Microscopes with 33mm parfocal capability?

[PeteM]

I've acquired a number of Lomo objectives and would like to find a good-performing stand for them. Anyone know what stands can focus that close, or which can easily shim the stage up?

I have an AO 4 that works and might get another. However that one already has a full complement of AO objectives.

I shimmed both the stage and condenser of a Wesco (decent Japanese from maybe the 80's) scope but I was only marginally happy with the somewhat fiddly focus. This scope stacks numerous ball tracks, two arrived far out of adjustment, and then are a pain to adjust. Seems more a scope for a single careful user than a bunch of kids.

Lomo stands seem hard to find and only so-so (from third party opinion) in operation.

I suspect that some of the early Olympus models might work, though I'm not a fan of their small stages and stage micrometers (the ones with concentric dials, sticking out on the left side).

Anything else out there of good quality that can either focus directly or shim just the stage (good condenser attached below)? I have enough Lomo lenses to equip maybe 3 scopes for our kids' program.

Thanks in advance for any suggestions.

[zzffnn]

Some Nikon model S (black in color, 34mm parfocal) scopes may work for you. I think at least some of its trinocular heads can provide simultaneous eye/camera views. And those heads are compatible/exchangeable with those of Labophot/Optiphot. But I am more sure about their condenser mount flexibility or mechanical stage, since I don't have one.

My Nikon model G (which is a lower model than S) can focus directly with short LOMO objectives. But its condenser mount is not easily compatible with other types of condensers. And its mechanical stage broke on me - fixing its ball bearing mechanism was difficult and not complete in my hands. Focus mechanism is nice, if you can find one that does not have a broken nylon gear

AO4's trinocular head cannot provide simultaneous eye/camera view. Its condenser mount may need modification to accept other condensers. If you cna get pass those cons, they should work.

Older Olympus is 36mm parfocal, IIRC. So they may or may not focus with short 33mm LOMOs.

I have a Biolam and do not like its stage/focus mechanisms (which is much worse than AO4). I am guessing their much bigger and expensive research scopes may work better.

I love my LOMO water immersion apos. So much so, that I modified a Nikon Labophot/Optiphot to use them. I raised up the stage 12mm with machine nuts and longer (M4, IIRC) screws. Then I used a Nikon condenser dovetail adapter and Legos/super glue to raise up condenser 12mm.

[PeteM]

Thanks, ZZ.

[lorez]

I can't help with your immediate question, but if you are looking for some scopes for student programs send me a message. I have a program in which you may be interested.

lorez

[Uxx4]

Ok. I use Lomos 40x.75na and APO 60x1.0na water immersion objectives with ease and at as fine resolution as one could hope for on a 200mm Meiji and a 170mm Ortholux I. Because of the objectives high na's, resolution is not compromised. To get around the length problem, I employ 15mm extenders. 10 or 12mm might work fine, but using the 15mm's assure that the regular sized objectives don't interfere when using a Petri dish, etc, on the stage. I suggest that this is a far easier approach than leggos, glue, changing stage heights, etc. As far as condensers, anything of sufficient quality and appropriate na should work fine. Just play with your irises, rack your condenser to satisfaction, and enjoy. For the 60x, I use a nikon abbe 1.30, iris usually wide open and racked down a little on the Meiji. On the Ortholux, it's a little more complicated because of the dovetail condenser, but I basically removed the leitz condenser, placed a B&L 1.30 abbe on / in the carrier. Believe me, there are some pretty easy solutions. For the 40x, a lower na condenser or adaptations I find necessary.

I imagine that you have conquered all of the daunting techniques since the time of your post. BUT, I wanted to comment in case others find this thread. BTW, on a whim, I experimented placing a drop or two of water (steam distilled) on the condenser. Shockingly great results! But, I will not recommend at this time because I just began experimenting.

