Objective - possible delamination problem?

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piotr
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Objective - possible delamination problem?

Post by piotr »

This is an image of a back focal plane of a 40x phase contrast objective (Zeiss Neofluar 0.75) that I received recently. As you can see, there is a gray smudge in a top right corner. Could it be a sign of a progressing delamination? So far, it doesn't bother me, because it is always covered by an aperture diaphragm (or a phase annulus), but I was just wondering.

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twebster
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Post by twebster »

Hi ya' Piotr :D

Yup, that's delamination. Will it progress? Probably not. I have it on good authority (Spike Walker) that delamination doesn't progress without a good reason, such as overheating the objective. I doubt that you can do that with your Zeiss Standard. According to Spike's website (the Ultraphot website) most delamination was caused by over-heating objectives with overly intense microscope lamps used in making videos or by some workers turning the microscope on and leaving it on all day :!: :D If the image looks OK I wouldn't worry about it. Heck, my 16x Neofluar ph2 has more delamination than that and the images are fine. :D

Best regards as always, my friend :!: :D
Tom Webster
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Post by piotr »

Thanks a lot, Tom! My first delamination. I begin to feel like a Zeiss expert ;-)

I'm using fibre optic illuminator (thans to Ron!), so excessive heat is not a big concern.

I have some problems with this objective. It is not parcentric nor parfocal with others, although the differences are not huge. And its contrast is not as good as I expeced from a neofluar. My 25x/0.65 seems to have a bit better contrast. On the other hand, this one gives a very nice phase picture. I need to test it more.
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twebster
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Post by twebster »

Hi ya' Piotr :D

I have a 40x Zeiss ph2 achromatic that is not concentric with the other objectives, too. It doesn't appear to affect the images, though. I have a 40x Zeiss Neofluar non-ohase objective and the 16x Neofluar ph2 objective. The 40x seems to have slightly better contrast than the 16x. I think the phase ring lowers contrast a tad. I find a slight tweak in Photoshop cures that. :D

Best regards, :D

PS. If you are really concerned that the 40x phase objective is defective, I'll be glad to take it off your hands for $50.00 :!: :wink:
Tom Webster
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Post by piotr »

Thanks for the offer, Tom!!! :-) :-) ;-) And for all your comments! :-)

I think I will give it another try. The seller I bought this objective from said that it is "clear and free from delamination", so I don't feel right about this. Phase picture is nice, but contrast seems to be washed out a little.
Piotr

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