Leica DMRB- which lenses and prisms for DIC

[pinkbeetle]

Hello,

I am very interested to upgrade by crap Amscope by buying this Leica DMRB. I'm wondering which lenses are best for DIC, and whether I have the right prisms (pic). I'd really like a low mag DIC lens 10-20x, I don't see any plan apos that are 10x anywhere, but maybe there are some 20x.. somewhere? But I guess just 'plan' is ok as long as it works with DIC. I've read HCX lenses are better suited for old scopes, but don't know how big of a difference that makes. I'd really love to get gorgeous colorful DIC images of plankton at 10-20x, just wondering what lenses are best (if they're even out there) and if I have the right prisms (if not where to start looking for them). And I suppose I cannot put a 10x Nikon DIC plan apo on it? There are more of those around. I just don't want to buy this microscope if I'm not going to be able to get lenses for it.

Also if anyone has general comments about the scope I'm all ears, and images they want to share along with their setup. I'm also looking for recommendations on a good 4-5x lens (DIC would be nice but I'd be more using it for darkfield).

I'm more interested in learning about lenses but eventually I might want to retrofit the mercury lamp with LEDs. I was thinking something like this paper, as I have experience with Arduino, and wondering if anyone else has done any DIY retrofit. https://journals.plos.org/plosone/artic ... ne.0143547

Thanks!

[PeteM]

The older "Delta" optic type DMRB has black lettering - like yours. Unmarked Leica objectives and those with an HCX will match the tube lens a bit better. You do want objectives that specify a letter (A,B,C,D...) on the objective or very early on a * to be compatible with DIC. If you find an "HC" objective (the newer system, with a different tube lens) at a good price, you might find it acceptable. You do want the right head and the right eyepieces (L Plan) for this earlier version. For one thing, the tube lens is typically in the stand and not in the head.

Leica makes several series of objectives. C Plan and Hi Plan have smaller fields of view. While they often work for DIC, they weren't the Leica recommendation. The N Plan versions are a step up and recommended for DIC. In my mind, Leica PL Fluotar objectives - commonly available in the 10x and 20x magnifications you want - are the sweet spot for DIC. They have higher resolution and better corrections than the otherwise excellent N Plan without being insanely expensive. Plan Apos are also available - being mindful of how they are marked, what prisms you'll need, and your notions of what seems reasonable cost.

You'll want to search around for a chart showing which upper turret and condenser turret prisms go with what. Armed with that you can make better buying decisions. In some cases, Leica will have made objectives using, say, both "B" and "C" versions (such as with 20x Pl Fluotar).

Your C & D upper prisms and K3 and K4 condenser prisms will match nicely with several objectives 40x and above. However, to match readily available 10x and 20x objectives, you'll probably need to pick up an "A" prism for the upper turret and a K2 prism for the condenser.

It's not clear from the photo what objectives are currently on this DMRB - but they don't look to be a proper match.

As for illumination, you can probably find a used 100-watt halogen source meant for this scope for well under $200 - and it will likely provide better illumination than a DIY LED replacement.

[pinkbeetle]

Thanks!

Would something like this work?: https://www.ebay.com/itm/225103348174
Combined with this lens: https://www.ebay.com/itm/225744897338
I guess I'm not sure what would happen if I left the K3 in there and didn't get K1, with this lens. I'm just not finding much on how to combine the prisms, I don't know how they combine. The LED stuff is for fluorescence, is what I'm interested in.
I cant find K2 anywhere.

Edit: I think I found my dream lens, though they don't ship to the us
But this would work with the 'D' and K1 prisms, correct?: https://www.ebay.co.uk/itm/335188292446 ... SwclxlkDx5

[PeteM]

The first eBay listing for the 10 PL Fluotar looks good. I believe it wants a K2. They do show up now and then.

