dan newberry
New member
I'm an inveterate tinkerer. I've been playing with some old porro prism binoculars for the last few weeks. I asked around the 'net for advice on how to clean and collimate old binoculars, but no one seemed to know much--or if they did they weren't sharing their knowledge. So I just decided to learn what I could on my own. /ubbthreads/images/graemlins/laugh.gif
Here's what I did learn:
It's not too much trouble to take apart a set of porro prism binoculars for cleaning. We'll talk about collimation after reassembly.
Generally, the main objetive lense housings just screw off in lefty-loosy fashion. Then you can remove the dust covers, which usually are held on by a single screw after you take off the objective lense housings.
Underneath, you'll see a prism, held in place by a spring clamp. This clamp will usually be held in place at one end by a slot which the spring fits into, and at the other end by a small screw. Take the screw out, remove the clamp, and then the prism can be dumped out into your hand. Remember the position of the prism when you remove it, so that it can be put back just the same. Do this to both sides of the binoculars. (In addition to the spring clamps, there may be a spot of glue holding the prisms as well. This can be scraped away and then replaced, if desired, by some silicone gasket type adhesive).
Now, to get the top apart...
Remove the small cap between the two occular lenses (eyepieces). It'll probably be held on with a small screw, but it also may just turn out, much like a screw. Underneath that cap you're likely to find a brass screw. It may be slotted for a flat screwdriver, or it may simply have two holes, one on either side. If it's the latter, you'll need to sharpen an old pair of needle-nose pliers with a file so that you can place a point into each hole and twist the screw out that way. But first! There will be a teeny tiny set screw (locking screw) which must be backed out. If you try to unscrew the main brass screw without first backing out this tiny set screw, you'll shear that little screw off and your binoculars will then tend to work loose with use. Use a tiny jeweler's screwdriver to gently remove this screw. It'll also be made of brass (most likely) and it will be very easy to shear the head off that set screw if you're not careful. If it doesn't twist out with gentle pressure, try some penetrating oil like Kroil on it.
Once the brass screw has been removed, use a small flat screw driver to gently pry the eyepieces off. The metal which is typically used in these pieces is not very sturdy; it's more like "pot metal." So go easy as you pry the eyepieces off.
Once the eyepieces have been lifted away, take note of any washers or other such hardware that might be part of the binoculars. Remember where it goes. /ubbthreads/images/graemlins/smile.gif
With the eyepiece assemblies removed, you can now remove the dust covers to the top side internals. These will likely just be held on in a fashion similar to the bottom dust covers. Probably a small screw or two, and you may find that you'll have to unscrew the short tubes that the eyepieces fit down over--these are generally used to help hold the top dust covers in place. Just firmly grip them and they should unscrew.
With the top dust covers removed, you'll see another set of prisms just like what you saw on the bottom. Remove the spring clamps as mentioned earlier, note the postions of these prisms (for correct reassembly) and then remove them.
You can now wash the prisms in soapy water. I used Dawn dish soap and it worked very well. Dry them with a cotton towel. Don't use paper towels or any type of napkin that will leave "fuzz" on the prisms. Don't use Q-Tips! You'll find little cotton "hairs" on the lenses when you put things back together. (To check how clean your binocular's lenses are, look through the binoculars backwards, at a light background. The debris will show up easily if it's there).
Next, wash your occular lenses, housings and all, in the soapy water. Dry with a cotton towel, and set these aside in a very dry area so that moisture can evaporate away.
If you're not afraid to take this cleaning a step farther, disassemble the eyepieces and clean those lenses as well. Generally, the eyepieces will have two lenses, and dust and dirt can get trapped between these lenses. I have found that a retainer ring, much like that ring you'll see inside the objective of a rifle scope, is used to hold the bottom lense in most of these eyepieces. If you use those sharpened needle-nose pliers we talked about earlier, you can span the retainer ring and insert the tips of the pliers in the opposing slots of that ring, and unscrew it. Then the eyepiece bottom lenses should fall out. Clean them in soapy water, and dry with a towel. You can wash the remainder of the eyepieces (before you put the bottom lenses back in) by dunking them in the soapy water and scrubbing with a soft brush. Rinse well, and dry with a cotton towel. Wad up a twist of the towel's corner and push it up inside the eyepiece to clean and dry the inside of the top lense.
Put the eyepiece lenses back in, tightening their retaining rings.
If you've encountered any areas which had grease on them, you'll probably want to use some gun grease or such to replace it.
Now. Put the binoculars back together. The prisms will just need to be placed to approximate center of their respective areas, and the spring clamps tightened down on all but the right objective lens (bottom) prism. This prism will be manipulated to get the binoculars back into collimation.
Do not put the dust cover on the right bottom side, but do screw the occular housing into its proper position. By leaving off the dust cover, you'll be able to reach the bottom right prism so that you can adjust it.
