Sears 10x50 porro prism binoculars (1 Viewer)

Bruce,

Steve posted something about this in another thread recently but I forget which at the moment. Basically you place the binoculars on a steady rest. Look through both barrels from a few inches away and decide which barrel looks to have a specific object centered in the field of view. Once you determine this then you can start tinkering with the other side. Make note of where the collimation ring slot is when you start and then just start moving it in small increments...clockwise or counter clockwise. Keep track of exactly how far you are moving it from the original starting point.

Eventually you will get it collimated.

Bruce,
You really can’t determine which side is off by eye. True collimation requires that each optical barrel be aligned with the center axle as well as each other. You can’t do that without a collimator. The best you can do is to align the right and left barrels to each other for your IPD only. Collimation will wander off for any other IPD setting, so be sure to have the binocular correctly set for yours when you do this.

Steve and Frank’s advice to go slowly and make marks for returning to original settings is good. Just start with one side, move it a little in one direction and check whether that helps or hurts, then go from there.

The photo below shows a typical arrangement of eccentric rings. You see there are two, a silver outer ring and a dark inner ring. Two are needed in order to give the objective lens a full range of eccentricity in every direction. You might get lucky and find a reasonable alignment from just a little tweak of one side or you might spend a couple of hours moving both sides back and forth and never quite getting it right. Have fun. ;-)

Henry

Henry is right about the collimation. However you can get close. I would do a couple of simple things first. You said somewhere you were amazed how easy the rings moved. This make me wonder if maybe time has simply loosened things up a bit. That was the case with the very first "collimation" job I did. The retaining ring had loosened up and had let a collimation ring slip a little. When I tightened up the retaining ring, there was a slight shift in the position of the eccentric ring, which evidently was all it took for that one. Beginner's luck for sure.

Another thing with the German/Zeiss style body of your binocular is that the objective barrels will unscrew from the rest of the binocular. Here also, the problem may be that one or both of the barrels has loosened up over time and shifted a bit. I'd try torquing/releasing the barrels one at a time and see what happens.

What I do is look for alignment two ways. First on a power line for vertical displacement (dipvergence). I also use a lone tree on a high ridge line a couple of miles away to check horizontal displacement (convergence, divegence). While not perfect, the use of a steady, repeatable rest will tell a lot about which way to move things. Also the ridge line will show dipvergunce at greater distance too.

Remember that one of the seemingly simplest things can also be one of the most frustrating and potentially damaging things to do. That is the simple fact of unscrewing things and then having to screw them back together. Be careful, deliberate, and patient or you can really screw things up.

You may have to tweak things several times. Without a true collimator, you can get to the point where you think you have it right, tighten things up, take a break. Next time you look, you think...that's maybe better than it was, but still not quite right.

I set the glasses up on a tripod this afternoon and made minor adjustments. I'm pretty close now. It will be very clear here in the mountains tonight. I'll aim them at a bright star and see how things look.

This has been excellent help. I've been living with this problem for quite a while. Actually I've just been using other binoculars. I was reorganizing a closet yesterday and came across these. It's the first time I've thought about getting them fixed since the internet came along (which shows you how long they've been in the closet). One Google search turned up this site, and I figured I'd find somebody with expertise here.

Thanks a lot. I'll let you know how they look after tonight.