I own a pair of old Zenith Tempest 10x50 binoculars (Japanese, probably 1970s vintage with porro prisms). They were my grandfather's.
On the weekend I dropped them and now they are knocked out of collimation (doubled stars).
They do not appear to have any collimation screws. In fact, after finding articles on servicing old binoculars I now know how to completely take them apart and clean them, but I haven't found any good information on how to collimate this type of binoculars.
Once I have figured out how to collimate them, I'm likely to use the sun projection method to guide the actual collimation process.
Yes, older binos can be difficult to collimate, sometime impossible by most untrained people.
If the binos need to be disassembled to collimate, it is a time consuming job.
But, some older binos, and most newer porro prism types, have one or two pairs of adjustment screws on the prism body. Sometimes you need to peel back the plastic or rubber grip that covers the body. The following info is for this type of binos. The other type that requires the binos to be disassembled, it is very involved. I can't remember where I saw an article on adjusting these. Maybe someone else has a link they can share.
If your binos are this 'external screw' type, these are very easy to collimate. You do it on a clear night when you have bright stars to easily find as you will be frequently going from a brightly lit room to under the stars to check on your progress.
Most rubber grips over binos are just lightly glued on along the rim/edge of the grip. This next part can be dangerous - you need to know how to handle a knife to do this safely, or you stand a real chance you will slice yourself open! A very sharp Stanley knife is essential here to not damage the grip and the binos. Start along the top of the body, and slowly cut away the grip, lifting it slowly a bit at a time to see where the glue is. You don't need to peel away the whole thing, just enough to access the screws. There might be just the one pair (one on each body like on my set pictured below), or two pairs, sometime even three.
Mark one side of the screw head and the body with a little line to indicate the starting point of your adjustments. You need this reference mark to keep track of which way you are turning the screws. These little screws might be the slotted head type, Phillips head or Allen key type. They will also be semi-glued in place with something like Loktyte just to hold them in place. A sharp, firm twist of the screwdriver will release them.
Before you begin adjusting, go outside and check the image to see how divergent the images are. Now back inside, and working with only 1/8th turns, turn one screw clockwise and the other counterclockwise. Go back outside and check your progress. If the images are closer to a single one, keep going this way. If the images are wider apart, turn each screw the other way. Easy.
Always take your time with this. Don't try to go more than 1/8th turns - you will get a lot of shift in the image this way and it is easier to control.
When finished, unless you have the appropriate bog to semi-fix the screws in place, leave them be. Yeah they are more likely to shift, but now it is easier for you to readjust them.
The rubber grip, using something like a silicone, and using very little, replace the grip, putting the glue where it was originally. Just enough is better than too much incase you need to make an adjustment later on.
In the picture below, you will see where I had made my reference mark on the bino body, and where the screwhead is now after the adjustment was made.
Mokusatsu you're binos most likely will not have the rubber armour covering them nor the collimation screws as linked in most posts
the arrangement will be in 1 of 2 ways
#concentric rings moved with an optical spanner wrench at the objective end [very difficult to collimate]
# prism tilt screws revealed once removing the eyepieces & back plate
the latter is more likely, before you begin what you need do is try & ascertain which barrel is causing the problem. to do this hold the bino steady & swing the R barrel thru the ipd range as you check the image..see if it is moving
secondly tip the bino upside down & repeat the process, use a distant reference point to see which barrel is off when you move the bino thru the ipd range...you do not want to be adjusting the alignment of the barrel which is still aligned with the central hinge of the binocuar
I've taken the covers off already, front and back, and have directly visualised all the different prisms. None appear to have any collimation screws. I've read enough articles on collimating binoculars that have external screws to know what I'm supposed to be looking for and I'm reasonably certain that there are no adjustment screws.
The good news is that by taking it apart and putting it together again, the collimation error seems largely to have been fixed! Also, having figured out how old binoculars can be taken apart and put back together, I've finally fixed my other grandfather's 7x50s which have had a loose prism rattling around in them. If pop hadn't died a decade ago I'm sure he'd be happy to finally have his binoculars back!
I'm not completely satisfied though that collimation in my 10x50s is perfect and will proceed to check it with the solar projection method. There is no point checking collimation if I can't adjust it though. Is there any information on collimating the type that does not have prism collimation screws and is it truly a job requiring special tools and expertise beyond that which an amateur with a set of precision screwdrivers could bring to the table?
if they do have eccentric rings on the objectives you need an optical spanner wrench/ or homemade device to undo the first ring -then you need to turn the rings-as they are not symmetrical they alter the collimation as you turn the rings
having played with this type of bino alignment i found it very difficult to get the rings in the right place -more often than not i made the alignment worse
it requires no screwdrivers
If they are anything like my old KING binoculars collimation is quite difficult. The prisms are just held in place by a spring clip and a few screws, with no real means of adjustment. I'm going to pull mine apart again and see if I can do anything with them. Shims maybe. I think I will get a more modern pair though.
This has been a truly interesting read guys. I hadn't even thought about collimating binoculars, and now I wonder why it never occurred to me. Duh!
Thanks for all the useful information.
By the way, what is a good type of grease to use for lubricating focus mechanisms and the like, and where would one get this stuff?
Over the past 40 years I have owned 8 telescopes, 3 spotting scopes, 8 pairs of binoculars, 11 riflescopes (inluding 5 zooms), 9 camera lenses (including 5 zooms) and 37 telescope eyepieces (many with screw up eyecups) and I have never in those 40 years had a need to apply any grease or lubricant to any piece of optical equipment I have owned. That having been said I look after my equipment very meticulously which means it stays pretty clean and if it gets dirty I clean it ASAP. I have a pair of Tasco 10x50 binoculars which are Japanese made by Towa Optical. I got these in about 1976 and I used them for hunting under some fairly harsh conditions. In the mid 1990's the focusing started to get stiff due to a 20 year accumulation of dust. I pulled them apart, cleaned the focusing parts, put them back together and they are still working perfectly in my sisters care. I gave them to her to use as the eye relief is too short for me and my glasses.
Not saying you shouldn't use a lubricant, but I would clean them properly and re check the movement of the focusing parts, before you start throwing grease around as grease and optics aren't a brilliant match when it gets in the wrong place. Just ask anyone who owned one of the early Meade S5000 UWA eyepieces. They were way over greased at the factory and the grease would ooze out when you adjusted the eyecup, get on your fingers and invariably end up all over the eyepiece.
These binoculars are about 40 years old and the grease seems to have had better days. I intend to clean the focusing mechanism with turps or something of the sort and then use the special Lithium grease I purchased from eBay, sparingly, only on the parts that are supposed to move freely.
The vendor sells various specialised greases and this one is marketed as intended specifically for optical and camera applications due to its long life, lack of volatile fractions that would vaporise and deposit on optics, and mechanical stability (i.e. no tendency to separate and run). The spiel might be BS, but as best I can tell and assuming the ad is not all lies, it's the stuff you want when you're greasing optical equipment!
