Introduction, and Questions re Darkfield on Lower-End Scopes

[hoarybat]

Hi all,

I’ve been lurking for a few days here, reading everything I can about your wonderful (and expensive!) setups. I’ve been reviewing the gallery, some wonderful YouTube videos (especially Bill Porters! Great editing and commentary!) and trying to learn the basics of what I’d be getting myself into if I started into this hobby.

Here’s my purpose: Brightfield and darkfield observation and photography of protists, fungal tissues & fungal spores. Photography and videography to be accomplished, at first and probably for the longer haul too, via an afocal iPhone or an Amscope MU300 USB camera. More advanced illumination techniques seem way beyond my budget, as do trinocular heads, photo eyepieces, and full-frame DSLRs.

Rather than buy a scope from eBay, I’ll probably be picking up a scope from the UC Davis “Bargain Barn.” In my price range, there are a fair number of Olympus and Zeiss scopes.

As far as potential scopes, the Olympus CH2 seems readily available, inexpensive, and easy to use with darkfield illumination (drop the darkfield stop into the filter-holder). I’d try to find a stand with the 30W tungsten lamp instead of the 20W tungsten lamp, but that doesn’t seem like a difference worth stressing about. I’d also try to find a scope with D Plan Achromat or D Achromat objectives, and avoid the ED Achromat objectives. Provided that I’m able to get a CH2 with the preferable objectives and at least 20W of illumination, are there any barriers to decent darkfield observation with this lower-end equipment?

For the Zeiss scopes, there are some interesting possibilities on the site. The descriptions are fairly vague, though, and I’m far less familiar with Zeiss nomenclature and model lines.

This scope: http://bargainbarn.ucdavis.edu/4sale/images/172777.jpg is described as “MICROSCOPE, ZEISS MODEL COMPOUND BRIGHTFIELD WITH 2.5X, 10X, 40X, AND 100X OIL OBJECTIVES, COMES WITH EXTERNAL POWER SUPPLY.” I can’t identify the model of this Zeiss scope, and I haven’t yet done the research to see how difficult it’d be to use for darkfield (there’s got to be a filter holder, right?).

Before I drop a significant outlay of cash on this, I’d greatly appreciate it if the forum would comment on the suitability of this level of equipment for my intended purpose, any red flags I should look for when checking out scopes in person, and anything else I should research or consider.

\\\

By way of a personal introduction, I’m a recovering environmental lawyer who went back to school to become a biologist. My biological passions include bats (especially Lasiurus blossevillii and cinereus), native California wildflowers (especially Calochortus), vernal pool Branchiopods, Mutillids, Pepsis and Chrysis wasps, Chrysina beetles, and fungi. I photograph as many of those passions as I can at normal macro distances with a 105mm lens on a DX-format body. I also love traditional film photography, and shoot people with a variety of medium and large format cameras. My nature photography lives here: https://www.flickr.com/photos/danielpneal/

I have two wonderful little girls who I can’t wait to introduce to the wee animalcules, and I’m very appreciative of any advice this forum can offer.

All the best,

Dan

[Chris S.]

Dan, welcome to the forum!

I lack the knowledge to help with your microscope questions, but look forward to seeing more of your images. I once photographed a bat-banding study, and found it both fascinating and fun. One question I had, that none of the bat biologists could answer, was why the eastern red bat (Lasiurus borealis) should be visually sexually dimorphic, when presumably, mate selection occurs in the dark. I still wonder about this. Similarly, those who study moths have shown me starkly visible sexual dimorphism among species that would seem to perform mate selection in the dark, and have not been able to explain why this dimorphism is adaptive. Of course, it's wonderful to have mysteries to contemplate!

Cheers,

--Chris

[hoarybat]

Hi Chris,

Thanks for the warm welcome.

My expertise is with the western red bat (Lasiurus blossevillii), which isn't sexually dimorphic. Mating and (presumably) at least some degree of mate selection in eastern red bats (L. borealis) take place in flight. You'd be surprised at the amount of daytime activity that takes place by L. blossevillii and hoary bats (L. cinereus), so I wouldn't rule out courtship and mate selection entirely during the day. These species are really tough to observe and study since they're foliage roosters, which means that, except for lactating females with nonvolant pups, they can roost in a different location every night.

My best guess on the dimorphism (and it's a shoddy guess) involves Lasiuran migrations. We know that several bats from this genus migrate in groups that appear to be segregated by sex, and that these single-sex groups take different migratory routes. There may be some subtle selection pressure on L. borealis migratory groups that results in the subtle sexual dimorphism in that species. Maybe. :-)

If anyone is curious, here's a short video compilation of a western bat maternity roost behavior: https://www.youtube.com/watch?v=tOlebRs ... WzeHs2NOSg The bat pups are adorable.