[billbillt]

Ok. I use Lomos 40x.75na and APO 60x1.0na water immersion objectives with ease and at as fine resolution as one could hope for on a 200mm Meiji and a 170mm Ortholux I. Because of the objectives high na's, resolution is not compromised. To get around the length problem, I employ 15mm extenders. 10 or 12mm might work fine, but using the 15mm's assure that the regular sized objectives don't interfere when using a Petri dish, etc, on the stage. I suggest that this is a far easier approach than leggos, glue, changing stage heights, etc. As far as condensers, anything of sufficient quality and appropriate na should work fine. Just play with your irises, rack your condenser to satisfaction, and enjoy. For the 60x, I use a nikon abbe 1.30, iris usually wide open and racked down a little on the Meiji. On the Ortholux, it's a little more complicated because of the dovetail condenser, but I basically removed the leitz condenser, placed a B&L 1.30 abbe on / in the carrier. Believe me, there are some pretty easy solutions. For the 40x, a lower na condenser or adaptations I find necessary.

I imagine that you have conquered all of the daunting techniques since the time of your post. BUT, I wanted to comment in case others find this thread. BTW, on a whim, I experimented placing a drop or two of water (steam distilled) on the condenser. Shockingly great results! But, I will not recommend at this time because I just began experimenting.

Hi Uxx4,

" I experimented placing a drop or two of water (steam distilled) on the condenser. Shockingly great results! But, I will not recommend at this time because I just began experimenting."

I would certainly like to hear more about this!...

The Best,
BillT

[Uxx4]

Hi Uxx4,

" I experimented placing a drop or two of water (steam distilled) on the condenser. Shockingly great results! But, I will not recommend at this time because I just began experimenting."

I would certainly like to hear more about this!...

The Best,
BillT

Hi BillT,

I will be sure to keep you posted!

[zzffnn]

Uxx4, welcome to the forum.

http://www.science-info.net/docs/etc/Tube-Length-na.gif

If you read the above figure. At NA 1.0, image quality will be degraded by spherical aberration, if you extend tube length to over 10mm. With water immersion, performace degradation is more than oil immersion (as shown in that figure). On you Leitz, you extended 25mm. Not saying one cannot do that, but you have to accept that trade off for convenience.

Your Meiji is an infinity model, correct? The situation is more complicated with that one. I would guess your 40x NA 0.75 would be ok, but not the 60x NA 1.0 won't perform as well as it should.

Water immersion on condenser is optically fine at below NA 1.2, but not mechanically. Most condenser top lens is not sealed against water and may leak over time. I have done water immersing a LOMO condenser and it now leaks water to its inside lenses.

[Uxx4]

Uxx4, welcome to the forum.

http://www.science-info.net/docs/etc/Tube-Length-na.gif

If you read the above figure. At NA 1.0, image quality will be degraded by spherical aberration, if you extend tube length to over 10mm. With water immersion, performace degradation is more than oil immersion (as shown in that figure). On you Leitz, you extended 25mm. Not saying one cannot do that, but you have to accept that trade off for convenience.

Your Meiji is an infinity model, correct? The situation is more complicated with that one. I would guess your 40x NA 0.75 would be ok, but not the 60x NA 1.0 won't perform as well as it should.

Water immersion on condenser is optically fine at below NA 1.2, but not mechanically. Most condenser top lens is not sealed against water and may leak over time. I have done water immersing a LOMO condenser and it now leaks water to its inside lenses.

zzffnn,

Thank you for the welcome. I really appreciate your taking time to provide EXPERT help and guidance which is needed and will be heeded and studied.

Yes, the Meiji is a 200mm ML8530+ infinity strain free polarizing system with huge, oversized 30mm O.D. objectives. I've had the 40x for years, just acquiring the 60x. The stock LWD condenser is fine for the 40x. I bought a very affordable Nikon 1.30 with diaphragm and blue filter for the 60x. After your instructions and comments, I'll report back regarding practical observations. It fits the Meiji perfectly.

I have a number of older black body B&L DynaSeries1.30 NA condensers, and greys as well. I'm using one of these for the leitz. Other than the top lens, there are no other. Mechanically, there is just the diaphragm. This is the only condenser that I have tried with water applied. Not much on the leitz to be damaged if water leaks, easy cleanup with no electronics exposed. I am very curious to learn if the condenser will leak. As I have just begun this methodology, I have less than an hour experience. Will sparingly test out the system over the next few weeks. As for the condenser. I'll immediately stress it, keeping it over watered, and observe when leaks begin.

