Olympus CX41 Objective. Damaged or just bad to begin with?

[Dreamspy]

I've recently acquired an Olympus CX41 microscope. I'm a bit disappointed in the quality of the image I get at 40 x and 100 x, and I assume I need to replace them. The 10 x looks pretty good to my, but I have no experience with microscopes so I couldn't tell.

My main two questions are:

Should I buy original objectives or are there better alternatives?

and

Is this a decent microscope, should I expect to get good results from it?

The objectives that I'm referring to are:

Olympus Plan C
40x/0.65
"infinity symbol"/0.17

and

Olympus Plan C
100x/1.25 Oil
"infinity symbol"/-

The 10x looks super sharp, but I'm wondering if the 40x and 100x are damaged, or they were just not good to begin with.

Now I can clearly see that the 100x is damaged, allot of scuffing on the glass when looked at under a microscope. There seem to be some marks on the 40x, but I'm not so sure.

Here are videos taken from through the objectives of some lycopodium spores. Does this look ok to you? (I have no experience with microscopes, but I think these look pretty bad)

40x: https://vimeo.com/user2777216/review/31 ... f6fb4f477c

100x: https://www.youtube.com/watch?v=Kh-Q31l0YfA

And an image sample from my 10x, this is pretty good, right?

Full image:





100% crop:

[Ichthyophthirius]

Hi,

How did you prepare the spores?

They need to be in water or mountant and covered with a 0.17 mm (No 1.5) cover glass. The spores need to be sitting directly on the underside of the cover glass.

The 100x needs immersion oil n=1.515.

Anything else leads to spherical aberration as seen in the video.

Oil immersion objectives can be quite scratched and still work well. If there are a few scratches on the 40x that won't be an issue either.

Instructions for cleaning the front lenses can be found here: https://microscopy.duke.edu/sites/micro ... scsope.pdf

Regards, Ichty

[Ichthyophthirius]

Should I buy original objectives or are there better alternatives?

and

Is this a decent microscope, should I expect to get good results from it?

The Plan C are Olympus' basic Plan objectives and they are meant for this stand (modest field number).

They are very good for what they are. I have used them once and they gave a very good image (for being Plan achromats).

You should never use objectives other than Olympus on this microscope because the tube lens is designed that way. You could buy Olympus objectives with higher correction (like PlanFl) but as a beginner that doesn't make much sense. You should get decent images with the objectives you have (unless they are severely damaged).

[Dreamspy]

Hi,

How did you prepare the spores?

They need to be in water or mountant and covered with a 0.17 mm (No 1.5) cover glass. The spores need to be sitting directly on the underside of the cover glass.

The 100x needs immersion oil n=1.515.

Anything else leads to spherical aberration as seen in the video.

Oil immersion objectives can be quite scratched and still work well. If there are a few scratches on the 40x that won't be an issue either.

Instructions for cleaning the front lenses can be found here: https://microscopy.duke.edu/sites/micro ... scsope.pdf

Regards, Ichty

Now that's something completely new to me. Had no idea I needed to prepare samples.

So do I need to put the spores on a glass slide, put a water drop on it, and then the cover glass on top? What is the benefit of this in contrast to photograph it just sitting atop of a glass slide?

Regarding the 100x and the oil. Would I then need to put an oil drop between the cover glass and the lens, creating a seal between then lens and the cover glass?

This is higly interesting, are there any resources that I should read in order to get going with sample-preparation techniques?

[Ichthyophthirius]

Hi,

The need for a cover glass and oil has to do with spherical aberration. The objectives are designed for having a 0.17 mm cover glass with a certain diffactive index (n=1.515) in the imaging pathway. The 100x also needs oil.

Without cover glass and/or oil = high diffractive index medium, for those objectives, no sharp image can be formed. It's the same index mismatch that prevents (most) humans from seeing a sharp image with the naked eye under water (most of us need goggles so we can see through air last before light hits the cornea).

Spherical aberration becomes more problematic the higher the NA of the objective. That's why the 10x/0.25 is OK but the 40x/0.65 and 100x/1.25 perform badly. High NA objectives require good sample preparation!

There is a great introduction here:
Carl Zeiss: Microscopy from the very beginning
https://microscopy-news.com/download-ce ... beginning/

It covers all the basics.

[JohnyM]

Oil is special, it's not kitchen or diesel version

More expensive one's are made for fluorescence and high resolution microscopy. Type A should be good for you. While LDF is superior in every aspect, but much more expensive and you wont notice it's traits. Avoid FF type. Probably just search for "microscopy oil" on auction portal and pick some lower priced, it should be A.

