What to do with Nikon Fluor 10x in poor condition?

[karhukainen]

I bought a Nikon Fluor 20x 0.75 160/0.17 on Ebay. It seemed a pretty good deal - until I got a Fluor 10x instead. And it's in bad shape. The seller agreed to return my money and let me keep the objective. I've been looking for a 10x Fluor too, so now I'm trying to figure out what to do with it.

I cleaned the front and back lenses, but it didn't help much. It seems the dirt is maybe inside and there are probably some scratches as well. The black ring on the front element has also scratches and the upper layer has parts missing. The mass around the lens (marked with a red arrow) is really soft. It started to come off when I used just distilled water with a little bit of dishwashing soap. The metal has some corrosion.

I tested the objective, and the image quality isn't actually that bad. I'll post a few sample images a bit later.

[viktor j nilsson]

Don't worry about the missing black, mine had that and it has negligible or no effect on image quality. I filled it in with matte black hobby paint.

The rest... Ugh. Is the image of the front lens before or after cleaning?

[karhukainen]

The rest... Ugh. Is the image of the front lens before or after cleaning?

After

The objective produces images that have a bit low contrast / some haze. These are straight out of camera, but obviously I would normally do some adjustments. I only have a 10x phase contrast objective which gives worse image quality, so I can't really compare.

[Alexander]

Considering the overall condition of that objective, I would try to clean the front lens as follows.

1. 10 % Potassium hydroxide for 15 minutes to remove biological dirt.
2. 5 % Acetic acid for 15 minutes to remove carbonic residues.
3. Xylene to remove what may have persisted.

If it is mechanical damage just forget it.

[karhukainen]

Considering the overall condition of that objective, I would try to clean the front lens as follows.

1. 10 % Potassium hydroxide for 15 minutes to remove biological dirt.
2. 5 % Acetic acid for 15 minutes to remove carbonic residues.
3. Xylene to remove what may have persisted.

Thanks. How would you go about applying these on the lens?

[Greg Howald]

When I enlarge your photo of the front lens I am convinced that the lens is indeed not scratched. I think the lens badly needs to be cleaned, but examining the lens in the photo makes me think of a dried up mold or fungi, and if that is the case, it can have a pretty good grip on the lens and be really difficult to clean. I would certainly want to follow Alexander's instructions.

[Greg Howald]

Be careful with the xylene (xylol). It is a great solvent, but it makes your hair turn white, your teeth fall out and your skin turn purple just before you die. Good for the glass, very bad for you .

[viktor j nilsson]

Agree that it looks a lot like a precipitate, or possibly fungus. Definitely worth trying out various solvents to see if any can get it off. Some grime can really take a lot of q-tips, solvents and elbow grease to get off.

[Alexander]

Considering the overall condition of that objective, I would try to clean the front lens as follows.

1. 10 % Potassium hydroxide for 15 minutes to remove biological dirt.
2. 5 % Acetic acid for 15 minutes to remove carbonic residues.
3. Xylene to remove what may have persisted.

Thanks. How would you go about applying these on the lens?

Carefully using some cotton swap. I am quite sure the lens will look much better after the first two steps already.

[karhukainen]

Carefully using some cotton swap. I am quite sure the lens will look much better after the first two steps already.

I mean, should I put a drop onto the lens and let it sit for 15 minutes or gently wipe it? I'm not fully convinced the stuff is outside the front element, but I'll definitely test your suggestion.

[Alexander]

Carefully using some cotton swap. I am quite sure the lens will look much better after the first two steps already.

I mean, should I put a drop onto the lens and let it sit for 15 minutes or gently wipe it? I'm not fully convinced the stuff is outside the front element, but I'll definitely test your suggestion.

Both the potassium hydroxide and the acetic acid need there time. Put a drop on the glass - just one drop it shall not float around - wait for 15 Minutes then suck it away using some tissue and gently wipe with the swap. Make sure you clean the objective thoroughly after each step. Mixing the chemicals may give strange results.