Thank you again! I haven't fully addressed your post. Forgive, please.

More Soon,

Uxx4

[apochronaut]

Uxx4. The black Dynoptic condenser , 31-58-07, a 1.3 N.A. abbe type, is a 2 lens condenser. Accessing the lower lens is done by removing the 3 screws on the side that lock in the iris diaphragm. The lower lens, can be then removed from below. For the grey 1.3 N.A. abbe condenser, the lens housing can be removed from the iris diaphragm, by unscrewing the lens housing from above.


With respect to the immersion of condensers. A small drop of oil on a condenser top lens, is no more difficult to clean off, than water. You don't really even need a solvent really, just an absorbent tissue will do and 99% of the residual oil will be captured. The rest wiped off with a second tissue. That is barely more effort than cleaning up water, with the added benefit of getting peak performance, not a watered down performance. Water, to boot is much more likely to spill off of the condenser nose an need to be cleaned off, farther down on the condenser, or spill into illuminator components.

If the limiting factor is the cost of immersion oil, which can be quite high, one can always substitute the clearest vegetable oil you can find, such as refined sunflower or grapeseed. While you will not achieve the spec'ed level of performance that a dedicated immersion oil provides, it certainly will be better than immersing the condenser in water, even glycerin would be better.

[75RR]

One can sometimes find Cargille immersion oil on ebay at very reasonable prices, but it can take a little time and patience.

In the meantime, here is a list of the Refractive Index of 'Common Household Liquids' as published in a Gemology website under the query:

Looking for inexpensive refraction liquids for your gemological testing?

This is the link to the site: https://www.gemsociety.org/article/refr ... d-liquids/

Use judiciously ... do not for example pour kerosene on your condenser! Cod liver oil on the other hand - might work well. :)

[zzffnn]

Cargille type A is less sticky than type B, and therefore easier to clean off, if that makes sense.

Do note that many types of oil can dry up and leave stains/residues that are not easy to clean. Cargille immersion oil is said to be never drying.

[apochronaut]

One can sometimes find Cargille immersion oil on ebay at very reasonable prices, but it can take a little time and patience.

In the meantime, here is a list of the Refractive Index of 'Common Household Liquids' as published in a Gemology website under the query:

Looking for inexpensive refraction liquids for your gemological testing?

This is the link to the site: https://www.gemsociety.org/article/refr ... d-liquids/

Use judiciously ... do not for example pour kerosene on your condenser! Cod liver oil on the other hand - might work well.

That chart seems overly optimistic.

There are various charts such as that on-line, some of them 50 or 60 pages long, with every fat you could imagine in them, even human oil . Very few charts agree totally but almost all oils are under 1.5, it is hard to find many common ones that are over. The n of commercially sold oils is controlled by a codex, theoretically but in industry, standards are very often toyed with. The n can vary widely as a result of the method of extraction, age of the oil , whether there are any additives or contaminants and the temperature amongst other things, not to mention accidental or overlooked blending with other oils. Many years ago , a large food distributor in Canada had it's 3 liter cans of basic vegetable oil( supposed to be soy and or canola and or corn) on sale for a ridiculous price, for months and months and months and months. I thought something was fishy, so I bought a jug and I was correct. The reason for the fire sale was that it smelled like fish. " VINCE!... YOU SCHMUCK, I TOLD YOU TO PUMP IT INTO A FRESH OIL TANK, NOT A FISH OIL TANK"!
I got it in mind once to try wild rosehip oil, for immersion, which is commonly available from Chile at quite low prices. The refractive index quoted by many sources was just north of that of cedar wood oil. In actual fact, I could not find a single supplier, who would guarantee me an n higher than 1.48. There is a cedar oil distillery, about 80 miles from me and I have had his product. It tests under 1.5. Too many turpenes.
Anyway, of the cheaply available oils, at the grocery store, soy is probably o.k. at around 1.47, but it is often a bit yellow. Grape , although a little pricey is quite neutral in colour, if anything a bit greenish. It should be around, 1.46, corn 1.47, peanut 1.46, ...safflower and sunflower can be over 1.47.
I have tried various oils for immersing objectives and the difference is noticeable when compared to immersion oil. I don't recommend it.
However.
The comment I made in a previous post, was expressly related to the immersion of the condenser, upon which the refractive index difference between oils has a similar effect to that on objectives but that does not translate as anything but a negligible effect on the resolution, since the prime arbiter of resolution is that of the objective.
You probably can get some small improvement in resolution, oiling your condenser with a transparent oil with a refractive index below 1.5.....but certainly one would see the difference in comparison to water immersion of a condenser engineered to use oil . In no way, can I see that using water on an oil condenser, is worth the effort.

