My bins are out of collimation?

[pipnina]

I decided to look at venus through my 10x50s the other night (Not much to see, I know, but it was more because I wanted to focus the bins right eye to the left) and noticed something dreadful!

I fear my bins are out of collimation! Based off what I saw and this web page's image near the bottom, It doesn't look promising... http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

I thought of this page because I (inadvertantly) performed a star test on venus and noticed that when the left eye (the fixed one) approaches focus, it forms three or more spikes that never converge into a point of light (as it should appear)

I understand that Newts aren't the only optics that need alignment (I'd heard of adjusting refractors etc as well) but I have no idea whether it's the objective lenses or the EPs that are out. I have noticed that the EPs are quite loose and wobbly. Perhaps they are the problem?

These bins are quite old (my great grandads, he got them in the 60s or so my dad tells me) and I'd hate for them to keep turning stars into celestial bear paws..

There is a fair bit of dust behind the objective lenses. Not sure if that will have an affect or not. (Maybe some fungus, too, but that's to be expected)

Help greatly appreciated!

    ~pip

[ghostdance]

Venus is quite a test being so bright, and then there are atmospherics to consider. What do stars look like with your bins?

[pipnina]

Venus is quite a test being so bright, and then there are atmospherics to consider. What do stars look like with your bins?

Hmmm. Once it is darker I will find out. (hope the clouds looming don't invade, the forecast was bad but it is clear at the moment.)

The sun is in the process of setting so perhaps an hour from now I can check. Perhaps I'll attempt a sketch if it doesn't look right. (WARNING: My drawing sucks!)

The pattern did seem quite distinct... Oh well, we'll find out soon.

[ghostdance]

Sounds also from your post that the 'bridge' (don't know the exact term for this) is pretty loose. I don't think that would help

If it's any consolation, Venus looks somewhat spiky with most of my bins. But not, as with poor collimation, a double image.

Stars tho, should be nice single pinpoints though bright ones (Arcturus,Vega) may show the effects of poor seeing. Good luck later

[Peter Drew]

I think you will find that irregular focused star images in small binoculars are a consequence of the optical  cementing of the two lenses that form the objectives. This is an effect that varies considerably even on examples of the same model. You can be very lucky and get a pair that has decent star images on each side, most often one side is better than the other. Buying expensive binoculars tends to improve the situation but is no guarantee. Small binoculars are designed for terrestrial use in the main which is far less demanding than astronomical use. 

[pipnina]

I found some bright pinpoint lights to focus (and defocus) on. The clouds are here now so testing it on actual stars will prove challenging to say the least.

It seems like the pattern is still there. But not as noticable as it was on venus. It sounds likely that what Peter Drew says is true.

Unfortunately tightening the 'bridge' did nothing to make the EPs stop wobbling, but it did make the bins harder to move outward

I'll be able to live with it if I can't fix it. Not like I can afford a new pair anyhow   I just thought "Hang on, this looks like that bad sign I read about" and didn't quite know what to do about it.

[pipnina]

Turns out the issue was more because of my eyes than anything else.

Because I have glasses (astigmatism, ughhh ) the EPs were quite far away from my eyes, this meant I couldn't quite tell if my eyes were centre to the EPs and because the eye relief on these bins is quite tight, I only see 40% of the total FOV.

I didn't realise at the time, but it turns out that I was looking at venus perfectly centred at the top of the bins FOV. Clever me!

Every time I use optics or my glasses dig into my nose, I feel like I want LASIK so bad, but the wikipedia article's video of the operation being done and the long list of side effects that may or may not arise from the surgery makes me really NOT want it.

    See you the next time I do a silly!

        ~pipnina