Objective has defect
Objective has defect
I bought an old Nikon lk-e with phase contrast on the cheap off ebay and the 10x obj has this defect. I guess it's a bin job right? All else on the scope is good.
Last edited by coominya on Sat Apr 21, 2018 6:58 am, edited 1 time in total.
- ImperatorRex
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Re: Objective has defect
Probabely some Immersion Oil inside? Before throwing away you can try to clean. I did dismantle and clean an Zeiss achromat 40 completely up to the front lense
Between the front lense and the following lense there was the oil. Actually I did not believe that I get all those lenses and stuff correctly centered and mounted. But surprisingly it worked quite well and I could not spot any issue afterwards.
So if you are patient give it a try, nothing to loose...except some of your spare time.
Between the front lense and the following lense there was the oil. Actually I did not believe that I get all those lenses and stuff correctly centered and mounted. But surprisingly it worked quite well and I could not spot any issue afterwards.
So if you are patient give it a try, nothing to loose...except some of your spare time.
- Crater Eddie
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Re: Objective has defect
Odd that it is green, or is that a trick of the lighting?
CE
CE
Olympus BH-2 / BHTU
LOMO BIOLAM L-2-2
LOMO POLAM L-213 / BIOLAM L-211 hybrid
LOMO Multiscope (Biolam)
Cameras: Canon T3i, Olympus E-P1 MFT, Amscope 3mp USB
LOMO BIOLAM L-2-2
LOMO POLAM L-213 / BIOLAM L-211 hybrid
LOMO Multiscope (Biolam)
Cameras: Canon T3i, Olympus E-P1 MFT, Amscope 3mp USB
- ImperatorRex
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Re: Objective has defect
The green color might come from the brass metall, some copper iones due to some corrosion etc.?
Re: Objective has defect
The green coloration is so uniform, strange that corrosion should appear like this. Besides, typical corrosion copper compounds are either blue or turqouise, not green. Is old Canada Balsam green?
An insane idea - did someone try to insert a green filter WITHIN the phase objective???
An insane idea - did someone try to insert a green filter WITHIN the phase objective???
Re: Objective has defect
Green is quite a common colouration when Oil or Grease oxidises in the presence of Brass.Hobbyst46 wrote:Besides, typical corrosion copper compounds are either blue or turqouise, not green.
... Sorry, I don't know the chemistry.
MichaelG.
Too many 'projects'
Re: Objective has defect
Grease in contact with brass often turns green. Copper roofs also turn green.
Economically the lens is probably a write off but if you like repairing things it is very well possible to rectify this lens.
Economically the lens is probably a write off but if you like repairing things it is very well possible to rectify this lens.
Re: Objective has defect
@MicroBob
@MichaelG
Actually the hue of that strange looking half-moon coloration is affected by the lighting and photography as well...
I hope that coominya will take the trouble and discover what it really is, just to satisfy (my) curiosity...
@MichaelG
Actually the hue of that strange looking half-moon coloration is affected by the lighting and photography as well...
I hope that coominya will take the trouble and discover what it really is, just to satisfy (my) curiosity...
Re: Objective has defect
The green area has a black border. This would be typical for a fluid medium between two surfaces.
Is there a forum here for bets?
Is there a forum here for bets?
Re: Objective has defect
Thanks for all the input guys, I decided to strip it down and as it turned out it was immersion oil caught between the bottom 2 elements. I cleaned them up with isopropyl alcohol and the empty objective barrel with petrol then isopropyl. I assembled it all by the numbers (But I think) the second bottom most lens may have flipped during insertion because the view doesn't focus crisply and the par-focal is out by a reasonable amount. Still, a good first foray into such a repair and I'll pull it apart again sometime soon and correct whatever is wrong.
Last edited by coominya on Sat Apr 21, 2018 7:07 am, edited 2 times in total.
Re: Objective has defect
Good progress there ... Looks like you might salvage it.
MichaelG.
MichaelG.
Too many 'projects'
Re: Objective has defect
If you haven't changed the order of the lenses it is no big problem to get it together again:
Five lenses, each two sides=2 ^5 =32 oportunities to get it right
Five lenses, each two sides=2 ^5 =32 oportunities to get it right
Re: Objective has defect
Nicely done. Thanks for posting and revealing the problem source.
Re: Objective has defect
Hi,
Thanks for sharing this interesting disassembly... Could you tell how the phase ring is put on the element.. Is it painted on?..
BillT
Thanks for sharing this interesting disassembly... Could you tell how the phase ring is put on the element.. Is it painted on?..
