Mitutoyo 10x 0.28 - damaged?

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Lou Jost
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Post by Lou Jost »

"Everytime he allows the lens to get that condensation, lens performance will deteriorate a bit as during drying there gonna be some crystalisation on the glass surface."
The condensed water is very pure. When water evaporates the first time, it leaves most of its impurities behind. When that water condenses again, it is pure and leaves virtually nothing behind.

My concern would be that this condensationindicates the lens was kept in a very humid environment, which generally leads to fungus. Check carefully for fungus.

ChrisR
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Post by ChrisR »

The manufacturer says you have to keep it between certain levels of relative humidity. Searching Mitutoyo documents I can't find the figure for their objectives but they quote upper levels of 70% or 80% pretty generally. Yours went higher!

If the vendor didn't ensure that would be maintained in shipping, then he mishandled it.

But about 99% of of the objectives which come to me, are thus mishandled!

I'd test it, and may find it's fine, but would always have a concern about it which would be greater than for a camera lens.

If buying a used thing then we never know the history, which is why we pay hopefully much less than the new price.
My hit rate for "perfect" Mitutoyos, many of which have had to pass through CS's critical hands, is of the order of half. It's hard to tell because there's variation between the good ones.
I feel it's ok to accept something which works well enough, if the price paid is low enough.

If it's a $2500, 50x, objective and I paid $500 then the bar is lower than for a $800 10x for which I paid $500.

If your objective has a seal which is faulty, it may get worse, who knows.. I have objectives which don't work as well as I thought they did. Rik has a documented case of a 10x which "went bad" and he replaced. We sort-of assume it was knocked, but we don't know.

One objective (7.5x) went back because it looked fine but was way off what it should have been. It reappeared for sale as "tested", at the same price. Same vendor, with a different ebay account.

Sorry if this sounds like a lecture :|, just how I've come to look at the murky world of ebay.
Chris R

JohnyM
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Post by JohnyM »

Lou Jost wrote:
"Everytime he allows the lens to get that condensation, lens performance will deteriorate a bit as during drying there gonna be some crystalisation on the glass surface."
The condensed water is very pure. When water evaporates the first time, it leaves most of its impurities behind. When that water condenses again, it is pure and leaves virtually nothing behind.
Sure, sure...
From SK80 i bought last winter i have only aperture left now, seller didnt sealed the package. (un)Fortunately someone else thought to document this. He had nice Zeiss Planar lens:

https://www.rangefinderforum.com/forums ... p?t=137880

ray_parkhurst
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Post by ray_parkhurst »

When I receive a package, I always leave it at least overnight in my den to come to temperature before unpacking. I do this for everything, not just optics. I do store some items in the garage, which is generally a fair bit colder than inside during winter, and I do the same thing with items I bring in. This allows a slow stabilization and keeps condensation from happening.

DavidG1980
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Post by DavidG1980 »

Thank you all.

Lou Jost
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Post by Lou Jost »

From the linked forum:
"As drops of water that condensed on the inner lens surfaces evaporate and shrink up, they collect the dust from the glass underneath the drop, and as they finally dry, they leave it in a tiny central spot each. It usually takes many iterations before the effect becomes visible in a clean lens - but strong condensation in a dirty old lens can create it in one single event."

So if a lens is clean inside, as I suspect a Mitu would be (originally), condensation will not leave marks.

JohnyM
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Post by JohnyM »

Yes, i guess he just used that planar for mining coal or something along that line.

Lou Jost
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Post by Lou Jost »

A lens that focuses by extension will breathe when it focuses. It draws air in, along with dust. A Mitu doesn't do that.

JohnyM
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Post by JohnyM »

So wasnt my dead schneider.

Lou Jost
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Post by Lou Jost »

I never met your deceased friend so cannot speak to that. But condensation in a Mitu should not, by itself, cause problems, except that it indicates high humidity which lets fungus grow.

Look for fungus by shining a light obliquely through the lens from behind, so that the field is dark. If there is fungus it will catch the light and be conspicuous.

neurodoc
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Post by neurodoc »

If this is condensation, and it sure looks like it, putting the objective into a vacuum chamber for a few hours and slowly evacuating the air might remove the water vapor. Then try to keep the objective from reacquiring moisture. That's easy to do if you have a vacuum pump or can borrow one (the kind used by refrigeration techs works fine). The problem with this amount of condensable water vapor in a lens is that it will eventually mess up the lens surface and coatings so you really do want to get rid of it and keep it from getting back in.
Man sieht nur, was man weiss--Goethe

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