MicrobeHunter.com Microscopy Forum

Can anyone provide a clear mathematical argument showing that the resolution of a simple condenser plus objective scenario (with no subject to confound matters) is not strictly limited to Min(NAcd, NAobj)? Until then, the confounding factor causing all the debate is the object being imaged. That can...

… Is there still more to it than this? I think the “more to it” is probably Modulation Transfer Function MichaelG. MTF is a way to characterize lens performance as seen in the image plane vs. distance off-axis from the center. I.e., the corners of a photo are generally less sharp and more distorted...

Figure's 58 and 59 in the volume cited above illustrates why a glass-air interface strictly limits the NA to a theoretical maximum of 1, and how oil (with approximately the same index of refraction as glass) allows up to about NA=1.5: https://archive.org/details/microscope02beckuoft/page/70/mode/2up...

The common equation for resolution of a condenser+objective combination, as seen in the Thor Labs link, is highly idealized, containing only 3 variables (wavelength and the NA's), and hence seems more like a simple rule-of-thumb than one that can deal with real-life complexities (such as the subject...

Oil is commonly used with microscopes at optical interfaces because its refractive index (RI) is higher than air (~1.5 vs. ~1). This allows light to be bent at a sharper angle than at glass-air interfaces (otherwise the rest of the light would be reflected internally). The sharper angle allows a bro...

Adding in the characteristics of a subject confounds the situation beyond the usual equations and into the realm of ruminations, but sure. Anyway, I'd suggest that the improvement some people find when using very expensive elite-quality objectives in the discussed situation has more to do with them ...

Thinking about the last point I made a bit more: Yes, provided that the sample radiates light broadly enough to fill the acceptance cone of the objective, some improved resolution can be obtained. But of course many or most biological samples requiring high magnification are nearly entirely transpar...

The result of those equations is the minimum distance between two points before they can be individually resolved - the "resolution." So if the NAcd is less than NAobj, then from the second equation the result is a greater distance (a worse resolution) than if the condenser's NA matched that of the ...

A dry (air-gapped) condenser will strictly limit the effective NA of any subsequent objective to a theoretical maximum of 1 (meaning somewhat less than 1 in practical terms). I've heard "an average of the condenser and the objective's NA" here more than once, but that's nonsense. The net, in fact, c...

On forums such as this, it's common to extol the (frequently genuine) benefits of buying used, but there are some benefits to buying new too. I have a Zeiss 508, bought new along with their Apo 0.63x auxiliary lens, stand and LED illumination. The optical quality is magnificent! Zero regrets. Anyway...

Thank you. The originals are reputed to be extremely difficult to use. One person commented that using one (an accurate replica) seemed almost impossible. In this, the eye relief is about 3mm. That's very close, but after a few seconds you figure out how to hold it comfortably. The flat body around ...

Hello forum members, I made a Leeuwenhoek homage microscope, and thought some of you might be interested. My goal was not to create a strict replica. Instead, it's an interpretation of one with a few modern twists. I did want it to remain recognizable - to those in the know - as descended from his c...

A little follow-up: I nicked myself shaving this morning, so I put a tiny smear of blood on my little 10mm "slide." At ~55x, yes, I could see blood cells as pale, basically featureless dots. I'm not sure anyone would guess what it was without a prompt, but I'll leave that slide as-is for now. Thanks...

Southern California is very dry, which really cuts down on them. I wouldn't call it paradise, but it's a big bonus. That tiny whine immediately launches a DefCon-5 seek-and-destroy mission, with no possibility of sleep until it's terminated. Yes, I agree an insect wing would be a very good subject! ...

Thanks, the "seed parachute" idea seems quite interesting. I'll scan the area around my home for possibilities. There are very few mosquitos where I live, thankfully, but I'll look around my residence for a dead spider or something like that. My "slide" is actually a 10mm optical window of borosilic...

Thanks. Important point that bears repeating: The view will be at 50X total magnification only. No possibility of any other magnification. Also, no possibility of using a cover slip or to scan the surface for something interesting. For testing purposes, I am currently using a streak of dry marker on...

Dear forum members, I need suggestions for one or two interesting and pretty subjects to view, and advice about mounting them. * Needs to be a dry subject that won't decay. * Should be a broad or continuous subject that doesn't need to be searched for. * Should be thin and transparent enough for goo...

Evidently, I'm forced to give up on "Evident," since I'm just being ghosted now. I'm also ghosted by two used-scope dealers that I've contacted. One asked what my budget was, and I responded with a more-than-adequate 5-figure sum. But apparently not adequate enough to bother hitting "respond." Such ...

Thanks for the feedback. Your suggestion for an inverted stand is particularly thought-provoking. I think I've felt reticent about that due to the greater possibility of damage to the objectives, etc. But maybe it's worth the risk. Future compatibility for DIC can be a problem in that many systems s...

Oh dear, those sharks, Bain Capital!? A grim prediction: A hollowing out for quick, short term profits will likely ensue, leaving behind little more than a zombie corpse. Reminds me a little of H.P. spinning off their famed instrument division (so they could focus on ... Compaq!? How did that work o...

It's always good to keep some perspective on what the intended use will be. Dust and environment control in a domestic setting is worth some planning in. Very true. Facetiously, the intended "use" is as a retirement present to myself, as I like learning and playing in technological fields (also for...

I'm new here and maybe I shouldn't have stepped into this topic. I've never seen or touched a Chinese-made entry-level big-4 scope, either. But I bet they arrive (a) well packed with a high degree of cleanliness, (b) excellent functionality and working order, (c) with a comprehensive manual written ...

McBain's web-site does not mention Evident or the sale of Olympus microscopes anymore (parts for them maybe, though). They sell Motic now as their big line, and just a few others. They do mention the sale of used microscopes, so I'll give them a call and ask what they have. They are within driving r...

Ok, the focal length of the tube lens. Sure, I can see the slightly longer focal length being a modest benefit. More troubling, I see references to corrections in the tube lens. I thought infinity optics meant all corrections in the objective, with none in the tube lens. A question: None of the big-...

That's a lot of goodies! Yes, sounds like a good value for all that at that price. I started with Zeiss because I've used them at work for a long time and hence know a bit about them. I've always found them to be great, and I'm pretty happy with the 508, too. But I've never used any other big-4 scop...

I prefer to believe that Zeiss, as well as Olympus, Leica and Nikon, went to China seeking to make the best products they could at the target price. The good faith invested in their names has real economic value and has to be maintained and defended over the long term. That is more important to them...

Yes, I saw that post and a few others about it, earlier. It's interesting, but I'd wager the net cost of that microscope, well-equipped, including 50 lbs of air shipping and import tariffs (I'd have to expect California's "use tax," even), would be somewhat over $10,000, and likely about the same as...

I agree. I'm just venting a bit about how difficult the process can feel. If I could find that awesome institution-sourced scope, unmolested and with most of the features and accessories I want, available at a steal as surplus, I'd go for it immediately. But it seems that used research-grade scopes ...

If you buy a Nikon camera that's made in China, does that make it an anonymous Chinese camera that Nikon simply put its name on? No. It's a Nikon camera made by Nikon in China. If Zeiss makes it's entry-tier scopes in China, does that make them some shoddy Chinese scope made in a rural barn that Zei...

Greetings All, I have used a variety of high-end microscopes over the years at work (for viewing integrated circuits, etc.), and am in the process of purchasing equipment for personal use. I recently bought a Stemi 508 stereo with 0.63 "apo" barlow, directly from Zeiss. I routinely use a Stemi 2000c...