Bino collimation

[matt]

Hi guys.

Bit of a newb bino question.

How can you tell if your knockies are out of collimation?

I recently received some new Pentax 10x50PCFWPII binos from OPT in the US.

While I'm happy enough with them so far, I do notice that even when I focus stars in the centre of the fov there still appears to be those little telltale spikes or comet tails that won't go away.

I've only ever owned a telescope so this is all a bit new to me

Is this actually normal?

Is there a test one can do (star test??) to check collimation?

Can this particular bino be collimated or is it factory set and therefore needs to be returned if the optics have been bumped out of collimation?

Many thanks

[[1ponders] (Paul)]

While I am not an expert by a very long shot Matt, I thought that if the binos were out of collimation you would get double images. Or is that orthagonality?

Help me too please.

[matt]

Thanks Paul.

Yeah. That's what I was thinking re: collimation and double images.

Maybe the spikes (comet tails) are just what you have to put up with in a $300 bino???

You get what you pay for, after all.

[skies2clear]

Hi Matt,
I'm no expert on bino collimation, but it seems to me you may have some collimation issues. Going by binos I've owned (Nikon 7X50, Andrews 20X90, etc) and others I've looked through, you should get a pretty good focus with stars in the centre of field of view. Only cheapo binos usually don't focus properly in the centre. Using only one eye at a time, check each side of the binos separately to see if they focus stars at the centre correctly. You may find only one side is out, or possibly both sides. You treat collimation 2 ways: You have 2 separate optical systems (or small telescopes) that must be collimated properly individually, and then, the 2 sides must be aligned together as well so that the views merge comfortably and you don't get double images or eye strain.

I would think any reasonable bino (Pentax included) should be able to be collimated, but this is best left to an expert, for the reasons stated above.
Probably best to check them out further and if you can get someone else to give you a second opinion after having a look through. Then if you are sure there is a problem, contact the supplier and see what they say first off.

I really hope you get satisfaction with your new binos.

Cheers

[Starkler (Geoff)]

Originally Posted by matt

While I'm happy enough with them so far, I do notice that even when I focus stars in the centre of the fov there still appears to be those little telltale spikes or comet tails that won't go away.

Matt do you get this also with long focal length eyepieces in your scope?
I do and its a symptom of a large exit pupil and astigmatic eyes. I get little flares/spikes on star images noticeable with exit pupil sizes > 2mm.

If your scope is an sct, you likely never see an exit pupil big enough to notice it.

[matt]

Hi Geoff

I only recently went for a routine eye check with an optician and was told I don't have astigmatism

I do, however, need glasses for distance vision. If I look up at the sky (just naked eye) I see 2 or 3 moons when I look at the moon.

But my short distance vision is very good. I don't need glasses for reading etc

Everything looks pretty good through a 24mm Pan in my 9.25 (f10) although even then I can see little tails if I'm not on-axis.

I generally tend to use the 10mm Pentax XW, 13mm Nagler T6 and 24mm Pan with my SCT

[casstony]

wrt astigmatism, I have mild astigmatism (0.25) but can easily see the distortion this produces when looking naked eye at a bright star. Lines radiating out from the star are non-uniform in the pattern of my astigmatism and this is different for each eye. So if you see a circular, uniform looking pattern around a star your astigmatism is probably negligible.

[Sausageman (Mike Boggan)]

I took my 10 by 50 bino's to Lostock and couldn't resolve a single image, I tried many times to re-set the focus correctly for each eye, but no luck.
Maybe it was the temperature of the day that caused the problem, it was extremely hot at Lostock.

Mike.

[circumpolar (Matt)]

Originally Posted by Sausageman

I tried many times to re-set the focus correctly for each eye, but no luck.
Mike.

Like Mike said, You must set the Dioptre adjustment correctly. This will compensate for differences in each eye. If the Dioptre is on the right side, close that eye and focus the image to your left eye first. Then adjust the dioptre to suit your right eye last. Done.

[Dennis]

Hi Matt

Ask a few friends/neighbours to look through (don't mention the specific defect) and ask if they can focus them easily and positively.

Are they rubber coated, or can you see 3 tiny adjustment grub screws on the body of the lens assembly?

Cheers

Dennis

[matt]

Originally Posted by circumpolar

Like Mike said, You must set the Dioptre adjustment correctly. This will compensate for differences in each eye. If the Dioptre is on the right side, close that eye and focus the image to your left eye first. Then adjust the dioptre to suit your right eye last. Done.

No worries on the diopter. I've got that set perfectly for my eyes. That's not the issue.

Originally Posted by Dennis

Hi Matt

Ask a few friends/neighbours to look through (don't mention the specific defect) and ask if they can focus them easily and positively.

Are they rubber coated, or can you see 3 tiny adjustment grub screws on the body of the lens assembly?

Cheers

Dennis

My partner can see the same thing.

Yes. They are rubber coated. Can't see any grub screws. They're Pentax 10x50 PCF WPIIs

[Dennis]

Hmm, doesn't look too promising if at least 2 of you report the same defect?

I would imagine that mis-collimation would produce double images and probably give you eyestrain when looking through the bino’s as the eyes struggle to integrate the images?

Spikes, to my way of thinking, would possibly indicate less than perfect lenses / prisms / eyepieces, but I really am just guessing here.

I once had a bino that was basically ruined by a prolific growth of fungus so there was nothing to lose by me taking them apart. I unscrewed the objective and discovered the fungus was in the prism assembly. I peeled back the rubber over the assembly and located 3 tiny grub screws. I backed off 1 of these and the prism assembly just slid out quite easily to reveal horrific damage by fungus, so I never put them back together again.

York Optical in Brisbane used to repair bino’s but I suspect that sending them off to an optical house would be an expensive path that you wouldn’t want to travel?

Cheers

Dennis

[Sausageman (Mike Boggan)]

Dennis,
My Bino's have worked fine until Lostock, I am sure it is a heat related thing.
Maybe it was a combination of thermal expansion and dioptric adjustment, They work fine again now. But the clouds stuff everything up, it is the wet season in Qld.

Mike.