MicrobeHunter.com Microscopy Forum

Oil immersion, does one apply oil on the bottom of the slide (top of condenser lens) and the bottom of the objective?

For maximum resolution you want to apply oil on both the condenser and objective. The resolution is R=1.22λ/(N.A.objective+N.A.condenser). Without oil the N.A. of the condenser would be limited to ~0.9

Some people can't see a difference, others do. Say you use 0.55 um light and 1.4 objective and condenser. Oiling both condenser and objective would give you 0.24 um resolution, without oiling the condenser you'd get 0.29 um.

lperepol wrote:Oil immersion, does one apply oil on the bottom of the slide (top of condenser lens) and the bottom of the objective?

I put oil on the top of the condenser top lens and on the top of the slide. Perhaps gravity works in the other direction where you live!
For microscope cleaning I use quality cotton buds with wooden sticks. The sticks are useful as a second use to transfer a drop to a place where a dropper doesn't reach.

Bob

Hi, here are a couple of images from yesterday I think. One is with the condenser (simple 1.25 Abbe) and the coverslip both oiled - what one may call 'fully-oiled'. The other 'half-oiled', that is, just the coverslip oiled and the condenser dry....

Not a sharp subject such as a diatom etc, but nevertheless the difference, although subtle and not in the form of, or exclusively related to resolution, is noticeable. Is this difference 'worth the trouble' of oiling the condenser as well, that's a question the answer to which must depend on the observer and intended use of the images/observations perhaps....

Here's the fully-oiled version,


and here's the half-oiled version....


You may decide either way I think?

Personally for these images I prefer the fully-oiled but hesitate to consider the extra 'oiling' of the condenser 'worth the effort' - given I was observing purely for enjoyment at the time.

Oh yes, the slide image is of the xylem of a dicotyledon and should be considered in the horizontal direction. The serially-produced xylem vessels, xylem ray-parenchyma between them (think horizontally here) and to the right the 2-3 cells across column (vertical) of blue-stained cells is the cambium whence the new cells originated before differentiation, if the image continued to the right more the phloem 'side' of the vascular bundle would be seen....

Both images were given light PP - brightness adjustment and PSEv9 'auto-smartfix' applied to both, to the same degree.

Hi John,
thank you for posting this comparison! The subject is not critical and even here the advantage of the oiled condenser is very obvious.
What objective was this?

Bob

MicroBob wrote:Hi John,
thank you for posting this comparison! The subject is not critical and even here the advantage of the oiled condenser is very obvious.
What objective was this?

Bob

Hi Bob, this is from the BX40 and is a pretty std UIS2 PlanC N 100x 1.25. The PlanApo of the Leitz was superior I think - but not by much. This one has plenty of resolution and correction for now, especially with the advent of the 60x arrival within my system.

I also must purchase some 'proper' Olympus immersion-oil - of the more viscous formulation I think would be my preference. I'd be silly not to optimise such easily addressed areas with such a 'scope as the BX40 I think.

If anyone has genuine Olympus (or Olympus recommended) immersion oil for sale, just let me know - I'm on the lookout for some.....

If anyone has genuine Olympus (or Olympus recommended) immersion oil for sale, just let me know - I'm on the lookout for some.....

What are you using now and why do you require high viscosity. I understand it take a bit more effort to remove it.

https://cargille.com/about-immersion-oils/#guide

https://cargille.com/immersion-oils/#A1floz

75RR wrote:

If anyone has genuine Olympus (or Olympus recommended) immersion oil for sale, just let me know - I'm on the lookout for some.....

What are you using now and why do you require high viscosity. I understand it take a bit more effort to remove it.

https://cargille.com/about-immersion-oils/#guide

https://cargille.com/immersion-oils/#A1floz

Hi 75',
I'm still using the little bottle I bought from Brunel Microscopes about 4 years ago! Unbranded, apart from BM that is.

Looking at the links you kindly supplied, I think I may be better with the less viscous type-A.

Hi John

Various viscosity's of immersion oil here:

https://www.sigmaaldrich.com/catalog/pr ... RecCold3-3

I can send you some Cargille A if you like.

Roldorf wrote:Hi John

Various viscosity's of immersion oil here:

https://www.sigmaaldrich.com/catalog/pr ... RecCold3-3

Thanks for the link Alan - the 100ml is too big, but that's the right type too.

75RR wrote:I can send you some Cargille A if you like.

That would be really handy 75'. Would you pm-me please and we can sort out costs my friend.

In my experience, there are two popular oil viscosities - similar to those of Cargille type A and type B, respectively. Regardless of the brand name.
Possibly type B is useful for inverted microscopes, to avoid too much dripping of the oil from the objective to the nosepiece and downward.

I find that the difficulty with the viscosity is not only removal; with "mechanically unstable" mounts, like wet mounts or even mounts of gelly or half-hardened resin, moving the slide on the stage can disturb the mounting severely, even dislocation of the coverslip. This happened to me even with type A; with type B, it might be worse.