-- Dan[/i]

[Pau]

Dan, wellcome aboard!
I think I can answer some of your questions as these are (aproximately) the two microscope models I most use.
The pictured Zeiss model is the named "Standard". There are many possible models and configurations and sadly the picture shows very llittle information. It's a very good classic stand and IMO its main beauty is the compatibility with a wide range of optics and other components available at the used market. My personal microscope is a Zeiss Standard but bundled with high end optics and lots of accesories
The Oly CH2 is too a good stand but more entry level oriented, so likely less upgradable. Im not sure about the CH2 model, the older CH (well, its chinese clones I work with) doesn't provide Köhler illumination, for exemple.

About darkfield it will be easier with the condenser of the Olympus, the typical BF Zeiss condenser doesn't allow to put a DF stop in it because its diaphragm is located inside between the lenses. With the Zeiss you need a dedicated DF condenser or for low magnification a Phase contrast one.
DF has its own limitations. With the Oly you could get good DF with 4X to 20X objectives, and maybe incomplete or not very good with the 40X 0.65. For good DF at 40X and higher you also will need a dedicated DF condenser. For objectives with high NA from 0.7 to 1.0 you always need an oil immersion DF condenser, for higher than 1.1 NA you can't get DF at all, but some 100X objectives have a diaphragm or can hold an internal funnel device to lower its NA for DF.
About other illumination techniques on a budget you can also use oblique illumination and cross polarization, two powerful techniques easy to implement with little DIY work (I do it with my students in a small microscopy course I teach with the Oly clones at high school).
Leitz microscopes are also excellent an often sell for lower prices than Zeiss, Olympus or Nikon.
About photography trough the eyepiece (what we call afocal), I supose you already have the iPone for other uses, but a compact camera with a short zoom paired with a high eyepoint (for eyeglasses users) eyepiece will be superior. Note that with that old microscopes the eyepiece performs complementary aberration corrections so you want it matched with the objectives you use.
Hope this could help a bit.

[hoarybat]

Thank you Pau for that information -- it was very helpful!

I'm now leaning against an Olympus CH2, as all of the locally-available sames seem to have the less-desireable ED Achromat objectives.

I've been reading about Köhler illumination vs. critical illumination, as its importance is stressed in mushroom spore observation (which requires high resolution at 1000x). From what I understand, achieving proper Köhler illumination is a matter of proper alignment and adjustment of the field and condenser irises ... this PDF from an intro pathology class has nice step-by-step instructions: http://www.bio365l.net/Documents/Readin ... csLite.pdf I think that both the CH2 and the Zeiss standard shown have the requisite adjustments to achieve Köhler illumination.

Do you have any idea why the Zeiss microscope described in my original post here: http://bargainbarn.ucdavis.edu/4sale/images/172777.jpg would be $150 cheaper than a Zeiss microscope that is explicitly referenced as a "Zeiss Standard" microscope here: http://bargainbarn.ucdavis.edu/4sale/images/172770.jpg ? Aside from the explicit reference to "Zeiss Standard" in the second scope's description, the darker gray finish, and an internal power supply, their descriptions are identical: COMPOUND BRIGHTFIELD WITH 4X, 10X, 40X, AND 100X OIL OBJECTIVES.

I'm planning on visiting the UC Davis bargain barn this week to check out these specific scopes. I'm going to be looking for smooth coarse and fine focus, basic functionality, element separation / damage / dust / cleanliness in the objectives, etc. Anything else you'd recommend I keep an eye out for?

[Pau]

Do you have any idea why the Zeiss microscope described in my original post here: http://bargainbarn.ucdavis.edu/4sale/images/172777.jpg would be $150 cheaper than a Zeiss microscope that is explicitly referenced as a "Zeiss Standard" microscope here: http://bargainbarn.ucdavis.edu/4sale/images/172770.jpg ? Aside from the explicit reference to "Zeiss Standard" in the second scope's description, the darker gray finish, and an internal power supply, their descriptions are identical: COMPOUND BRIGHTFIELD WITH 4X, 10X, 40X, AND 100X OIL OBJECTIVES.

I'm planning on visiting the UC Davis bargain barn this week to check out these specific scopes. I'm going to be looking for smooth coarse and fine focus, basic functionality, element separation / damage / dust / cleanliness in the objectives, etc. Anything else you'd recommend I keep an eye out for?

