Simple aid for some alignment checking

[Flying Eye]

Hi all,

Being a newb to all this I'm looking around to see what kind of things you need to know and check for.

I spotted a site where a guy has a few videos describing collimation and conditional alignment. During watching them it became clear to me that one important aspect is correctly detecting the image coming each individual optical tube in the pair. In explaining all this the guy used some graphics and showed each tube image in a different colour so he could explain it more clearly.

I pondered for a few seconds , and it hit me, for me as a newb one way to make things easier might be to try colour filters on each tube to make things a little more obvious to my inexperienced eyes. Sure enough, I grabbed a pair of 3d red and blue anaglyph spectacle clip ons that were laying around, popped them over the ends of the bins, and looked at a street light some distance away (in normal daylight) and bingo I found some sort of dipvergence going on in my bins. I felt something subtle was possibly not quite right with them after finally getting them steady by mounting them on a tripod, but was not too sure what it could be, now I'm able to be pretty certain.

I've no idea how I shall do anything about it, or even if there is anything to be done, but at least I now have an easy way to help me highlight OTA pairing differences in binoculars.

I've not seen this mentioned anywhere, so thought I'd pass on something which to this Optical Idiot is a handy tip!

Why this is helpful is that it appears to stop (or greatly slow down) the brain from allowing for and even fixing errors in the instrument.

YMMV & HTH

[Mr Q]

If you want to try collimating the bins, go to the astronomy forums at the link below and click on the "EdZ" link. He's very knowledgeable in bin use and repair.Telescope Reviews: LINKS to Web - Binocular and Astro Info

[Flying Eye]

Thanks for those, always good to have more links for even more explanations for this procedure.

In this particular case there is probably not much to be done as my present bins are cheap pocket compact jobs with 2 hinges, and no access as far as I can discover. And to make it even harder they are roof prisms at a guess. They certainly have not been abused at all since I have been looking after them, so probably a factory or merchandise channel failure.

For later though it will be good to know I have options.

I'm just glad I found a way to make the problem so much easier to spot by having the colour differences to highlight it. For a newb I don't think it is possible to make it too easy to spot these things. I can now just see it without the filters but having them made it simple to spot even for the dummy which yours truly happens to be!

[Mr Q]

I'm not familiar with the bins you have but the question of "should I try to correct the problem?" or "Is it worth the trouble?" may depend on your brain trying to compensate for the problem. If so, and the alignment is off enough, you may experience eye strain or headaches after a short period of time. If this happens, you have the choice of trying to fix them or get another higher quality pair.

Some bins with folding options or zoom focusing usually scrimp on other aspects of the bin's more important design features. This may explain why your bins have this problem.

[BinocularSky]

one way to make things easier might be to try colour filters on each tube to make things a little more obvious to my inexperienced eyes. Sure enough, I grabbed a pair of 3d red and blue anaglyph spectacle clip ons that were laying around, popped them over the ends of the bins, and looked at a street light some distance away (in normal daylight) and bingo I found some sort of dipvergence going on in my bins.

What you have discovered is that detecting miscollimation is easier if you can fool your visual system (which is essentially your brain) that the eyes are seeing different things -- it then tried less hard to merge the images. It's usually done either by defocussing one side (on a star) or with different coloured "Quality Street" cellophane wrappers, but 3-D specs is a good idea (consider it nicked! ). If you use crossed Bahtinovs (see the thread instigated by "Pleiades"), you not only get the fooling of the visual system, but critical focusing as well.

Another way I've found to detect it is to observe bright objects through the twigs of tree in winter. I'm not entirely certain of the physiology of why it works, but it does.

However, although these things can detect miscollimation, as long as it is within the accepted tolerances, it is nothing to be concerned about. If it exceeds the tolerances, this is when it causes headaches and/or nausea.

[Flying Eye]

(consider it nicked! )

It's high praise indeed, and I'll happily settle for that, Doctor!

I'm just left feeling a bit miffed that my brain is "reliable" enough to have allowed me to be fooled like that. From useful sharpish implement to at best a modest chisel in one fell swoop - a rather sobering experience that one!