You'll need to slightly loosen the screw which holds the spring clamp in place on the bottom right prism. This will allow that prism to be shifted back and forth more easily during collimation adjustments.
Now. Bring the binoculars up to your eyes. Try to focus on a sharp lined object somewhere in the distance. Unless you're the Power-Ball Lottery winner, the collimation will be AWFUL. /ubbthreads/images/graemlins/laugh.gif So don't try to focus your eyes here; you'll get a headache!
Using a flat bladed screwdriver, fit it into the open area around the exposed prism, with the blade laying along side the prism. Try to position the screwdriver's blade so that when you twist the screwdriver you cause the prism to shift position slightly. Look for a couple of other places around the prism where you can insert the screwdriver, and by twisting it, slide the prism. These will be your adjustment points.
I have noticed that you can get quite a bit of collimation correction by moving the prism end to end, longways in its slot. You can fine tune by moving the prism left to right at either end.
But you don't actually adjust the prism until you're looking through the binoculars. This is easier than it sounds. Just put the binoculars up to your eyes with the screwdriver inserted alongside the prism. (Keep your fist out of the line of sight, of course). Then twist the screwdriver very slightly and see if the dual images begin to converge. If they do, continue twisting the screwdriver until the prism either stops moving (it reaches its limit of travel) or the image clears up.
Play with moving the prism back and forth until the image looks immediately clear when you bring the binoculars up to your eyes. Remember that your eyes will have a natural tendency to align themselves with the misaligned binoculars if you stare too long. What I did was I would close my right eye and check that the image was clear on the left, then closed my left eye and focused the right occular, and then I looked away at an object (without the binocs) so that my eyes were in normal convergence--and then I looked quickly into the binocs to see if the collimation was good.
If you simply cannot find a position for the prism where collimation appears acceptable, it may be necessary to take the top of the binoculars apart again and move the upper prism one direction or the other, then try again.
With trial and error, I've gotten three old pairs of theretofore useless binoculars back into service. One particular pair of "Vega" 7 x 50's which had been submerged in a dirty creek are now back to new condition, optically speaking. And I have a pair of early Swift 6 x 30's which I will not sell! I love those little things, and I got 'em for a dollar because the collimation was out, and they needed cleaning.
I did destroy one pair of early "Pilot" brand binoculars. /ubbthreads/images/graemlins/blush.gif Call them a casualty of the learning process! /ubbthreads/images/graemlins/smile.gif
If you're a tinkerer like me, you'll enjoy fooling with some old porro prism binocs. Give it a try! /ubbthreads/images/graemlins/laugh.gif
Dan
Here's what I did learn:
It's not too much trouble to take apart a set of porro prism binoculars for cleaning. We'll talk about collimation after reassembly.
Generally, the main objetive lense housings just screw off in lefty-loosy fashion. Then you can remove the dust covers, which usually are held on by a single screw after you take off the objective lense housings.
Underneath, you'll see a prism, held in place by a spring clamp. This clamp will usually be held in place at one end by a slot which the spring fits into, and at the other end by a small screw. Take the screw out, remove the clamp, and then the prism can be dumped out into your hand. Remember the position of the prism when you remove it, so that it can be put back just the same. Do this to both sides of the binoculars. (In addition to the spring clamps, there may be a spot of glue holding the prisms as well. This can be scraped away and then replaced, if desired, by some silicone gasket type adhesive).
Now, to get the top apart...
Remove the small cap between the two occular lenses (eyepieces). It'll probably be held on with a small screw, but it also may just turn out, much like a screw. Underneath that cap you're likely to find a brass screw. It may be slotted for a flat screwdriver, or it may simply have two holes, one on either side. If it's the latter, you'll need to sharpen an old pair of needle-nose pliers with a file so that you can place a point into each hole and twist the screw out that way. But first! There will be a teeny tiny set screw (locking screw) which must be backed out. If you try to unscrew the main brass screw without first backing out this tiny set screw, you'll shear that little screw off and your binoculars will then tend to work loose with use. Use a tiny jeweler's screwdriver to gently remove this screw. It'll also be made of brass (most likely) and it will be very easy to shear the head off that set screw if you're not careful. If it doesn't twist out with gentle pressure, try some penetrating oil like Kroil on it.
Once the brass screw has been removed, use a small flat screw driver to gently pry the eyepieces off. The metal which is typically used in these pieces is not very sturdy; it's more like "pot metal." So go easy as you pry the eyepieces off.
Once the eyepieces have been lifted away, take note of any washers or other such hardware that might be part of the binoculars. Remember where it goes. /ubbthreads/images/graemlins/smile.gif
With the eyepiece assemblies removed, you can now remove the dust covers to the top side internals. These will likely just be held on in a fashion similar to the bottom dust covers. Probably a small screw or two, and you may find that you'll have to unscrew the short tubes that the eyepieces fit down over--these are generally used to help hold the top dust covers in place. Just firmly grip them and they should unscrew.
