Sciencemadness Discussion Board

What kind of microscope to judge crystals ect.

Gargamel - 8-7-2019 at 11:46

Hi guys

I often come to the conclusion that my inventory lacks a microscope...

For example to judge crystals size and shape, but also anything else that might come up...

What kind do you use?
I honestly have no clue WHAT to buy.

I'm inclinded to go for an USB device, since my computer is running most time anyway and I also like to share some pictures on the internet. But are there arguments for an oldscool microscope like those used in schools too?

[Edited on 8-7-2019 by Gargamel]

Sulaiman - 8-7-2019 at 20:19

some usb microscopes have surprisingly good optics,
the main difficulties (with any microscope) are suitable illumination and positioning (X, Y, Z)

P.S. read the specifications carefully,
e.g. a 640x480 pixel sensor (0.3Mpx.) can be advertised as 2Mpx. or even 10 Mpx. (using software interpolation, which gives no extra detail)

You could try gambling that this is not a scam :D

[Edited on 9-7-2019 by Sulaiman]

Herr Haber - 9-7-2019 at 03:24

I got myself one of those to cheap to be true USB microscopes from eBay.
Wherever you type USB microscope you always get microscopes (especially the body) that look the same.
That goes for the 200 Euros version from my regular lab supplier to the 15 Euros one on eBay.

That makes me assume that they are all more or less of equal quality unless someone works Q&A and puts them into different bins depending on how well they pass the tests.
So I concluded they are all crap and decided to get a badass magnifying glass instead.
I might not be able to see as close as a microscope would allow me to but at least I know it'll work !!

Gargamel - 11-7-2019 at 10:43

Sorry, I should have posted this in "Reagents and Apparatus Acquisition".

Maybe somebody can push this over there...

In find this very difficult, I cant find anything but china junk and super expensive stuff...

I dont need a screen. I would use my computer anyway. But I would like to have a little more magnification... For things like watching amoeba and stuff, like back in school :)

teodor2 - 11-7-2019 at 14:01

Quote: Originally posted by Gargamel  

What kind do you use?
[Edited on 8-7-2019 by Gargamel]

This model is really very good one (optically), the trinocular version costs 600 EUR, so, possible it is expensive if you are not mad on optics like me. Actually you can buy stereomicroscope much cheaper, say 300-400 USD.

If it is your first microscope I recommend to buy exactly this type of build (stereomicroscope, should contain 2 objectives and allow to look both in transmitted and reflected light. Biological microscopes can be used only with transmitted light - not suitable e.g. for crystals).

[Edited on 11-7-2019 by teodor2]

BromicAcid - 11-7-2019 at 14:38

I bought a USB microscope (brand Pluggable) from Amazon, I use it together with ImageJ software (free) to measure crystal size. Also good for taking pictures.

Gargamel - 23-7-2019 at 11:22

Thanks for your answers.

The problem with stereomicroscopes seems to be that they are only available with rather low magnification.
I would prefer to have some 400 or 500...

Is stereo really worth it - especially compared to a really good monocular device?

An is it possible/advisable to use a microscope that has only a light from below with an additional improvised light from above?

teodor - 23-7-2019 at 12:31

Quote: Originally posted by Gargamel  

The problem with stereomicroscopes seems to be that they are only available with rather low magnification.
I would prefer to have some 400 or 500...

Is stereo really worth it - especially compared to a really good monocular device?

An is it possible/advisable to use a microscope that has only a light from below with an additional improvised light from above?

I already tried to answer these questions in this thread. So, generally, the resolution is not the same as magnification. I have no idea what kind of crystals you try to look, but for the most of them the magnification up to 45x is enough. 45x is huge magnification for things like powders. With a good optics you will be able to see particles with size of 5 microns. What you said is that you prefer to look in a very small area . I am not using microscopes professionally but I know from my experience that that magnification you mentioned is possible only with flat and specially prepared things under special light. Otherwise you will not see what you like to see. I don't know how to describe it, just try, possible you will see a lot of rainbows with no idea what is the actual shape of the crystal. But if you know how to look crystals under such magnification, well, probably I never had a "really good monocular device" :).

Just some ideas how to increase magnification over 100x -

Also, check this wikipedia article, there are some pictures. But my opinion that it should be not the first device you use for general observation. And it is already seeing something different than just 3D shapes. For 3D shapes we obviously should use a stereomicroscope.

Sure, it is possible to add some light from above if there is a gap between your objective and the sample. But on high magnifications there is no much gap and the light from above becomes a light from a side. So, most of the time you will be able to see long shadows or something like color circles due to different light artifacts.

Check "dark-field microscopes" to get the idea of devices designed for that purpose.

[Edited on 23-7-2019 by teodor]

Gargamel - 24-7-2019 at 12:09

Thanks again.

So I'm going to look after a 2nd hand stereomicroscope with both top- and bottom light (which seems to be rather unusual...)

teodor - 24-7-2019 at 13:03

You are welcome.

Some things worthy to attention when buying a stereo microscope.

1. Maximal available magnification.
Usually it should be possible to raise the magnification either by changing the eyepieces or screwing an additional lens on the objectives side or both. Check the availability of these additional components - for every vendor or model they are different. Also check in the manual which maximal magnification you can get with those additional components. For middle-quality stereo microscope the maximal magnification should be around 150-200x (for example, basic - 45 x, 2x by eyepices and 2x by an additional lens = 180x). But very quality models like Zeiss write the max. magnification up to 600x. Never had a chance to test that but you can probably compare optical quality by this parameter - I think only very precise optic could work with so powerful additional lenses.
2. Zoom is really useful. The most important in zoom is precise adjustment, you should be able to zoom picture without refocusing. It can be problematic if your sight is not 100%, for that purpose eyepieces have dioptric correction. Check the range of correction, you can zoom without refocusing only if the correction is enough for your sight (also it is possible, of course, to look through glasses).
3. Every stereomicroscope head can work with different stands. Basically, the most important think is a head, you can have several stand types to mount the head. The light and focusing is connected to a stand.
4. Old optics (not sure, possible 20 years +) often very seriously degraded in quality because of mold grows on lenses. If the picture has a yellow tint it is the case. This is impossible to repair, so some good old microscopes can be very cheap exactly by this reason. Best models of optics have argon or nitrogen filling inside lens groups which prevents the mold grows but I never saw this in microscope specifications.

[Edited on 24-7-2019 by teodor]