Corrosion on used Olympus objectives (and SPLANs vs DPLANs)

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Crater Eddie
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Corrosion on used Olympus objectives (and SPLANs vs DPLANs)

#1 Post by Crater Eddie » Tue Jan 31, 2017 1:49 pm

Some of the used Olympus objectives that I see for sale look from slightly to very badly corroded. What the heck causes this? The seller always swears that the optics are in great shape, and often provides blurry pictures to prove it, but I have to wonder. If the barrel is in this bad shape, what has been done to the glass? Is fungus or clouding likely in these cases? Or am I just obsessing over a cosmetic issue?
CE
Last edited by Crater Eddie on Wed Feb 08, 2017 4:07 pm, edited 3 times in total.
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charlie g
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Re: Corrosion on used objectives

#2 Post by charlie g » Tue Jan 31, 2017 4:11 pm

It's for me intresting how I've 'adopted' vintage (pre-WWII) Spenser and Buffalo Spenser stands...with heavily tarnished (?same as corrosion?) objectives..yet optically fine to excellent performances.

I sense Olympus a more recent time of manufactured stands...so I'd be wary of corroded objectives on these stands or objectives components.

EBay vendors over the years have for me played out into a lot whom I can trust on what they offer for sale. I'd go with such vendors rather than the images put up in the EBay market stores. I really would never relish 'sending a defective item back to a vendor'..lot's of valubal time consumed..just packaging and getting to a post office during postal hours.

What really irritates me regards to images offered with sale items...often everyview of an objective except wether it's 160 TL, vrs infinity, etc....along with no mention of these important specs in sellers description...ahhh!

charlie guevara who still wonders when 'as is condition' is worth the time,and money for a sale.

billbillt
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Re: Corrosion on used objectives

#3 Post by billbillt » Tue Jan 31, 2017 5:09 pm

Crater Eddie wrote:Some of the used Olympus objectives that I see for sale look from slightly to very badly corroded. What the heck causes this? The seller always swears that the optics are in great shape, and often provides blurry pictures to prove it, but I have to wonder. If the barrel is in this bad shape, what has been done to the glass? Is fungus or clouding likely in these cases? Or am I just obsessing over a cosmetic issue?
CE
I am also leery of corroded objectives that provide fuzzy photos.. Most of them will state that they "know nothing about" microscopes and such.. If the fuzzy photo is the best they can do I shy away from them..

BillT

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Crater Eddie
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Re: Corrosion on used objectives

#4 Post by Crater Eddie » Tue Jan 31, 2017 7:12 pm

To perhaps clarify a bit, the barrels of the Olympus objectives (DPLAN SPLAN etc) have a chrome plating, or at least something that looks like it. In these cases the plating is pitted, sometimes badly, and/or flaking off in spots. It would be silly to pass up a bargain price just because of aesthetics, assuming that the optics are indeed unaffected. I was wondering what would cause the damage to the "chrome", and if damage (possibly hard to spot) to the optics is also likely. I guess I'm still a little suspicious of used objectives after getting so many delaminated LOMO objectives.
CE
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apochronaut
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Re: Corrosion on used objectives

#5 Post by apochronaut » Tue Jan 31, 2017 11:34 pm

One never knows what an objective will get in contact with in industrial or research microscopy. Unfortunately, chrome isn't the best plating material. Even though it is fairly impervious to corrosion, chrome plating is very thin and porous, so reagents eventually get to the brass base material and cause corrosion and lifting of the chrome.
In the old days, chrome was never used. Labs weren't as controlled as they are now and not just reagents were a little more liberally used but gases were a little more evident. Objectives were brass, usually. Most companies lacquered the brass, as a protectant with the tip plated,. Cheaper models had nickel tips but iridium or rhodium was also used, at a time when there were few other uses for these rare metals. I even have one objective with a sold rhodium or iridium front lens housing , from the mid 19th century. The seller said it was stainless steel. Duh! Possible corrosion from reagents was taken seriously. Spencer, sometime in the 1920's realized that lacquered brass wasn't really good enough for their research objectives, so chose to gold plate them. If you see Spencer 160mm apochromats for sale , irregardless of their age, they are usually bright and shiny, while their counterparts from the other makers are usually dull and or corroded. Spencer also used a non-corrosive alloy for plating the front lens housing, until recently. Hard to say what it is but it is likely an iridium or rhodium alloy.

The thing is, despite how beat up an objective looks from metal corrosion, the compounds that affect metals, do not often affect glass. I have in my possession objectives that are so corroded , as to seem unusable, yet the glass and image they produce are faultless. On the other hand, I have objectives, that look pristine, yet have separated elements and are useless. You cannot tell a book by it's cover.

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Re: Corrosion on used objectives

#6 Post by carlh6902 » Tue Jan 31, 2017 11:42 pm

I see a ton of the E A ( educational) objectives that are severely corroded. The A, D, and S series seem to fare better.

Carl
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apochronaut
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Re: Corrosion on used objectives

#7 Post by apochronaut » Wed Feb 01, 2017 12:05 am

That's likely because they were put into nasal passages and ear canals, frequently.

