Gear Talk > What the Nerds Do
Blemish inside 16mm 3.5 rear element
Snoogly:
--- Quote from: Akira on January 13, 2022, 07:06:43 ---Just called Kiitos. Kiitos is a repair shop founded by the ex-Nikon repair persons.
The repair person on the phone said that the rear group of Snoogly's 16/3.5 fisheye is very probably suffering from the balsam separation. He further explained that the rear group of this fisheye consists of two glued elements and is sensitive to the shock or any sort of force. If such force is applied, it is prone to separate which is irreparable.
If the seller sold the lens as "junk", I would say he is at least honest.
--- End quote ---
I hear you :-(
Gone:
--- Quote from: Snoogly on January 13, 2022, 00:32:20 ---I can’t even remove the offending group though :(
--- End quote ---
Warm the whole assembly that you have removed from the lens, maybe in a warm oven?
Snoogly:
Well, I sent photos of the damage to the Taiwan repair man, and he said he is confident he can repair the grouped element. I will send the lens to him on Monday, but Covid may delay its arrival …
Fingers crossed he can do it, and that it will be for the $150 he estimated.
Macro_Cosmos:
Measure the thickness of the doublet. Use a good calliper set.
Use a heat plate, immerse the element(s) in a container and use low-ish temperatures. Depends on the bonding agent, around 45-50 Celsius should be adequate. Typical balsam type resin used in older lenses has a melting point of around 40 degrees Celsius. Separate it and clean up the glue, then rebond the glass with optical adhesives, Norland ones work well. https://www.edmundoptics.com.au/f/preloaded-norland-optical-adhesive-syringes/39757/
It is doable, and should give better results than a milky haze. From what I am reading, I think there are other issues as well unfortunately. I used to own one, it is an incredible lens.
Snoogly:
It should be arriving the hands of the Taiwan repair man any day now, and he said he would report back to me after he has inspected it.
We shall see!!!
It’s such a hard lens to figure out what is going inside, without fully opening it up. Looking from the front it’s hard to see any issues with the glass, and looking from the back it’s hard to see further than the closest group. Inscrutable …. :(
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