Collimation (1 Viewer)

Hi All:

Across the board, I get the impression the average observer on Birdforum is a few shades more mature and cranial than the average observer on Cloudy Nights. However, with all those who never cease talking about getting their binocular to perform to a standard above that which it is capable, I am amazed that there is so little emphasis on collimation. This is noticeably true for three reasons.

1. The QA efforts that go into so many inexpensive Asian offerings are considerably lower than we have come to expect from the old guard in Europe, or the top tier of Asian firms.

2. Even small errors in collimation can affect the performance of an instrument more than a combination of Seidel aberrations. And

3. It is the ONE aspect of performance the observer can address for himself or herself (Conditional Alignment) or, if dealing with the big dogs in the industry, can have brought back to true, 3-axis alignment—collimation.

I am not seeking another endless debate. But, I would like those with an opinion on this matter to share it with me. |=)|

Thanks,

Bill

Bill:

I agree with your post, and when I purchase a new or new to me binocular, the first thing
I do, is check the collimation. I use my method of focusing on a distant target, then pulling
the binocular away several inches, then closing my eyes to lose my focus, then giving it
another look. Our eyes will accommodate small collimation issues, and this is a good way to test for
yourself. There is a thread on here about that very subject.

I looked up the definition of the Seidel aberrations, and that is a complex subject, way above
my interest.

I do have some experience with conditional alignment, as I have a number of Nikon porros
that I have obtained over the years. I have found that I can often get them into alignment
by screwing the objective barrels in or out, and have had great success making them work out.

Also, I have the famous Celestron Skymaster 15-70, that should come with instructions for
collimation. I have played with the prism screws to get it somewhat "good".
If you do a search on that one, the net is full of advice on that issue.

You may know how many good independent binocular shops there are in the US.
The last binocular I had an issue with, was properly fixed by a skilled shop in Houston, TX.
There can't be a large number with collimators, and the skills needed.

Another question, is how many binocular Manufacturers do this proper service.
I know the Big 4 do it, but how many others. I am just guessing here, but am thinking
Kahles, Bushnell, Leupold, Meopta and maybe Vortex.

Jerry

NDhunter said:

Bill:

I agree with your post, and when I purchase a new or new to me binocular, the first thing
I do, is check the collimation. I use my method of focusing on a distant target, then pulling
the binocular away several inches, then closing my eyes to lose my focus, then giving it
another look. Our eyes will accommodate small collimation issues, and this is a good way to test for
yourself. There is a thread on here about that very subject.

I looked up the definition of the Seidel aberrations, and that is a complex subject, way above
my interest.

I do have some experience with conditional alignment, as I have a number of Nikon porros
that I have obtained over the years. I have found that I can often get them into alignment
by screwing the objective barrels in or out, and have had great success making them work out.

Also, I have the famous Celestron Skymaster 15-70, that should come with instructions for
collimation. I have played with the prism screws to get it somewhat "good".
If you do a search on that one, the net is full of advice on that issue.

You may know how many good independent binocular shops there are in the US.
The last binocular I had an issue with, was properly fixed by a skilled shop in Houston, TX.
There can't be a large number with collimators, and the skills needed.

Another question, is how many binocular Manufacturers do this proper service.
I know the Big 4 do it, but how many others. I am just guessing here, but am thinking
Kahles, Bushnell, Leupold, Meopta and maybe Vortex.

Jerry

Click to expand...

Hi Jerry:

Your method works just fine, IF you know how to just STARE. Some people can’t do it; some people need to work at doing it; some people don’t think it matters. If they’re happy, I’m happy for them. Still it doesn’t serve them well. What you don’t know CAN hurt you.

Yes, your eyes will “accommodate” SMALL collimation issues. However, with the right binocular, they don’t have to. This makes for a better view with less or no eyestrain.

—“I looked up the definition of the Seidel aberrations, and that is a complex subject, way above my interest.”

Likewise, it is way above my INTEREST, too. But, so many people who wallow in speculation about optical anomalies wouldn’t have to do so, if they understood these aberrations and how they are interconnected. Which is more productive, two nights reading about aberrations, or spending years participating in conversations in which neither the speaker nor audience understand the subject matter? If you see a man at the top of a mountain, there’s a good chance he didn’t fall there!

—“I do have some experience with conditional alignment, as I have a number of Nikon porros that I have obtained over the years. I have found that I can often get them into alignment by screwing the objective barrels in or out, and have had great success making them work out.”

