How to check the collimination of binoculars?

In another thread on ALCON, Shawn Grant, said:

"The venders at ALCON were great. I bought an awesome pair of 15 X 70
binoculars from Bill Burgess. He even made sure they were perfectly
collimated before I purchased them."

Although refractors are much foregiving to misalignment than
reflectors, what's an easy field test to determine if your binos are
misaligned?

- Kurt

"PrisNo6" wrote in message
om...
In another thread on ALCON, Shawn Grant, said:

"The venders at ALCON were great. I bought an awesome pair of 15 X 70
binoculars from Bill Burgess. He even made sure they were perfectly
collimated before I purchased them."

Although refractors are much foregiving to misalignment than
reflectors, what's an easy field test to determine if your binos are
misaligned?

- Kurt


Hi Kurt,

The easiest way that I've found is to, while looking through the binoculars,
cover one of the two binocular objective lenses with your hand for about
twenty seconds or so. While you are doing this both eyes are to remain
opened. Then quickly remove the hand which is covering one side of the
binocular and observe if the image is "apart" and slowly comes together as
your "brain" collimates the two misaligned views. In a perfectly collimated
binocular when you remove your hand the two images would be perfectly
aligned immediately. This may not be the easiest or the most accurate way,
but it's the standard by which I keep my binos collimated.


Martin

Although refractors are much foregiving to misalignment than
reflectors, what's an easy field test to determine if your binos are
misaligned?

- Kurt


Easy. Put the binoculars on a tripod. Find a telephone or electrical wire
strung between two posts about 100 yards away and focus on it. If the
binoculars are grossly misaligned the wire wont meet in the middle of the
FOV. This is the gross test. For the fine test, walk back, away from the
binoculars about a foot, while still looking through both eyepieces. if the
wire doesn't meet in the middle of both eyepieces, then they are mildly
misaligned and as long as they meet when your eyes are right at the
eyepieces this shouldn't be a problem.

Take Care,

JAS

PrisNo6 wrote:
In another thread on ALCON, Shawn Grant, said:

"The venders at ALCON were great. I bought an awesome pair of 15 X 70
binoculars from Bill Burgess. He even made sure they were perfectly
collimated before I purchased them."

Although refractors are much foregiving to misalignment than
reflectors, what's an easy field test to determine if your binos are
misaligned?

There's alignment of each half, which is just like aligning a refractor
telescope, and is seldom a concern; and there's alignment of the halfs
wrt each other. The latter is the usual concern with binoculars.

Try
http://www.cloudynights.com/howtos2/binoc-collimatin.htm
http://www.cloudynights.com/howto/15x70%20bear%20collimation.htm
http://www.dvaa.org/ATM/BearCol.html

The first site is for general alignment of binoculars. The latter two
sites are for specific binoculars but may also provide some insight for
your model.

what's an easy field test to determine if your binos are
misaligned?

- Kurt

It's easiest if your binoculars are mounted. To check total barrel
alignment, look at the edges of the field of view in each barrel.
Objects at least 100 to 200 yards away should appear in the same place
at the edges, up, down left and right. That's the first thing. That
checks fov, and I think it's the best way to check fov.

Now you need to check to see if the images are merged. You can try to
look at a very small brightly lit spot in the center of the fov.
Personally I do not trust the daytime test to check merged images, but
I sometimes try it. I have never found a daytime alignment for
merging images that has been exactly on when I checked it on a star.

To do a more precise test to see if images are merged there is no test
better than the star test. Let your eyes relax. Back away from the
binocs maybe 6" or a little more, maybe 12". You will eventually get
your eyes practiced enough so that you can see a separate star image
in each eyepiece. Now is the time to let your eyes relax. The images
will start to come together.

Care must be taken here and it comes with practice. As the images get
real close your eyes will try to force them together. With practice
you will find that you can bring the images to the closest approach
and they will stop. At this point you can see the severity of
mis-collimation. If you do this on a wide double star (vDra, nu Draco
is 62") of known separation, you can determine exactly how much off it
is measured in arcmin.

There are several terms of mis-collimation: Vertical (the worst),
Divergence = spread, Convergence = crosseyed. There are different
limits of error for each.

The most common error people make when they try to merge the images in
their mis-collimated binoculars is this. They merge the images but
they mis-align the field of view from one barrel to the other. If
your images are merged but you do not see the same field of view in
each barrel then your binoculars are not collimated.

I hope this helps.

I wrote one of the articles noted above. It is more in depth than
this explanation. It pertains to any common standard porro prism
binocular. You can find it at

http://www.cloudynights.com/howtos2/...collimatin.htm

edz