Howdy all
I just bought some second-hand binoculars -- cheap, because they're old-school 10x50s, and weigh about a Kg.
They're great for what I want, but the image seems a little "foggy". I don't know if this is due to the lens coatings deteriorating, or if dirt has somehow got into the assembly (unlikely, it seems to me).
Is there any way to clean them up and make the image clearer? Anyone?
Cheers John
Look at reflections on the surface of the lenses. If they are cloudy you are in luck. Go to your local opticians or camera shop and get a bottle of lens cleaner and a decent cloth, then polish. Gently.
If the reflections are shiny the dirt is inside. Find a _good_ camera shop...
Andy.
well if a wipe with optical cloth doesn't sort them, that's that. Nothing to be done for less then buying decent ones.
I've found Russian kit to be a bit clunky, but optically good value for money.
Or even a _good_ camera clinic - save on the commission charged by the camera shop. Agreed on the other recommendations.
Whatever you do, DON'T use Kleenex or similar paper tissues to clean the lens faces. The wood fibre in the tissues WILL scratch any coating on the lenses. Use microfibre cloth or even a clean cotton duster or a bit of Terry towelling.
Watch for Lidl's regular binoculars appearing. Excellent value at purely nominal price. Boat hirers here find them excellent, even in a marine environment.
I regularly use kleenex, paper towels and even toilet tissue to clean my binoculars and camera lenses. I've never had any hint of scratches appearing on any optical surface. The only thing you have to be careful about is that some tissues come impregnated with balms or other goop that's supposed to make the user look pretty - but just smears all over the lenses. (Maybe that's how it works - for glasses wearers? :-) )
On a practical note, remove any large pieces of dirt or grit that might be caked onto the lenses _before_ wiping with a cleaner. Moving these around in contact with the glass will scratch it. Even small dust-sized particles will abrade the surface and will eventually lead to a dulling of the glass - no matter what sort of cloth/paper you use to clean it. If there is grease on the lens, a drop of washing up liquid very diluted in water and then just enough to dampen a cloth will remove it.
Another source of "foggy" views is condensation inside the body of the binoculars. You can either take them apart, which is a bit drastic or leave them to dry out in a warm dry place (but not a warm humid one) for a week or two.
clean
Cheap kitchen roll is OK, at least when I have cold that doesn't make my nose sore like tissues do. I also use kitchen roll on my glasses but that is really only for drying after the daily wash with detergent (not soap it smears) and warm water.
Distinct possibilty and a problem for camera lenes as well. To avoid the problem of internal fogging on the interior interview cameras at sporting events they keep a spare lenes in the interview area and swap the lens when the camera(s) come inside from being out in the cold.
If they're military, sell them untouched on eBay to a collector and buy yourself a new pair. Makers like Ross, or the Naval spec 7=D750s always fetch a very good price.
Otherwise it's: Look, clean, dry, re-assemble.
If they're old, they're probably not coated (unless they're very high quality), so coating breakdown won't be a problem. You might find that they're simply mucky, in which case cleaning them externally is all you need. This is best and by far the simplest. If they're damp inside, if there's mould inside, or if the lens cement is failing then you have to open the case to deal with it.
It's not practical to restore a coating. It's easy to do (you either have a vacuum deposition machine, or you give money to those who do), but we're talking big-budget restoration now.
External cleaning involves working wet and using a non-scratch cloth. These used to be made of rag paper, but now they're made of microfibres. You can get them free from the optician, or just buy a clean microfibre duster. Don't use paper that isn't lens-cleaning paper - wood fibre and dust is abrasive.
Work wet when cleaning them. Rinse carefully afterwards with soft water, then dry somewhere warm and dry (top of a radiator conditions, shielded from dust).
If they're decades old, then there's no reason not to open the case - even if they're gas filled. They've probably been opened already anyway. You will need appropriate tools though, as bodging with a screwdriver is a great way to slip and damage a lens. Try one of the online watch & optics suppliers for an adjustable lens ring / pin spanner. I even saw them listed at Maplin.
When opening, watch out for fragile sealing rings. You'll probably ruin these, if they're old. Replacement (in uk.d-i-y) can be done with gasket compounds, but be careful not to smear them around! Best sort is applied to one surface as a built-up ring, then left to dry before assembly.
With the lenses removed, you can inspect both faces. Interior mould cleans off fairly easily. An ultrasonic cleaner is useful, but be careful as you can damage cemented lenses. You also need to ultrasonic them in a trivet, so only the edges and not the faces are resting on anything else.
Cemented lenses are where it gets awkward (and may fall apart if you ultrasonic them). Breakdown of the cement or mould growth into balsam cement is difficult to deal with. Your best bet (at sensible cost) is to find an amateur telescope maker or university lab tech who makes their own lenses and have them help you out in stripping the doublet and re-cementing. Or just read up some lens grinding tech and go for it yourself. It's a daft way to acquire binoculars, but I understand the lure of the "project".
While they're apart, check and fix the mechanics. If the focus slides or even just the hinges are worn, sort it out now.
