CESDewar
GorillAstronomer
Reged: 01/16/05
Posts: 1812
Loc: Morganton, GA, USA
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It is sometimes a bit difficult to determine if binoculars are well-collimated or not. Partly this is due to the fact that the brain can very quickly adapt to mis-collimated optics, albeit with eye strain that in time becomes disconcerting. When adjusting the collimation, one often has to resort to tricks to avoid having the brain "fix" the problem too quickly.
However, there is a very simple way to overcome this: select a fairly bright star, focus one barrel to be as sharp as possible then throw the other barrel significantly out of focus. When you do this, the natural tendency of the brain to align the images is blocked and you will then see the pinpoint image of the star superimposed over the out-of-focus image. Even a slight mis-collimation is then easily detectable as perfectly collimated optics should show the sharp star image perfectly centered in the fuzzy blob of the other image. You can reverse which barrel is out of focus to be sure that there is no lateral image shift when changing the focus.
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Wes James
Carpal Tunnel
Reged: 04/12/06
Posts: 2457
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That is a question/problem I myself had been thinking about... had a couple of pairs of binoculars out just a few minutes ago, wish I'd have known about it then! Will try it out the next time I'm out. Had a pair of bino's in my hands that were pretty badly out of collimation today.. would have loved to tried it on them- though they were so bad there was no question about it!
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Wes
Atlantic Beach, FL
Some bino’s from Miyauchi 5x32 Binon's up through Garrett 20x110 Signature's,
Some telescopes from a Stellarvue 80mm NHNG up through a couple of 8” reflectors…
And a wonderful 4.25" Delmarva Shiefspiegler!
Some good friends, made here on C/N.
Oh- several cats and a wonderful wife!
Anyone want a cat???? :-O
"When your work speaks for itself- Don't Interrupt" -Gamble Rogers
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mark22c
sage
Reged: 08/12/07
Posts: 343
Loc: cornwall UK
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hi
could you tell me how to find out which side and prism needs adjusting ie left right or front back?
regards mark
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opticron "imagic" BGA SE 8x42 roof's
10x42 roof's
meade/bresser (lidl) 10x50 porro's
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DLitster
member
Reged: 09/16/07
Posts: 16
Loc: Dublin, Ireland
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Hi CESD,
thats clever and good timing for me. Waiting patiently on skys to clear here to test my new fuji 10x50s so will try then.
Regards.. David.
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CESDewar
GorillAstronomer
Reged: 01/16/05
Posts: 1812
Loc: Morganton, GA, USA
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Quote:
could you tell me how to find out which side and prism needs adjusting ie left right or front back?
This is not a simple issue to resolve. Just knowing that the optics are out of collimation does not tell you which one should be adjusted. I would defer to the experts on this forum to answer that one!
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Gordon Rayner
professor emeritus
Reged: 03/24/07
Posts: 506
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If I help out here, do I get promoted, or a royalty?
You need a hinge reference. There are several ways to do this, some requiring more equipment than others. One is a vee block, riding the hinge, with some type of small, low power telescope, such as a weapon sight attached to the vee block , and whose line of sight is parallel to the vee axis. Weapon sights have adjustments to accomplish this as you rotate the barrel of the sight in the vee which is opposite the vee resting on the hinge. Adjust until the reticle is stationary during rotation. Now you have a line of sight parallel to the hinge.
Now center a target in one of the binocular barrel's line of sight, and compare its position in the scope whose v-block mount rides the hinge. Then repeat with the other barrel. Now you know which side is in more need of attention.
The process is more exact, and faster, if you have a comparator which combines two lines of sight for simultaneous viewing. JTII make(made?) one, or you can make your own . Or, slide a crosshair equipped telescope, on some accurate mechanism(such as a machinist's layout surface gage), between the hinge reference telescope and one of halves of the binocular. Repeat with the other half. It is likely that a tilted orientation of the binocular will be needed for the use of a sliding surface gage, because the hinge reference will be above the binocular eyepiece otherwise,and the surface gage would tend to fall off its supporting surface if not restrained in some way other than gravity.
With this equipment, true collimation/alignment for any and all interpupillary distances can be accomplished. That is, all three axes can be made mutually parallel. 
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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Quote:
hi
could you tell me how to find out which side and prism needs adjusting ie left right or front back?
regards mark
Gordon's response basically says the same thing that Bill C has repeated over and over ever month for about 2 years now, but in different words. It's a job for a tech.
