do with it, or is it that eye placement is much more critical with long eye relief eyepieces?
Thanks for any insight.
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Patrick
8" f/6 NewStar dobsonian
Orion Starblast 4.5" f/4 mini dobsonian
42mm SuperView, 17mm Nagler T4, some other cheapies
Omcon 7x50, Oberwerk 11x56, Olympus DPS-R 7x35, Olympus Magellan 8x25
homemade 50mm right-angle bino-scope prototype
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KennyJ
Reged: 04/27/03
Posts: 10446
Loc: Lancashire UK
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Patrick ,
My own experience is that while it's undoubtedly true that longer eye - relief eyepieces generally require more careful positioning of the eyes , per se , eye relief is not related to chromatic aberration .
Zeiss 7 x 42 BGAT , Nikon Superior E and Captain's Helmsman all have eye relief I would classify as TOO long for anyone who doesn't wear glasses , but all three are amongst the most CA -free binoculars I've ever had the pleasure of looking through .
Regards , Kenny
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If everyone is thinking the same thing , no-one is thinking - General George S.Patton
Zeiss 7 x 42 BGAT
Captain's Helmsman 7 x 50
Nikon 10 x 42 Superior E
Swift Audubon Kestrel 10 x 50
Helios 15 x 70 Observation
Strathspey 20 x 90
Televue 76 APO
Zeiss 85 Diascope
Helios 102 f5 refractor
Various eyepieces barlows tripods mounts etc.
Panasonic Lumix DMC - TZ5 digital camera
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Alan French
Night Owl
Reged: 01/28/05
Posts: 1502
Loc: Upstate NY
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I agree with Kenny - mispositioning of your eye in the exit pupil can lead to various chromatic effects. I've seen this with eyepieces with long eye relief and with binoculars with smaller exit pupils.
The eye relief is not a big issue if the binocular has good, adjustable eye cups that aid in positioning your eye.
Clear skies, Alan
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patter1
professor emeritus
Reged: 01/19/05
Posts: 597
Loc: Canada
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Thanks Kenny & Alan. The thing is that I get this in at least one side even when the eyecup distance and IPD is properly set and my eyes are properly centered (I tried all kinds of eye positions and configurations).
It doesn't seem to necessarily be worse in binocs with larger exit pupils; my 7x35 has virtually no on-axis CA while my 8x25 has noticeable amounts of it.
My Oberwerk 11x56 and Olympus Pathfinder 8x42 (subsequently returned) have the most on-axis chromatic aberration; at that price level I wouldn't expect that.
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Patrick
8" f/6 NewStar dobsonian
Orion Starblast 4.5" f/4 mini dobsonian
42mm SuperView, 17mm Nagler T4, some other cheapies
Omcon 7x50, Oberwerk 11x56, Olympus DPS-R 7x35, Olympus Magellan 8x25
homemade 50mm right-angle bino-scope prototype
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