BillT
Re: Objective has defect
I didn't notice to be honest, I lost my loupe a while ago and used only eye glasses so could not see any great detail. I have a few ordered so when one arrives I'll rebuild it and then see if I can ascertain the method used. I also suspect I have somehow left a smear of oil on those two bottom elements so what would be the best way to ensure they are totally clean? I was thinking of a quick rinse in engine degreaser, then mild soapy water, then fresh water and finally isopropyl alcohol or white spirit.billbillt wrote:Hi,
Thanks for sharing this interesting disassembly... Could you tell how the phase ring is put on the element.. Is it painted on?..
BillT
I am just relieved the lenses are all separate with no compounds to deal with.
Re: Objective has defect
Hi,
I think I would stay away from the engine degreaser... It may be too harsh... I think the Isopropyl alcohol would be fine .... Someone used cleaned plastic tweezers to handle cleaned elements once and had no complaints... Keep us informed on your progress...
The Best
BillT
I think I would stay away from the engine degreaser... It may be too harsh... I think the Isopropyl alcohol would be fine .... Someone used cleaned plastic tweezers to handle cleaned elements once and had no complaints... Keep us informed on your progress...
The Best
BillT
Re: Objective has defect
Coominya,
Here is a link to web page about cleaning most anything optical... It may give you more info..
https://www.photonics.com/a32199/Cleani ... est_Method
BillT
Here is a link to web page about cleaning most anything optical... It may give you more info..
https://www.photonics.com/a32199/Cleani ... est_Method
BillT
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Re: Objective has defect
You are doing well so far. Make sure to check any doublets near the bottom very carefully for oil invasion. To have turned green, the oil has been there for a while and the cement, could be starting to be compromised without it being yet noticeable.
I have done dozens of these and it is amazing how much dirt or film can cling to those lenses, quite unperceived by good eyesight or even a small hand lens, even after scrupulous cleaning.
My standard routine is to clean all non lens items in a weak detergent solution , usually with a small soft brush. Air dry them under cover. When dry blow them off with a compressor, then put away under cover.The unmounted lenses I cleran as well as I can with quite conventional surfactants. I use a tiny amount of very plain, clear unscented dish detergent to remove the oil and rinse completely with isopropyl and water, drying and polishing with fine absorbant paper. Then lightly brush each surface with a fine very clean artists brush under some blower pressure, or use a very clean blower brush. Mounted lenses, I clean with cotton swaps and a very small amount of lens cleaner that has some surfactant in it, and then isopropyl. Isopropyl itself, is not good at removing deposited film, especially if it has an oily base.
All lenses need to be inspected individually under a stereo microscope. There can be contaminants on those lenses, that you cannot see otherwise. Once each surface has been certified film and fleck free, I put each one in a covered spotlessly clean petri dish. At reassembly, I again inspect each surface under a stereo microscope. There is almost always something more to remove. I pick up tiny debris with a very fine very clean artists brush.
I have done dozens of these and it is amazing how much dirt or film can cling to those lenses, quite unperceived by good eyesight or even a small hand lens, even after scrupulous cleaning.
My standard routine is to clean all non lens items in a weak detergent solution , usually with a small soft brush. Air dry them under cover. When dry blow them off with a compressor, then put away under cover.The unmounted lenses I cleran as well as I can with quite conventional surfactants. I use a tiny amount of very plain, clear unscented dish detergent to remove the oil and rinse completely with isopropyl and water, drying and polishing with fine absorbant paper. Then lightly brush each surface with a fine very clean artists brush under some blower pressure, or use a very clean blower brush. Mounted lenses, I clean with cotton swaps and a very small amount of lens cleaner that has some surfactant in it, and then isopropyl. Isopropyl itself, is not good at removing deposited film, especially if it has an oily base.
All lenses need to be inspected individually under a stereo microscope. There can be contaminants on those lenses, that you cannot see otherwise. Once each surface has been certified film and fleck free, I put each one in a covered spotlessly clean petri dish. At reassembly, I again inspect each surface under a stereo microscope. There is almost always something more to remove. I pick up tiny debris with a very fine very clean artists brush.
Re: Objective has defect
There are none, it's an old scope and all lenses thankfully are single elements.apochronaut wrote: Make sure to check any doublets near the bottom very carefully for oil invasion....
Sounds like sound advise.I have done dozens of these and it is amazing how much dirt or film can cling to those lenses, quite unperceived by good eyesight or even a small hand lens, even after scrupulous cleaning.
I knew I should have bought that stereo inspection microscope the other day, I just didn't want to be greedy. I already have 3 and it's only been a month and a half back into the hobby.
All lenses need to be inspected individually under a stereo microscope....
Re: Objective has defect
Thanks bill. I'll study it before I proceed.billbillt wrote:Coominya,
Here is a link to web page about cleaning most anything optical... It may give you more info..
https://www.photonics.com/a32199/Cleani ... est_Method
BillT