When adjusting the lenses, you might be better served by leaving the “barrels” alone, choosing instead to adjust the eccentric rings or collimation setscrews—unless the adjustment is slight. When adjusting the lens housings too much, you may shear off metal shards that can get on the prisms. Almost always, when going about alignment this way, you are depending largely on accommodation and not collimation. Would it be good enough for me? As often as not, yes. I just get tweaked when the armchair technician calls that operation “collimation.” Semantics? Of course; collimation? Nope!

—“Also, I have the famous Celestron Skymaster 15-70, that should come with instructions for collimation. I have played with the prism screws to get it somewhat "good". If you do a search on that one, the net is full of advice on that issue.”

I am well aware. A few million of those words are mine and represent my futile attempt to save people from themselves. But just like the Gold Ring thread, some folks find much more pleasure in speculation than in listening to one who has the inside track on the subject. I’ve known, through a number of reasons, Leopold didn’t manufacture binos themselves. But just like Cloudy Nights, I had to rear up on my hind legs and expend a few thousand words to put the subject to rest—for a few weeks … maybe!

A STORY

As an optics merchant, it would be foolish to turn away sales of a popular binocular. Yet, that is exactly what I once had to do.

A particular instrument kept arriving from a prominent importer out of collimation—right out of the box. Therefore, the next time I received a shipment, I set aside time to check each one before putting them away. When the first eight were out of collimation—by even the most lenient of industry standards—I decided not to waste any more time on the project, and sent the entire shipment of 20 back to the importer.

I could have collimated them. However, that could have caused other problems. First, it would have been a waste of time and money for my company. Then, too, how could I know the instruments would hold their collimation and not soon cause problems for my customers? Knowing it would cost more in handling and shipping to return individual instruments to the importer, than it would to simply return the lot and remove the model from inventory, I felt that was the best option. Popular or not, that model was a waste of money.

Then, when I saw the binocular being treated as the neatest thing since sliced bread on a certain Internet binocular forum, I felt I was obliged to make other participants aware of my findings. I was quickly reminded that no good deed will go unpunished and that you can’t save some people from themselves.

I pointed out that I had been a supporter of the importer for years, had more than two dozen models of their telescopes and binoculars in inventory, and was a friend of a long-time president and CEO of the company. It made no difference; the price point overshadowed rational experience. Apparently, some people thought I had a hidden agenda.

Finally, several others with practical experience with that model came forward to say things like, “I ordered four, before I got one that was collimated,” “their quality control really stinks,” and “I found it wasn’t worth it, and just gave up.” Still, the price point kept dredging people up who would swear to the excellent performance of the binocular. Barring collimation issues, they were right. Yet, those issues kept showing up in the majority of cases.

As I said, you can’t save some people from themselves. The best I can do is quote the age’s old adage on quality:

“The bitterness of poor quality will linger long after the sweetness of a low price has been forgotten!”

—“You may know how many good independent binocular shops there are in the US. The last binocular I had an issue with, was properly fixed by a skilled shop in Houston, TX. There can't be a large number with collimators, and the skills needed.

—“Another question, is how many binocular Manufacturers do this proper service. I know the Big 4 do it, but how many others. I am just guessing here, but am thinking Kahles, Bushnell, Leupold, Meopta and maybe Vortex.”

I can assure you it’s MUCH worse than you think. The following is from my ethereal book:

“Since most binoculars are not used at either the highest or lowest IPD setting, the maximum errors in parallelism can often be ignored. However, with collimation errors subject to the alignment and tilt of 4 prisms and 2 objective lenses (in a traditional Porro prism binocular), the exact cause of the displaced image is not easily established.

“This misunderstanding is not limited to amateurs. Some professionals, at major importing companies, just know how to ‘get it in the box,’ giving little thought to the ‘whys’ of the procedures. Fellow Navy Opticalman Cory Suddarth was with me at Captain’s the day I took a call from a fellow who had been a repair MANAGER at his company for more than 10 years. His call went something like this:

‘Bill, I don’t understand it; I’ll get the binocular collimated, but when I move one of the barrels, it’s off again!’

This fellow had been selling a conditional alignment job as ‘collimation’ all those years, and it was this experience that caused me to suggest: There’s a big difference between 20 years of experience and one year of experience 20 times.’

