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Equipment Discussions >> Binoculars

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BillC
on a new path
*****

Reged: 06/04/04

Loc: Lake Stevens, WA, USA
Re: Binocular FOV allignment new [Re: Gordon Rayner]
      #5652612 - 01/30/13 03:55 PM

Gordon:

Many are the times—including lately—you have asked CN members to just check out collimation with “the JTII "hand collimator, or equivalent.” Frankly, I don’t think most members know what one is, let alone have a selection lying around the house. That makes your “or equivalent” more intriguing.

Thus, within the mileage and dollars of the average observer, could you please, briefly state what you perceive that “equivalent” to be. Is it something readily available? At what store is the "JTII hand collimator" available-- should one want a unit--and how much does one cost?

BillC


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Mark9473
Postmaster
*****

Reged: 07/21/05

Loc: 51°N 4°E
Re: Binocular FOV allignment new [Re: ngc 9999]
      #5652667 - 01/30/13 04:17 PM

Quote:

I was told that it doesn't necesarily has to be right in the center, if it's at least half way to the center it's ok.



I agree with that, especially if it's mostly horizontal displacement.


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ngc 9999
sage


Reged: 08/13/12

Loc: Sunrise, Fl. 26 degrees N
Re: Binocular FOV allignment new [Re: BillC]
      #5653014 - 01/30/13 06:54 PM

Quote:



“Now fields of view are about half a degree from the actual field stop. I wonder how to reset it again.”

I don’t understand—I don’t have to mindja. But, fields of view are inextricably attached to field stops.''

What I mean is when I look at a distant target the two barrels field of view have some degree of overlapping.

I have the Garrett SS 10x50 binoculars.

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ngc 9999
sage


Reged: 08/13/12

Loc: Sunrise, Fl. 26 degrees N
Re: Binocular FOV allignment new [Re: BillC]
      #5653017 - 01/30/13 06:56 PM

[quote)

“Now fields of view are about half a degree from the actual field stop. I wonder how to reset it again.”

I don’t understand—I don’t have to mindja. But, fields of view are inextricably attached to field stops.





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ngc 9999
sage


Reged: 08/13/12

Loc: Sunrise, Fl. 26 degrees N
Re: Binocular FOV allignment new [Re: BillC]
      #5653028 - 01/30/13 07:01 PM

What I mean is when I look at a distant target I see a considerable degree of field of view misalignment, which seems that with minor tweaking can be corrected. And my binoculars are 10x50 Garrett SS. I emailed Garrett and he sent me the intructions.

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ngc 9999
sage


Reged: 08/13/12

Loc: Sunrise, Fl. 26 degrees N
Re: Binocular FOV allignment [Re: ngc 9999]
      #5653255 - 01/30/13 09:34 PM

I finally got everything into alignment again!!

The astigmatism caused by focusing did not came from my eyes but was caused because the images were out of the optical axis while attempting my first ''collimation'', and the images did not move the way I though they were supposed to move, the images movement was mostly diagonal instead of up and down.

I also merged the field of view of each barrel so, there is no more barrel overlap anymore, the field of view looks circular again. And it seems that this binocular has the true '' 3 axis collimation''. And the bad alignment also seemed to affect the diopter adjustment, now I can focus with less diopters than before.

I am so sorry about the disturbances provoked to this forum because of my lack of experience.

Thanks for reading.


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BillC
on a new path
*****

Reged: 06/04/04

Loc: Lake Stevens, WA, USA
Re: Binocular FOV allignment new [Re: ngc 9999]
      #5653452 - 01/31/13 12:02 AM

I FINALLY GOT EVERYTHING INTO ALIGNMENT AGAIN!!

That’s SUPER!

But, though your problem is solved, let’s look at a few points for future reference.

THE ASTIGMATISM CAUSED BY FOCUSING

Astigmatism is not caused by focusing. It is caused by the curvatures and spacings of your lenses.

I ALSO MERGED THE FIELD OF VIEW OF EACH BARREL SO, THERE IS NO MORE BARREL OVERLAP ANYMORE, THE FIELD OF VIEW LOOKS CIRCULAR AGAIN.

That’s great to hear. People get too wrapped around the axle about that, and old wives tales abound. Judge only the coincidence of your images — period. If you view a distant target — with your eyes RELAXED — and the images are merged, that’s all you need to worry about. If you look for the images to not be concentric . . . they won’t be because you’re crossing your eyes. If they’re still faulty, with the target image merged completely, then your problem is MECHANICAL not OPTICAL. Field stops don’t form an image — optics do.

AND IT SEEMS THAT THIS BINOCULAR HAS THE TRUE '' 3 AXIS COLLIMATION''

If you have been tweaking screws on BOTH sides, your chances of being right on that one is VERY remote!

Don’t worry about it! You’re happy now; just enjoy your binocular under the stars! There will be plenty of time to worry about such things the NEXT time a problem arises. You’ll probably grow an inch or two (optically) in the mean time.

