Conditional Alignment (1 Viewer)

Hi Gang,

There is no way you guys are as geeky as members of Cloudy Nights. However, there are probably a few here who might find the attached of interest. I’m doing an article on Conditional Alignment for S&T and while they will not need or want all the graphics in the PDF, I thought it might worthwhile to post here. :cat:

Cheers,

Bill

a little to technical for me to follow....:smoke:

to the untrained mind just a lot of hand jive....

gunut said:

a little to technical for me to follow....:smoke:

to the untrained mind just a lot of hand jive....

Click to expand...

Some things can’t be explained simply; others simply can’t be explained. You will note, I didn’t post this to OpticsTalk. Even so, if you think about it, I’m sure you will understand. If not ... I ain’t going in the brush when you’re around.

On a serious note, a few years before I left Washington, a Ft. Lewis soldier went into the brush to relieve himself and didn’t come out alive. :cat:

“I thought it was a bear ... so, I shot it.”

Bill

Good pics, I await my copy of S&T eagerly....

Peter

wllmspd said:

Good pics, I await my copy of S&T eagerly....

Peter

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Hi Peter,

He won’t set a pub date until he reviews the whole article. My original proposal was for a piece on the problems related to spatial and dioptric accommodation. The proposal was straightforward and the topic important to observers, although never considered.

Sean changed the topic to collimation vs. conditional alignment, which would have been like trying to poke a battleship through a bullet hole. Then, he settled on describing how to make the conditional alignment—that the Internet aficionados see as collimation—more efficient. That could be done ... so I did it. He should start his day tomorrow with the final in his email box.

Knowing it was important, I sold the original idea to Times of the Islands magazine and it will be in their winter issue. :cat:

Bill

Knowing there are different ways is a start... that you can “make it look right”, but that it’ll still be off to a degree. For more information we have some detailed accounts if people care to look.
PEter

wllmspd said:

Knowing there are different ways is a start... that you can “make it look right”, but that it’ll still be off to a degree. For more information we have some detailed accounts if people care to look.
PEter

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I have NEVER been opposed to conditional alignment when it is ADEQUATE to make the instrument serviceable (at the expense of some degree of spatial accommodation) for a single user and when 3-axis collimation is beyond the means of the observer.

I just get agitated when, after all that has been said and written, people still come along calling the process what IT IS NOT!

“Hey, y’all, look at me; I just developed a sure-fire 20-minute brain surgery.”

That just continues to promote the JUNK SCIENCE that afflicts us all. :cat:

Bill

Bill (and other knowledgeable members),

I am curious to know what happens to the image formed by an objective lens if

a) the erector prism is shifted laterally
b) if the erector prism is tilted

I have made a simple diagram to explain the question. Does the image shift in both cases or only in case (b)?

Thanks,
Omid

Omid said:

Bill (and other knowledgeable members),

I am curious to know what happens to the image formed by an objective lens if

a) the erector prism is shifted laterally
b) if the erector prism is tilted

I have made a simple diagram to explain the question. Does the image shift in both cases or only in case (b)?

Thanks,
Omid

Click to expand...

191008

Hi Omid,

One of the reasons the eccentric ring method of collimation is desirable is that the line of sight is shifted laterally.

As for the prism, remember that a light ray exits a reflecting surface at TWICE THE ANGLE of incidence. Then figure out the number of reflections involved. Aristotle addressed this in his Remedial Optics 5.06 Course when he said:

“Bad juju!” :cat:

Bill

I think the right way to model erector prisms is that they are a combination of mirrors + plane glass plate. For our purpose, we can ingonre the plane glass part and only consider the mirror aspect. Now, let's state the question slighly diferently: Do erroctor prisms have an optical axis? Would they need to be perfectly centered on the optical axis like a lens?

The answer seems to be yes and no. No from aberration control point of view and yes from image position point of view. Image erecting is equivalent to rotating it 180 degrees. So there is a center of rotation (which we may call the optical axis of the erector system). Based on this analogy, if the erector prism is shifted, the image will shift by twice that amount.

Now what about tilt? Is it correct to say if the erector prism is tilted by an angle Alpha, the image will tilt by an angle 2xAlpha?

Omid said:

I think the right way to model erector prisms is that they are a combination of mirrors + plane glass plate. For our purpose, we can ingonre the plane glass part and only consider the mirror aspect. Now, let's state the question slighly diferently: Do erroctor prisms have an optical axis? Would they need to be perfectly centered on the optical axis like a lens?

The answer seems to be yes and no. No from aberration control point of view and yes from image position point of view. Image erecting is equivalent to rotating it 180 degrees. So there is a center of rotation (which we may call the optical axis of the erector system). Based on this analogy, if the erector prism is shifted, the image will shift by twice that amount.

Now what about tilt? Is it correct to say if the erector prism is tilted by an angle Alpha, the image will tilt by an angle 2xAlpha?

