Checking Collimation (2 Viewers)

[james holdsworth]

i’d like to get an opinion on collimation testing, and whether or not the down and dirty method of looking at straight lines with barrel separation is reliable. I have a binocular that seems clearly out to me, my eyes swoon as I pull them back, and when I look at a horizontal line and pull the binocular away, the right barrel is clearly well below the left, in terms of where the lines are positioned.

otherwise, I need to do some of the other methods mentioned here, which are obviously considerably more complicated, and often well above my pay grade. Thanks in advance.

 

[Rg548]

Ok... I can tell instantly if it's out just by looking through them. Without wishing to sound arrogant, I am yet to be proved wrong.
I was trying out some Vortex UHD's at Focus Optics, and told them they were a tad out. They disagreed, but after taking them out the back for a few minutes, I guess to check them on some machine, they indeed agreed they were just out.
The same at Ace Optics, when I bought my FL's, they also were slightly out.
Gary at East Coast sorted them superbly, but did add that he was amazed I had noticed.
These are just two occasions.
Oh... My Swaro CL's were very slightly out.... sorted by Swarovski no problems.
My Zeiss Conquests and also my Niko SE's were spot on from the off.
So if you look through them and cannot get total relaxation with your eyes after dioptre adj.... then they are out.
Your eyes are telling you plain and clear.

 

[albie...]

One way of checking collimaton that I learned from Cloudy Nights and you might already know this is to focus on a star at night . Once it's focused as well as can be totally unfocus the one side using the diopter setting. The focused star should be inside the unfocused star's circle(blob) . As long as it's inside the circle the collimation is fine although the closer to the center the better .

 

[james holdsworth]

Can anyone answer the question asked? But, both, thanks for the input.

 

[takitam]

I think you got two great answers here, with actually the best methods for checking collimation at home.

In my opinion, judging collimation the way you mentioned is a bit problematic. It was the first method that I have learned, but it has several issues:

• our hands shake more with binoculars away from the eyes
• I think I tend to change the orientation of the bins as I move them away from my eyes, making them more horizontal
• a lot of people, including me, have one eye slightly below the other
• while looking through a binocular we can get away with slightly imperfect IPD adjustment when that binocular has large exit pupils. Moving it away from the eyes amplifies even minor mistakes and both eyes can see a slightly different picture

There's probably more but that's all that comes to my mind right now. I know that a long time ago, when I was obsessed with checking collimation this way, even a perfectly comfortable pair could seem off. I think in these cases, it's a flaw of the method, not a binocular. Unless you do it on a tripod, which I have never tried.

IMHO, the two methods described above are a much better way of determining collimation.

edit. My mistake, I misunderstood the method you described. I somehow understood that you meant one where you look at a distant object and slowly move the bins away from you, while still looking at the same thing.

 

[Binastro]

We are here only discussing alignment at one IPD setting.

Even if the alignment is good it does not mean the binocular is collimated for other IPD settings.

If there is discomfort when using a binocular either the alignment is off or the person's eyes have problems or both.

Regards,
B.

 

[james holdsworth]

I’ve got many pairs of bins but this is the only one that shows a big offset between barrels. Changing IPD or rotating the binocular while viewing doesn’t change the disorientation of the two images, and hand shake is not a factor.

Still, looks like I need to try the star method, even though I’m a bit cloudy on the technique, despite explanations.

These need to be sent back a second time, because the initial inspection claimed alignment was satisfactory.

 

[Maljunulo]

1. Focus on a star
2. Slowly move the binocular away from your eyes while continuing to look at the star.

If you see two stars (one from each barrel) the glass is misaligned. The two images should be coincident, assuming that the axes of your eyes are parallel when focused at infinity.

 

[james holdsworth]

Ok, so a star test reveals the focused star image remains within the unfocused blob, but near the edge. Angling the binoculars even slightly tended to move the orientation closer to the blob centre.

 

[Maljunulo]

Ok, so a star test reveals the focused star image remains within the unfocused blob, but near the edge. Angling the binoculars even slightly tended to move the orientation closer to the blob centre.

I think we’re talking about two different tests.

 

[james holdsworth]

I think we’re talking about two different tests.

See post 3

 

[Maljunulo]

That's not that same as what I said.

 

[Rg548]

Can anyone answer the question asked? But, both, thanks for the input.

My answer is.... you don't need anything compicated to tell if they are out.
If you are an experienced bino user, and your eyes are 'twisting/ pulling' ...... and this doesnt happen on your other, or previous optics....
Then they are out.

 

[Hermann]

James:

You are a very experienced user. If a binocular looks out of collimation to you, it's out of collimation. Send it back for alignment.

Hermann

 

[Brink]

Rafael Ramon Chabos has shared a few easy methods to objectively quantify misalignment of binoculars (and an algorithm to collimate them at home).

HOMEPAGE

Collimation of Binoculars using a Lamp, a Mirror and a Screen (recommended)

sites.google.com

 

[james holdsworth]

James:

You are a very experienced user. If a binocular looks out of collimation to you, it's out of collimation. Send it back for alignment.

Hermann

If I’m sending them back a second time, I really need to quantify the collimation error somehow, hence my initial question. I get clear misalignment when viewing a horizontal line and pulling the binocular back from my eyes, but also get a “in collimation“ indication with the star test.

What happened first time, I would assume, is they tested for collimation and found it within spec.

 

[Paultricounty]

James, I agree with Binastro here. Depending on how the binoculars were collimated will determine how much IPD range there will be where the optic is still aligned. If someone collimated their binoculars by eyeballing, then chances are it will be only collimated for a small range of IPD. I believe one would need to be collimated using a three axis collimator so the binoculars will be in alignment with larger IPD range. If I’m explaining that correctly.

The method of looking at a fence line or some other level horizontal object, roof line of a house or top of a billboard sign at a distance has been very effective for me. Because there is deviation with a person eye level this is best done on a tripod, because you can tweak the angle for the difference in your level, if they’re out of alignment then even if you move the bins to compensate , you’ll still see they’re out.

Paul

 

[dorubird]

I really need to quantify the collimation error somehow

I saw in my SF some out of collimation vertically, so I tried to qantify this collimation error as follows:
I put the binoculars on a tripod without moving it during the test. Look alternately with only one eye in each tube in turn and put a distant object in my right eyepiece so that it touches the edge of the FOV at "12 o'clock". Thus, in the other eyepiece, the object did not touch the edge of the FOV due to the difference in alignment between the tubes. I took a picture through the left eyepiece and calculated the deviation percentage with the object lowered towards the center and wrote the result to Zeiss. After service they confirmed the diviation! With your binoculars, being deviated only horizontally, the object will not descend towards the center but will be to the left or to the right of "12 o'clock"

 

[hopster]

Can anyone answer the question asked? But, both, thanks for the input.

albie...s method above using stars is the one I use and seem fairly reliable and foolproof unless somebody knows a reason why not.

 

[Maljunulo]

If I’m sending them back a second time, I really need to quantify the collimation error somehow, hence my initial question. I get clear misalignment when viewing a horizontal line and pulling the binocular back from my eyes, but also get a “in collimation“ indication with the star test.

What happened first time, I would assume, is they tested for collimation and found it within spec.

If this only happens with the glass in question, when compared with others, that is a pretty strong indication that it is out.