The Myth of the Digital Microscope

[DonSchaeffer]

I was buying digital microscopes for a while. I was touting the images I obtained as micrographs. I tested the digital microscopes I have against a stage micrometer and retuned a startling conclusion. They don't resolve like microscopes. These are as magnified as they get. One brand is slightly stronger than the other.

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[PeteM]

Don, can you provide a link to the types of digital microscopes? Parents ask about these for their kids and it would be useful to know a bit more.

[MichaelG.]

I’m guessing that there are two factors at play, Don
1. Low native resolution
2. Lots of jpeg compression

+1 for Pete’s information request.

MichaelG.

[Scarodactyl]

There are a wide range of digital scopes available, ranging from 10-20 bucks to 10-20k+ bucks. But they do tend to aim somewhat low on resolution--even something like the Leica DVM6 only has a 10mp camera integrated, so it's hard to imagine some corners aren't cut since you can't get more than that 10mp out of it.

[DonSchaeffer]

I bought a number of them over the years. Some of them make claims to be 1,000 power. Actually the magnification comes from how close the subject is from the lens. These pictures of my stage micrometer were taken with the camera sitting on top of it, as close as you can get. The most magnified picture covers the entire micrometer scale. My poor little Amscope (with my humble 640X480 eyepiece camera) is at least 10 times better. One of my digiscopes is the Pluggable model, top rated.

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[MichaelG.]

I bought a number of them over the years. Some of them make claims to be 1,000 power.

That sort of number is produced by including the assumed monitor size.
Leica does the same ... so it must be considered to be ‘honourable practise’

MichaelG.

.

Ref. https://www.leica-microsystems.com/scie ... ally-mean/

.
Edit: Here is the specification page for one of the Plugable microscopes:
https://plugable.com/products/usb2-micro-250x

[DonSchaeffer]

The magnification number isn't important--the same thing can be said for any camera. If you present it in IMAX, it will look huge. It's a resolution issue really. It's not honest to say 250X when on an ordinary monitor you don't get anything like 250X.

[Scarodactyl]

It's certainly not an honest or useful way to present magnification.

[MichaelG.]

The magnification number isn't important--the same thing can be said for any camera. If you present it in IMAX, it will look huge. It's a resolution issue really. It's not honest to say 250X when on an ordinary monitor you don't get anything like 250X.

Sorry, Don ... I’m struggling to understand your grievance [please forgive me if I’ve missed the point] and you still haven’t said exactly which ‘Digital Microscopes’ you are complaining about.

The ’Plugable’ one that I linked is just a modified webcam, claiming 1600x1200 resolution for ‘snapshots’ and 640x480 for ’video’ ... if that’s similar to yours then the performance surely comes as no surprise [?]

As you so rightly said:

It's a resolution issue really.

MichaelG.

[DonSchaeffer]

I have no grievance. That camera claims 250X. When I was using it, I thought I was getting 250X. Then when I tried it on an objective criterion it turned out to be like a magnifying glass. I know a lot of people using them for welding and looking at circuits. These commercial products are no more than digital magnifying glasses. To me it was a revelation (sorry).

[MichaelG.]

Just for general information :

I have not found a specific reference to what sensor is used by ‘Plugable’ [and it may be superior]
... but GC0308 is commonly used in the so-called ‘digital microscopes’

Summary brochure: http://www.chinesechip.com/files/2015-0 ... 375d31.pdf
Technical datasheet: https://www.min.at/prinz/fp-content/attachs/GC0308.pdf

Most of this is just amazing electronics stuff, but there are some very relevant numbers disclosed:

Optical Format : 1/6.5 inch
Pixel Size : 3.4um x 3.4um
Active pixel array : 648 x 488
ADC resolution : 10 bit ADC
Max Frame rate : 30fps@24Mhz,VGA

So ... in practical, optical terms : The chosen lens is imaging onto 640x480 pixels which are each 3.4 microns square. This gives us the native resolution, and everything after that is ‘image processing’

Note: The higher resolution claimed for ‘snapshots’ is produced by interpolation.

MichaelG.