I suspect, but don't know, that the 10x Plan Apo wants a K2 as well. Note that you're not getting higher resolution than the same .30 N.A. Plan Fluor. You get slightly better correction of chromatic aberration (whose effects are somewhat masked by DIC relief) at the expense of $$$, working distance, and additional lens elements to lower contrast.

Your best bet is to search the Internet for a chart listing what condenser prisms go with what objectives. Basically, a K1 prism will have about twice the "shear angle" of a K2. On my Leica's it corresponds to a 5x objective. It can vary, though - why you want to find a cross-reference. For example, most of the 10x objectives I've seen want an "A" upper prism. I won't be able to help you find a cross-reference as I'm getting ready for a project.

You can lose resolution if the prism shear angles are greater than the objective's resolution. It's possible that your K3 will give a partial effect. With the top condenser lens down, you might get more of a DIC effect. Rotated partly in the condenser, you might also get a sort of DIC-oblique effect. Eventually, though, you'll want the proper prism.

[pinkbeetle]

Sorry I'm confused- a lot of the 10x's I've seen say 'D', not A. So my 'D' should be ok, it's just that I would want a K2, I think. I'm starting to understand, thanks!

[wabutter]

As Pete M pointed out, the Condenser Prism and Objective Prism in this scope are for the 40x and 100x objective. I too am curious what objectives are on this scope, They don't appear to be Leica objectives. I don't recall there ever being black barrels on any Leica objectives except for the very low end student educational scopes. and they were achromats.

The K1a with D1 works with a number of 5x ojbectives while the K2 with either a A or D1 prism is covered many of the 10x objectives. The K2 with either a C or a D1 works with selected 20x objectives. Typically, if you use a condenser prism that for use with a different objective, you will not get an uniform interference band across the field so your colors will be inconsistent.

[pinkbeetle]

Thanks! So just to clarify for 10x I would want D1 instead of 'D', for best results? (I am finding some 10x lenses but they just say 'D' not D1). There isn't a chart anywhere that says all this? Probably not.

I am thinking, maybe it's not worth buying since I can't find the k2 anywbere, if its too hard to find parts maybe its not worth it. I suppose I could contact Leica but I shudder at what they would charge.

[pinkbeetle]

The lenses are not Leica, see below what comes with it. $5.5k but I still need to get some objectives (for now just 5x and 10x, maybe 20), and a k2 prism. Worth it?

DMRB stand in excellent condition with 100w lighting.
Phase and DIC turret
Polarizer for DIC
Phase 1, 2, 3 annuli
Darkfield annuli
Accu-Scope Plan 10x Phase objective
Accu-Scope Plan S-APO 10x objective
Accu-Scope Plan S-APO 20x objective
Accu-Scope Plan 40x objective
Nikon Plan Fluor Phase 40x objective with correction collar
10x/22mm eyepieces
Fluorescent illuminator with HBO 300 hour bulb
DAPI, FITC and TRITC Fluorescence Filters

[PeteM]

As I understand it the difference between B and B1 or D and D1 (etc.) prisms is in the shear angles. The letter alone (A, B, C, D . . .) is a balance between 3D effect and ultimate resolution. The B1 (etc.) designation (as I understand it) has a bit less shear, a bit less contrast and 3D effect, but a bit better resolution for some subjects.

Recognize that this is a massive scope. You'll want a permanent place to use and keep it - rather than tucking it away somewhere between sessions. Something like a DMLB will be easier to move (sized more like an Olympus BX or Nikon E600, 80i) and capable of identical optical performance. Your DMRB sounds fairly priced, but not a super deal in my opinion - especially since it has the wrong objectives for that infinity system and is also the older generation. $6K could probably get you a DMLB with 10-20-40-100x Plan Fluotar objectives and DIC.

[Alexander]

I wouldn't buy a microscope with objectives from another brand.

[pinkbeetle]

Found it! A list of prisms and objectives
https://www.mikroskop-center.de/media/w ... ves_EN.pdf

Yea I’ll have to think on this scope. I do have an art studio it can stay in so size is not an issue. I’m also interested in darkfield, phase, and fluorescence, which it is setup for (though ideally would get some leica phase lenses). Still very tempting as it can be hard to find something set up for all 4 imaging modalities. But it’s true it’s not entirely set up for them, have to get prisms etc.

