Ortho2000
sage
Reged: 01/09/07
Posts: 278
Loc: Northern Virginia
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I have been also reading the CN refractor forum, and there are many new small aperture APO refractor designs coming on line at unheard of low prices. Astro-Tech for example has a 90 mm APO triplet annnounced for about 12-1300 USD. Meade has an 80mm APO Triplet for 599 USD.
Canon has some great 10x42 L glass series binoculars available, but I have not seen that much in terms of more affordable Chinese manufacturer offerings. I am thinking of ED glass APO quality optics.
I don't follow the industry that closely, but I am curious whether the advent of so many superb new small aperture APO designs in 2006/2007 might translate into 80 and 100 mm binoculars with ED glass and APO performance levels in the near future.
I'd love love love to see an affordable Oberwerk BT 100-45 or BT 125-45 in an APO level glass at an affordable price. With standard 1 1/4 inch interchangeable eyepieces of course 
Any thoughts ..???
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Ancient Orange Astro C-90 Celestron
Ancient Meade 2080 8 inch Schmidt-Cassegrain
Vixen ED115S APO 4 1/2 in Refractor & GPD2 Mount.
Meade ETX125 Mak
Unitron 60 mm F/15 Equatorial Refractor
Unitron 100 mm F/15 Equatorial Refractor
Stellarvue 80mm NHNG on Vixen Portamount
Meade 80mm DS-80AT F/11 GoTo Refractor (yardsale)
Vixen 16x80, Zeiss 10x40, Tasco #124 7x50 WA, Leitz 8x20 Roof Prism, Olympus 10x25 Roof Prism
Lunt 60mm Solar Scope on Order
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camvan
Carpal Tunnel
Reged: 05/02/05
Posts: 2086
Loc: British Columbia
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it would be a boon! I'm not sure how much extra good it would do the bino's, but if it can reduce at least some of the CA on bright objects, I guess it's a bonus...just depends on the pricemark that it comes in at. 
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Cameron
"Aperture can only be replaced by even more aperture. Dark transparent skies cannot be replaced by anything else." - Stathis Kafalis
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yagon
sage
Reged: 01/23/06
Posts: 204
Loc: Sydney, Australia
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I'd love to see a 30x60 APO bino. Straight-thru, fixed mag, small size (FL).
What is the use for such a bino? Portable, inexpensive, 2 eyed, full-orb LUNAR observation. 
I'm thinking of the Tak 22x60 but in 30x mag. It would be a big step up from my 30x80 barska x-trail.
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Pepin The Short
member
Reged: 11/24/06
Posts: 31
Loc: Wroclaw, Poland
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Good APO means usually not only reduced CA, but also better contrast and resolution. The problem is that binocular design, in contrary to a simple refractor, include prisms too. They would have to be exceptional, to avoid introducing additional CA that have been previously elliminated by the APO objective (I think so).
But here is a little light in the tunnel for all the bino fans:
http://www.united-optics.com/products/Binoculars/Giant_Binoculars/BA8_Series/BA8.htm
Emphasis on:
"70mm APO versions are designing".
I wonder how Oberwerk would name them - "Ultra Ultra" or "Super Duper Ultra"? Maybe just "Ultra APO" :-)
Edited by Pepin The Short (02/16/07 05:09 AM)
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camvan
Carpal Tunnel
Reged: 05/02/05
Posts: 2086
Loc: British Columbia
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30x60  I dunno how well you'd see with a 2mm exit pupil 
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Cameron
"Aperture can only be replaced by even more aperture. Dark transparent skies cannot be replaced by anything else." - Stathis Kafalis
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yagon
sage
Reged: 01/23/06
Posts: 204
Loc: Sydney, Australia
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2mm exit pupil on the moon works well for me, but not on much else
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camvan
Carpal Tunnel
Reged: 05/02/05
Posts: 2086
Loc: British Columbia
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I guess that's why you said for 'full orb moon viewing'.
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Cameron
"Aperture can only be replaced by even more aperture. Dark transparent skies cannot be replaced by anything else." - Stathis Kafalis
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yagon
sage
Reged: 01/23/06
Posts: 204
Loc: Sydney, Australia
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I really enjoy observing the moon in binos. It really makes you feel as though you are floating in space.
