[HarisF1]

Hi guys,

I've just noticed the dreaded balsam separation issue on my K 50mm f/1.2 lens. The lens was delivering some very dreamy bokeh compared to some of my previous 50/1.2 lenses and I can imagine it was due to this separation. It's on the edges of one of the internal elements so will require a repair.

I would like to know whether anyone has had a lens repaired for balsam separation previously, and the rough costs for this service. If it's too expensive, I may just sell the lens for spares/repair and take the hit.

Best Regards
Haris

[WPRESTO]

I've not looked into the matter, but I do not think that there is any reasonable way to repair balsam separation. To do it properly the lenses would have to be completely separated, completely cleaned of any residual balsam (which would probably damage or destroy the coating on the outer lens surfaces). then the lenses would have to be reglued with new balsam, a precision job that may be all but impossible out of a factory setting. I've have never read of anyone offering to do such or job, or someone reporting a successful repair of balsam separation.

[Bob 256]

It can be done. The lens has to be completely disassembled and the element group with the issue treated to separate them (no expert but I've done it with optical glass pieces and it involves immersing the two in distilled water and bringing it to a slow boil (this assumes balsam was used - sometimes it's optical epoxy and that is more or less permanent). I think the coatings will survive (but don't take my word for it). The facing surfaces then need extra solvent cleaning once they separate, and are re-cemented, a somewhat skilled task. Finally the lens needs to be reassembled. Getting all that done is an involved process.

No idea on current costs but it could be worthwhile to consider a replacement

[pentaxus]

Re-camenting is difficult and you don't have the appropriate instrumentation you will spent a lot of time making a decentered lens.

[Fenwoodian]

.
I tried it once - botched it - never again...


I know one guy who claims to do it. But when I asked for his price he wouldn't give it to me. Also, he admitted that he does not have the tool to align them properly when re-cementing.


What I did after my botched re-epoxy job was to buy a cheap/ugly lens of the exact same type. I took it apart. Removed the good doublet from the new/ugly lens, and then put it in the old/minty lens. Now I have a perfect lens again.


You might want to consider doing the same as re-glueing a doublet is difficult. Replacing lens elements is much easier.

[HarisF1]

Good advice

That's exactly what I did for a 50/1.4 lens I had. The idea had left my mind.

Until I can find one, I wouldn't mind having a play with them. I'm planning on using balsam as long as I can find it. Did you manage to separate the elements safely?

[Fenwoodian]

Good advice

That's exactly what I did for a 50/1.4 lens I had. The idea had left my mind.

Until I can find one, I wouldn't mind having a play with them. I'm planning on using balsam as long as I can find it. Did you manage to separate the elements safely?

Yes, I ended up buying a very strong acid to dissolve them. Took about a week. Also, purchased a special UV activated glue to re-cement them. It was cheap, if I did it again I'd use the expensive optical glass glue. Worked sort of OK, but I'm certain that it was not "centered", the glue was not totally transparent, and I chipped the edges of one element in the process.

Hint: the UV cured glue sets up IMMEDIATELY upon bringing it out into the sunlight!

[Bob 256]

If you do get into it, mark the edge of the lens components prior to separating them. Those alignment marks are needed to get the two back together properly (if rotated relative to one another, you can loose centering and best fit).

Clean the mating surfaces fastidiously and blow them clean just before assembly.

Use two pegs to position a lens element against and move the other into position using the same two pegs to align it (using the edge marks for rotational alignment). The hardest part is getting them together without trapping any air bubbles (or dust particles). As I mentioned, this is a bit of an art.

Using epoxy or UV curable cement is a one-time fix because you won't get them apart again. Balsam will dissolve fairly easily but modern cements require strong solvents and even then it's pretty iffy to separate them. A good Canadian Balsam fix will last a long time and can be redone if needed.

[HarisF1]

I'm looking for a source of balsam cement here in the UK and keep finding 'natural, filtered' supplies of around 100ml from sciency suppliers. Would these be close to what I'm looking for?

[stevebrot]

I've just noticed the dreaded balsam separation issue on my K 50mm f/1.2 lens.

Would it be rude to ask why you think the lens has separation? There are several things that mimic separation.

Going forward, your lens has only one cemented group and while alignment may not be difficult (mark edges for precise alignment to factory orientation), the actual process may be more than most DIY'ers might be interested in. Given the value of the lens, having a professional do the job might be a good idea. If camera repair shops are unwilling, microscope or telescope service might be an option. In theory, knowledge of materials and access to an optical bench for alignment are the required assets.

That being said, here is a link about materials. Balsam (tree sap) has not been the standard for some time and it is likely that a synthetic cement was used on your lens.

The Bonding of Optical Elements: Techniques and Trouble Shooting. From Summers Optical


Steve

[HarisF1]

The main indicator of cement separation on my example is the maze like pattern that has developed on the edges of one of the elements (or doublet). It's definitely not fungus (spider webs) or haze (clouding/thin layer of condensation). It's quite a pretty pattern!

With regards to the repair advice, I'll be looking for professional repair services in the UK to start with, but there's a point at which the cost of repair would be greater than selling for parts and buying a replacement. If it gets to this point then I'm not afraid to experiment myself

I've done a bunch of repairs for fungus/hazing and other minor lens ailments so this would be another educational experience I guess.

[Tonytee]

I have this issue on my SMC Pentax-M Macro 1:4 100mm 1:2 lens. I brought it over to Advance Camera had Paul examine the lens and told me it is adhesive separation, however I should not ever have a problem with it showing up in my photographs. He recommended I just continue enjoying it. It is an old manual lens and something like this over time is to be expected. So I have taken his advice and no problems at this point.

Hope this helps.

Tony

[joeji]

I had an smc a 50 f 1.4 which was bundled with P 30 bought from olx, completely foggy which I was sent to a person in Mumbai for repair.
He had dismantled the elements, cleaned and glued. I couldn't find any problem visually on lens or photographs. Subsequently I have sold the lens and the buyer also didn't complain.

[gio91ber]

He had dismantled the elements, cleaned and glued. I couldn't find any problem visually on lens or photographs. Subsequently I have sold the lens and the buyer also didn't complain.

Would love to have something like that done to one of my lenses. How much was it?

Thank you