To re-assemble, they should be inert gas filled. If they have a red painted filling screw (military), they were certainly filled originally. Fillings really ought to be dry nitrogen, but nitrogen, carbon dioxide, or dried air are worth it. Easiest way is just a squirt of photographer's inerting spray (used to be available fro storing darkroom chemicals), or I use a squirt of argon from the MIG welder cylinder. You're trying to displace moisture here (and ideally oxygen), not to achieve a totally pure gas fill. Squirting enough of a jet through a straw into the filler plug to flush out the casing, and then re-inserting the plug quickly is perfectly adequate. You don't need to assemble in a gas-filled glove box! It is worth doing at least something here. Otherwise just re-assemble in an atmosphere of dry, cool air (chuck it in a sealed plastic box for a few hours, along with a couple of big, fresh silica gel bags). Don't use warm dry air, as relative humidity will bite you in the future. That warm air has a low RH but might have still quite a high absolute humidity. When it goes cold, you still see condensation.
Another trick that's worth it (if there's a suitable space alongside a prism) is to assemble them with a small silica gel dessicator inside the case. Wedge, tie, or superglue this in place. Remember to re- activate the gel before use and don't have it contacting an internally reflective face of the prism (stick it at the side) or it can appear as a ghost. Don't put adhesives on the optics either. In fact don't use superglue - it's handy, but remember CSI and the vapour's use for revealing fingerprints! Use it in an empty casing, but don't have the optics in the room at the time.
To be honest, a new pair from Lidl will probably be better quality and lighter. Modern design and manufacturing has really changed optics at this level.
Another make worth looking at is Luger. I bought a pair of their cheap compacts recently (8=D725, =A325-ish) and they're one of the best and brightest pairs of binoculars I have.
Lidl's are odd. Their "mainstream" binoculars are as you say, cheap and excellent. Quite light too. These are the ones I use most for planned trips, as I can throw them around and leave them in the car. Likewise Aldi's spotting scopes for under 30 quid.
Their "boat" binoculars though are expensive, especially those with the built-in bearing compass. A look at eBay or Chinese sites shows the same thing for less.
Their compact binoculars are, like most cheap compacts, poor quality with dull images and narrow view angles.
Lidl's are odd. Their "mainstream" binoculars are as you say, cheap and excellent. Quite light too. These are the ones I use most for planned trips, as I can throw them around and leave them in the car. Likewise Aldi's spotting scopes for under 30 quid.
Their "boat" binoculars though are expensive, especially those with the built-in bearing compass. A look at eBay or Chinese sites shows the same thing for less.
Their compact binoculars are, like most cheap compacts, poor quality with dull images and narrow view angles.
By narrow view angle - do you mean they give a telescopic image? surely the greater the magnification the narrower the angle.
Good binoculars will give a wider field of view than cheap ones at the same magnification.
Andy
Doesn't magnification equate to a narrower area of view?
My background is in photography and the greater the telephoto power means a narrower angle of view. Isn't it the same? (a 35mm camera standard 50mm lens had a field of view of about 90degrees)
Sorry to labour this but if for example I want to see a distant object and have it fill my field of vision then the angle of view from the lens has to be very small (eg a ship in the distance) If the angle of view is wider then I will see more than the ship and therefore the ship isn't occupying the whole of my field of view (ie - not as magnified)
If they're military, sell them untouched on eBay to a collector and buy yourself a new pair. Makers like Ross, or the Naval spec 7×50s always fetch a very good price.
Otherwise it's: Look, clean, dry, re-assemble.
If they're old, they're probably not coated (unless they're very high quality), so coating breakdown won't be a problem. You might find that they're simply mucky, in which case cleaning them externally is all you need. This is best and by far the simplest. If they're damp inside, if there's mould inside, or if the lens cement is failing then you have to open the case to deal with it.
It's not practical to restore a coating. It's easy to do (you either have a vacuum deposition machine, or you give money to those who do), but we're talking big-budget restoration now.
External cleaning involves working wet and using a non-scratch cloth. These used to be made of rag paper, but now they're made of microfibres. You can get them free from the optician, or just buy a clean microfibre duster. Don't use paper that isn't lens-cleaning paper - wood fibre and dust is abrasive.
Work wet when cleaning them. Rinse carefully afterwards with soft water, then dry somewhere warm and dry (top of a radiator conditions, shielded from dust).
If they're decades old, then there's no reason not to open the case - even if they're gas filled. They've probably been opened already anyway. You will need appropriate tools though, as bodging with a screwdriver is a great way to slip and damage a lens. Try one of the online watch & optics suppliers for an adjustable lens ring / pin spanner. I even saw them listed at Maplin.
When opening, watch out for fragile sealing rings. You'll probably ruin these, if they're old. Replacement (in uk.d-i-y) can be done with gasket compounds, but be careful not to smear them around! Best sort is applied to one surface as a built-up ring, then left to dry before assembly.
With the lenses removed, you can inspect both faces. Interior mould cleans off fairly easily. An ultrasonic cleaner is useful, but be careful as you can damage cemented lenses. You also need to ultrasonic them in a trivet, so only the edges and not the faces are resting on anything else.
