Meopta lens problems

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Thl05
Posts: 14
Joined: Wed Nov 27, 2019 6:10 pm
Location: SW England

Meopta lens problems

Post by Thl05 »

My Meopta objectives have poor contrast. Resolution seems to be ok? but it is like looking through a mist !
Do they 'just' need cleaning. If so is there a good "How to" ? Not sure of its vintage, guess at 60s or earlier, would acetone be ok ?
The 1st pic is of the Meopta 10:1 and the 2nd is another10:1 that I am using as a reference.

The 3rd pic is with the Meopta 45:1 and is dismal as you can see when compared with the ref10 scaled up by 430%, in the 4th pic.

The three 'pixel peek' comparisons show that the resolution of the 45 is, as would be hoped, better than the scaled-up 10.

Thanks for any thoughts?
The specimen is a dried blood smear. My blood ! peeling potatoes is dangerous and should be left to experienced significant_others :) !!
Meopta10_5138s.jpg
G10_5139s.jpg
Meopta45_5137s.jpg
G10X430%-5139s.jpg
sPixelComp.jpg

Scarodactyl
Posts: 444
Joined: Sat Apr 14, 2018 10:26 am

Re: Meopta lens problems

Post by Scarodactyl »

They could be grimy. There could be internal mold or delamination. You'd need to have a close look at them. A stereo microscope works well for this type of inspection.

Ichthyophthirius
Posts: 1094
Joined: Thu Mar 07, 2013 5:24 am

Re: Meopta lens problems

Post by Ichthyophthirius »

Hi,

The 45:1 requires the object to be covered with a cover glass. Ideally, there should also be a mountant between the blood smear and the cover glass as well (balsam or a drop of immersion oil). The open, uncovered smear results in strong spherical aberration. https://www.olympus-lifescience.com/fr/ ... spherical/

Never, ever use acetone on these vintage optics (the very worst). Some older systems don't even tolerate ethanol. Xylene was recommended by most companies and medical grade petroleum ether is a good and safe choice. There are some excellent instructions here: https://microscopy.duke.edu/sites/micro ... scsope.pdf

Thl05
Posts: 14
Joined: Wed Nov 27, 2019 6:10 pm
Location: SW England

Re: Meopta lens problems

Post by Thl05 »

Thank you both,

mold and delamination sound scarily terminal !

and I promise never ever to let acetone anywhere near them. I suspected that may be contraindicated, hence the question but that is all that I have at the moment except household detergent ! so will give them a reprieve for now.

Thanks for the recommendation to the pdf.

Immersion oil, I wouldn't have thought of that, I have several small bottles unused, in my box of inherited gifts. No other mountants came my way. I have been using the Legg-Dioni fructose methods. I also learned from OliverK that I should have diluted it with water, oh well, next time I stab myself many other experiments will follow ;)

kutilka
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Re: Meopta lens problems

Post by kutilka »

Previously, a 3: 1 mixture of diethyl ether and ethanol was used in Meopta to clean optics. Acetone + ethanol of about 9: 1 is now used.

Thl05
Posts: 14
Joined: Wed Nov 27, 2019 6:10 pm
Location: SW England

Re: Meopta lens problems

Post by Thl05 »

kutilka wrote:
Tue Jul 28, 2020 12:03 am
Previously, a 3: 1 mixture of diethyl ether and ethanol was used in Meopta to clean optics. Acetone + ethanol of about 9: 1 is now used.
Thank you for the information.
To be sure I am understanding correctly : they now use (Acetone+ethanol 9: 1) on both old and new lenses ?

kutilka
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Location: Czech republic
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Re: Meopta lens problems

Post by kutilka »

Meopta service of old lenses no longer does ...
Acetone is only used for current production.

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