UKH

I partially home school my daughter and generally do the sciencey stuff with her. She's keen on animals and biology and I want to do a project on cells with her and I'd love to be able to view cellular structures with her. I was more on the physics and chemistry side education-wise so I'm not particularly familiar with what we'd have to do and what equipment we'd need.

Some questions I've got are -

We've had various microscopes in the family of the years and all have been disappointing to use. I'm not sure if that's because I've been crap or they've been crap. Or both. What's the minimal quality microscope I'd need that would be useful? Also it would be great if I could get something that displays on a screen rather than having to peer through an eyepiece.

Is something like this - https://www.indiegogo.com/projects/imicro-q2-an-800x-microscope-for-any-sma... likely to be worth having or will it be shit?

In terms of cells to prepare and view what's likely to get me the best results? Also in terms of preparing slides and stains, etc what's important?

I probably don't know enough to ask the questions I need to know the answers to!

I got an upright microscope with a rotating turret with 4x, 20x and 40x objectives of Amazon for about £80.  We use it with a 5 megapixel eyepiece CMOS camera that was about £50 online.  It has a variable diaphragm for the illumination and a slide holder.  To view the camera I use VLC on a Raspberry Pi 400.  So far we’ve only looked at human cheek cells and onion cells, both without a stain.

The photo below is my cheek cells scraped off with my thumb nail and splayed across a slide.  I was surprised how good the results were for such a lazy effort at prep.  A sharp craft knife did a good job for the onions.   

Having the “proper” microscope configuration with illumination, a slide holder, focus control, a turret and illumination control puts it worlds apart from one of those barrel shaped “USB microscopes” and isn’t that far removed from a low magnification teaching lab microscope.  It does need a steady, practiced hand to move the slide about when on 40x in the absence of an XY stage.

If you want to get something very good - keep an eye on the Hilditch auction site

they often sell very nice Leica microscopes ex NHS

Are they really only 20x & 40x?! Or is there some kind of multiplication for the eyepiece?

They're pretty good!

Sadly something very good is probably out of my budget for a homeschool project but I'll keep my eye on the auctions (no pun intended)!

Cheap microscopes (£100 or so? Maybe less) do work but more expensive ones are a lot easier to use. I worked with microscopes on a daily basis for years and once you've got the cells in focus cheap ones are fine. It's just they're a lot less forgiving when you're trying to get something in focus. Start on the lowest magnification, rack the slide up to the objective lens and slowly lower it until it's in focus, then move up the the next magnification and repeat. It also helps to keep the diaphragm shut on low magnification, though at higher magnification you'll have to open it up or it will be too dark. 

When I worked in a lab I mostly used Gram stains for bacteria which I doubt you'll need. Methylene blue is the one I use mostly now as it's useful for determining yeast viability but it also works as a general purpose stain. On a very small scale ebay is the best place to get lab equipment as laboratory supply companies don't tend to sell in small amounts or will charge lots of postage if they do. 

Air bubbles if you're looking at wet preparations (slide, thing in liquid, coverslip) are the question you didn't know to ask. Avoid them as much as possible and google what they look like so you know not to think they're something significant. 

Probably multiply by ten for the eyepiece lens.

I find the whole idea of “40x” maddening.  It’s a marketing number not a science number when it comes to non-professional microscopes.  It’s pretty meaningless for many professional applications.

1. How many pixels are there per mm of the sample?  
2. What is the diffraction limit of the system expressed in terms of the full width half maximum of a point source in the sample plane expressed in terms of pixels on the detector plane?

Assuming sufficient signal to noise and matched numerical aperture illumination, those are the key questions.

I think my little eyepiece camera is only viewing the centre of the eyepiece’s field of view , meaning the effective magnification expressed as an “x” factor is higher, but I don’t know as I never looked down the eyepiece.  

See my rant in the message above.  The objectives were labelled “20x” and “40x.  Whatever that means they were nothing special given the total cost.  But then when you look at how long ago the pioneers saw these things with hand made lenses and hand made microscopes illuminated by candles, or reflected daylight, you realise that modern toy-level technology far exceeds what they had.  The key is to get an instrument you can learn to use and master.  Simple, robust, good focus control without too much lashback, parfocal objective turret, illumination controls.  Mine isn’t perfectly parfocal but it’s close enough that focus is quickly recovered upon an objective change.  Onion is a really good sample to practice focusing with - you need to develop an intuitive skill at focusing.  A good onion prep has two discrete layers which really helps develop that skill.

That was within an hour or so of unboxing.  I’ve built a few seriously low image quality microscopes for professional life science applications over the years - they made progress because sometime being able to take an image in a “natural” environment is more important than absolute image quality - so perhaps I’m more used to working with limited instruments.  But it didn’t seem very difficult TBH.

I keep forcing myself not to buy a used Leica body for my home lab because the money needs to go in to the pot labelled “Porsche 981 Cayman (yellow)”.  The Leica is probably a better investment.

If you want I can give you one free, old microscope used for university teaching 10x up to 100x objectives 

Very good quality just old you would need an eye piece camera to capture images 

That would be great! That’s so generous of you!

No problem PM me and see if we can sort out collection.

I’m in Leicestershire 

My tuppence:  for £400 get a binocular, secondhand x100-250 and have change for stains, good lighting etc.  

That's easily enough to look at most cells.

The magic of lancing your finger, making a perfect "fingernail" smear, staining and seeing the different white cells is wonderful at any age.

Get some pond water too...and blue cheese...and onion skin with iodine...