I doubt many repair facilities have people onboard that would willfully cheat their customers. Too often, however, they just don’t know what they don’t know. But, if the bino is returned with clean lenses and is aligned well enough (near the user’s IPD), that user will get on the net and brag about the company’s great work. I have seen glowing testimonies of the work of others when I knew they were considerably short of the services they were selling. But, the customer is king.

For the last few years, one major seller of binoculars has been claiming that “Conditional Alignment” is a “myth.” For years, this fellow told Cory and me that he doesn’t NEED a collimator, largely due to the fact that he can “eyeball” an instrument’s collimation to “100 power.” Well, that’s his tail; I sit on mine. He has even produced two video tapes (for sale, of course) to prove his assertion.

I feel that if he were correct, optical scientists at the University of Arizona’s Optical Sciences Center and leadership of SPIE (the Society of Photo-optical Instrumentation Engineers) wouldn’t have invited me to give a lecture on Conditional Alignment at their 2012 conference. He has since taken in one of Cory’s classes on collimation. If that did not tweak him, I would be pleased for him to try to correct me to the PhDs at SPIE and the OSC in Tucson. Frankly, I think that would be a hard sell. :flyaway:

Cheers,

Bill

I dislike the term "collimation" in binoculars. In telescopes, collimation means the correct alignment of optical axis of the objective and eyepiece. It has significant effect on the image quality. In binoculars, most people use the term for parallel alignment of the two optical axes and the hinges. I will rather use the term "alignment" in binoculars. In fact, poor collimation (in telescope sense) will greatly affect images in bins, but not many have addressed the point.

WJC said:

...

For the last few years, one major seller of binoculars has been claiming that “Conditional Alignment” is a “myth.” For years, this fellow told Cory and me that he doesn’t NEED a collimator, largely due to the fact that he can “eyeball” an instrument’s collimation to “100 power.” Well, that’s his tail; I sit on mine. He has even produced two video tapes (for sale, of course) to prove his assertion.

I feel that if he were correct, optical scientists at the University of Arizona’s Optical Sciences Center and leadership of SPIE (the Society of Photo-optical Instrumentation Engineers) wouldn’t have invited me to give a lecture on Conditional Alignment at their 2012 conference. He has since taken in one of Cory’s classes on collimation. If that did not tweak him, I would be pleased for him to try to correct me to the PhDs at SPIE and the OSC in Tucson. Frankly, I think that would be a hard sell. :flyaway:

Cheers,

Bill

Click to expand...

I suppose here's the videos in question, free of charge:

http://www.bigbinoculars.com/vcontents.htm

I know nothing about this issue, so don't kill the messenger.

I know too little about it to add anything to the conversation, but I am reading all this stuff. :t:

I just look through them, after a few hours of birdwatching with no strain I never give it another thought.

akltsang said:

I dislike the term "collimation" in binoculars. In telescopes, collimation means the correct alignment of optical axis of the objective and eyepiece. It has significant effect on the image quality. In binoculars, most people use the term for parallel alignment of the two optical axes and the hinges. I will rather use the term "alignment" in binoculars. In fact, poor collimation (in telescope sense) will greatly affect images in bins, but not many have addressed the point.

Click to expand...

Hi Akltsang:

The term "collimation" has a greater need to be used in binoculars than in telescopes, because not only does EACH telescope need to be collimated, BOTH telescopes need to be collimated to each other AND the axle. This is something that 99+% of bino users never think of—they should. I wish I had a dollar for every time a customer presented me with a “Won’t Focus” binocular that was just out of alignment. I certainly understand and appreciate your preferring the term “alignment.” Still, carpenters “align,” mechanics “align,” welders “align,” and such. Optical technicians “collimate”; it’s just part of our heritage.

Even so, I don’t think I have taken things past their logical conclusion. One credentialess (but well-read) wannabe over on Cloudy Nights always had a NEED to better me at every turn. He wasn’t happy enough with the with my “3-axis collimation,” which was understood by most forum members by the way I used it. He thought he could be more noticed and erudite if he called it “TRI-AXIAL PARALLELISM.” Technically correct? Yes. But, Oh, please! So you see, “collimation” may not be that bad, after all.

Akltsang, you said: “Alignment … will greatly affect images in bins, but not many have addressed the point.”

That was my original POINT. Of all the gremlins observers complain about, slight collimation errors easily overshadow most. In addition, it’s the only ONE that can be corrected!