About the Zeiss Standard,
- The grey tone likely is the same, the image brightness no. I'm only aware of three colors: black for older models, grey for most the time and white for last series (at least someones made in Mexico)
- The price will change with the microscope condition and with the optics and other accesories bundled with, could you disclose the prices they are asking for?
- About illumination: The built in halogen is of course more compact and portable but with the models with rear light source the illumination is more uniform and easy to set up Köhler like, the base heats less and you also can change the light source. The light intensity when compared halogen 10W with rear tungsten 15W is similar. I have both models and I prefer the second type.
- About optics: You want at less Plan objectives, Neofluar are better color corrected but less plan corrected (I qualify them as semiplan, Zeiss never did it), for high magnification this will be barely noticeable and Neofluars are excellent, Planapo are the best but likely outside your budget. With Zeiss objectives you need compensating eyepieces: KPL are the best, followed by CPL and C types, the ones with eyeglasses symbol are more comfortable and the most adequate for photo.
- About heads, trinocular is best for photo but more expensive. Sliendorf (folding) type are more convenient because they don't change focus with the interpupilar distance.
- Condensers: the typical 0.9 switch out is very convenient for most BF uses but as I said it doesn't allow DF or oblique, other condensers are more expensive.

- Aside the the inspection points you plan (delamination is often a problem with Zeiss) carry a good prepared slide plenty of detail and (maybe) immersion oil and do actual tests of the equipment. The prices will be likely higher than at ebay but you must be able to profit the testing advantage. Also inspect the objectives surface, a 10X eyepiece used reversed is a good magnifier.

- You can downloadod lots of Zeiss info at: http://www.science-info.net/docs/zeiss/
- A good document about Z. Standards models in german: www.klaus-henkel.de/standard.pdf

[hoarybat]

Excellent tips, thank you Pau. I imagine it can be rather tedious to repeat the same advice, and I've endeavored to research many "what should I buy?" and Zeiss Standard threads on this forum. I've been reading the Zeiss PDFs at science-info, and have found them most helpful.

The first scope I described is $400, the second is $550.

I'm very excited to visit the scopes in person and see what kind of condition they're in!

[phil m]

I'd put the brakes on , if you haven't already made a commitment.
In reviewing their stocklist, it seems they are deleting a number of "lines" of microscopes from their system. A/O 150's, a workhorse student and small lab microscope; Zeiss Standards, an older model of these, with remote power supply; again a workhorse student and small lab microscope ; Olympus CH2s, a slightly newer student and small lab design, A/O 110's ; a slightly higher end lab microscope with in base electronics and a number of more modern features than the above; and lastly some lesser stereo microscopes. There are a few singles , of various models too and some individual objectives.

Within those general groupings there are some , with extra features however, and they don't appear to be charging extra for those. There are a number of CH2'S with phase contrast, which in lieu of having darkfield, is definitely a bonus.They all seem to be 3 objective only but I would think a 20x ph and if not already present a 20x phase annulus could fairly easily be found. You would have oil immersion phase( 100x objective), which you will not be able to obtain with any of the microscopes in dark field without some complicated conversions.
A couple of the A/0 110's have teaching heads( double heads). Now, those microscopes have: in base electronics, they have reversed nosepieces which look to be 5 hole , they have a fixed stage with a focusing head,infinity optics, 20mm field of view, halogen illumination. Since you are interested in afocal photography, your camera could be dedicated to one of the eyepieces in the extra head ...basically making it trinocular.
These are definitely the cream of the crop, on that list ; infiniity plan objectives are cheaply available for them( they can even use D.I.N. objectives,which opens the door to planapos), even the darkfield condenser shows up on ebay regularly for as low as 50.00.
However, the CH2'S with phase contrast are pretty tempting but not as easily and cheaply improveable as the A/O 110's.
The Zeiss are good microscopes but very outdated. Parts are becoming difficult to find and delamination of optics ,is everpresent. You hardly ever see A/O infinity optics delaminated and those objectives are excellent. That's where Leica scored their infinity optics from.

[Pau]

I also have taken a look at the site and I can see for a bit more CH2 (they seem to have Köhler illumination) and Z. Standard for Phase. For so small difference I think they are worth. Being university surplus I think they must had an intense laboral life in student hands...be aware of.

The Zeiss are good microscopes but very outdated. Parts are becoming difficult to find and delamination of optics ,is everpresent. You hardly ever see A/O infinity optics delaminated and those objectives are excellent. That's where Leica scored their infinity optics from.

Phil, all those scopes are outdated by several decades.
Take a look at ebay: there is plenty of parts for the Zeiss Standard line. Delamination is a problem often affecting Zeiss optics from that era, but not so widely as you suggest.
AFAIK Leica research scopes are based more in Leitz models than in AO, AO were rebranded Reichert and then Leica, but for the low end models. I may be easily wrong, I know very little about AO, they are almost inexistent in Europe and I never put my hands in one of them.

