Nikon objective question

Sumguy01 · Post by **Sumguy01** » Sun Nov 25, 2018 12:07 pm

Hi guys
I recently purchased a Nikon CF 160 Fluor 40/1.30 oil DIC objective.
It has a correction ring with a range that is 1.3 - 0.8
What is it correcting?
I have other objectives that correct for coverglass thickness, they have a range 11-23.

rjlittlefield · Post by **rjlittlefield** » Sun Nov 25, 2018 12:16 pm

Are you sure that's a correction ring? It sounds more like control for an internal iris.

--Rik

Pau · Post by **Pau** » Sun Nov 25, 2018 12:36 pm

If it isn't an aperture diaphragm as Rik suggests it would be a "cover glass" correction ring, in this case it would be to be used in an inverted microscope to see through the slide itself, not the cover.

Ichthyophthirius · Post by **Ichthyophthirius** » Sun Nov 25, 2018 12:57 pm

Hi,

As has been said, this is the control for the internal iris. It reduces the NA from 1.3 down to 0.8. This allows the objective to be used for darkfield observation (to great effect).

Regards, Ichty

Sumguy01 · Post by **Sumguy01** » Sun Nov 25, 2018 3:40 pm

Hi guys
Thanks for the reply's
I will play with it some to see how it does with DF.
It probably is an iris control.

Pau · Post by **Pau** » Sun Nov 25, 2018 3:49 pm

If it is an iris you must be able to see it close to the rear part of the objective

iconoclastica · Post by **iconoclastica** » Sun Nov 25, 2018 4:20 pm

Speaking of nikon objectives: could anyone tell me what's the difference between cf-n, cf-e and cf-s?

Sumguy01 · Post by **Sumguy01** » Mon Nov 26, 2018 1:31 am

Thanks for the help guys
I was able to check it out this afternoon.
It is for iris control.
If I stop it down to 0.8 I can get DF but most importantly for me I can get better oblique.

JohnyM · Post by **JohnyM** » Mon Nov 26, 2018 1:49 am

Dont overdo that iris, best to keep it open. 40x/1.3 is already ~F16
Sole purpose of this, is to allow ~ 1.1 NA darkfield vs 0.95 for dry lens.

Getting rid of coverlsip correction is a bonus

Ichthyophthirius · Post by **Ichthyophthirius** » Mon Nov 26, 2018 2:38 pm

iconoclastica wrote:Speaking of nikon objectives: could anyone tell me what's the difference between cf-n, cf-e and cf-s?

Hi,

I've never heard of cf-e or cf-s. Do you have a reference or illustration? All I know are Nikon CF, CFN, and CFI.

viktor j nilsson · Post by **viktor j nilsson** » Tue Nov 27, 2018 1:21 am

Ichthyophthirius wrote:
iconoclastica wrote:Speaking of nikon objectives: could anyone tell me what's the difference between cf-n, cf-e and cf-s?
Hi,

I've never heard of cf-e or cf-s. Do you have a reference or illustration? All I know are Nikon CF, CFN, and CFI.

Maybe you are referring to the SC objectives, which are not CF, but was a series of student microscopes that had an extra lens system between the objectives and head? Discussed here: http://www.photomacrography.net/forum/v ... hp?p=64987

Otherwise I don't know what cf-s is either.

The CF series is well described in this folder, as I'm sure you are aware: http://www.krebsmicro.com/Nikon_CF.pdf

CF achromats and CF E achromats are very basic with pronounced field curvature. Some like the 10x is fine for stacking though as shown repeatedly on this forum.

CF E is the economy series. They are plan achromats and a VERY pronounced step up from the plain achromats and E achromats. I like them, very good value.

CF N is again a clear step up from CF E, but not as pronounced a step up as from plain achromats to E plan I'd say. They are also describred as plan achromats, but have higher resolution than CF E Plan. Nikon describes the CF N Plan as similar to Fluor objectives, which sounds about right.

And then there is CF N Plan Apochromats that I'm sure are superior but which I cannot afford.

I use 4x 10x and 100x from the CF E Plan series and 20x and 40x PH3 from the CF N series on my microscope and I'm pretty happy with all of them. I also have the CF achromat 10x which I am not using anymore but was OK for stacking when I was starting out.

iconoclastica · Post by **iconoclastica** » Tue Nov 27, 2018 3:56 am

Hm, it seems that in my eagerness to get confused I misread CFI-S for CF-S, for I cannot find the reference back indeed.

Anyway, your explanation of the -E and -N is most helpful and much clearer than the Nikon folder! Upto now, I avoided the E series, thinking that 'economic' meant cheapest and simplest...

viktor j nilsson · Post by **viktor j nilsson** » Tue Nov 27, 2018 5:56 am

If you are on facebook you can join the Amateur microscopy group, where Ken Schwartz some time ago posted a really good comparison of CF E Plan 40x 0.65 and CF N Plan 40x 0.70

It's here:
https://www.facebook.com/groups/Amateur ... 573470193/

Not sure if you can see it if you are not a member.

iconoclastica · Post by **iconoclastica** » Tue Nov 27, 2018 6:14 am

Yes, I am allowed to see it as non-member. Very intructive.