Help please - collimating binoculars

[erick]

Problem:- I cannot find the second pair of prism tilt screws on a pair of Andrews 20x80 Triplet binoculars. I can find the front pair near to the eyepieces, but not the "rear" set, at the other side of the prism housing. I've eased up the rubber all the way around and nothing found. Can someone point them out to me?

Background:- A friend recently acquired a secondhand pair of these binoculars. They seemed fine but I suspected the collimation could use a tweak. Additionally, at the top of the field of view in both left and right eyes, the image was out of focus - didn't worry my friend, but I was sure it could be better. I've just learnt how to collimate binoculars and have worked through my four pairs over the weekend. They were many and varied, but I got the hang of it. The 30x100s were particularly difficult - horizontally, the images were too far apart, so I had to tackle all four screws. It took a while, but I'm pleased with the result and look forward to a cloud-free night with no other commitments, to test them.

So I tackled the Triplet pair today. Vertical collimation was out and horizontally was a little in the wrong direction. However, I wanted to make a major adjustment to see what effect that had on the out of focus top of image problem. Well, I finally ended up in a situation where, if I release each "front" tilt screw, the images are horizontally way out of collimation and, as I push in each screw, it only gets worse. I can achieve vertical collimation, but horizontally, I'm stuffed! I've given up worrying about the out of focus problem - I'll have to come back to that. If I could find the other tilt screws, I think I can solve whatever has happened. I have tried sharp taps on the prism housing, but that has no effect so the prisms seem to be seated well.

Very grateful, in advance.

Yes, but the way, I have to read this in detail tomorrow since it gives lots more information that I have at present:- http://www.cloudynights.com/item.php?item_id=416


If everything fails, can anyone recommend someone in Melbourne who can collimate them and check them out for me (and show me what I've done wrong at the same time :sadeyes: ) - one of the stores?

[Dennis]

Also http://www.cloudynights.com/ubbthreads/showthreaded.php/Cat/0/Number/73181/page/0/view/collapsed/sb/5/o/all/vc/1

Good luck!

Dennis

[janoskiss]

Have you got the collimation instructions from AOE? I think they are pretty thorough and should guide you through the process. I should have a copy somewhere, PM me if you need it.

[erick]

Thanks Dennis and Steve. I have the AOE instructions, Steve. That article adds more useful information, thanks Dennis. With a bit more research, I know where to look for the other screws now - at 90deg to the first screws. Must be under a bit of the rubber that was glued down. I'll carefully look under there tomorrow. I'm not beaten yet!

Mind you, some of the reading suggests that collimation by eye is a poor substitute for the use of proper alignment tools. :sadeyes:

I also read a great tip for collimating at night, on a star - defocus one side with the diopter adjustment and then you'll have a sharp star image and a fuzzy ball. That doesn't fool the eyes and you can adjust to place the sharp image centred in the fuzzy ball. Sounds like a good approach.

[erick]

I think I'm beaten now :sadeyes: I located the other two screws, once I knew where to look. I cannot achieve simultaneous vertical and horizontal collimation. The best I can do when I centre a distant object in the middle of the left hand view is to have it half way between the centre and the left edge in the right hand view. Each screw does to that side's image what it is supposed to do. I think something else is wrong - a mis-aligned objective lens, perhaps - a prism not seated properly. The exit pupil for the left barrel never becomes a clean round circle - it stays a "cat's eye" through all adjustments of that side - that is suspicious. But nothing rattles and no problem is obvious to my eyes.

My twisted brain can snap the two images into one (in the centre) but the owner's ordered brain cannot.

I still have some poorly focused edges in both views. The centre focus drive is also showing a bad spot.

I think it's off to the Binocular Repair Shop for a good checkup.
Can anyone give a recommendation for a Melbourne repairer? Please?

[astro_nutt]

Hi Erick...give Roger from Bintel a call..
Good luck!!