1. Chromatic Aberration—no.
2. Field Curvature—no.
3. Astigmatism—no.
4. Edge Sharpness—no.
5. Etc., Etc., Etc.—no, no, no.

As I have said, I don’t have a horse in the race. I have enough “Alphas” and . . . Deltas, to last the rest of my life. I just find it interesting that folks will spend pages talking about anomalies they can’t change but almost NEVER address the one they CAN! :t:

Cheers,

Bill

Kammerdiner said:

I suppose here's the videos in question, free of charge:

http://www.bigbinoculars.com/vcontents.htm

I know nothing about this issue, so don't kill the messenger.

Click to expand...

Kammerdiner:

No killing? Spoilsport.

I think I'll pass; it made me angry enough when I saw them the first time. Cory and I knew he was using his personal Accommodation to get the job done, and just shook our heads. We wondered how he knew his personal accommodation would match that of the customer who sent the bino in!

Don't get me wrong; I LIKE the guy--always have. But being a bino RETAIL mogul does NOT make you a tech or give you the knowledge and experience to be one. Yes, he works on his binos. But he is still some distance from having the whole picture, or WAS when those tapes were made.

Bill

perterra said:

I know too little about it to add anything to the conversation, but I am reading all this stuff. :t:

I just look through them, after a few hours of birdwatching with no strain I never give it another thought.

Click to expand...

When using my "Alphas," I'm happy. When using my "Deltas," I'm happy. But just think how tiny these threads would be if we didn't have something to complain about. I just like to try to keep my friends between the ditches . . . when possible.

Bill

PS It was 20 degrees here this mourning. Imagine how cold it must have been in Amarillo! :eek!:

WJC said:

When using my "Alphas," I'm happy. When using my "Deltas," I'm happy. But just think how tiny these threads would be if we didn't have something to complain about. I just like to try to keep my friends between the ditches . . . when possible.

Bill

PS It was 20 degrees here this mourning. Imagine how cold it must have been in Amarillo! :eek!:

Click to expand...

We were 27º, Amarillo with nothing between it and the north pole but a few barbed wire fences had to be a block of ice.

perterra said:

We were 27º, Amarillo with nothing between it and the north pole but a few barbed wire fences had to be a block of ice.

Click to expand...

Binoculars, Binoculars, Binoculars. Now, with THAT out of the way:

In 1972, my collegiate bowling team (ASU) won a spot at the regional tournament at Canyon, just south of Amarillo. As the rookie, I was to be tossed into the swimming pool. Well, the freeze came before the motel had time to drain the pool for the winter.

They threw me in the pool, all right. But, I just slid to the other end and got out.

Bill

WJC said:

Binoculars, Binoculars, Binoculars. Now, with THAT out of the way:

In 1972, my collegiate bowling team (ASU) won a spot at the regional tournament at Canyon, just south of Amarillo. As the rookie, I was to be tossed into the swimming pool. Well, the freeze came before the motel had time to drain the pool for the winter.

They threw me in the pool, all right. But, I just slid to the other end and got out.

Bill

Click to expand...

LOL

Great museum in Canyon, I was through there last year.

Hi Bill,

You are perfectly right to say that collimation is the only one that can be corrected, and

1. Chromatic Aberration—no.
2. Field Curvature—no.
3. Astigmatism—no.
4. Edge Sharpness—no.
5. Etc., Etc., Etc.—no, no, no.

In fact, correct collimation (telescope sense) can help improving all the above significantly (turning a $700 bins into a $1000 bins), but correcting the collimation (bino sense) will almost certainly upset the perfect optical axes of the two Telescopes. This is because the direction of views of the two Telescopes are often adjusted by tilting the objectives, prisms and eyepieces. This has much to do with the accuracy of the mechanical parts (perfect parallel hinges for example) and bin users have no way to do anything. That's partly why alphas bins are more expensive from non-alphas, I guess. Mechanical accuracy is also important for expensive bins.

akltsang said:

Hi Bill,

You are perfectly right to say that collimation is the only one that can be corrected, and

1. Chromatic Aberration—no.
2. Field Curvature—no.
3. Astigmatism—no.
4. Edge Sharpness—no.
5. Etc., Etc., Etc.—no, no, no.

