New Plan Fluor lens

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st_m
Posts: 28
Joined: Sun Jan 08, 2006 7:10 am
Location: Germany

New Plan Fluor lens

Post by st_m »

Some weeks ago, I have posted a message asking about the capabilities of a Nikon Plan Fluor 40x objective.
As noone answered, I guess, they're not widely distributed.
After thinking about buying one (for the price of a whole microsope) for two months, now I got one:

Image

(Sorry for poor image quality, but photo was taken with camera in the right hand, and using the left hand as a flash diffuser).

I got it yesterday and didn't have much time to try it out so far, but this evening I was using it for some hours.
My first impression is, that it has an incredible image quality.
Before I bought it, I had two concerns:
1) Does the high NA (0.75, dry) lead to a too shallow depth of field, and
2) Is it too sensitive on cover glass thickness variations.

But both is untrue. Absolutely no problem so far. I mostly viewed prepared slides, which are even worse in that respect.

I cannot see even the smallest amount of chromatic abberation, nor field curvature.

And the higher NA gives a much brighter field, at comparable settings (Am I right, brightness goes with the square of the NA, anything else left constant - I think so)?

rene
Posts: 125
Joined: Thu Mar 17, 2005 4:14 am

Post by rene »

Nice lens, stm, this NA is typical for a semiapo 40x. The more shallow depth of field is noticable in pics, but not really so much more then the standard 0.65. Same for it's sensitivity for coverslips. Even with the apo's 40/0.95, it's difficult to set the correction collar for coverslip thickness variation exactly right, it will become more noticable when going to extremes like DF, oblique lighting and using the lens with ful aperture (something you wouldn't do very often in brightfield).
Deviation will introduce sferical abberation, which makes the whole image more hazy, nothing to do with field curvature or chromatic abberation.

This seems like a lens for interference contrast (DIC) which might explain the extraordinary price (? What did you pay for it??)
No idea what the M/N2 on the lens means.

Good luck, Rene.

st_m
Posts: 28
Joined: Sun Jan 08, 2006 7:10 am
Location: Germany

Post by st_m »

Well, but it's not especially designed for DIC. The "M" means "medium aperture (0.5 - 1.0; because of slider)", and "N" Nomarski. What's the "2" for, I don't know.
But I don't use it for DIC (although I would like, but have a look how much brand new Nikon DIC equipment is).
There are no other flourite lenses. But the price of them is generally high if bought brand new (I paied about 1000$).
I wanted to exchange my old 40x achromatic lens, because its performance was just mediocre.
And I'm really happy with the new one.
Maybe, it's a very good idea to recommend people sometimes buying these things new (and not from eBay of whereever).
Soon, I'll also excahnge my 10x against a Plan Fluor, and my 4x against a real Plan APO. But the 100x oil immersion is still a problem. The really good ones cost about 10000$ (just one objective, really). That's too much.
Soon, I'll post some photos taken through this lens.
Steffen

rene
Posts: 125
Joined: Thu Mar 17, 2005 4:14 am

Post by rene »

Hi Steffen, steep price you paid for it, but I guess that's the curse of modern infinity. You have to compete with professionals and dito pricing. Didn't realise Nikon uses DIC on their objectives only to mention it COULD be used for DIC. But it makes sense, and the 2 might indicate condenser setting.
You're going the right way, I think high end is far better value for money at the low magnifications. With the 100x, differences between lenses quickly go to non-observable differences in brightfield, so you'd better try and get one on loan to compare what you really get for your buck. The modern high end series are amazingly complex to include all kind of corrections like eg flat response from 300 to 900nm or so. Great for R&D, but severely overspecified for brightfield use...
I do phytoplankton analyses professionally, I rely on just two lenses that I acquired last year. For old version 160mm I paid E500 for a 20/0.7 dry and E1250 for a 60/1.4, both olympus splanapo's. They are nearly the brightest objectives you can find. Especially the 20x seriously puts my camera (coolpix990) to shame. The 60x I got from Optovid in Germany, you should ask for a quote if you need anything.

Looking forward seeing your pictures,
Rene.

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