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Damn that was a good post! I will read again several times. MEK is Methyl Ethyl Ketone? If so, I just happen to have one gallon of the stuff for a different purpose, that didn't materialize. Do you...

Does anyone have anything against this balsam or it needs to be some optical grade Canada balsam?
https://arttreehouse.com/artstore/product/canada-balsam/?attribute_canada-balsam-sizes=8+oz.+size

I plan to rest the lenses flat on a surface plate, the bottom of one lens is concave, so it will sit flat on its perimeter. Then I will position them against the edge of a v-block, lying on its side...

The accuracy of internal diameter I can verify with an inside micrometer. If printed with let's say 0.1mm layer thickness, and adjusting the extruder settings, I think it's possible to make a good...

Yes the Symmar. I was thinking a 3D printed jig with two pockets for the two lenses with different diameters, we covered it a bit earlier. For the lenses of same diameter I could rest the lenses on...

well if we use the jig to get everything aligned shouldn't that work? after grinding the mechanical and optical axes should coincide. If we re-align mechanically to about 0.001", should that be...

Well, we're not really grinding too deep but polishing, and even if we were to grind then the spherical shape would be retained mostly.
No, that's not how I like to do things, lens polishing makes...

I do have some books on telescope making mentioned at the beginning of the thread. If you find some good books, let me know the titles if you don't mind.

the v blocks are the way to go for concentric lenses for sure, but the harder one is a combination of two lenses with different diameters.
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Makes it seems like the excess balsam squeeze out is a big issue. Does it stick to everything that hard? Is it possible to cure the cement without heating the lenses, just by waiting for the balsam...

Thanks for your balsam thread. I will read through it before trying on my own.

I wonder why it is only the Canadian balsam tree that has these qualities, and why it has to be a special UV lens...

Can you share more details/pics of your process? Sounds like you do it a lot. Any experience with UV resin?
Could you use 3d printing SLA clear resin?

So what is the solvent used in the Canada balsam cement itself, is it Xylene? How long does it take for the solvent to dry fully when a new one is applied? it will probably take a while as the...

I'm now thinking of a 3D printed jig.

I'm now thinking if both lenses are same diameter (like the one on above-left) I could rest them on a surface plate against a v-block. That should be more accurate than any other method. For the...

Ok that makes sense now. I took out some of my separated lenses and they look like they've been edge-ground after cementing. So optical alignment is purely angular in a concentric jig. I could...

Most of them will be purchased online anyways, so does it really matter if in UK or not? I've seen 100ml bottles online for 60 euro. I wonder if all it is, is tree sap dissolved in some solvent. ...

I've considered the plaster expansion as a good thing actually. The expansions should not be too great and should facilitate easy removal from the plaster jig.

I thought about making a metal jig,...

Any suggestions for separating the lenses other than heat? The only effective method I've seen is gradual/uniform heating. Also solvent was mentioned.

I completed the polishing today and found the rear element of my 360mm apo-ronar also had a fungus smudge. So I took out that element and polished it out as well, which took about 30 min for one...

Concerning realignment of cemented optics, I am thinking of using a cast-plaster jig, molded around the lenses before separating them, for radial realignment. Prior to that, coating them with...

"How to Make a Telescope" by Jean Texereau. This book has good illustrations and is considered a classic for this topic. Archive does not have a downloadable version, but you can borrow the book...

Thank you for the feedback. I came across a passage in "How to Make a Telescope" that surface accuracy on lenses needs to be 1/4 of what is required in mirrors. Not sure if this makes any potential...

Usually it is one or two surfaces that are damaged by fungus, and in a typical 4 element lens there are 8 surfaces. So we will loose about 1/4 of the total anti-reflection quality if the coatings are...

The most interesting part will be balsam separation fix, I already have a plan, but that will be later. I will share the before/after photos of the lens fungus etch when I get back to polishing the...

Awesome, thanks. Turns out I have a model I.

attachments don't work

Appreciated, thank you for reading. I figured that fungus damage is quite common on vintage lenses and many good ones are scrapped, unfortunately. And no information is available other than...

Later on I want to add information on balsam separation repair, which will involve creating an alignment fixture, separating the lenses with heat, cleaning old balsam, applying new lens cement, and...

Here is a link to the book, "Amateur Telescope Making, Advanced" which can be downloaded as a pdf. I bought the original paper version for a few bucks.
...

I completed the polishing today and found the rear element of my 360mm apo-ronar also had a fungus smudge. So I took out that element and polished it out as well, which took about 30 min for one...

Pouring the pitch into a mold formed with aluminum tape, and pressing the lens into a softened pitch. The square channels are visible. The white compound is the polishing slurry.
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I want to share a technique for re-polishing lens surfaces etched by fungus residues. In the best case, fungus can be removed with acetone, but usually fungus permanently etches the glass. If the...

Hi, I did not remove the backstop strip actually, I just made it a bit more narrow. Technically it should be removed and a separate backstop strip should be glued to the side, but I didn't want to...

I just bought a micromega focuser. It appears to have a top surface aluminized mirror which is prone to scratching, I guess that's why there' a little protective door in front of it.

Does anyone...

going from enlarger to camera mode, would you say I need to space out farther or closer?

thanks for the feedback BTW.

Can anyone elaborate on the nuances of mounting enlarger and process lenses into standard shutter bodies like Copal and Compur?

I have a Schneider G-Claron 270mm WA, f6.3, which threaded into a...

Well my model does not have a chain, it's got cables, per my previous posts. The issue was the notchy bearings, which I loosened and lubed, but did not grease.

Focusing is good now, better than...

Compared to my Saunders/LPL 670 MXL, the De Vere focuses more smoothly. Easier on the De Vere in terms of control and comfort, on the same 6x7 negative.

Anyways, the notchiness came from dry ball bearings on the focusing stage carriage. I removed the bearings and lubricated with automotive oil. Though it should be grease.

The old grease has...