Objective collar stiff / spring stuck

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boomblurt
Posts: 153
Joined: Sun Aug 18, 2013 1:37 am
Location: Australia

Objective collar stiff / spring stuck

Post by boomblurt »

I have just recieved an ebay purchase of a Nikon CFN Apo 40x/0.95, as seen at http://www.krebsmicro.com/Nikon_CF.pdf

Although in good condition, the adjustment collar is very stiff - it will rotate but takes a lot of force, and the spring doesn't seem to be working.

What can I do to get the objective back in goood shape please?

Edit: The two rings with knurlings are easily unscrewed, but I'm reluctant to try to remove anything more. The lever that moves the adjustable lens group is smooth. Could it be solidified lubricant between the lens and the casing?
Geoff

boomblurt
Posts: 153
Joined: Sun Aug 18, 2013 1:37 am
Location: Australia

Post by boomblurt »

I don't know if this was the right way to go but a few tiny drops of de-solv-it quickly made everything smooth again. I used as little as possible and removed any excess.

Although it works well with DIC, image quality of the 40/0.95 appears similar to the 40/0.70 DIC, although I haven't taken any photos yet so it's just a first impression. My CFN 10/0.45 Apo was a noticeable improvement over the 10/0.30 Ph1.
Geoff

Pau
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Location: Valencia, Spain

Post by Pau »

No actual experience with that model. I bough a Zeiss Planapo 40/0.95 that also had the correction collar stiff. I removed just the lower shell and cleaned of residues without solvents nor lubricants. Now it works fine.

The difference between 40/0.70 and 40/0.95 is not so evident at first look, but it is when you get used to the correction collar and with subjects with details small enough like some diatoms. The 0.70 is more forgiving when coverglass thickness and sample thickness are not optimal. I continue using both objecives.
Pau

JohnyM
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Joined: Tue Dec 24, 2013 7:02 am

Post by JohnyM »

If you're into focus stacking... enjoy your new correction collar.
There is a reason why i got 0.7 AND 1.4 lenses, without anything between.

After using solvant, make sure you remove old grease before it gets stuck again. If you wont do that fairly quick, grease will get where you dont want it.

boomblurt
Posts: 153
Joined: Sun Aug 18, 2013 1:37 am
Location: Australia

Post by boomblurt »

Just did a few quick stacks of diatoms and see that the 0.95 Apo is clearly better, for both BF and DIC. Although I've seen discussions of NA and coverslip thickness and spherical aberrations it is still surprising how much difference the collar setting makes.
Geoff

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