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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CESDewar
GorillAstronomer
Reged: 01/16/05
Posts: 1812
Loc: Morganton, GA, USA
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I should also add that I'm guilty here of using the word "collimation" when what I'm really talking about is mutual alignment of the optical paths. In other words, this test just tells you if the two optical paths are accurately aligned with each other, but says nothing definitive about whether they are properly collimated or not, which is a related, but different issue.
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Mark9473
Carpal Tunnel
Reged: 07/21/05
Posts: 2699
Loc: 51°N 4°E
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CESD, I've now had the first opportunity to test your method, and I believe it can be very useful! But it wasn't quite as easy as I had imagined it. Seems that my eyes/brain are still shifting the images back and forth, so that the star's position isn't rock steady in the other side's halo.
Anyway, with carefull testing on alpha Persei and Wega, and comparing with the distances between nearby pairs of stars, I've determined that my Swift 8,5x44 are probably out of collimation by about 2-3 minutes of arc towards upper right.
Now the question is: is this a serious error?
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Mark
Leica 8x20; Vixen 8x42; Swift 8.5x44, 10x50 and 20x80; TS 7x50; Orion 15x63
WO Megrez II 80 FD + Baader 90° T2 Amici
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CESDewar
GorillAstronomer
Reged: 01/16/05
Posts: 1812
Loc: Morganton, GA, USA
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Quote:
I've determined that my Swift 8,5x44 are probably out of collimation by about 2-3 minutes of arc...Now the question is: is this a serious error?
I'm rather hoping we can get some results from other people to find out how far off their binoculars are. It's only serious if you are unable to merge the images comfortably. In this case 8.5x binos are going to resolve around 20-25 arc-seconds (perhaps a bit better on a good mount with really good eyesight). So the mis-alignment here is about six times the best resolution - I think most people could easily accomodate that without much eyestrain.
I did test my Leica 10x42's tonight and they appear perfect: the in-focus star appears dead center in its unfocussed twin - but then again I would expect that given what I paid for them. 
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EdZ
Professor EdZ
Reged: 02/15/02
Posts: 12581
Loc: Cumberland, R I , USA42N71.4W
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The various standards are posted in the Best Of Thread on Collimation.
See Collimation Standards
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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Rafael
member
Reged: 09/21/06
Posts: 48
Loc: Madrid (Spain)
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Hello, CESDevar.
Other collimation test method is here described:
http://rchamon.iies.es/collimation_methods/sun_images_method.htm
See specially the paragraph "Simplified version of sun images method"
Regards
Rafael
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Nikon 7x50 IF HP WP Tropical
Nikon 8x30 E
Nikon 12x40 CF WF
Nikon 7x35 Sporting
Nikon 7x20 Travelite III
Pentax 8x30 BIF Marine
Pentax 8x40 PCF III
Carl Zeiss Jena Jenoptem 7x50 WF
Carl Zeiss Jena Jenoptem 8x30 WF
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Les
professor emeritus
Reged: 04/22/06
Posts: 666
Loc: Maryland
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Quote:
When adjusting the collimation, one often has to resort to tricks to avoid having the brain "fix" the problem too quickly.
However, there is a very simple way to overcome this: select a fairly bright star, focus one barrel to be as sharp as possible then throw the other barrel significantly out of focus. When you do this, the natural tendency of the brain to align the images is blocked and you will then see the pinpoint image of the star superimposed over the out-of-focus image.
This is the method I use and reported on previously, with very acceptable results.
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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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BillC
on a new path
Reged: 06/04/04
Posts: 2110
Loc: Washington, USA
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For conditional alignment.
For example: If you do this for a 54 mm IPD, you MAY find yourself well out of alignment at, say, 72mm.
Just a thought.
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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Les
professor emeritus
Reged: 04/22/06
Posts: 666
Loc: Maryland
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Well understood by me and I hope others on this forum.
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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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Mr. Bill
Carpal Tunnel
Reged: 02/09/05
Posts: 2759
Loc: Just passing through.....
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Also there is an intra barrel collimation check to see if the objective lens are collimated (centered and square) to the mechanical axis. This can be checked quite easily with a Cheshire eyepiece with the objective covered to block light from the front.