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Here's just one very simple impracticality as I see it.
take the example of a TV85 apo refractor. It's 600mm focal length. If fully corrected to apo it's red-blue color focal lengths do not vary from the green focal length by more than 600/8000. = 0.075mm
Many binoculars are about f/4 to f/4.5. let's be generous and say f/4.5. A 70mm binocular that is f/4.5 has a focal length of 315mm. To correct a 70mm f/4.5 lens to apo, 1/8000F error, the objective lens must be corrected so the blue red focal lenghts do not vary by more than 315/8000 = 0.04mm.
As you can see, to get a 70mm binocular objective corrected to apo, it means the physical length of error, or the allowable focal length of the color spread, must be cut to about one half that of a fine 85mm f/7 apo refractor.
There are a whole list of other reasons why you don't need apo correction in a 70mm binocular. But that won't stop anyone from wanting it.
I suggest reading Telescope Optics - A Comprehensive Manual for Amateur Astronomers, by Harrie Rutten and Martin van Venrooij, 1988-2002 Willmann-Bell, Inc.
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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Erik D
Carpal Tunnel
Reged: 04/28/03
Posts: 2554
Loc: Central New Jersey, USA
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Perhaps not APO level correction, but the Burgess Optical 22X65 SD introduced 2 years ago was an attempt to add ED glass to a 65mm Binocular. A 22X Takahashi but Lite on your wallet....Unfortunately the 22X65 ED has not made it into production yet:
http://www.highpointscientific.com/store/news_newburgess.asp
I use my big binos often for terrestrial viewing. For me CA is visible but acceptable in binos up to 20X80. Almost evey 100mm binouclar I have looked thru show annoying false color in the daytime( including the Miyauchi Saturn III F7.5, no experience with BT 100/ 45 deg) so I don't use them for terrestrial viewing. I would certainly welcome well executed ED binos in the 80mm and up size. I am willing to pay the price premium.
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"Will More ED & APO Refractors mean More ED Binos?"
I certainly hope so...
Good topic, Ortho.
ERik D
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edwincjones
Post Laureate
Reged: 04/10/04
Posts: 4423
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I would guess that some of the China companies will move into this area more (at some time), but the market/demand is small for the big, expensive binoculars.
edj
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n w arkansas
Binocular, Solar, General Amateur Astronomy
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Rich V.
scholastic sledgehammer
Reged: 01/02/05
Posts: 985
Loc: Carson Valley, Nevada USA
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In another thread about regrets, member 15x60 stated: "I must be honest: Miyauchi 20/26/37x100 45° angled, ED version (non apo version) because I thought the control of cromatic aberration was better............. "
IIRC, the ED version of the 100mm Miyauchi costs nearly double the "standard" non-ED version. If, for the money, the ED version STILL shows noticeable color, then it would seem impractical to expect TRUE apo performance from nearly any binocular.
Anyone out there have similar experience with Miyauchi standard vs. ED glass? How much improvement does the ED version provide?
Rich V
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Binoculars:
33-150x100 Saturn III, 16x70FMT-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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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Quiz time.
Who said:
"The term "ED" does not imply any kind of color correction. All that ED means is that this glass has Extra-low Dispersion. By itself, this has no meaning as far as color correction, one way or other.
Dispersion, whether extra-low, semi-extralow, low, medium, semi-medium or high has almost no bearing on the final color correction of a doublet, triplet or multi-element lens. Dispersion does not govern the color correction of a lens. There are extra-low dispersion glasses that produce bad color correction, and there are high dispersion glasses that produce excellent color corrections."
anybody know?
Just in case you don't get the point, ED and apo are not synonymous. Just because a lens uses ED glass does not necessarily mean it has better color correction. It might, but it might not.
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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Erik D
Carpal Tunnel
Reged: 04/28/03
Posts: 2554
Loc: Central New Jersey, USA
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Quote:
I would guess that some of the China companies will move into this area more (at some time), but the market/demand is small for the big, expensive binoculars.
edj
edj,
The market may be bigger than you think. Really depends what you consider "big" & "expensvie".
To some $600+ for the Fujinon 16X70 is expensive, to others it's the entry level for the premium giant binocular experience. 5 years ago ownship of a $900 Japanese 25X100 put one in a select group of "Ultra Giant" binocular owners club. These days entry fee is under $300 and hundreds are sold every month. As a result, there is more awareness and demand for bigger and better binoculars.
