UCF 8-16x21 Binocular collimation - Help on collimating binoculars

Gary S

Link Posted 16/01/2003 - 17:35
Hi Group

I'm a new user to the group and have already found a lot of information, very heldpul information too.

However, I have a pair of UCF 8-16x21 binoculars that haven't been right since the day I bought them. Being naive I thought that I could sort them out or I wasn't using them properly. Basically, at 8x they are fine, at about 10x upwards, I get two images that won't resolve into one. I'm assuming the collimation is off. Is there any adjustments I can make to collimate the 16x image? If not, have I got a dud pair of bimoculars?



John Connolly

Link Posted 17/01/2003 - 09:32
Hi Gary

I'm a first poster too though I've been in the group for a few months just watching.

First of all the idea of a pair of 16x21 binoculars is a bit ridiculous anyway. The amount of light you get through the binocular is dependant to a great extent on the ratio of the magnification to the objective lens size ie 8x40 = 1:5, most people look for a ration of 1:4 or 5 (8x30, 8x40, 10x40 etc).
16x21 only gives a ratio of approx. 1:1.25 so your not going to get a good image at this magnification and you'd also have difficulty holding the binoculars still enough to get a good view at 16x anyway.

It sounds as if the binoculars have a problem if you're ok at 8x but double imaged above that. You could try supporting the binoculars at 16x magnification and see if you can balance the image by adjusting the eyepieces individually to see if it's possible to get a single image at that magnification.

The other thing that's worth trying, especially with these small binoculars, is moving the two halves of the body in and out relative to each other to try to get them lined up with the width of your eyes. Some people find small binoculars impossible to use because they can't line up the eyepieces at a comfortable width for their eyes.

Personally I'd get a new pair with a fixed magnification and if you want a small model keep to the 7 or 8x magnification or get a bigger pair of 8x40 or 10x50 (these are quite big however) and pay as much as you can afford for a decent pair. I've never regretted paying more than I intended for optical equipment but have sometimes regretted pennypinching. Second hand ones can be a good buy if you get a good make.

Hope this helps


Gary S

Link Posted 17/01/2003 - 15:59

It hasn't helped really, you've knocked the binoculars and haven't told me how to fix them

Using them on a mount, I still can't get them to resolve at 16x. I bought these for general use and moonwatching, it's fine for that... At least it would be if they worked!


John Connolly

Link Posted 18/01/2003 - 23:45

I'm sorry if you thought I was just knocking your binoculars, I was just trying to give you the facts of the matter.

If you've tried adjusting them on a mount and can't get a good image they probably are faulty. I don't believe there's any repair you could do yourself so if they are still under guarantee take them back to the shop and exchange them or get a refund. If they're outside the guarantee you're at the mercy of the shop- they may or may not do anything for you.

If you can get an exchange I'd try to get a pair with fixed magnification.

Best of luck


Pete Bargh

Link Posted 22/01/2003 - 14:50
Hi Gary
That sounds like you may have to get them to a binocular repairer. Pentax UK will do them and if you are a member of the club you get a 20% discount. I can't think how you could do the repair yourself.
Magezine Publishing Ltd


Link Posted 08/09/2015 - 11:15
I ran into the double-image problem many years ago with a well-used pair of Bushnell 8x30s. Took them apart and somehow made microadjustments to the prisms (can't remember the exact process, but I suspect there must have been a few adjustment screws, although the prisms were also held in place by blobs of adhesive). They now work properly but, to be honest, this is probably more due to luck and lots of trial and error). I wouldn't attempt it again. Zoom binoculars are obviously more complex and would take a fair degree of skill to adjust. A proper repair shop is really the answer, or an exchange if the warranty allows this. I'd always go for fixed-magnification binocs, but we all have different needs.
Last Edited by Aero on 08/09/2015 - 11:16
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