With the xylene, wetten a swap and wipe gently.

[JGardner]

This may be a rhetorical question, but I have to ask it: How does so much of this high-end professional equipment get into such bad shape? Do professional and university labs typically treat their equipment so roughly and store it so poorly that it ends up in this state?

[viktor j nilsson]

Carefully using some cotton swap. I am quite sure the lens will look much better after the first two steps already.

I mean, should I put a drop onto the lens and let it sit for 15 minutes or gently wipe it? I'm not fully convinced the stuff is outside the front element, but I'll definitely test your suggestion.

Both the potassium hydroxide and the acetic acid need there time. Put a drop on the glass - just one drop it shall not float around - wait for 15 Minutes then suck it away using some tissue and gently wipe with the swap. Make sure you clean the objective thoroughly after each step. Mixing the chemicals may give strange results.

With the xylene, wetten a swap and wipe gently.

I always put a drop of the solvent on the swab and do a spiralling motion from the center to the periphery. Most sources will tell you to never apply the solvent directly to the lens, although I'm sure that it won't do any serious damage in most cases. I can burn through 50 or more q-tips when I've received a seriously dirty lens (but hopefully it'll never get that dirty ever again).

The Clean Microscope from Carl Zeiss is an excellent resource:
https://hcbi.fas.harvard.edu/files/hcbi ... cope_e.pdf

[karhukainen]

Thank you, great advice! Now I just need to wait for the acetic acid to arrive - the only places that seem to sell it over here are bee farming supply shops...

This may be a rhetorical question, but I have to ask it: How does so much of this high-end professional equipment get into such bad shape? Do professional and university labs typically treat their equipment so roughly and store it so poorly that it ends up in this state?

Beats me, but my experience is that quite many people use microscopes even for work without any deeper understanding on how they should be used. I've studied biology at a university, and it was quite typical that minimal (+ bad) guidance was given when microscopes were used.

[Alexander]

Thank you, great advice! Now I just need to wait for the acetic acid to arrive - the only places that seem to sell it over here are bee farming supply shops...

Just use the vinegar in the kitchen. It is very much the same. No Balsamico of course. The cheaper the vinegar the better.

[karhukainen]

Just use the vinegar in the kitchen. It is very much the same. No Balsamico of course. The cheaper the vinegar the better.

Ah, I thought it would be better to dilute the stronger one with distilled water.

[Alexander]

Yes, it is better to use high quality chemicals and dilute it with aqua bidest. In real life some cheap vinegar does the job well enough.

[apochronaut]

This may be a rhetorical question, but I have to ask it: How does so much of this high-end professional equipment get into such bad shape? Do professional and university labs typically treat their equipment so roughly and store it so poorly that it ends up in this state?

Production or industrial microscopy by 9 to 5ers that don't own the equipment.

[karhukainen]

Well, I was able to clean the lens but like I suspected, it has multiple scratches. I'm still a bit surprised how little the image quality improved. I was lazy and didn't do a proper before-after image set, but the difference seemed barely noticeable.

[apochronaut]

It is sometimes surprising how much murk can be on the front lens surface and not cause much effect, particulatly if it is a transparent film. Deep scratches can be an issue due to refraction.
I have a Bausch & Lomb Balplan phase 100X that has a front surface that looks like it has been sandblasted. It is oil of course but you would never suspect it's condition during use.

[viktor j nilsson]

Good cleaning job. Those scratches won't have a big effect on image quality. You need to scratch a front lens like that quite badly before the image quality start to deteriorate significantly. But the grime that was there before certainly would have an impact. So if the image quality didn't improve with cleaning, there has to be something else wrong with that objective. Unless other lens elements are also covered in grime, I'd suspect that it may have been dropped and misaligned.

At NA 0.5, sample prep is starting to be pretty important. So I'd probably look at a good diatom slide, or a cover-slip covered micrometer slide as a target when testing.