I would think anyone who has purchased or considered the purchase of a Canon 10X42/15X/18X IS, Tak 22X60, Nikon Astrolux, BT 80mm 45, APM 20/40X100 45, Miyauchi 71-100mm 45, BT 100, GT 100 could be a potential customer for 60mm or bigger binos with ED glass.
THIS forum is a big factor driving that demand....;-))
ERik D
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Joe Ogiba
Post Laureate
Reged: 02/14/02
Posts: 3361
Loc: NJ USA
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The Pentax DCF ED 10x50 Binocular is almost twice the price of the Pentax DCF SP 10x50 Binoculars so they will not be cheap.
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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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Erik D
Carpal Tunnel
Reged: 04/28/03
Posts: 2554
Loc: Central New Jersey, USA
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Quote:
IIRC, the ED version of the 100mm Miyauchi costs nearly double the "standard" non-ED version. If, for the money, the ED version STILL shows noticeable color, then it would seem impractical to expect TRUE apo performance from nearly any binocular.
Rich V
I do not expect "true APO" performance just by having ED glasses in a short focal ratio bincoular. But if we can reduce visible purple/green fringe levels 33-50% in a 25 or 30X100 in a $1,000< "Semi-APO"/ED Chinese binocular it will make long range terrestrial observation with 100mm binos much more enjoyable. I assume it will be of SOME benefit for astro use also.
When I think of "affordable" ED refractors I think of the Orion 80/100ED. I don't think anyone consider them "premium APO" refractors, but I guess most feel using FPL53 glass introduced a new level of performace for the under $1K class of refractors. The challenge is to make it happen in twin refractors with 1/2 the focal ratio.
The Miyauchi 100mm 45 APO version cost 66.8 % more.
Burgess priced their 22X65 SD at $295 intro price in 2005. If WO or any other importer can DELIVER one to the US for twice that it will still be a very attractive price.
Erik D
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LunaC
super member
Reged: 10/06/06
Posts: 198
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Is there a *mild* fringe killer that can be used that doesn't kill brightness much or alter color? Just enough minus violet to reduce but not eliminate the false color.
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Erik D
Carpal Tunnel
Reged: 04/28/03
Posts: 2554
Loc: Central New Jersey, USA
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Interesting idea. The new GO 100mm are threaded to accept filters. Brightness shouldn't be an issue in daytime viewing with 100mm aperture. Workable or not will depend on the quality, cost and availability of such a filter.
I am guess violet filter for a 82mm or bigger achromat spotting scope should be much less costly than going to FL or ED glass....
ERik D
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Les
professor emeritus
Reged: 04/22/06
Posts: 666
Loc: Maryland
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My only experience is with the Baader 1.25" Fringe Killer. It is advertised as having very good brightness. Coloration is in the eye of the beholder but is seems to me to put on a pronounced color cast. Stellarvue is introducing their own filter for which the claim is even less coloration. These solutions are only for binos that have interchangeable 1.25 eyepieces.
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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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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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I've copied this post of mine from a thread posted here in thiss forum back in 2005
Quote:
If I may post some information here summarized from a post by well known Roland Christen on the term ED.
summarized from an Astromart post by Roland Christen:
ED means Extra-Low dispersion. generally any glass having a Vd value > 70 is extra low dispersion. BUT, not all glass having this property will produce measurably better color correction than a standard crown-flint combination achromat.
It is not the property ED that produces better color correction. It is that some glasses using fluorite elements in their construction will have abnormal dispersion, which allows two dissimilar materials (crown and flint) to have opposite and equal color errors. Most glasses, those with normal dispersion, do not have equal and opposite color error. So, for any two normal dispersion glasses (which could very well include an ED element) combined in a doublet there will always be color error.
Roland summarizes, "it is NOT the extra-low dispersion (ED) glass which allows for better color correction. Rather, it is the Abnormal Dispersion properties of a glass which allows for better correction."
See the entire thread here, which by the way is linked thru the "best Of" - Chromatic Aberration.
BTW2
answer is Roland Christen.
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Teach a kid something today. The feeling you'll get is one of life's greatest rewards.
member#21
Edited by EdZ (02/16/07 01:10 PM)
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