I have and ancient CC Harrison full plate lens which I've been using for two years. It does a beautiful job when I use strobe but does have a ton of cleaning marks on it so outdoors it's very soft and hazy. I'm wondering if there's a good way of cleaning up these marks and making it more useable for natural light?
If you are daring, make good friends with a hobbyist telescope maker and give it a go.
Yup, glass pusher here, but a long time ago. You need to make a pitch lap and try cerium oxide as a polishing agent. You mold the soft pitch with the lens itself thus perserving it's radius. The finer marks should polish out, the deeper gouges won't. Of course the lens element has to be removed to work it on the lap. The trouble is getting only small amounts of the materials you need.
If you are daring, make good friends with a hobbyist telescope maker and give it a go.
Yup, glass pusher here, but a long time ago. You need to make a pitch lap and try cerium oxide as a polishing agent. You mold the soft pitch with the lens itself thus perserving it's radius. The finer marks should polish out, the deeper gouges won't. Of course the lens element has to be removed to work it on the lap. The trouble is getting only small amounts of the materials you need.
One can buy small amounts of diamond lapping/polishing compound, pretty reasonably, from McMaster-Carr.
If it's an ancient lens, it had none originally. And single coatings are available. I can't remember now the Leica guy who could repolish the older Leica lenses and redo the coatings as part of his repairs/restorations. He would recoat any lens, as I recall.Now, if only somebody has come up with home-made lens coating, we've got it made.
If it's an ancient lens, it had none originally. And single coatings are available. I can't remember now the Leica guy who could repolish and redo the coatings on the older Leica lenses as part of his repairs/restorations. He would recoat any lens.
Now, if only somebody has come up with home-made lens coating, we've got it made.
So, MgF2 has a boiling point of 4100 F. That's pretty hot. So you'd need to achieve this temperature and get the gas inside a container with your lens, like cigarette smoke on your windows. Hmm... I need to think this thing through. A bell jar seems easy enough to come up with. A vacuum pump could be the intake side of any air compressor. I saw a fancy machine on ebay for several thousand dollars, but certainly don't have a pile of cash I can peel off a few bills from. Certainly this can be done at home.
Lets see... An old Nuarc platemaker uses HV to strike an arc with carbon sticks. This causes smoke. The smoke fogs up the vacuum frame glass. Substituting MgF2 in this analogy, you would want the gas from that to deposit on your lens. From that point the coated lens is to be baked to get the deposit like glazing pottery.
Carbon arcs are typically 35v - 90v, and use high current not high voltage. The vacuum would be a few mm of Hg, not as high as a radio tube. The vapor deposits on pretty much anything cooler than it, you have to shield what you don't want coated. Electron beams have been used to heat the coating materials, remember Fuji EBC coatings?
The trouble is that anything in a vapor phase will deposit on anything cooler than it, so I don't think a carbon arc would produce a clean enough MgFl vapor to result in a useful coating. It would sure supply the heat though.
Look into the work done by Katherine Blodgett for Generous Electric.
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