[75RR]

Do note that many types of oil can dry up and leave stains/residues that are not easy to clean.

Quite true - though cleaning up after each session - as I try to do and as correct procedure dictates - will avoid this potential problem.

Here is a link to the Zeiss booklet 'The Clean Microscope': http://microscopy.duke.edu/downloads/Th ... scsope.pdf

I find that just using Isopropyl alcohol and cotton wool (made up into swabs) works well with Cargille Type A immersion oil.

Which is fortunate as I have had difficulty sourcing petroleum ether locally (and cheaply) in order to make up the Zeiss Cleaning Solution L which consists of 85% petroleum ether and 15% isopropanol. See page 12 in the booklet.

It is important to discard each swab after each (single) spiral swipe - reuse will not only risk scratches but set you right back by re-smearing the lens with oil, forcing you to start all over again.

[Uxx4]

Thanks to each of you who posted after my earlier post. You have caused me to consider and reconsider my approaches to achieving the best performance possible with my equipment, as well as avoiding many pitfalls.

Thanks to all once again, and please continue to post and update!

[PeteM]

Just to follow up, I ended up buying an Olympus CHA microscope (for short barrel Olympus lenses) for the Lomo water immersion etc. lenses.

It's will be an easy modification to raise the stage, and the condenser rack looks to have enough range to follow the stage up just by altering the stop.

The focus mechanism seems smooth and robust and the lighting is modern enough.

[75RR]

Sorry about the hijacked thread!

[PeteM]

No problem . . . even the diversions on this forum are informative and welcoming.

[IanW]

Hello Peter - I am joining in late when all the fun is over but was very interested since I went through the same difficulty as you (and others on here have) - in my case with LOMO water immersion lenses on a Carl Zeiss stand. I couldn't raise the stage enough and used spacers which I found a pain and unsatisfactory since I still had to unscrew them a bit to reach focus.

i eventually purchased an older Zeiss Jena NF stand (which LOMOs are based on) and it works perfectly, and I can of course use my existing Carl Zeiss lenses on it as well.

Glad to hear that you have found a solution also.

[75RR]

Hello Peter - I am joining in late when all the fun is over but was very interested since I went through the same difficulty as you (and others on here have) - in my case with LOMO water immersion lenses on a Carl Zeiss stand. I couldn't raise the stage enough and used spacers which I found a pain and unsatisfactory since I still had to unscrew them a bit to reach focus.

Was it not possible to raise the stage itself (12mm?) with a custom made spacer?

[zzffnn]

You may use some longer screws and machine nuts, if original screws that hold the stage are too short.

[IanW]

I looked into raising the stage but considered that even if I was able to do this (I'm not much of a DIY man) that I'd then have the problem of raising the condenser high enough, as it seemed to have travelled its highest with the with the stage raised at its normal highest state. Getting the NF seemed the logical progression, and I am very pleased with the ease with which parts can be added to it from the enormous LOMO / PZO range. The Standard 18 is much easier to get working with quickly though, so I will keep both.

[75RR]

... I'd then have the problem of raising the condenser high enough ...

Fair enough - no sense complicating thing unduly.

[zzffnn]

Sorry, I forgot to mention that I also raised my condenser with adpater and Legos.

And for 33mm objectives, DIN scopes may have to be modified semi irreversibly. For example, my Nikon Optiphot can switch between 37mm and 45mm objectives in a minute by loosing and tightening a stage height locking screw. But it cannot reach down to 33mm LOMOs with forward-facing turret without DIY modifications.