[hoarybat]

I'm continually grateful for the advice and feedback I'm receiving.

Phil: I hadn't considered an A/O scope. I used a very beat up A/O 150 in my zoology and botany classes. I'm perusing P.S. Neeley's AO page, and am going to be looking into the A/O 110.

Zeiss certainly has more sex appeal than A/O!

The UC Davis Bargain Barn's CH2s with phase contrast for $450 are tempting, especially since they seem to have several samples available for sale, so I'd be able to cherry-pick the best example.

I have to keep referring back to my original purpose, as my planning keeps experiencing feature-creep.

My primary goal is to have a quality scope capable of Köhler illumination with a high-quality 100x oil objective to observe and measure fungus spores in brightfield. I know I'd be able to get this with a good condition $300 A/O 150, a $400 Zeiss Standard, or a $400 Olympus CH2.

I'd really like to experiment with afocal photography and videography of protists at 400x using darkfield ... I find darkfield aesthetically more pleasing than the phase contrast examples I've seen. That said, if, as Pau has mentioned, darkfield at 400x on the CH2 with its stock Abbe condenser won't really work without a darkfield condenser, I'd be more inclined to go with a $450 phase contrast CH2 that is ready to go out of the box, so to speak.

... as far as the CH2s go, it looks like they're $400 for brightfield with an Abbe condenser and ED objectives, or $450 with the phase contrast condenser and A10PL and A40PL objectives . That feels like a no-brainer (at least between the two).

[phil m]

Yes, Yes. There are 4 altars somewhere with the words Zeiss, Leica, Nikon and Olympus over them, although Olympus is at least historically accurate, for an altar.
A/O microscopes are complete sleepers. Way better, than most people assume , packed with innovative features, most of which they invented and had copied by others, sometimes decades later. They regularly show up on ebay for peanuts, which is good news for people looking for a terrific microscope for very little.
The Reichert Microstar 410 and Diastar 420, both of which have fully compatible planfluorite and planapos, are just AO acopes with a yes, sexier Austrian name and then when Wild-Leitz merged with Cambridge/Reichert/AO/B&L, it was pretty much a no brainer to get even sexier with the drooling word, Leica, rolling off the tongue , like a dollop of Hessian sauerkraut, even though the company is headquartered in Washington D.C.

Previously, E.Leitz clung to fixed tube lengths but after the merger with 2 innovators , knee deep in infinity optics and another ankle deep, they have miraculously immersed themselves in infinity corrected microscopes with great gusto since about 1998. At least the contingent from C. Reichert, didn't have to learn a new language.

[hoarybat]

I won't lie -- I am avid photographer who has lusted after, but never been able to afford, Zeiss and Leica gear. It's thrilling to think about owning a Zeiss or Leica scope. The best dissecting scope I've had the pleasure to use was a Leica.

But, your point is taken on name brand cachet and sleeper equipment. My favorite camera is a 1958 Minolta Autocord LMX. It was significantly cheaper than a Rolleiflex, and has given me ten years of enjoyment. The limiting factor in my photography certainly isn't my off-brand TLR, it's my operating skill!

I put a lowish offer in on a fully-featured A/O 110 that has nice Plan Achro objectives. Maybe the seller will accept, and I'll have a great bargain. But, even if I win, I'll still lust after Leitz and Zeiss glass ...

[hoarybat]

After looking at a lot of eBay listings, I've purchased a used Microstar IV for $125.00. I couldn't turn down this price, especially when it looks like new parts are available from http://www.reichertms.com/microstar.php, and the objectives (even the really high end ones) seem to be available cheaply. This is probably the closest thing to a Leica I'll ever own (other than a very worn Leitz tiltall tripod).

I'm going to budget some money to have the microsoft serviced when I receive it.

Thanks all for the feedback! I'm very glad I didn't drop $400 on an Olympus CH-2.

[hoarybat]

... and I received a very broken Microstar IV for my $125. The 10x objective is delaminated, there are deep pitted scratches in one of the eyepieces, and, most problematic, the focusing train is really messed up. The MicroStar IV "autofocusing" setup is described as idiosyncratic, but the sample I received was well and truly broken.

On the plus side, the optics were excellent (even though I had to manually hold the coarse focusing knob to keep the view in focus), and the Olympus darkfield filter I picked up worked well at 4x and 10x.

I'm going to be out $40 for shipping, but so it goes.

[hoarybat]

Update: I have an Axiostar Plus on the way. $290.24 shipped, but it needs a new bulb (and maybe more).