In fact, correct collimation (telescope sense) can help improving all the above significantly (turning a $700 bins into a $1000 bins), but correcting the collimation (bino sense) will almost certainly upset the perfect optical axes of the two Telescopes. This is because the direction of views of the two Telescopes are often adjusted by tilting the objectives, prisms and eyepieces. This has much to do with the accuracy of the mechanical parts (perfect parallel hinges for example) and bin users have no way to do anything. That's partly why alphas bins are more expensive from non-alphas, I guess. Mechanical accuracy is also important for expensive bins.

Click to expand...

Hi Akltsang:

Correcting collimation in a “bino sense,” as you say, is only detrimental for those who follow the foolish . . . “Ya just have to turn these screws” method. Those of us who know what we’re doing don’t have to worry about such nonsense.

Yes, tilting prisms willy-nilly CAN Conditionally Align an instrument good enough to make most observers happy—if the error was minimal at the start. I’ve done it for some of my own, AND done it for customers who didn’t want to pay the price for a REAL collimation job. But, with every tweak of those screws, at least two or three of those pesky Seidel aberrations become more prominent.

It should be understood that the push/pull screw method of collimation was devised as a production shortcut to increase profit. It was not to increase optical performance.

For many years, the eccentric ring method was the leading method of collimation—by far. With it, the lens moved LATERALLY so as not to introduce aberrations, and the prisms were SQUARED on the prism self or cluster—no tilt.

Following the “Just tweak these screws” method puts one on a slippery slope and opens up a whole kettle of worms for those who stay aloof from the realities of the project. Is collimation hard to do? No way; else I’d be lost. It’s just that some people enjoy spending more time talking, than they do in trying to understand what they want to talk about.

The following is from my ethereal bino book.

“ACCOMMODATION FOR MISALIGNMENT

“In 3-axis collimation, the hinge must be taken into consideration, as in Hanna’s view the hinge is the ‘heart’ of a binocular. (9) Even so, this vital piece of the process is rarely mentioned in popular literature or on the web. Instead, both sources are filled with inexperienced technicians sharing what they’ve read, or an importer trying to offer knowledge as a service.

“IF one optical axis is parallel to the axle, and IF screws are only adjusted on the offending side, technicians will find elementary techniques involving rooflines, power poles, or anything else—given the object is distant enough*—adequate to restore the binocular to its original collimated condition, without the need of more sophisticated test equipment.

* The US Navy used 1 nautical mile—roughly 2,000 yards.

“A problem arises when following the, “You just have to turn these screws” method of alignment, and one starts turning screws (or eccentric rings) on the wrong telescope.

“When that happens, a binocular that COULD have been collimated, with the adjusting of the correct screws, will now have to be replaced or repaired by a technician who has been trained in something more sophisticated than observing a roofline. And, although I have been taken to task more than once for my stance on this, I will stand by my assertion that qualified technicians are almost extinct.

“Yes, I know some people would say, “What about …?” and offer a list of well-known importers. But, while the armchair enthusiast is long on opinions, and short on facts, I will simply repeat: they are almost extinct. Rare is the importer that has a collimator of any kind, and fewer have personnel who have been trained to use one.

“Knowing how collimators are unduly rare and expensive, I’ve often thought of producing some for resale. In speaking with a couple of binocular importing CEOs, I’ve learned they might not sell well to those who need them most.

“ ‘They don’t want those machines out there; they wouldn’t want people to know just how bad collimation was on their binoculars.’

“Those who buy from the legends of the industry need not worry; everyone else, well, that’s a different story.” :t:

Cheers,

Bill

Bill, I think Akltsang has raised an interesting point about the collimation of the individual telescopes. Could you talk a bit about the causes of "cat's-eye" exit pupils, and how it can affect the quality of the image at the eyepiece?

peatmoss said:

Bill, I think Akltsang has raised an interesting point about the collimation of the individual telescopes. Could you talk a bit about the causes of "cat's-eye" exit pupils, and how it can affect the quality of the image at the eyepiece?

Click to expand...

Hi “Peat”:

Most of the cat's-eyes I've seen have been relative to a lateral displacement of a primary baffle or a field stop. In this unit, the field stop—which can be seen 6/10ths of an inch in front of the field lens—can’t come loose, in that it is made into casing. In many cheaper units, it is a very thin piece that screws into the eyepiece. In the photo—attached—you will note a black piece of plastic, between the objective lens and the prism cluster; that is the primary baffle. Sometimes, it will come completely loose—as this one did while I was cutting the bino in two—or it may tilt. This may cause the small end to cut into the light cone.