Also any tips for getting colorful DIC images? Often they can be kind of grey. I’m not sure if I need something in addition to make them colorful.

Edit: he just dropped the price to 4k. Hmmm…

[PeteM]

The Accu-Scope objectives on this are semi-apo. In other words, more like plan fluorite than plan apo. The ones I've had did not perform as well as their Olympus, Nikon, and Leica counterparts. They were better than plan achromats but not as good as the better plan fluorites from major makers.

They're also meant for a 180mm reference tube length (at least mine were) while the Leica wants 200mm. In addition, the tube lens and eyepiece corrections will be wrong.

Assuming they are on adapters from RMS to Leica 25mm thread size, they won't be parfocal and possibly not parcentered with any additional Leica objectives you get. It won't be entirely unusable -- though you will have to take great care not to damage the non-parfocal objectives -- but also not particularly good. At $4000 (plus tax and shipping?), you're paying for very good.

If you did decide to buy it, the best way to get your money's worth might be to sell or swap those Chinese objectives towards getting the Leica ones that are compatible. If you can find a buyer for those, your scope has about $3000 worth of Leica components, counting the stand, the four DIC prisms, and the condenser. Those Accu-Scope objectives might do better on something like an Olympus BX. I don't know what they'd bring on the used market.

You can use a quarter wave plate and/or offset the upper prisms slightly to get colors.

As a wild guess (your art studio), I imagine you want this scope for the potential of amazing images. If that's the case, darkfield, oblique, and DIC will likely delight you - fluorescence not so much if it's plant and animal cells. Those images tend to be fuzzy until you get into much more expensive equipment. You may know all of this, but if not, I'd reconsider the importance of fluorescence. Sufficiently bright sources (mercury vapor) also represent a potential hazard to vision if care is not taken and a potential hazard to your entire studio if an old bulb bursts. They aren't meant to be run more than 50 hours or so before being replaced - and turning them on and off degrades life particularly fast.

Phase contrast also tends to be a sort of fuzzy halo around specimens - anywhere there's a difference in refractive index. While this is great for seeing semi-transparent living structures, the artist in you may not find the images as sharp as stained brightfield or darkfield, oblique, and DIC. Know also, that if you're looking for Leica prisms, they call them "ICT" in the transmitted light versions.

Also, be aware that depth of field plays a huge part in image quality. A 5x may show imperfections in the slide and coverslip. Beyond a 20x objective, it gets increasingly difficult to get the entire depth of the specimen in sharp focus (unless you do focus stacking).

[pinkbeetle]

I’m aware of some of this. I do plan to sell most of the accuscope stuff. I want to do something I call ‘plankton painting’ with darkfield and possibly phase contrast, see: https://jessholz.com/plankton-painting/
And I don’t mind fuzzy fluorescent, I have used confocal but don’t mind the fuzz of widefield. I plan to eventually retrofit it with LEDs for fluorescence, don’t want to touch the mercury lamp. And DIC would just be, well, amazing.
I’m interested in phase as an artistic effect as well. I like having the option to image something in different ways.

I read she uses an olympus BX51- who made this reel:
https://www.instagram.com/reel/C5Lt20du ... N5MGVtc2V0
She probably has apos, and a fair amount of post processing, but I’m wondering if something like this would be possible on this DMRB with a quarter wave plate like you said. Or maybe I’m just dreaming… I mean maybe at some point I could get some apos..

For now just searching around for a k2 and d1 prism. Nowhere to be found online but I’m asking around. It really depends if I can source these parts. Anyway, thanks for your thoughtful and informative reply! I’ve been learning a lot here.

EDIT: Found the prisms! From microscopia.de, not listed on their website. Have a lot to think about but this may actually work out!