[DobDobDob]

Hi Eric, firstly I can't help you with your collimation problem, but am certain that I will need to do what you end up doing at some stage in the future, so I am very interested in how you go from this point forward.

By way of a suggestion, when you finally do fully resolve your issue, it would be great if you could document it combined with suitable images, for storage here locally within IIS, as opposed to going out of house to Cloudy Nights etc.

Also, I hope I don't dilute this thread, but have you ever actually cleaned your lens, and if so, how did you do it (exactly) and what did you use. I am yet to clean them, and I am only speaking of cleaning them from possible dust or just grime that would come after time. I am totally scared to touch the glass with anything, but I also realise that sooner or later I am going to have to clean them, any advice?

[erick]

I'm not sure you really want to know! Early on, when I found dew on my (cheap) 20x80s objective lenses one evening, I pulled out my hankie and wiped it off! I looked next day and, yes, I'd added a couple of fine scratches to the coating!

I've been much more cautious with my 12x60s and 30x100s.

My approach now is:-

1) dew guards
2 ) I've bought a 12V hairdryer and a 12V battery - they test out OK in the garage, so I'm looking forward to a field test soon.
3) I carry a photographic "puffer" to first blow off dust etc.
4) If I've picked up smears, front or rear, and I notice that eyepieces being so close to eyes and face, seem to attract something that smears, then I breath on the lens and gently wipe with the cloth that was supplied (after I've "puffed" the dust away.
5) But, usually, just ignore minor stuff.

[DobDobDob]

Ok, I am cool with all you said, I bought a puffer for that exact reason, however, I did hear somewhere that you could use a cotton swab or bud, with a solution and gently wash the lens. I am not sure what the solution was, maybe alcohol or fingernail polish remover, I just can't remember what I heard or where I heard it.

[erick]

You are thinking of Scott Mitchell's article?

http://www.iceinspace.com.au/index.php?id=63,344,0,0,1,0

I think I'm more "Oscar" than "Felix" with my cheaper binoculars. But, I suspect I'll be paranoid when I finally have a multi-hundred dollar mirror to worry about

[okiscopey]

Screeds of stuff on the Net about this ... it's isopropyl alcohol (used by many, shunned by a few). Never use ethanol, you drink that. And certanly not nail polish remover, that's ?amyl acetate? which will probably do awful things to your optics.

I think the procedure is: get every speck of dirt/dust off with the blower or a non-greasy camel-hair brush, inspect under a bright, 'harsh' light, and if clear of dust, breathe on the lens (produces distilled water!) and wipe with a micro-fibre cloth (from opticians / camera store?).

If smears remain, use the isopropyl alcohol as a last resort (or expensive proprietary lens cleaning solution which probably contain in addition small amounts of ammonia and a special detergent). Add it sparingly to the cloth, not to the lens.

If a final inspection reveals newly-made scratches, that's the time to look out any ethanol in the house and drink the lot.

[astro_nutt]

Cleaning bino lens would be the same as cleaning eyepieces..If it's only dust then blow off as much as you can..any dust remaining shouldn't affect the image...for a smear..dust off then use a tip of a rolled up tissue dipped in isopropyl alcohol and with the weight of the tissue only move the tip side-to-side across the lens..it also helps to wipe your eyelashes with a clean tissue to soak up any eyelash oil before viewing.
Cheers!

[erick]

Thanks astro_nutt, I'm off to see Roger today with binoculars in hand! :)


ps. Happy Birthday, mate!:party:

[DobDobDob]

Thanks Erick, Mike & Astro_nutt, I appreciate all your info, plus I read the article by Scott Mitchell. I'm sure that when the time comes I will be ready to clean my beloved binos :scared:

[erick]

Update - Roger has them - next week I'll know. :prey:

[DobDobDob]

Fingers and eyes crossed for ya :rolleyes:

[astro_nutt]

Thanks erick..hope it's all good for you.
Cheers!