Other than people seeing what they consider anomalies, that the manufacturer doesn’t, I have experienced very few cat’s eyes.

As far as affecting the image, there is always a slight degradation due to diffraction, or a vignetting due to the displacement. People may notice the obstruction, but will rarely notice the loss of light.

Please tell me more about the bino that is causing you trouble, so I can look into it . . . no pun intended. Well, okay; maybe a little.

Bill

Hi Bill, and thanks for the photo (that must have been pretty tough sawing that bin in half so neatly!). When I mention "cat's eye", I'm talking about what could also be described as "gibbous moon" shape, or what others might call "truncated". I've seen a few recent roofs with exit pupils like this, but what I was specifically thinking about was a review of a popular binocular a few years ago, and the discussion that it generated here on the Forum. The binocular was the Zenray 8x42 ED2, which was reviewed by Allbinos here:

http://www.allbinos.com/254-binoculars_review-Zen-Ray_Optics_ZEN_ED2_8x43.html

That review lead to a thread on the Forum, where Henry, in post #10, drew a connection between the "truncated" exit pupils and what he called "laterally misaligned optics". His comments actually seem very sensible to me, but I was wondering what your perspective as a binocular tech might be on this.

http://www.birdforum.net/showthread.php?t=245889

peatmoss,

A simple way to understand how the lateral movement of eccentric objective rings introduces coma and vignetting is to imagine that you are sighting through two circular apertures. One is twice as large and twice as far away as the other. As long as your eye and the two apertures are perfectly aligned you will see a perfect circle where the two apertures seem to be the same size. If you move the more distant aperture laterally that will cause the two apertures to overlap in a way that the eye will see as the shape of a cat's eye or gibbous moon.

Sighting through the interior of a binocular is much the same. The distant aperture is the objective lens and there will be at least one internal aperture (say the first aperture of the prism shelf) that is sized to align with the edge of the objective light cone so that it appears from the eyepiece to be about the same size as the objective (usually, really, just a little larger). The only condition under which these apertures will align perfectly is the one where the eccentric rings are set for perfect centering of the objective in its cell. If any eccentricity has to be introduced to collimate the binocular the objective will move out of alignment with the prism aperture (introducing vignetting) and out of alignment with the eyepiece optical axis (introducing coma). In a fine telescope intended for high magnification even a little misalignment like this matters. A star at high magnification will show lopsided diffraction rings, narrow and bright on one side of the Airy disk, diffused and dim on the other. In a low magnification binocular much more coma can be tolerated before it becomes a real problem.

FWIW, If I'm really serious about checking the collimation of a binocular I use an old Bausch & Lomb "Double Collimator" like the one below (thanks to the generosity of BF member "Surveyor"). It can't be used to properly collimate a binocular, but it does allow me to measure how far off the collimation is at the collimator's fixed IPD of 65mm.

Henry

Well my first experience was most assuredly conditional. I bought through the big internet auction site a large Binolux 7x35. It is a Hyoshi (J-B 56) and looks identical to the Swift Holiday series with the tripod adapter cast into the right side frame.

When I got the thing out of the box, it rattled like a tin can full of screws. I thought to myself...this can't be good. Thankfully my whole outlay was only about $20, including shipping. So I decided I really had nothing to loose. I had enough basic skills to get it apart and I literally poured parts onto a towel on the top of my bench. Most of the screws were completely loose inside, free from their threaded bounds. Those that were not free were very loose. One of the prisms was completely detached, the others loose. Both objective lens eccentric rings were so loose the lens moved freely. So with one side apart, I spent the time I needed to figure out where everything went. Then the other side. I wish at least one objective would have been solidly in place, but neither side was. So I then did the other half of the binocular. I cleaned the lenses and prisms to the best of my limited ability. There are some specks still in the view I strongly suspect are scars from everything rattling around in its journey from New Jersey to Oregon. The amazing thing was everything was there, no extra screws, no places without a part.

Talk about a seriously screwed up view, this was the poster child. So it was winter and chores were at a minimum and I had some spare time. Using far more of that spare time than that binocular is worth, I slowly pecked away,conditionally aligning, bit by bit, one side until it looked to be about centered. Then the other side. Then I began to get both sides together. It took several weeks, sometimes I was so frustrated at times I had to just walk away before I used a hammer on the bloody thing. But I did get it back to conditional collimation for my eyes. It also seems to be OK for my brother and my nephew who both have narrower IPD than I do, my brother being narrower than my nephew.