[BramHuntingNematodes]

Yeah looks good scratches will cause some loss of contrast in proportion to the total surface area they take up which is not much. My Nikon 10x plan apo.has a chip out of it but you don't notice in use, especially as it's such a low power with a big good size front element

[PeteM]

Careful centering of the condenser and adjustment of the field and aperture irises can bring a bit more contrast to the images.

After that cleaning, it seems your 10x is now about as good as it's going to get - usable for brightfield and likely pretty decent for UV if you end up cobbling a fluorescent system together.

[karhukainen]

Forgot to add these.

Yeah, a micrometer slide would have been good but I couldn't find it, so it's just a waterflea for now. It would be interesting to know what this objective is capable of. The image quality is still far superior compared to my old Leitz 10x. I don't currently own any 10x for brighfield microscopy (just phase contrast), so I can't do much comparison.

Should I do something about the soft sealing mass that circles the lens? I can see there's some dirt also inside the objetive, so that probably lowers contrast a bit.

[brettpim]

Good cleaning job. Those scratches won't have a big effect on image quality. You need to scratch a front lens like that quite badly before the image quality start to deteriorate significantly. But the grime that was there before certainly would have an impact. So if the image quality didn't improve with cleaning, there has to be something else wrong with that objective. Unless other lens elements are also covered in grime, I'd suspect that it may have been dropped and misaligned.

At NA 0.5, sample prep is starting to be pretty important. So I'd probably look at a good diatom slide, or a cover-slip covered micrometer slide as a target when testing.

I bought a Leitz 10X for very cheap on ebay and it had some scratches on front lens, but I found it had negligible effect on image quality also. Does the impact of front element scratches get worse as magnification increases? My guess is yes because the scratch is getting closer and closer to the sample focal plane. From apochronaut's comment it seems like even at 100x damaged front elements are still quite usable sometimes.

[Alexander]

The 100x are immersion objectives. They are very tolerant against scratches on the front lens because the oil fill them op and there is extremely little refraction between glass and oil.

[viktor j nilsson]

Good cleaning job. Those scratches won't have a big effect on image quality. You need to scratch a front lens like that quite badly before the image quality start to deteriorate significantly. But the grime that was there before certainly would have an impact. So if the image quality didn't improve with cleaning, there has to be something else wrong with that objective. Unless other lens elements are also covered in grime, I'd suspect that it may have been dropped and misaligned.

At NA 0.5, sample prep is starting to be pretty important. So I'd probably look at a good diatom slide, or a cover-slip covered micrometer slide as a target when testing.

I bought a Leizt 10X for very cheap on ebay and it had some scratches on front lens, but I found it had negligible effect on image quality also. Does the impact of front element scratches get worse as magnification increases? My guess is yes because the scratch is getting closer and closer to the sample focal plane. From apochronaut's comment it seems like even at 100x damaged front elements are still quite usable sometimes.

The way I've understood it is that all points on the surface of the front lens contributes to image formation, and that each point at the image plane receives photons from all points on the front lens.. So a scratch doesn't affect a specific part of the image - the effect is spread over the entire image. The effect of scratches and chips are thus mostly manifested as reduced sharpness and contrast. And the deterioration is proportional to the % of the front lens surface that is damaged. Low magnification objectives tends to have fairly large front lenses, so even a fairly substantial scratch or chip usually only covers a fairly small percentage of the image-forming area, with little impact on image quality. But high-mag objectives tends to have much smaller front lenses, so a similarly-sized scratch will cover a much larger percentage of the front lens, and hence have a larger effect on the image. High magnification and high NA dry objectives are thus especially affected. For oil objectives, the effect of scratches can often be mitigated by oil filling the scratches.

In my experience, very small pits spread over the entire lens surface can have disastrous effects on image quality, but one or a few larger chips and scratches that combined cover a few % of the area have very little effect (and can often be very good buys if the price reflects the condition).