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Tim61
sage
Reged: 04/05/06
Posts: 281
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From what I have read so far, I gather that Indiviual fousers are somewhat better for astro binos than center foucs? Or does it really matter all that much? What advantages are offered by both styles?
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8x40 Nikon Action Ex
10.5x 70 Ultras
Vixen R150S (looking to find a new home)
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charen
scholastic sledgehammer
Reged: 05/28/05
Posts: 786
Loc: New Zealand
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2x of my binos have I.F.s a 15x80 and a 10x50, both Japanese made. The benefits I find with I.F.s are 1/ once 'set' for astro ie. pin point stars, they can be left alone 2/ they give more of a 'fine' focus 3/ they have less 'play'[movement]then center focus ones.
I do prefer them for astro use.
No real great disadvantages - unless different obeservers use them it can be a challenge to re-focus for them and then re-focus back for your eyes. Just my thoughts.
Edited by charen (08/21/06 11:16 PM)
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BillC
on a new path
Reged: 06/04/04
Posts: 2109
Loc: Washington, USA
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If what you are looking at in the heavens is rapidly changing its proximity--wherein CF bino would be better--you have MUCH more to worry about than looking through a binocular!
Setting a world speed record for repentence would be high on my list.
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 V.
scholastic sledgehammer
Reged: 01/02/05
Posts: 984
Loc: Carson Valley, Nevada USA
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For those of us who have normal vision or who must wear eyeglasses when observing, IF or CF doesn't really make much of a difference, aside from IF glasses usually having less close focus ability. For astronomy, focused at infinity, there are pros and cons but it is really an individual choice.
However, for some of us, the range of focus provided by these two systems DOES make a difference. For example, an IF Fujinon binocular provides approx. +/- 7 diopters focus range. These will give infinity focus for uncorrected vision up to +7 diopters for farsighted eyes and -7 for nearsighted eyes, probably enough for most eyeglass wearers to leave their glasses off for observing.
CF binoculars shift the +/- range way to the + side for closer focusing. A typical CF binocular may provide a +12/-5 range instead of the +/- 7 range of the IF.
If you are nearsighted, with the CF, you will not have as much range to achieve focus without eyeglasses. IF will give more focus range.
If you are farsighted, with the CF, you will have much more range to achieve focus without eyeglasses. IF will give less focus range.
I am aware of this as I am very farsighted and have had to modify the focus range on the IF Fujinons so that I can use them either with or without correction. My CF bins all work fine without my glasses due to their greater + range.
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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rushintuit
sage
Reged: 04/01/06
Posts: 263
Loc: Farpoint Observatory
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My Canon's are center focus, while the Fuji's are individual. I prefer the center focus for ease and convenience. I don't wear glasses.
One of the many neat things about an IS bino is tracking a jet aircraft across a starfield. You'd be out of luck with an individual focus setup.
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/// Stellarvue SV102ED /// Nikon 12x50 /// Fujinon 16x70 /// SkyTools 2 /// The Desktop Universe All Sky CCD Mosaic In Monochrome Mode ///
Edited by rushintuit (08/22/06 11:31 AM)
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Littlegreenman
Pooh-Bah
Reged: 05/09/05
Posts: 1021
Loc: Southern California
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For astronomy I found that a good quality binocular with IF (Stellarvue 15x63) was preferable to Orion 15x70 CF that I had to keep fiddling with. The Stellarvue are almost set 'em and forget 'em. On the other hand, when more than one person was using them the IF became an inconvenience.
On the other hand, I have a pair of nice pair of CF 11x80 Celestron's that I'm keeping. (I've had my mitts on 4 or 5 11x80's and mine was the best. I've also have owned or pawed 5 Orion binocs; only one was a keeper).
On the other hand, I had a pair of Fujinon 6x30 IF, and found that I was constantly changing the focus for earthbound viewing. Give me CF for terrestrial viewing.
..and, I have a pair of 25x100's CF, only used once but seemed fine.
Individual focus binocs have simpler mechanics. Center focus binocs can suffer from focus shift as you press your eyes into the eyepieces.
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grbrown
professor emeritus
Reged: 07/09/05
Posts: 643
Loc: Ampthill, UK, 52:02N 0:30W
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Quote:
Individual focus binocs have simpler mechanics. Center focus binocs can suffer from focus shift as you press your eyes into the eyepieces.
When mounted on a tripod, I/F is not too bad. I actually like using this type, even hand held.
There are actually two types of C/F, one good, the other bad, in my view. The internal focus variety are great, with all the advantages of I/F, in being reliable and stable when focussed. The extending tube variety can indeed shift their focus all too easily and I wouldn't give them house room! I have never owned any.
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Graham
"one eye good, two eyes better...the more I look, the more I see"
BT100-45 degrees, plus 35,24,17,13,9mm Sieberts
15x80, 7x50 Steiners
12x50, 10x42, 8x20 Leica Trinovids
7x35 Minolta
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Cory Suddarth
Vendor
Reged: 08/10/06
Posts: 9
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I say to each there own, but I suppose, if the world was flat and everything was perfect, IF for astronomy, CF for terrestrial. That said, I am in constant violation on both accounts! If I could have only one type, for me it would have to be CF for the ease of fiddling and fine tuning.
Cory
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