Cedarwood oils (do they even make them anymore?) was drying and you needed to clean the front lens. The one we have is never drying, making cleaning the lenses practically needless. So avoid natural, bio, ecologic

With 100x you could skip cover glass (if you oiled the lens) and get usable image, but 40x is very sensitive to cover slip errors, so pay uttermost attention while preparing with dry 40x in mind. As silly as it might sound, but with coverglass... you get what you've paid for. Cheap coverglasses are very... unstable with their quality across the box. You won't notice any difference with 10x or 20x objectives.
We actually buy cheap coverglasses for quick "wet" slides, where we use dry 10x and 20x, and 40x oil. When slide will be prepared for permament mounting we use Zeiss supplied glasses.

Oh and if you prepare pollen or spores for high mags, mount them with OIL, not WATER. You'll get much better results. They tend to be hydrophobic tho and it's quite difficuilt taks with water and oil alike.

Also... you could get a DRY lens with NO COVER GLASS correction to avoid preparing at all. It's good for cases like that.

[Scarodactyl]

You should never use objectives other than Olympus on this microscope because the tube lens is designed that way.

I thought Olynpus did corrections largely in-objective, so the tube lens wasn't as critical (so in theory you could use other well-corrected infinite objectives with reasonable results). Does that just not end up being practical?

[Ichthyophthirius]

You should never use objectives other than Olympus on this microscope because the tube lens is designed that way.

I thought Olynpus did corrections largely in-objective, so the tube lens wasn't as critical (so in theory you could use other well-corrected infinite objectives with reasonable results). Does that just not end up being practical?

Hi,

Olympus uses RMS threads; the only other fully CF lenses are Nikon, which are M25. Zeiss ICS is the only other system with RMS lense, and Zeiss needs a very special tube lens. The Olympus 180 mm tube lens is also the only one that will give the rated magification.

So it's Olympus only, for practical reasons. Also, there's unlikely to be objectives that will fit to this microscope better than Olympus' own.

The design of the tube lens isn't that trivial. It needs to have the right correction (so it doesn't introduce new CDM), the right diameter and the right distance from the objective.

[JohnyM]

Zeiss - correction in tube.
Nikon - different size.
Leica - correction in tube (not 100% sure here)

What's left... Olympus

[Pau]

The only other option I know is the Nikon CF MPlan infinites (not the CFI60) that are RMS and 45mm parfocal and of good quality for uncovered specimens. The magnification at a Olympus microscope will be 10% smaller than nominal but they will work well

[JohnyM]

Oh, and BE plans! They are suprizingly good.

[Scarodactyl]

I was thinking of Nikon in particular. Are they too fat for an adapter to be practical on an olympus nosepiece?
Sorry for asking dumb questions, my only compund scope is an alphaphot so I am looking to uograde in the future.

[Pau]

I was thinking of Nikon in particular. Are they too fat for an adapter to be practical on an olympus nosepiece?
Sorry for asking dumb questions, my only compund scope is an alphaphot so I am looking to uograde in the future.

Fat is not an issue but long can be (and infinite too!).

I can use CFI 60 objectives on my DIN microscope Zeiss WL because its stage can be placed much lower than with my other microscopes (Zeiss Standard 18 ) but I need to do it with a tube lens and bellows, not with its trinocular head.

[Dreamspy]

Hi,

The need for a cover glass and oil has to do with spherical aberration. The objectives are designed for having a 0.17 mm cover glass with a certain diffactive index (n=1.515) in the imaging pathway. The 100x also needs oil.

Without cover glass and/or oil = high diffractive index medium, for those objectives, no sharp image can be formed. It's the same index mismatch that prevents (most) humans from seeing a sharp image with the naked eye under water (most of us need goggles so we can see through air last before light hits the cornea).

Spherical aberration becomes more problematic the higher the NA of the objective. That's why the 10x/0.25 is OK but the 40x/0.65 and 100x/1.25 perform badly. High NA objectives require good sample preparation!

There is a great introduction here:
Carl Zeiss: Microscopy from the very beginning
https://microscopy-news.com/download-ce ... beginning/

It covers all the basics.

Thanks this should get me started. I have background in physics and optics, which might help me out here

[Pau]

I was thinking of Nikon in particular. Are they too fat for an adapter to be practical on an olympus nosepiece?
Sorry for asking dumb questions, my only compund scope is an alphaphot so I am looking to uograde in the future.

Fat is not an issue but long can be (and infinite too!).

I can use CFI 60 objectives on my DIN microscope Zeiss WL because its stage can be placed much lower than with my other microscopes (Zeiss Standard 18 ) but I need to do it with a tube lens and bellows, not with its trinocular head.

Well, fat can also be an issue depending of the space in your turret. Yesterday I mounted two Nikon CFI with adapters in my 5 hole DIN Zeiss WL turret and they can't be placed in adjacent holes...so no more than two can be mounted. With a 4 hole or a wider turret it would not be an issue.