Cemented lenses are where it gets awkward (and may fall apart if you ultrasonic them). Breakdown of the cement or mould growth into balsam cement is difficult to deal with. Your best bet (at sensible cost) is to find an amateur telescope maker or university lab tech who makes their own lenses and have them help you out in stripping the doublet and re-cementing. Or just read up some lens grinding tech and go for it yourself. It's a daft way to acquire binoculars, but I understand the lure of the "project".
While they're apart, check and fix the mechanics. If the focus slides or even just the hinges are worn, sort it out now.
To re-assemble, they should be inert gas filled. If they have a red painted filling screw (military), they were certainly filled originally. Fillings really ought to be dry nitrogen, but nitrogen, carbon dioxide, or dried air are worth it. Easiest way is just a squirt of photographer's inerting spray (used to be available fro storing darkroom chemicals), or I use a squirt of argon from the MIG welder cylinder. You're trying to displace moisture here (and ideally oxygen), not to achieve a totally pure gas fill. Squirting enough of a jet through a straw into the filler plug to flush out the casing, and then re-inserting the plug quickly is perfectly adequate. You don't need to assemble in a gas-filled glove box! It is worth doing at least something here. Otherwise just re-assemble in an atmosphere of dry, cool air (chuck it in a sealed plastic box for a few hours, along with a couple of big, fresh silica gel bags). Don't use warm dry air, as relative humidity will bite you in the future. That warm air has a low RH but might have still quite a high absolute humidity. When it goes cold, you still see condensation.
Another trick that's worth it (if there's a suitable space alongside a prism) is to assemble them with a small silica gel dessicator inside the case. Wedge, tie, or superglue this in place. Remember to re- activate the gel before use and don't have it contacting an internally reflective face of the prism (stick it at the side) or it can appear as a ghost. Don't put adhesives on the optics either. In fact don't use superglue - it's handy, but remember CSI and the vapour's use for revealing fingerprints! Use it in an empty casing, but don't have the optics in the room at the time.
To be honest, a new pair from Lidl will probably be better quality and lighter. Modern design and manufacturing has really changed optics at this level.
Another make worth looking at is Luger. I bought a pair of their cheap compacts recently (8×25, £25-ish) and they're one of the best and brightest pairs of binoculars I have.
That's an interesting account thanks Andy.
I once asked about how compound lenses are stuck together, on the Wikipedia pages about lenses. I have an old, but much loved. pair that had like a gold iris effect on one side. I've cleaned and realigned both barrels, and the optics quite nicely, but I never had the nerve to try tackling the 'gold iris effect', which is where the two parts of a compound lens are presumably suffering from the balsam that holds them together drying out and crystallising from the edge.
I did wonder if soaking the lens in xylene might gradually swell the dried balsam back into a more see through condition. If not, how does one separate the elements and what are they stuck together with these days?
Cheers,
S
that is with a fixed negative size. Now google vignetting
I am familiar with it. So what Andy Champ meant was a "clearer view across the whole of the narrow field of view"
Better (i.e. more expensive) eyepieces in binoculars and telescopes give you a larger image than cheap eyepieces. So when you look at something through cheapo binoculars, you might see (say) a house in the distance and it'll be surrounded by the black circular "frame" in which the rest of the vista is cut off from sight. With better equipment that has a higher _apparent_ field of view, that black circle is larger, although the magnification will be the same (so the house is the same size in both pairs of binoculars). The result is that you see not just the house but the things around it, too. That's assuming the same focal length binoculars and the same magnification eyepieces. You just see more stuff in the view.
No, its more total angle of view. I.e vignetting down to complete dark..The eye has about 135 deg. angle over which it can see things. So at a 10x magnification you would hope for the same angle of illumination behind the glasses, and 13 degrees total distant coverage. You get nothing like that.
In the limit the angle is dictated by the primary lens diameter and its focal length and then by the power of the eyepiece lens. I've forgotten all the maths. But more glass is better IIRC :-)
The retina is always far larger than the area that is illuminated by the glasses.
So the field of view is actually small and circular. Good glasses have a much wider field of view. That's why they are more useful than either a telescope or a telephoto lens.
I think balsam was still used into the '80s, but the quality did vary between makers (late WW2 German ersatz stuff is supposed to be particularly iffy) and its fairly easy to work with.
You strip them down with heat, I would suggest using a waterbath on a hotplate at a bit below boiling point. Go easy on speed of raising the temperature though. LET THEM FALL APART AND DO NOT PRY AT THEM! Clean up once apart with acetone (or I guess xylene too).
Re-assemble with canada balsam, which is available and easy to work with. Your big problem here is centring the lenses, and the difficulty of that depends on how accurately their edges were ground, relative to the optical centre. If that's accurate, you can align them mechanically with a few accurate blocks on a surface plate (and remember that optical benches are stable, but far from flat). Best alignment is done with some sort of laser interferometer and doing it optically, but its years since I dealt with that level of geekery.
If they're synthetically bonded rather than with balsam, it's really not worth bothering. However if you do, it's a long soak (and I mean days upwards) is a solvent like xylene or most likely MEK. I've never done this myself, and I think the success rate isn't encouraging.
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