Click to expand...

Hi Omid,

That WOULD be the goal. However, “perfect” is a word that should not find its way into discussions concerning optics. In mirror making, a surface that looks pristine and infinitely smooth will look like a rock quarry under ample magnification. :cat:

Bill

PS To the 14 folks who copied this image, I apologize. The second image was for a mirrored system and not a prism system. The graphic has been changed.

Bill:

This is an interesting subject, and have studied up on this subject myself. I have a number of Nikon porro
prism binoculars. I have spent time using a tripod mount and have tested many binoculars for proper collimation.

It is very easy to do a proper check if you know what you are doing.

The method I use for alignment, is to screw the objective barrels in and out so I can reach perfect
collimation, ie. allignment.
Jerry

NDhunter said:

Bill:

This is an interesting subject, and have studied up on this subject myself. I have a number of Nikon porro
prism binoculars. I have spent time using a tripod mount and have tested many binoculars for proper collimation.

It is very easy to do a proper check if you know what you are doing.

The method I use for alignment, is to screw the objective barrels in and out so I can reach perfect
collimation, ie. allignment.
Jerry

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191011

Okay, Jerry, you have said that you appreciate my cut-the-crap way of explaining things. So, based on your endorsement, I will add a little seasoning to the subject.

[I will be available for being taken to the woodshed after 4:00 today. But ND is COLD this time of year, so please make it quick; I’m already on blood thinner.]

1. Even if you had a collimator and years of experience you would not have achieved “PERFECT” collimation. A tiny fraction of perfection that is so close only God and Superman could see the difference ... absolutely! But perfect? Sorry, no. Let’s suppose you DID collimate your bino perfectly. The condition would be temporary at best as temperature, humidity, and changes in your physiology are always in flux.

DOES THAT LEVEL OF NITPICKY MATTER? In the real world, it does not. I only brought it up to teach.

2. Screwing the objective bells in and out? This CAN certainly do the trick. BUT, that trick is dependent on YOUR degree of spatial accommodation. You can rotate one side, rotate both sides, or turn one or both lenses in their cells. One of the attached graphics is OM2 Eric Magnusson using a lens centering machine at Captain’s to get the best arrangement of the crown and flint elements of an objective lens. Buy rotating one objective, you can only make the line of sight spin in an arc of a certain size, as illustrated by the attached drawing. Rotating both can get you farther down the road.

You say, “It is very easy to do a proper check if you know what you are doing.”

I say, doing a complete 3-axis collimation job is a piece of cake, unless the instrument needs repair, if you know what you’re doing. The problem is, so many “experts” ... aren’t!

I just got off the phone with Cory. He was averaging 1 per hour at the Okie-Tex Star Party. :cat:

Cheers,

Bill:
I know all of this, but I wanted you to give us all your take on the subject. I do have your books so
I am well educated...

I do want to know, who are those 2 chaps in your last photo ?

Jerry

NDhunter said:

Bill:
I know all of this, but I wanted you to give us all your take on the subject. I do have your books so
I am well educated...

I do want to know, who are those 2 chaps in your last photo ?

Jerry

Click to expand...

Bill Nye the Science Guy and the Munchkin is me. :cat:

Bill

Bill, how do manufactures collimate in factory and at service point?

eronald said:

Bill, how do manufactures collimate in factory and at service point?

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Hi eronald,

At the factories, at least in Asia, most use a Fujinon U.B.M.M. collimator (attached). Europeans use those and various other devices of various ages (also attached). And some of those deal mostly with some form of conditional alignment.

I frequently get into trouble—what with being a self-serving, condescending, arrogant, know-it-all—because I won’t say pretty things—lie—in an effort to be liked. But most technicians outside the factories, drumroll, please ... ARE CLUELESS regarding clinical collimation!!! And I did water that down.

Our own Jan, Gijs, Gary Hawkins, Harrie Rutten, Richard Berry, Tony Kay, the Orwell Astronomical Society (Ipswich), Swift’s Paul Cerra, and others can testify that I have put a lot of effort into finding technicians who really understand 3-axis binocular collimation.

The fact is, you can count some of the techs in the US who understand and can perform the task, on one hand—with fingers left—and some of those were taught by either Cory or me. I would always have been pleased to recommend someone—anyone—to those in need of service. But people just point out some silly book or article and profess the author is an "expert."

I’m truly sorry to be so blunt but honesty dictates it.

“Honesty is the first chapter in the Book of Wisdom.” — Thomas Jefferson

I would like to be liked, but I won’t do what is necessary if it means dancing around the issue or being disingenuous.

“The truth is incontrovertible. Malice may attack it; ignorance may deride it. But, in the end, there it is.” — Winston Churchill

Maybe, after I’m long dead, someone will come across some of my work and say, “Hey, that guy really did care.” :cat:

Bill