I found that the right barrel of my new BT100s had noticeable astigmatism and this was confirmed by observing that the objective triplet reflections didn't stack up using the Cheshire.
The left barrel showed round extrafocus diffraction patterns and this was confirmed by nearly perfectly stacked objective element reflections.
Of course, this technique can only be done with binoculars that have removable, 1 1/4 eyepiece barrels.
Probably a good thing for binocular manufacturers and vendors that their eyepieces can't be removed to examine objective collimation or there would be a lot more returns than simple inter barrel alignment issues.
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10x50 Fujinon FMT-SX binos
15x70 AP binos + Paragon p-mount
Oberwerk 100BT 45 degree + Hercules fork mount
120mm f/5 Orion achromat + Moonlite focuser
140mm f/5.7 Vixen NeoAchro Petzvel refractor
150mm f/6.5 Antares achromat
150mm f/8 homemade achromat....EE Barnard MW Sweeper
8 inch newt with f/5 Swayze mirror
10 inch f/4.7 Orion newt + Paracorr
15 inch f/5 Discovery split tube
35mm Pan, 26mm Nagler, 17mm Nagler, 13mm Ethos, 8mm Ethos
Member IDA
Edited by Mr. Bill (11/25/07 03:40 PM)
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Gordon Rayner
professor emeritus
Reged: 03/24/07
Posts: 506
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Do you attibute your problem to wedge in the elements, or a sloppy cell, a loose retainer ring, or ...? You can also check this sort of thing from the front with an autocollimating alignment telescope, preferably darkfield, by focusing on each surface of the objective in turn. I have a boat anchor optical bench to lend if you want to get into this activity regularly for QC reviews.
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Mr. Bill
Carpal Tunnel
Reged: 02/09/05
Posts: 2759
Loc: Just passing through.....
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I know HOW to check for the problem...I'm not sure HOW to correct it (other than recentering the elements.)
Since these are new, an exchange is my solution, the hope being the new pair is better aligned.
OBTW, thanks for the offer, but I have enough "boat anchors." I just got rid of a pair.
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10x50 Fujinon FMT-SX binos
15x70 AP binos + Paragon p-mount
Oberwerk 100BT 45 degree + Hercules fork mount
120mm f/5 Orion achromat + Moonlite focuser
140mm f/5.7 Vixen NeoAchro Petzvel refractor
150mm f/6.5 Antares achromat
150mm f/8 homemade achromat....EE Barnard MW Sweeper
8 inch newt with f/5 Swayze mirror
10 inch f/4.7 Orion newt + Paracorr
15 inch f/5 Discovery split tube
35mm Pan, 26mm Nagler, 17mm Nagler, 13mm Ethos, 8mm Ethos
Member IDA
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Robert A.
sage
Reged: 01/21/05
Posts: 218
Loc: Milwaukee, WI Northern USA
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I remember this being discussed in 2006, Zen and the Art of Binocular Collimation Even Bill Cook discussed it. Do you remember it? Is that thread helpful to consider your questions?
Rob.
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Oberwerk 11x56, Nikon 12x50se, Fujinon 16x70, Stellarvue 20x85, Oberwerk 25/40 45degree 100mm
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Mr. Bill
Carpal Tunnel
Reged: 02/09/05
Posts: 2759
Loc: Just passing through.....
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Thanks, Rob
Never saw that one....looks like I'm retreading well worn ground.
The difference I see between my use of the Cheshire and the one mentioned in the Zen thread is that I cover the objectives and thus can examine both the alignments mentioned and also the alignments of the objective lens with respect to each other because of their internal reflections.
These are not seen if the objectives are left uncovered because the light washes out the internal reflection images.
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10x50 Fujinon FMT-SX binos
15x70 AP binos + Paragon p-mount
Oberwerk 100BT 45 degree + Hercules fork mount
120mm f/5 Orion achromat + Moonlite focuser
140mm f/5.7 Vixen NeoAchro Petzvel refractor
150mm f/6.5 Antares achromat
150mm f/8 homemade achromat....EE Barnard MW Sweeper
8 inch newt with f/5 Swayze mirror
10 inch f/4.7 Orion newt + Paracorr
15 inch f/5 Discovery split tube
35mm Pan, 26mm Nagler, 17mm Nagler, 13mm Ethos, 8mm Ethos
Member IDA
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