In terms of arc-seconds, how would a full collimation (done and tested well)
and a conditional collimation (done and tested well) differ?
But wait....
This says conditional collimation can be perfect for one interpupillary distance (IPD),
but it will not hold for a different person if it isn't done along the axis of the hinge:
http://spie.org/Publications/Proceedings/Paper/10.1117/12.931108
That seems to be the gist of it.
So, a more informed question would be:
----If I collimate for my eyes at an IPD of 63mm, how far off could they be
(if the collimation moved both axes off the hinge) at an IPD of 55mm or 75mm ?
Assuming the axes were properly set up before a 'bumping' incident, it seems
that trying to fix that with something like eccentric objectives alone would
be the worst possible approach (since that directly disturbs the axes), but
aligning the prisms to find the original axes would fare much better.
O_N:
You said: “In terms of arc-seconds, how would a full collimation (done and tested well)
and a conditional collimation (done and tested well) differ?”
First, the term is “conditional alignment.” I deliberately didn’t use “collimation” because some people work ever so hard at being confused and I wanted to remove the temptation to confuse the terms. It’s technically accurate, I just chose not to go there.
In terms of arc-seconds … there is no way to know. That is dependent on if ONE or BOTH prisms are out of alignment, by how much, and in which direction(s).
You also said: “But wait....
This says conditional collimation can be perfect for one interpupillary distance (IPD),
but it will not hold for a different person if it isn't done along the axis of the hinge:
http://spie.org/Publications/Proceed...1117/12.931108”
Wrong! The words “collimation” and “perfect” only go into sentences proffered by the inexperienced. You will note the “perfect” I used was surrounded by quotation marks. An alignment may be perfect for practical purposes, but nothing in optics is “perfect.”
You go on:
“That seems to be the gist of it.
So, a more informed question would be:
----If I collimate for my eyes at an IPD of 63mm, how far off could they be
(if the collimation moved both axes off the hinge) at an IPD of 55mm or 75mm ?
Assuming the axes were properly set up before a 'bumping' incident, it seems
that trying to fix that with something like eccentric objectives alone would
be the worst possible approach (since that directly disturbs the axes), but
aligning the prisms to find the original axes would fare much better.”
Nope! O_N, when I first went “head-to-head” with you, it was because you had a propensity for jumping to conclusions that didn’t exist, and often made pronouncements better left unstated. For example, wouldn’t your:
“… but aligning the prisms to find the original axes would fare much better”
have been stated better as:
“… but WOULDN’T aligning the prisms to find the original axes fare much better?” :t:
In the first statement, you seem to be taking on a concrete position of authority that you really haven’t the experience to take on. Was I offended? NOT IN THE LEAST! Being a little too human, I just get frustrated when I see the tail trying to wag the dog.
Your assessment of the situation is pretty good from the standpoint of a kitchen table technician. I’m not a kitchen table technician.
In the Navy, I was NEVER tasked to repair one small problem of the binocular. When a binocular came to the shop, it was to be COMPLETELY—as in every screw—cleaned, painted, lubed, and, finally, collimated. The prisms were exactly where the needed to be before an eccentric ring was touched! The tilt prism method became popular as a repair shortcut allowing the technician’s firm to pocket more profit. If the prisms are where they should be, the eccentric-ring convention is superior in rigidity, and in moving the LOS laterally.
Attached, you will find a subset of the article which was created well before the article.
I hope it helps.
Bill
