I wanted an digital microscope that's good enough to be an useful tool but inexpensive enough I would be willing it to use it as a future project subject. After a quick survey of offerings from Amazon vendors, I chose an Andonstar AD246S-M (*) and I think it meets my criteria nicely. Its capabilities are roughly in line with what I expected at its price point, for both good and bad.

USB Oddness

The bad news first: USB camera capability is sketchy. Sometimes when I plug it in, the microscope only draws power. The computer doesn't recognize it as a USB peripheral at all.

Other times, I will get a "USB" menu after the "Welcome" boot screen, asking me to choose between two modes. "Mass Storage" turns this device into a microSD card reader, and "PC Camera" turns it into a USB webcam. Reasonable enough, except I only have two seconds to act. After two seconds the screen turns black, then "Welcome" boot screen, and I have another two seconds to choose before it resets again. If I press down arrow + OK within that two second window, it seems to work fine as a webcam, but this startup situation does not bode well.

Solid 1080P Resolution

In their race to attract buyer attention, all sales listings for similar devices throw out the highest numbers they can. This particular device listed UHD and my skepticism was confirmed after a few tests: the practical limit is full HD, or 1920x1080. It is possible to record UHD video or even higher resolution pictures to the memory card, but that only resulted in bigger (likely interpolated) blobs with no additional useful detail.

Ignoring the UHD claim, the device was fine at 1080P. Using the included mini-HDMI to HDMI cable, I hooked up a 24" 1080P monitor and it reported receiving a 1920x1080 @ 30FPS signal from the microscope. Comparing the two screens, I think the little 7" integrated screen is either a real 1080P panel showing all the same pixels, or faking it well enough my eyes can't tell the difference. However, the little screen lacks fine color detail I can see on the 24" monitor's IPS panel. And if I save an image to memory card and bring that into a photo editor, I can pull out even more color detail. The sensor is better than the screen and I much rather have it this way than the reverse.

Looking at sharpness of these images, I think optical path is fairly well matched to a 1080P sensor. The color data is pretty noisy, like what I would expect if I turn my Canon camera up to a high sensitivity ISO 12800 or similar, but imaging detail is about right for 1080P. A lower resolution sensor would miss out on some detail, and upgrading to a higher resolution sensor won't gain much. The exact amount is a function of magnification, which depends on which lens is installed.

Interchangeable Lenses

The interchangeable lens capability was my justification for spending ~$30% more than a mostly equivalent product. Three lenses came in the box, each identified with a letter whose meaning I don't understand and a range of distance it is intended to sit from the subject under examination.

  • Lens "A" for 12-320mm

  • Lens "L" for 90-300mm

  • Lens "D" for 4-5mm

These lenses fits disturbingly loosely in their mount, far short of the level of precision I associate with Canon cameras' EF lens mount. But it gives me confidence I can match that (lack of) precision with 3D printing. Each lens is fastened with a pair of M3 heat-set inserts and I have lots of that, too. This lens mount mechanism leaves the door wide open for optical experimentation. Which is great for the future, but today I want to better understand this trio. My Adafruit Memento thermal camera was still on my workbench, so I used its front face plate RGB LED as the test subject.

Lens "A" Near and Far

When I pulled this microscope out of the box, lens "A" was the one already installed. I understand it is equivalent to the fixed-lens counterpart of this microscope, and it proved to be the most versatile of the trio.

Here is the view with Lens A roughly 320mm away from the LED. This is probably sufficient for surface mount soldering work. I have a Digi-Key ruler here for scale. Note the IC in the middle of the LED, roughly 0.5mm in length, because that's what I'm zooming in on.

And here it is with Lens A roughly 12mm away from the LED. The level of magnification is very impressive! But unfortunately it is way past my ability of getting a sharp picture. Part of this is the extremely shallow depth of field. Focus is done manually with a knob on the camera, so turning it exerts some pressure. I can turn the knob to the best focus of my ability but, when I release my hand, that tiny bit of flex moves the camera off focus.

The sharpness of this picture was also limited by the LED module's clear plastic cover, which was not intended to give me a clear view of the chip.

Oh, and that little black speck near the 4 o'clock position? That's inside the camera. I could disassemble the camera to try to clean it off, but doing so may introduce even more specks. So I will leave the spot, which will now be the signature of this microscope on every picture I take with it.

Lens "L" Near and Far

I raised the microscope back up and changed lens to "L".

Here's the view through "L" roughly 300mm from the LED. It has a tighter field of view than "A" at a similar distance.

And here it is roughly 90mm from the LED, as close it can get while still in focus. Again this is a tighter view than "A" at a similar distance, but in both cases I can move "A" closer to obtain the same picture. So what's the point? I think of "L" as a telephoto lens, used to take close-up pictures without getting close. Like National Geographic photographers who don't want to get eaten by the lions they're photographing, or someone who don't want to scare a mama bird away from her nest. In this application, it means "L" would be useful for soldering work where I want the camera out of the way of my soldering iron, far from sputtering flux, etc. but still offer a closer view than what I can get from lens "A" at the same distance.

Lens "D" Near And... Well, Just Near

And finally I switched to lens "D". With a listed distance from object of 4-5mm, there's not much range of motion. Such close distance also means it's really hard to aim LED illumination into that narrow gap from the side, as the lens cast a shadow otherwise. This lens is best suited for illumination from the back, like science lab microscopes projecting light from beneath a glass slide. (A set of five prepared sample glass slides and an illuminated slide holder was included in the box, which was a novelty but not why I bought this thing.)

Back to the Memento LED, I could get even closer to the little chip inside. Again I had to deal with a very shallow depth of field. In this picture I focused on the chip itself, and we can barely make out some features etched on the chip. Quite impressive especially since we're peering through the LED module's not-perfectly-smooth plastic cover.

The narrow range of lens "D" has an upside: it means the entire range of my focus adjustment knob is divided across a much shallower range of focus. In other words, it is easier to find the best focus I can and, when I let go with my hand, the spring-back doesn't move as far off-focus as when using lens "A".

Recommendation Depends On Usage Scenario

Given this first round of experiments, I think most people would be well served by a fixed-lens counterpart permanently mounted with the equivalent of lens "A". With identical electronics (sensor, screen, HDMI-out, etc.) it offers all important capabilities for a lower price. That said, I am happy with my purchase. Even though I felt this trio of lenses fail to justify the price premium, I didn't just buy the lenses. I also bought the lens mount and I think the real value lay in future optical experiments with that mount. And if I never get around to those experiments because I got distracted, well, that's not the microscope's fault.

(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.