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94bamf
professor emeritus
Reged: 12/15/08
Posts: 722
Loc: Kansas City,Mo
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Is there such a thing as apochromatic binoculars? It suprises me with how smaller doublet "apo" scopes are dropping in price, that we wouldn't see more binoculars listed as "apo", if for no other reason than a good marketing ploy. If my understanding of chromatic aberration is correct, it gets worse with higher magnifications, so maybe it would have limited usefulness on binoculars? Still it seems they could sell alot of binoculars based purely on having the word "apochromatic" in the description. What do you guys think?
Ken
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Telescopes:
Celestron C6 SCT on CG4 mount
Skywatcher 8 inch F/5 Newt on a GEM
Celestron 8 inch Starhopper Dob
Celestron Oynx 80ED
Celestron C130 Mak
Celestron C102HD
Binoculars:
Nikon 7x35 Action
Nikon 7x50 Action
Zen Ray Summit 10x42
Celestron 10x42 Noble
Orion 10x50 Scenix
Celestron 10x50 Noble
Pentax 12x50 PCF WP II
Celestron 15x70 Skymaster
Oberwerk 20x60
Zhumell 20x80
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KBK
member
Reged: 08/05/09
Posts: 68
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If the world economy can hang in there for one more full manufacturing cycle, you just might see them appear. I'd expect that due to costs, oddly enough, they might appear out of China first. German manufactured and the like, uh. would be pretty darned costly.
Also, my ignorance of the matter with respects to optics and pathways makes me ask if the complexities are just too far gone to be efficiently handled in systems like these that combine magnification and the flats of prisms-all at the same time.
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It is the image of the ungraspable phantom of life; and this...is the key
to it all.
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Rich V.
Pooh-Bah
Reged: 01/02/05
Posts: 1395
Loc: Carson Valley, Nevada, USA
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The closest thing to an "apochromatic" binocular was the Takahashi 22x60 which used the Tak 60mm fluorite doublet from their 60mm telescope. It's focal length is longer than most other binoculars and has a rather narrow, but superby corrected image. No other binocular compares, AFAIK.
They are hard to find on the used market these days.
Binoculars are commonly a short f ratio- around f4 so a true "apo" would be very difficult and expensive to produce.
Rich V
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Binoculars:
33/50/75/150x100 Saturn III, 16x70 FMT-SX, 10x50 PCF-V, 10x43 DCF-SP, 10x35 E2, 7x35 E, 8x30 E2, 7x26 Custom, 8x23AS Diplomat, 8x23 Travelite
Scopes:
C9.25, 6" f8 reflector, SV80S
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DJB
Carpal Tunnel
Reged: 02/23/05
Posts: 1590
Loc: Lisle NY
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Hi all,
I do agree that these are difficult to find.
Also, this term would be (almost) meaningless in the lower powered binoculars that, probably, 80-90% of us typically use for the most part.
Considering telescopes, however, I believe we are discussing a slightly different connotation here. Just my observations--that's all.
Best regards,
Dave.
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 14732
Loc: Cumberland, R I , USA42N71.4W
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Here's a recent discussion on ED glass in binoculars, with exception, the closest most binoculars get to apochromatic.
The terms mean the same whether discussing binoculars or telescopes.
The usefulness in binoculars does have its limits.
Quote:
Binoculars are commonly a short f ratio- around f4 so a true "apo" would be very difficult and expensive to produce.
This is correct. For example, apochromatic implies a color correction of at least 1/8000 the focal length. In an f/8 100mm scope that would mean color error from the red to blue focus would need to be corrected to within 800/8000 = 0.1mm. Now look at the same for a binocular. Assume a common 50mm f/4. The color correction to achieve the exact same level would need to be 200/8000= 0.025mm, for times finer than the 100mm scope, an incredibly tight tollerance. Even if we assume the same size lens, 100mm, the correction would need to be to half of the f/8 scope, still more difficult to achieve.
However, read this thread linked below and you will begin to understand why it is unnecessary to achieve that level of color correction in a low power binocular.
ED glass in binoculars
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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edwincjones
Postmaster
Reged: 04/10/04
Posts: 5671
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my miyauchi 20x100mm fluorites were called APO,
but not quite
the alpha birding binoculars are probably APO,
but they do not call them APO
edj
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moynihan
Carpal Tunnel
Reged: 07/22/03
Posts: 1606
Loc: Wisconsin
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The only special glass for color correction binocular (ED,APO, whatever) I have personal experience with is the Swift Audubon 8.5x44 ED. In daytime use the improvement is very noticable, to me. In night use, not really, except say, the Moon, which lacks the usual color error running around the edge. But, how often does one use the a binocular for Lunar observation?
Zeiss (Victory FL), Leica (Ultravid HD) and some Kowa bins have ED-whatever. The rumour in birding world is the new Swarovski's will have it. For daytime use, ED-whatever is a true plus in small, low mag bino's.
The first model (with ED-whatever) years ago i remember hearing about was the 9.5x44 Celestron ED's, which some folk still rave about.
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"Gosh, you've... really got some nice toys here"
Dual mount/ambient temperature Hominid Widefield Photon Collectors®
Pleistocene™ ˝ watt Wetware Integration Unit.
entia non sunt multiplicanda praeter necessitatem
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Les
professor emeritus
Reged: 04/22/06
Posts: 731
Loc: Maryland
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My Swift Ultralite 8x44 have ED glass. One may speculate whether it shares elements in common with the Audubon ED. The Canon 10x42L IS has ED elements in the eyepieces for field flattening. I have never had the experience of a lack of color fringing on the full moon with any binocular that I have observed with. I envy those that possess such a binocular.
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Les
Canon 10x42L IS
Oberwerks BT80/45, Helix Hercules mount on Oberwerks Standard Tripod
Swift 8x44ED Ultralite
Questar 50th Anniversary Model, 501 head on Manfrotto 475 tripod
Stellarvue SV90T 90mm Fluorite refractor Bogen 3236/Televue Tele-Pod Head
Questar 7 Astro
Vixen GP-DX on Baader Surveyor Tripod
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charen
Pooh-Bah
Reged: 05/28/05
Posts: 1083
Loc: New Zealand
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I have an excellent BD 10X58 BR ED Minox roof binocular. This does display 'minor' lateral CA on bright night time objects and color fringing is noticed on trees / aerials etc. in day time in periods of high contrast viewing.
It is no 'APO'. The thing is however it is not distracting and I am reasonably sensistive to color fringing.
The color saturation, fidelity and resolution is noticable and is superior to my other 8x non ED roofs.
Chris
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35 binos.
80mm Cat.
WO66ED
SV NH 80mm / EQ3
Meade 8in.LX90
Skywatcher Equinox ED120 / Goto HEQ5.
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Littlegreenman
Pooh-Bah
Reged: 05/09/05
Posts: 1370
Loc: Southern California
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I've had two pair and looked through a third pair of Celeston 6.5x44 ED. I'm kicking myself for selling them. I'm pretty sure those and the 9.5 versions were made by Vixen. This stimulated in quick response similar ED binoculars by Swift/Audubon and Eagle Optics. They came out sometime in the early-mid 1990's?
The 6.5's were only passable astronomy binoculars. They just weren't bright enough, and a decent 7x50 could easily out perform them on the night sky. But in the daytime, they had some of the best color and 3D sense I've seen. They are also very light and ergonomically shaped.
LGM
Several unused binoculars and one really annoying cataract.
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