With the top dust covers removed, you'll see another set of prisms just like what you saw on the bottom. Remove the spring clamps as mentioned earlier, note the postions of these prisms (for correct reassembly) and then remove them.
You can now wash the prisms in soapy water. I used Dawn dish soap and it worked very well. Dry them with a cotton towel. Don't use paper towels or any type of napkin that will leave "fuzz" on the prisms. Don't use Q-Tips! You'll find little cotton "hairs" on the lenses when you put things back together. (To check how clean your binocular's lenses are, look through the binoculars backwards, at a light background. The debris will show up easily if it's there).
Next, wash your occular lenses, housings and all, in the soapy water. Dry with a cotton towel, and set these aside in a very dry area so that moisture can evaporate away.
If you're not afraid to take this cleaning a step farther, disassemble the eyepieces and clean those lenses as well. Generally, the eyepieces will have two lenses, and dust and dirt can get trapped between these lenses. I have found that a retainer ring, much like that ring you'll see inside the objective of a rifle scope, is used to hold the bottom lense in most of these eyepieces. If you use those sharpened needle-nose pliers we talked about earlier, you can span the retainer ring and insert the tips of the pliers in the opposing slots of that ring, and unscrew it. Then the eyepiece bottom lenses should fall out. Clean them in soapy water, and dry with a towel. You can wash the remainder of the eyepieces (before you put the bottom lenses back in) by dunking them in the soapy water and scrubbing with a soft brush. Rinse well, and dry with a cotton towel. Wad up a twist of the towel's corner and push it up inside the eyepiece to clean and dry the inside of the top lense.
Put the eyepiece lenses back in, tightening their retaining rings.
If you've encountered any areas which had grease on them, you'll probably want to use some gun grease or such to replace it.
Now. Put the binoculars back together. The prisms will just need to be placed to approximate center of their respective areas, and the spring clamps tightened down on all but the right objective lens (bottom) prism. This prism will be manipulated to get the binoculars back into collimation.
Do not put the dust cover on the right bottom side, but do screw the occular housing into its proper position. By leaving off the dust cover, you'll be able to reach the bottom right prism so that you can adjust it.
You'll need to slightly loosen the screw which holds the spring clamp in place on the bottom right prism. This will allow that prism to be shifted back and forth more easily during collimation adjustments.
Now. Bring the binoculars up to your eyes. Try to focus on a sharp lined object somewhere in the distance. Unless you're the Power-Ball Lottery winner, the collimation will be AWFUL. /ubbthreads/images/graemlins/laugh.gif So don't try to focus your eyes here; you'll get a headache!
Using a flat bladed screwdriver, fit it into the open area around the exposed prism, with the blade laying along side the prism. Try to position the screwdriver's blade so that when you twist the screwdriver you cause the prism to shift position slightly. Look for a couple of other places around the prism where you can insert the screwdriver, and by twisting it, slide the prism. These will be your adjustment points.
I have noticed that you can get quite a bit of collimation correction by moving the prism end to end, longways in its slot. You can fine tune by moving the prism left to right at either end.
But you don't actually adjust the prism until you're looking through the binoculars. This is easier than it sounds. Just put the binoculars up to your eyes with the screwdriver inserted alongside the prism. (Keep your fist out of the line of sight, of course). Then twist the screwdriver very slightly and see if the dual images begin to converge. If they do, continue twisting the screwdriver until the prism either stops moving (it reaches its limit of travel) or the image clears up.
Play with moving the prism back and forth until the image looks immediately clear when you bring the binoculars up to your eyes. Remember that your eyes will have a natural tendency to align themselves with the misaligned binoculars if you stare too long. What I did was I would close my right eye and check that the image was clear on the left, then closed my left eye and focused the right occular, and then I looked away at an object (without the binocs) so that my eyes were in normal convergence--and then I looked quickly into the binocs to see if the collimation was good.
If you simply cannot find a position for the prism where collimation appears acceptable, it may be necessary to take the top of the binoculars apart again and move the upper prism one direction or the other, then try again.
With trial and error, I've gotten three old pairs of theretofore useless binoculars back into service. One particular pair of "Vega" 7 x 50's which had been submerged in a dirty creek are now back to new condition, optically speaking. And I have a pair of early Swift 6 x 30's which I will not sell! I love those little things, and I got 'em for a dollar because the collimation was out, and they needed cleaning.
I did destroy one pair of early "Pilot" brand binoculars. /ubbthreads/images/graemlins/blush.gif Call them a casualty of the learning process! /ubbthreads/images/graemlins/smile.gif
If you're a tinkerer like me, you'll enjoy fooling with some old porro prism binocs. Give it a try! /ubbthreads/images/graemlins/laugh.gif
Dan