Teeny tiny rulers

With cheap USB microscope, I got a clear plastic sheet with ruler markings on it. Exactly what you want...

This might help start a search: https://www.ebay.co.uk/itm/175127027642

#microscope #calibration #graticule

A trinocular, zoom stereo is a good start Iain

But it’s worth noting that the photo-tube will only be imaging one path, and you may get some trouble imaging horizontal surfaces [try tilting the specimen, to see what I mean]

On the matter of Graticules/Reticles … have a browse here for inspiration: **LINK**

https://www.graticulesoptics.com

I doubt you will want, or need, to spend that sort of money; but it shows what’s possible.

MichaelG.

Edited By Michael Gilligan on 14/01/2023 11:16:46

Just for the record, here are images of the central area cropped from the HiView v1.4 software, showing the cross axes (scale factor can be calibrated) and other measuring tools.

Looks entirely adequate for the job, Malcolm

Iain would just need to calibrate his zoom magnifications.

MichaelG.

.

Ref. __ http://www.hvscam.com/soft.asp?lang=en

Edited By Michael Gilligan on 14/01/2023 14:43:55

Michael - the microscope is 'simul view' which means it uses both sides (binocular) for the camera. And no, I have no idea how that works, but it's meant to provide a true monocular view to the camera.

I think what I will do is two things. Easy: I will buy the 0.25 marked grating from Jack's ebay link. I should be able to estimate down to +/0.025mm or so - a thou, which Is about as good as I could expect from a hand measurement.

I will also extend my software to provide a means of measuring a snap and applying a scale factor depending on the zoom. I'm not sure if I can realistically do that directly from the setting on the microscope as the scale appears neither linear nor precise, but at the worst case I can use an object of a known size to provide the scale factor (be it the grating or something else - to be determined).

Many thanks as always, that was helpful and interesting.

Iain

.

That’s excellent news, Iain

MichaelG.

.

Ref. __ from another forum, in 2017

.

[ click to enlarge ]

Edited By Michael Gilligan on 14/01/2023 17:24:53

I have some Rabone Chesterman stainless steel rulers which have scales down to 1/100" and the six and twelve inch slim ones could be cut down to make mini rulers. They also have mm, 1/2 mm and fractions down to 1/64". Smaller scales would be very hard to use manually.

Following the various ideas and advice from the forum, I've ordered the calibration scale (not arrived yet) and updated my software.

General View

The use case for this tool is mainly to keep a history of watch disassembly so I can see what goes where when I put it back.

The image above shows how 'WatchSnap' works. Top left is the live view (which won't snip for complicated technical reasons - imagine a live video . Bottom left are all previous pictures for that 'project' (all in a specific directory) and to the right is the latest snap.

It's the right hand side which has been updated.

The first thing I do is to put a ruler in place and snap it. Then use the set scale option to work out how many pixels per mm.

The red line is drawn and and the software works out how many pixels it is. This is shown for information and sanity at the bottom of the page. I'm considering adding a 1cm option as the precision at low magnifications (this is about 4.5x) is poor.

Then I can measure something. I take away the ruler and do a new snap and then I can measure, just by clicking and dragging.

This (roughly) the distance from the centre wheel to the balance pivot.

When you zoom (25x) in you need to re-do the scale.

remove the scale, resnap and you can then measure small things.

This shows the diameter that the watch hands will need to push on to bus an approximation of the wheel dimensions. Note that I can set the colour of the dimensions to work best with the background.

In fact the focus on this on the camera could do with a bit of tuning. The camera and eye focus don't track perfectly as you zoom - it's much clearer through the eyepiece.

Still a few things to do, but you get the idea!

Many thanks for the impetus and ideas.

Iain