First Impressions of the Amscope SM-3TX Microscop

First Impressions of the Amscope SM-3TX Stereo Zoom Microscope



I’m sure there are many hobbyists and professionals out there working with very small electronics components who need a microscope. I have used a stereo scope for the last 20 years and could not function without one now that my vision is catching up with my age. But a microscope is a bit like a good RF signal generator, they are just so darn expensive to get a good one that you end up with something cheap and second rate or something very old (which might be just fine) or just do without. That’s especially true for hobbyists or those new to the business. Well, we recently had need to buy one, but on a tight budget, and here is how it went.

To begin with, I decided I wanted more working room than my old scope, adequate optical quality, zoom feature, and smooth controls. I sought advice in scientific and electronic forums on what to buy. Commenters generally advised to go for one of the top name brands in optical gear, either new or used. My own experience in electronics R&D laboratories has been with Nikon, Olympus, and Bausch and Lomb units, so I tried to find one of these names at the right price. But after many hours of ebay shopping, I found myself coming back again and again to all those hundreds of Amscope listings that overwhelm your basic search for “microscope”, and that led me to the Amscope website (www.amscope.com *). There are several low-cost sellers that use ebay (and many more in general) but this company had the mix of product features that I wanted. Their prices are so compelling that in the end I could not resist and ordered one of the SM series models, the SM-3TX.

Now that it has arrived, I have some first impressions on this unit. First off, I will back up a moment to mention that this product was easy to buy. The amscope.com website is well designed, it was easy to understand the product variants, checkout was smooth and delivery prompt.

On first unpacking, some of my fears about product quality began to wash away as the initial impression was very good. On quick inspection I could see that the milling and finishing of the metal parts appeared to be very good, the paint finish was fine, and the controls operated smoothly. While the unit was well packed, there was still some concern about things coming loose in shipment, but I found only one control that had made some attempt to unscrew itself and was trivially easy to screw back in.


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General view of the scope head. Note the camera port on top, and the small metal handle just in front of the zoom control for switching to this port.

Now, we understand that when we buy something at the lowest price, from a distant and unfamiliar supplier, that some allowances may have to be made. I approached this evaluation with that sort of attitude. The first sign of “low price” came with the user’s manual, which is minimal and refers to model numbers other than what I bought, and is obviously generic to an entire model lineup. I did not refer to this manual beyond a quick initial scan.

On assembly, I noted that the eyepieces slip nicely into their tubes, but the tiny setscrews that hold the eyepieces in are not included.

The image with these eyepieces is larger than I am used to. The image size at minimum magnification (about 7x without the Barlow lens attached) is 30 mm, while my old scope was 26 mm at best. A wider image is good. I wear glasses and unlike my old scope, with this one I had no trouble at all seeing the entire field width while wearing my glasses.

I am not a microscope expert, I am just a user, but to me the image seen in this microscope is extremely good. Starting without the supplied Barlow lens accessory, I was able to focus to an intensely sharp and clear image at 7x magnification. The image was in sharp focus from edge to edge. The depth of field is normal for the degree of magnification. The brightness of the image is much better than I’m used to in my old (and probably dirty) scope. On zooming to maximum, the image is still fine, although a small adjustment of the focus was needed, and of course the image gets darker at higher magnifications, which is normal. I did not purchase one of Amscopes lamps and prefer a simple desk lamp for low magnification work.

I then attached the Barlow lens. If you don’t know what this is, well, it is an additional lens that screws onto the bottom of the microscope body. It alters the magnification, in this case by halving it. Why in the world would I want to do this? Good question. The reason I use this is to increase the focused distance between the bottom of the scope body and the printed circuit board that I am working on. This gives more room to hold tools nearly vertical when working on a board, a feature that is useful when working with hot air tools in particular. Without the additional lens, the working distance is 100 mm (about 4 inches) which is not bad. With the Barlow lens the working distance increases to about 175 mm (almost 7 inches) which is even better. Since this lens halves the magnification it also doubles the width of the field of view which is also nice. Of course, if you then zoom back to 7x magnification, the field width is as it was before the lens was attached, but the focus remains at 7 inches. Since I usually work at about 8x, having some adjustment range above and below this is useful. The Barlow lens increased the price of the scope by $40.

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Extra working room due to the Barlow lens. Vertical clearance is 7 inches.


The model that I bought has an attachment point for a camera, the so-called trinocular head, but I did not evaluate this feature. It added $30 to the price. On this model, the camera port can be selected in place of one eyepiece by moving a control in our out. You can’t have stereo vision and the camera port working at the same time. Amscope offers a higher priced series that can do this, referred to as “simul-focal” models. Scope cameras can also be attached in place of one eyepiece on most microscopes with an appropriate adapter, so the trinocular feature is not critical, just a convenience really.

Amscope offers many different stands for their models. I was torn between the basic single post table stand and the single arm boom stand. I opted for the boom stand because it is a bit more flexible for viewing larger items, but must admit that I have almost always used a simple table stand on previous scopes and have never really run into a limitation. I feared the boom stand might allow too much play, but those fears were groundless. This is every bit as good as any boom I’ve used before. It is stable, steady with no play and easy to adjust. The boom clamps are good, using internal pressure rings not just a bolt end jammed into the pipe. The only real downside is that it takes up more space, and if you are working at a bench with a riser, there might be some fit problems. The scope head can be rotated of course and the boom oriented towards the side rather than behind the scope head.

I can’t say how well this product will wear with use. As I am easy on my things, and now that I’ve had a good look at it, I would not expect this microscope to give me trouble. On the other hand, I can’t tell how durable the metal is in the moving parts, for example, nor can I know what will happen to the lenses when cleaned by ham-fisted engineers, or for that matter, if anything breaks as the controls are repeatedly rammed against their stops. In a corporate R&D or production environment where the users often don’t appreciate their tools, who knows how long it will withstand the punishment? Durability is one key aspect of how the old established brands have built their reputations.

I paid $379 for this product and the initial quality is every bit as good as I had hoped for and far better than what I had feared. Overall, this scope is a bargain compared to what I’m used to in the corporate world. The same basic scope, less the trinocular feature, the Barlow lens and with the large table stand (well suited to electronics work, model SM-1B) only costs $319 which is within reach of the serious hobbyist and a reasonable alternative to paying an ebay seller $175 for an ancient Bausch and Lomb Stereozoom4, in my opinion. On the other hand, if you don’t have an oscilloscope yet, get that first.

* Amscope is short for American Scope Inc. who also does business on ebay as Precision*World. I am not connected to this company in any way other than as a customer.