Fluor vs Plan Fluor?

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Fluor vs Plan Fluor?

#1 Post by Sauerkraut » Wed Mar 18, 2020 5:13 pm

I'm curious what the difference is between these 2 objectives as far as optics quality for my Optiphot:

Fluor 40x ph3 DL:

https://www.ebay.com/itm/Nikon-Fluor-40 ... SwRwddM0ik

and Plan Fluor 40 ph3 DLL:

https://www.ebay.com/itm/Nikon-Plan-Flu ... Sw4KdeWYnu

Thanks for any input.

I've been away awhile. First the holidays got me. And now with coronavirus, I unsuccessfully scour the supermarket shelves each day for toilet paper. Presumably my neighbors all have 500 extra rolls stashed in their attics.

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Re: Fluor vs Plan Fluor?

#2 Post by MichaelG. » Wed Mar 18, 2020 7:57 pm

At the risk of stating the obvious ...

The first has a correction collar, which is useful if you use a range of coverslip thicknesses.

https://www.microscopyu.com/tutorials/a ... on-collars

The second does not; but it’s Plan, so will be in good focus across the field [assuming that the correct 0.17mm coverslip thickness is used].

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Re: Fluor vs Plan Fluor?

#3 Post by Wes » Wed Mar 18, 2020 8:07 pm

The correction collar on the Fluor objective is probably there because of the high N.A.

The Plan-Fluor has a lower N.A. and therefore doesn't need such stringent control over coverslip thickness. If you plan on doing photomicrography I'd go with the Plan lens. If you just look for eye candy on the go I'd choose the higher N.A. lens.
Sauerkraut wrote:
Wed Mar 18, 2020 5:13 pm
And now with coronavirus, I unsuccessfully scour the supermarket shelves each day for toilet paper. Presumably my neighbors all have 500 extra rolls stashed in their attics.
I don't understand the toilet paper meme. I'm under lockdown now, not doing anything, no energy requirements and I eat way less than normal. Why would I need the extra tp? Might get mobilized soon to test samples for coronavirus which would break the epic boredom though.
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Re: Fluor vs Plan Fluor?

#4 Post by apochronaut » Thu Mar 19, 2020 12:13 am

Terms such as fluor , Fluor, F, fluorite, Fluorite , advanced achro or semi apo are meant to describe the degree of colour correction : basically how limited the chromatic aberration is .
Although different manufacturers use differing designs, generally speaking the level of ca control is measured on axis or dead center. For this type of objective , the ca correction is between an achromat and an apochromat. There will still be corrections for coma, curvature of field, ca, astigmatism and spherical aberration required increasingly as the view extends towards the periphery of the field. The wider the field, the more extreme the corrections required.

The addition of the term plan to a design, means that many of those other corrections have been accounted for and rectified up to a defined field of view. Since the degree of planarity is also manufacturer dependent, the degree of correction for flatness of field varies with the manufacturer.

Many microscopes of the past claimed plan optics but it was only up to 18mm. The better designs had conquered 19mm and 20mm long ago , which makes a big difference to the value of the view.

When considering any plan objective, one needs to investigate just how far does the plan imaging extends. One could easily have a plan objective/eyepiece combination with a 16mm f.o.v. Put that same objective into a system with compatible eyepieces that offer a 20mm field of view and all of a sudden those objectives which were designated as plan at a 16mm f.o.v. , are no longer plan.
That was a common trick played out with some older Japanese stuff and now being played out with cheaper Chinese optics. .

Under a current paradigm of optical configurations for the microscope, one should expect plan to be at least 20mm f.o.v. and fluorite without any further flatness of field descriptor should be corrected to around 16mm f.o.v. , so reasonably flat and well corrected that far but probably falling off considerably in most optical corrections at 20mm. This is also mfg. dependent.

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Re: Fluor vs Plan Fluor?

#5 Post by viktor j nilsson » Thu Mar 19, 2020 1:22 pm

I have the non-phase version of the Fluor 40x 0.85 with correction collar. I also have the 10x and 20x Fluor CF objectives from the same series.

Unfortunately, I cannot compare them to the Plan Fluor objectives as I have never used any of those. The Plan Fluor were some of the last objectives Nikon developed for the 160mm CF system. So I think you can safely assume that they are going to deliver great performance. I believe they weren't produced for very long as Nikon rather soon went over to infinity systems. But I can give some hints as to the performance of the CF Fluor (non-plan).

The older CF Fluor objectives are really, really nice.
I just had a closer look using a coverslip-covered micrometer slide and Klaus Kemp's 8 form test slide. All of the dry Fluors (10x, 20x and 40x) are very well corrected for field curvature as far as I can see with my 10x/18 CFW eyepieces. I can only detect a slight decrease in sharpness at the very extreme periphery.

I directly compared the 20x 0.75 CF Fluor to a 20x 0.75 CFN Planapo using Klaus Kemp's 8 form test slide. While the PlanApo had a slight edge in resolution and LoCA (out-of-focus CA), they are very very close. They really don't differ much at all in field planarity across the 18mm visual field.

I also compared the Fluor 40x 0.85 to a CF PlanApo 60x 0.90. The Fluor has higher contrast and delivers an overall nicer image than the PlanApo 60x, as you can expect given the higher NA/Mag ratio. It's definitely my favourite dry high-NA objective. Just a little bit of LoCA compared to the PlanApo.

The FLuor 40x 1.30 oil on the other hand is defintely not plan to a 18mm FN. It's very sharp in the center, though!

My main conclusion is that Nikon were very modest when they decided to not put the "Plan" label on their earlier-generation CF Fluor's. I am sure the newer Plan Fluors have at least a slightly larger usable field, but the old ones definately do not suffer in this department.

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Re: Fluor vs Plan Fluor?

#6 Post by MicroBob » Thu Mar 19, 2020 3:47 pm

Sauerkraut wrote:
Wed Mar 18, 2020 5:13 pm
I unsuccessfully scour the supermarket shelves each day for toilet paper.
Bad luck, no corona-virus fortress for you!

http://debeste.de/120592/Die-deutsche-F ... -den-Virus

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Re: Fluor vs Plan Fluor?

#7 Post by Sauerkraut » Fri Mar 20, 2020 3:00 pm

Wow, this is a lot of great information from everyone. Many thanks. It's going to take me a bit to re-read and digest, but sounds like either one would ultimately be fine. I just hadn't seen an objective with the plan designation along with the fluor.

As for the correction collar - I have a few objectives with them but haven't felt a need to make any adjustments, so my needs are likely not that stringent.

No toilet paper fortress for me, MicroBob. Hopefully this shortage is not a commentary on Americans and their bathroom habits. I promise there are a few normal people here. Somewhere...

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