More objective questions

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wstenberg
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More objective questions

#1 Post by wstenberg » Wed Aug 01, 2018 2:31 am

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Still trying to figure out my objectives. I think I'm getting closer!

Here's one I just can't figure out...

I have 2 Zeiss Plan 2.5 objectives. The first one is straightforward. it says "Plan 2,5/0.08"

The second one is more complicated. It has a larger lens. It says "Plan 2,5/0.08" on the front, but on the back it says "Plan 2,5/0.0".

So the question is: why does it have a larger diameter lens? Why is it labeled differently on the front and the back?

What's the difference between the two?
William
Astoria, Oregon

Zeiss Axiomat
Zeiss Stereomikroskop
Zeiss Tessovar

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zzffnn
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Re: More objective questions

#2 Post by zzffnn » Wed Aug 01, 2018 3:47 am

Maybe the "8" paint was scratched off? Different front diameter may indicate slightly different optical design.

Zeiss owners 75RR and Charles should be able to tell you the exact model difference.

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75RR
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Re: More objective questions

#3 Post by 75RR » Wed Aug 01, 2018 5:55 am

Front lens diameters look to be different sizes (optical illusion?) but both are 11mm as far as I can tell.
Both have NA of 0.08
Missing '8' on yours is no doubt due to an etching error.
Though they both say Zeiss West Germany, the one on the left has an older design feel to it.
Have not noticed any difference between them in performance. (Note: I did not conduct a test to confirm this impression)
Missing '8' on yours is no doubt due to an etching error.
If it were a stamp it might be worth more ;)
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photomicro
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Re: More objective questions

#4 Post by photomicro » Wed Aug 01, 2018 9:31 am

wstenberg wrote:IMG_0367.JPGStill trying to figure out my objectives. I think I'm getting closer!

Here's one I just can't figure out...

I have 2 Zeiss Plan 2.5 objectives. The first one is straightforward. it says "Plan 2,5/0.08"

The second one is more complicated. It has a larger lens. It says "Plan 2,5/0.08" on the front, but on the back it says "Plan 2,5/0.0".

So the question is: why does it have a larger diameter lens? Why is it labeled differently on the front and the back?

What's the difference between the two?
They are just from slightly different eras of manufacture. The one on the left is the older design, and is like the ones shown in an early 1970's Zeiss publication I have. The other is much later, when the writing is printed rather than engraved (though might be both) and the outer casing design was changed. Fundamentally, they are the same lens. Since some of the older Zeiss objectives suffered separation (often termed delamination) of lens elements due to what they used to bond them, which they later changed, the later one may be a better bet. Plus lens coatings improved.

The serial number is a clue, as the one on the right has the catalogue number shown as 6-4 digits. 6 digit numbers were still used in a brochure dated 1983, so I guess yours is younger than this. Perhaps someone knows when Zeiss changed over.

regards

Mike

wstenberg
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Re: More objective questions

#5 Post by wstenberg » Fri Aug 03, 2018 1:35 am

Thanks everyone for the help. I was hoping it was something more exotic!
William
Astoria, Oregon

Zeiss Axiomat
Zeiss Stereomikroskop
Zeiss Tessovar

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