I have sometimes been curious how closely I got to real collimation and I ought to send it someplace and see. But I'll never do that again, and I'll never complain about competent repair costs.

Bill, I happen to use Swift's former head optics guy, Nicholas Crista. You are a lot closer, maybe you'd be interested in giving these a look.

henry link said:

peatmoss,

A simple way to understand how the lateral movement of eccentric objective rings introduces coma and vignetting is to imagine that you are sighting through two circular apertures. One is twice as large and twice as far away as the other. As long as your eye and the two apertures are perfectly aligned you will see a perfect circle where the two apertures seem to be the same size. If you move the more distant aperture laterally that will cause the two apertures to overlap in a way that the eye will see as the shape of a cat's eye or gibbous moon.

Sighting through the interior of a binocular is much the same. The distant aperture is the objective lens and there will be at least one internal aperture (say the first aperture of the prism shelf) that is sized to align with the edge of the objective light cone so that it appears from the eyepiece to be about the same size as the objective (usually, really, just a little larger). The only condition under which these apertures will align perfectly is the one where the eccentric rings are set for perfect centering of the objective in its cell. If any eccentricity has to be introduced to collimate the binocular the objective will move out of alignment with the prism aperture (introducing vignetting) and out of alignment with the eyepiece optical axis (introducing coma). In a fine telescope intended for high magnification even a little misalignment like this matters. A star at high magnification will show lopsided diffraction rings, narrow and bright on one side of the Airy disk, diffused and dim on the other. In a low magnification binocular much more coma can be tolerated before it becomes a real problem.

FWIW, If I'm really serious about checking the collimation of a binocular I use an old Bausch & Lomb "Double Collimator" like the one below (thanks to the generosity of BF member "Surveyor"). It can't be used to properly collimate a binocular, but it does allow me to measure how far off the collimation is at the collimator's fixed IPD of 65mm.

Henry

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Hi “Peat” (Will you please tell me your real name?):

Nawh! Sawing the bino was a piece of cake. I used a diamond blade optical saw. The objective was the hardest part. So much heat builds up, if you do not take it slowly you can cause the lens to fracture. The worst part of the operation was in the smell of aluminum as the saw went through.

I have checked out your links, and will try to address you and Henry at the same time.

First, the Zen-Ray ad: The words “perfect” and “collimation” do not belong in the same sentence. Admittedly, collimation can be so close to the theoretical “perfect” that any difference is totally inconsequential. Still, having collimated thousands of binos, I’m at a loss to say I have collimated any one of them “perfectly.” Far beyond anyone’s threshold of recognition? Yes. “Perfectly?” ‘Doesn’t exist.

Henry said: “why would they would go on to treat this unit as representative?”

Bill says: “they don’t know what they don’t know.”

Henry said: “As for distortion, we know that Allbinos naively treats pincushion distortion as an aberration rather than a design choice.”

Bill says: They’re BOTH. Just because you’re paranoid it does not mean they’re not out to get ‘ya. Likewise, while pincushion distortion is often a design a design choice, it still remains a first order geometric “aberration.” Yes, we could have binos with all the aberrations inconsequential. However, few people on this forum could afford such an instrument. AND, from a practical standpoint, creating such a toy would be akin to wrecking the car to turn the radio off.

Henry, you point out that moving the objective laterally can introduce aberrations. I wasn’t going there because of the nature of this forum. You are clinically correct. However, I think you will admit that there aren’t any more aberrations from an objective that has been simply moved laterally—that they come from a misalignment of the optical train, in general. And, that errors leading to the induction of aberrations are assuredly smaller than those who want to “collimate” by tilting one—or more—elements.

Finally, Henry, I am so glad you said of the B&L Double Collimator, “It can't be used to properly collimate a binocular . . .”

That was the old Navy Mk 1 that was recognized as obsolete shortly after WWI. With it, and others like it, one has to wonder, “Is the collimator collimated.”

If anyone wants to read my SPIE piece on Collimation vs. Conditional Alignment, just send your request and REAL email address to:

wjc 11 11 (at sign) hot mail dot com

I have been beaten about the head and shoulders, by one of my postdoc friends, because of my differentiating binoculars from “field glasses,” and I’m going to change that next year.

Cheers,

Bill