Nikon Plan 10 / 0.30 - DOF and using it

AndrewC · Post by **AndrewC** » Sun Nov 09, 2008 2:47 am

Hi,

I've got a Nikon microscope objective which I think is a Plan 10 / 0.30. Hard to be absolutely sure because the objective markings are printed not engraved and it has been rather enthusiastically cleaned.

I can't find this lens in Nikon's microscopy U site but it is referred to several times on this site.

Would I be right in thinking it has a DOF of 7.2um assuming a Nikon D200 sensor with COF of 20um ? Calculated from Nikon's formula

dtot = ln/NA2 + (n/M•NA)e assuming 590nm light in air.

So with a a DOF of 7.2um, what is the actual step recommended when stacking ? Something like 60% of DOF or maybe 5um in this case ?

I'm making a stage and trying to work out some stepper motor / linear slide specs and as this will probably be my highest power magnification, if I can work with it it I should be able to use the lower power reversed enlarger objectives I'm thinking of.

Thanks

Andrew

rjlittlefield · Post by **rjlittlefield** » Sun Nov 09, 2008 10:55 am

That all sounds correct. I use 5 microns step with my Nikon CF N Plan Achro 10X NA 0.30. If that lens is really what you think it is, you're in for a treat.

--Rik

AndrewC · Post by **AndrewC** » Sun Nov 09, 2008 11:54 am

Do you know a way of tracking a lens from it's serial number (114679) because that is clearly legible ?

Nikon presumably know but so far have not responded.

Andrew

rjlittlefield · Post by **rjlittlefield** » Sun Nov 09, 2008 12:36 pm

Sorry, I don't know that one. One of our other members might, or you can ask on the Yahoo Microscope group.

--Rik

Charles Krebs · Post by **Charles Krebs** » Sun Nov 09, 2008 2:10 pm

Andrew,

I don't know about serial numbers, but you can usually tell from the appearance of the mount. If it has a NA of 0.30, has the printed ID information (wears off easily

) , shiny barrel with three rows of rectangular knurling as shown below then that's it.

Like Rik, I typically use steps of 5 microns.

(I'll check my serial numbers on mine tonight. Might give a clue)

dmillard · Post by **dmillard** » Sun Nov 09, 2008 2:33 pm

AndrewC wrote:Do you know a way of tracking a lens from it's serial number (114679) because that is clearly legible ?

Nikon presumably know but so far have not responded.

Andrew

Hello Andrew -

I have two of the Nikon CF Plan 10/0.30 objectives; they have serial numbers 214046 and 212241.

David

rjlittlefield · Post by **rjlittlefield** » Sun Nov 09, 2008 3:01 pm

Mine are 111466 and 111933.

--Rik

AndrewC · Post by **AndrewC** » Sun Nov 09, 2008 3:01 pm

Physically looks identical to Charles' - except his has more paint

Andrew

Charles Krebs · Post by **Charles Krebs** » Sun Nov 09, 2008 3:13 pm

112679 for one of mine.

NikonUser · Post by **NikonUser** » Sun Nov 09, 2008 3:16 pm

Another photo HERE
# 116362

AndrewC · Post by **AndrewC** » Sun Nov 09, 2008 3:20 pm

thanks for all the pictures - I'm very sure it is the same lens

So what kind of bellows extension should I use for this objective ? The lens seems to have 160/0.17 under the "Plan 10" which I think means 160mm from the thread of the objective to the eyepiece tubes. So 160mm of bellows extension should do the trick more or less ?

... and the 0.17 means what ? 0.17mm working distance ? Surely not ...

Andrew

rjlittlefield · Post by **rjlittlefield** » Sun Nov 09, 2008 3:35 pm

Strictly speaking, the lens is designed to form its image 10 mm from the end of the tube, where the eyepiece's field stop would be. That means 150 mm from the shoulder of the mounting threads to the sensor plane. The lens will give 10X at that setting.

The 0.17 specifies nominal coverglass thickness. In theory, presence/absence of coverglass affects the lens resolution and spherical aberration. However, even at NA 0.30, objectives are quite tolerant of variations in tube length and cover glass thickness. (See http://www.science-info.net/docs/etc/Tube-Length-na.gif for details about tube length.)

Bottom line is that you can play around with bellows extension until you get the magnification and coverage you want, without having to be very concerned about degrading the image quality. And there's no need to worry about absence of coverglass, since that has no obvious effect on the image.

According to my records, the working distance of that lens is 9.22 mm. By observation, it's certainly close to that.

--Rik

AndrewC · Post by **AndrewC** » Sun Nov 09, 2008 3:47 pm

rjlittlefield wrote: According to my records, the working distance of that lens is 9.22 mm. By observation, it's certainly close to that.

--Rik

That's pretty much what i just concluded from looking into the bare lens from about 150mm away with a subject about 10mm on the other side

Thanks for the explanation

Andrew