AND THE BAD ALIGNMENT ALSO SEEMED TO AFFECT THE DIOPTER ADJUSTMENT, NOW I CAN FOCUS WITH LESS DIOPTERS THAN BEFORE.

As Rafiki, that great optical sage of the Serengeti would say . . . “WRONG!”

I AM SO SORRY ABOUT THE DISTURBANCES PROVOKED TO THIS FORUM BECAUSE OF MY LACK OF EXPERIENCE.

Hey, guys — and gal — he provoked a disturbance. Doesn’t the TOS talk about that? I know I would . . . NEVER.

THANKS FOR READING.

Don’t mention it. It’s kinda what we do. If we had lives we wouldn’t. But then, that’s a tremendous “IF.”

Now, go OBSERVE something!

BillC


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Simon S
Carpal Tunnel
*****

Reged: 01/07/07

Loc: Crawley West Sussex UK
Re: Binocular FOV allignment new [Re: BillC]
      #5654413 - 01/31/13 02:20 PM

Bill, I seem to remember you saying that you have never seen rotational missalignment, and that I can well believe in good quality binoculars.
I have however seen this many times in cheap examples that have a prism shelf smaller than the prism hypotenuse.
This error from my humble experience is sometimes difficult to spot. The usual side effect is objects like stars look aligned with no eye strain at all, but looking at an object with any detail results in serious eye strain.

What input do you have on this fault?


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Gordon Rayner
Carpal Tunnel
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Reged: 03/24/07

Re: Binocular FOV allignment new [Re: BillC]
      #5654626 - 01/31/13 04:22 PM

Re: JTII "hand "collimator" " or equivalent:

Deja vu:

Not available in stores. Collectors/users item. There might be some available in Japan. Searching this binocular forum with the keyword "dinka" and/or "nuer" will return relevant posts.
Another search, using "comparator" will bring in other relevant discussions.
One will see two images of a nearby t-shirt, via a JTII. those images would be fused if the target were distant, and if I had not rotated the comparator on its axis (unintentionally) with respect to the camera. I bought that shirt at a local celebration on the day of South Sudanese independence.

Also shown are pictures of a comparator I assembled using a rhomboid prism alone, with no added half-silvered right angle prism beam combiner cemented to one end of the rhomboid prism. Instead, the eye's pupil, whose lateral position must be more closely controlled, and over a more limited IPD range than the JTII or a reversed, eyepieceless binoviewer, accepts a waxing half-moon shaped beam from one side of the binocular directly, and a waning half-moon shaped beam, via the rhomboid, from the other other side of the binocular.

A good semi-equivalent to the JTII , with the advantage of variable interpupillary distance, is a well-adjusted, reversed and eyepieceless, quality binoviewer sold unreversed and using two eyepieces, for monocular telescope conversion to 50/50 left/right illumination . There is a CN forum devoted to those .

I discovered that independently, but see www.akoehler.de

I have not said to "check out "collimation" " with JTII etc. Rather , confirm/refute 2- axis parallelism at one IPD or nearby, or use as part of a more extensive kit to achieve 3-axis parallelism ( as a peek-around provider of a direct image which has not passed through the binocular which is being adjusted/evaluated).


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GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Binocular FOV allignment new [Re: Gordon Rayner]
      #5654775 - 01/31/13 05:52 PM

Simon,
Re. rotational misalignment. Indeed, you're correct when noting that when concentrating on a point source (or other sufficiently small target) in isolation, differentially rotated images will pose no problem. But when examining a large object or the overall scene, the effect is to make your eyes feel as though they're trying to torque themselves into a chameleon-like twist.


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BillC
on a new path
*****

Reged: 06/04/04

Loc: Lake Stevens, WA, USA
Re: Binocular FOV allignment new [Re: Simon S]
      #5654892 - 01/31/13 06:59 PM

Quote:

Bill, I seem to remember you saying that you have never seen rotational missalignment, and that I can well believe in good quality binoculars.
I have however seen this many times in cheap examples that have a prism shelf smaller than the prism hypotenuse.
This error from my humble experience is sometimes difficult to spot. The usual side effect is objects like stars look aligned with no eye strain at all, but looking at an object with any detail results in serious eye strain.

What input do you have on this fault?




First, you must note that, with a Porro prism, the optical axis is shifted TWICE the angle of prism seat deviation. With two in a cluster, it doesn’t take too much to get the line of sight displaced by a large measure — and almost never visible by just looking at the prisms in place.

When viewing a star or planet on axis, there no VISABLE problem. As the problem gets worse off axis, your spatial accommodation takes over. Also, since star positions are not seen relative to any form of concrete reference it’s often hard to see. When it is not really atrocious, many people just blame the fuzziness on their vision.

Did any of this answer your question? This was not meant to supplant anything Glenn said. But, I was already started and was too greedy to give up the keystrokes.

BillC


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