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Crater Eddie
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Re: Corrosion on used objectives

#8 Post by Crater Eddie » Wed Feb 01, 2017 1:14 pm

I had never thought about bogeys and ear wax as being particularly corrosive, now I have something new to think about.
Anyway, have decided to give one of these bargain corroded objectives a try. Thanks for the discussion.
CE
Olympus BH-2 / BHTU with Olympus E-P1 MFT camera mounted
LOMO BIOLAM L-2-2
LOMO POLAM L-213 / BIOLAM L-211 hybrid
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Crater Eddie
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Re: Corrosion on used objectives

#9 Post by Crater Eddie » Fri Feb 03, 2017 1:46 pm

The corroded 20x SPLAN objective arrived, and I must say that it looks better than I expected from the photos. The front lens was spattered with "stuff", but very gentle and cautious cleaning got most of it off. The views it provides are very nice, noticeably brighter and crisper than the 20x DPLAN. For under $100 I'm very pleased.
CE
Olympus BH-2 / BHTU with Olympus E-P1 MFT camera mounted
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charlie g
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Re: Corrosion on used objectives

#10 Post by charlie g » Fri Feb 03, 2017 5:14 pm

Congrats, CE, on your happy result of this purchase gambit! charlie guevara

Thanks as always , apochronaut for your shared expertise of the microscope components as manufactured at various times.

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Crater Eddie
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Re: Corrosion on used objectives

#11 Post by Crater Eddie » Fri Feb 03, 2017 6:04 pm

Thanks charlie g!
When I first examined this Olympus 20x SPLAN objective under my inspection scope I was very apprehensive, the front lens was covered with specks, spots, and streaks. My first thought was that these were etched into the glass, but remembering Apochronaut's advice I carefully and patiently cleaned it off, and now it is almost spotless.
CE
Last edited by Crater Eddie on Mon Feb 06, 2017 6:59 pm, edited 2 times in total.
Olympus BH-2 / BHTU with Olympus E-P1 MFT camera mounted
LOMO BIOLAM L-2-2
LOMO POLAM L-213 / BIOLAM L-211 hybrid
LOMO Multiscope (Biolam)

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Crater Eddie
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Re: Corrosion on used objectives

#12 Post by Crater Eddie » Mon Feb 06, 2017 5:58 pm

Image
Here is the 10x SPLAN, the worst of the two. Is there a way to clean some of the fogging from around the lettering? The glass is spotless, its just an aesthetics thing with the chrome. I have been looking up ways to clean chrome, most of what I find online is for motorcycles and car bumpers.
CE
Olympus BH-2 / BHTU with Olympus E-P1 MFT camera mounted
LOMO BIOLAM L-2-2
LOMO POLAM L-213 / BIOLAM L-211 hybrid
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PeteM
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Re: Corrosion on used objectives

#13 Post by PeteM » Wed Feb 08, 2017 6:54 am

If it's a surface deposit rather than pitting through the chrome layer, you might try a very fine abrasive (e.g. a high quality 600 grit silicon carbide paper). I've had decent luck putting a corroded lens on a parfocal extender, chucking it in a lathe (actually collet), and very carefully polishing the barrel. You need to be dead sure of not touching the lens with the abrasive. You also need a high quality abrasive paper so the grit stays bonded rather than straying into the air. Afterward, meticulously clean as if some grit had wandered despite your best efforts.

I wouldn't try this on a lens you're not willing to take the gamble that a nicer looking objective won't please your more than a mistake in handling will ruin your day.

FWIW, my own understanding with Olympus DPlan and SPlan objectives is that within a 20mm or so field, they look pretty much the same. That is, the main reason for the SPlan is that super wide field?

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Crater Eddie
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Re: Corrosion on used objectives

#14 Post by Crater Eddie » Wed Feb 08, 2017 2:20 pm

Thanks for your thoughts PeteM.
The biggest jump in apparent FOV came in switching from a standard binocular head to the Super Wide trinocular. Comparing the FOV between objectives in the SW trinoc, the SPLAN does show a bit wider total field than the DPLAN, but its not dramatic. It might well perform better out toward the edges than the DPLAN, you are probably right about that. Overall, the view through the SPLAN does seem brighter and a bit crisper, but that could be wishful thinking, or might be due to the slight increase in NA. I found these dirt cheap because of the corrosion and couldn't pass them up. If I had paid a few hundred $$$ apiece for them I might not have thought it worth the outlay... as it is I am pleased.
Interesting idea about chucking them in the lathe to try and polish the chrome, I hadn't thought of that. It is a risk though, I'll probably just use them as they are and be happy.
CE
Last edited by Crater Eddie on Wed Feb 08, 2017 4:12 pm, edited 2 times in total.
Olympus BH-2 / BHTU with Olympus E-P1 MFT camera mounted
LOMO BIOLAM L-2-2
LOMO POLAM L-213 / BIOLAM L-211 hybrid
LOMO Multiscope (Biolam)

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Re: Corrosion on used objectives

#15 Post by 75RR » Wed Feb 08, 2017 3:08 pm

Interesting idea about chucking them in the lathe to try and polish the chrome, I hadn't thought of that. It is a risk though, I'll probably just use them as they are and be happy.
That is probably the wisest decision.
If you do decide to do something about it make sure to cover/seal both the lens and the rear opening.
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