How to solve a problem related to oiling the condenser to the slide

[gekko]

One of the reasons I try to avoid oiling the condenser to the slide, even when it would be optically advantageous to do so, is that when I move the stage sufficiently in a lateral direction, the oil at the bottom of the slide gets between the slide and stage and the slide sticks to the stage. I thought of gluing two thin strips of long cover glass, one under each long side of the slide in order to have a separation between bottom of slide and stage, but I've not tried this yet (I've not yet had success in cutting two good strips ), so I don't know if it would work. Does anyone use a different method or have other ideas (other than "don't move the slide too far sideways" ? Many thanks!

Added later: It just occurred to me that I don't need to have the strips along the whole length of the slide, as just raising the four corners should work, making it much easier to do.

[charlie g]

Hello, gekko, I just went and measured my Labophot (my work horse stand usually) stage 'portal opening'...it measures 2 cmX7 cm in dimension!

So you have 15 mm to roamX65mm with a slide oiled to the condenser...for me that's a lot of roaming space.

If you need more area to observe...use a glass square...rather than a glass slide...and place your 22mmX40mm coverslip on that glass plate with the cover slips long axis aligned with the 65 mm stage opening. I eBay low cost purchased these glass plates (same thickness as glass slides). Let me know offlist if you'd like to try a few.

I still love (but don't use it!) my Reichert/Austria Biozet (student model of the famous:"Zetopan")...well my Biozet has a 25mm diameter stage openning to roam about with an oiled substage condenser.

I have Nikon S-ke(?)..it has over 30 mm stage openning to roam about with an oiled condenser.

The reason I suggest all try rectangular coverslips..these offer 80% room to roam still keeping an oilded condenser lens face far from the fluid at the coverslips border fluid moat. all the best, charlie guevara

[JimT]

My basic question would be have you noticed a significant difference between oil on slide to objective and oil from condenser to slide to objective?

Given my week eyes I probably wouldn't and wouldn't bother. MHOP.

JimT

[gekko]

Hi Charlie,
Thank you very much for your very interesting suggestion: I hadn't thought of that. I'll try it (I have some wide slides-- they may not be the right thickness but they'll do to test the idea). Yes, I've always used 40x22 mm cover glass for the reasons you mentioned. Thanks again for sharing your excellent ideas!

[gekko]

My basic question would be have you noticed a significant difference between oil on slide to objective and oil from condenser to slide to objective?
Given my week eyes I probably wouldn't and wouldn't bother. MHOP.
JimT

I guess you are asking if, when using an oil-immersion objective, I see a difference between oiling and not oiling the condenser to the slide. I think so. With the condenser dry, the NA of the condenser is limited to about 0.9. with oil, 1.35. However, now I need to document my answer and show pictures, so I'll try to do that and I may well end up disproving my assertion .
With Abbe condensers, you may well be right, because their aplanatic numerical aperture is supposed to be limited to something between 0.45 and 0.60, so that is another interesting comparison to do. Getting complex, but I (and maybe others) will probably learn something (assuming I do the testing right).

[JimT]

Since my Amscope has an Abbe condenser, and since I have no desire to clean another surface on the few times I use my 100x OI obj. I will await your test results.

Sounds like an article (with photos) for Oliver's next edition

[zzffnn]

Glycerine is less viscous than immersion oil and optically very similar (in terms of refractive index). So it is a lot easier to clean up and may work for you. But do clean up carefully as it is NOT resistant to fungus like immersion oil does.

[gekko]

I do not see a problem with cleaning up. I use Zippo lighter fluid on a piece of Pec-Pad (or microfiber cloth) and the immersion oil cleans right up. The first couple of times, it did seem somewhat of a bother to apply the oil to the objective and condenser, but it became an easy routine after that. At least that has been my experience.

[gekko]

Sounds like an article (with photos) for Oliver's next edition

You are right, of course (assuming I do get something useful/interesting). Actually I had started on two other articles, one on size indication of images, and the other on choosing the right size for the DF/Rheinberg center stop for a given objective. But I am a terrible writer and seem to constantly go up blind alleys, so I have not managed to finish either of them.

[vasselle]

Bonjour Gekko.
Quand je me sert de objectif 100 X a immersion je doit avouer avoir jamais mis une goutte huile sur le condenseur alors que je peux.
Il faudrait que essaye un jour.
Cordialement seb

[gekko]

Bonjour seb,

If you do, please show us the results. It would be very interesting to see if it results in any improvement. Many thanks!

[apochronaut]

Since my Amscope has an Abbe condenser, and since I have no desire to clean another surface on the few times I use my 100x OI obj. I will await your test results.

Sounds like an article (with photos) for Oliver's next edition

As far as condensers go, abbe condensers are the most ubiquitous and offer surprisingly poor imaging unoiled, when using an oil immersion objective.
OIled abbe aspheric are far superior, and oiled achromats superior again but the difference between those two is not that great. Neither are great unoiled but the high N.A. oil Achromats suffer the most from being diverted from their design requirements. It seems the lower the designed N.A.and sophistication of the design, the less a condenser suffers from being deviated from it's potential to achieve that N.A.

The pick of the litter unoiled are achromats with N.A.'s as close to 1.0 as possible. These are usually .90 but .95 are around too.
I did this test, for another thread. There are two sections to it 5th and 7th post.
viewtopic.php?f=5&t=1182

[gekko]

My basic question would be have you noticed a significant difference between oil on slide to objective and oil from condenser to slide to objective?
Given my week eyes I probably wouldn't and wouldn't bother. MHOP.
JimT

I guess you are asking if, when using an oil-immersion objective, I see a difference between oiling and not oiling the condenser to the slide. I think so. With the condenser dry, the NA of the condenser is limited to about 0.9. with oil, 1.35. However, now I need to document my answer and show pictures, so I'll try to do that and I may well end up disproving my assertion .
With Abbe condensers, you may well be right, because their aplanatic numerical aperture is supposed to be limited to something between 0.45 and 0.60, so that is another interesting comparison to do. Getting complex, but I (and maybe others) will probably learn something (assuming I do the testing right).

I obviously had a neural communication failure somewhere in my brain, as apochronaut had already made and posted such comparisons, and much better than I can hope to do.