After doing a lot of reading online and considering various types of microscopes, I finally decided to go for one that's made specifically for this sort of job. One that allows you to easily solder or do various mechanical tasks under it and that doesn't cost as much as a car.
The obvious choice was AmScope (Amazon URL), which are well priced and have a big range of options and I almost went through with buying from them, but I live in Europe and the price of shipping + import taxes can't be ignored for such an item. A bit more digging around revealed that there are several online microscope shops in the EU and a few more brands popped out, like Optika and BTC. What I found was that the industrial line of microscopes looked strikingly similar across all of them and there were even some no-name ones being sold, that looked exactly the same. I figured there must be at least one company in China that's making them and that all these companies are probably rebranding, so I set out to find the OEMs in the hope of getting a better deal.
After some more searching (it did took a bit of effort), I found http://yydag.com/ which appears to make these microscopes and is probably the OEM. I don't know this for sure, but it looks that way and if anyone has information that can confirm or deny this, please let me know.
Needless to say, I contacted them by e-mail, told them what I need and requested a quote, including shipping. They answered surprisingly fast and the communication since the first contact was smooth, pleasant and the contact person was extremely helpful. Sadly, they prefer having your own freight account number, but they did agree to ship it to me via TNT, which made this review possible. The whole thing was about $680 (including shipping) and I paid by wire transfer.
What and how I got it
Given how we normally use microscopes for electronics work, going for the boom stand was a no brainer, but I had a choice between two boom stands, STL1+A1 and STL2+A1. While the later one is much more robust, since it can slide back and forth easily, I decided to go for the STL1, because it's a bit smaller and fits better on my desk. If you have plenty of room, the STL2 version seems like a better choice.
For the head, I went for the SZM7045T trinocular, because I already have a SLR camera and I figured I could use that to document various things. In order to fit the camera, I also needed a CTV adapter for the 3rd port and a connector that was able to connect the SLR camera to the CTV adapter.
The objective is a 0.7X to 4.5X zoom objective, which in conjunction with the 10X eyepieces give you 7X to 45X of continuous zoom magnification at a working distance of about 10 cm. I wanted to increase the working distance so I also ordered a 0.5X auxiliary lens which gives you about 16 cm of working distance, while reducing the magnification to 3.5X to 22.5X. On top of this, I figured I might want to fool around with other things so I also ordered a 2X auxiliary lens and 20X eyepieces.
To have a complete setup, I also ordered a 56 LED ring light.
After the payment cleared, I received the box at my door in about 4 days. It was very nicely packaged, in a foam enclosure specifically made for it - I kept it for safe transportation in the future.
Everything had its own bag or tiny, individual box, just as you expect from a new product and as an added bonus, it also came with a dust cover (a rather high quality plastic bag, that fits over the microscope when you're not using it).
The base of the stand is much more heavier than it looks, which means that it can sustain the head, a SLR camera and a lot more other stuff you feel like mounting on the head, with ease, with out running the risk of tipping over and falling. I was concerned about this before I got it, but not anymore. I really like it.
The arm can slide back and forth, but it requires a bit of effort on your part. I knew this was the case with this particular stand (not an issue with the other one), because it only has a single rod, but I don't mind it since I'd rather move the unit I'm inspecting, rather than the microscope anyway. Moving it sideways is effortless and it can be locked in a specific position with the use of a screw on the side. Can also be tilted, but that's of little use to me and I'm unlikely to ever do it, so I locked it facing straight down.
It's also possible to flex it in such a way that the arm comes at a different angle, other than straight at you, while keeping the eyepieces directed towards you. This can come in handy when space is tight.
Both the focus and zoom knobs are in pairs, one on each side, so no matter which hand you have free, you can still focus and zoom with ease. They have a nice feel to them, putting just enough resistance not to feel flimsy and to allow you to get the desired zoom/focus, with out making it hard to operate. The focus knob also seems to lock in place and requires a tad more effort to get moving again once you stopped. I don't know if this is by design or not, but it feels good.
One thing I was aware of before purchasing it, but it's not entirely obvious and some people might expect differently, is that the third port is not always on. You can either have the left eyepiece working, or the camera port. This is switchable by pulling or pushing a slider on the side of the head.
The only other microscopes I used were biological microscopes, in school, so I can't really compare it to other microscopes and I'm not an expert in everything optics either, however I've been using SLR cameras for many years and I've had both good and crappy lens so I have at least an idea on what can be achieved in terms of optics as well as how bad it can get.
I believe the optics of the objective is good towards very good and the image quality with no extra lens + the 10X eyepieces is absolutely stunning. The same can be said when using the 2X auxiliary lens, which I find myself using more often than I would have thought. With the 2X auxiliary lens + the 10X eyepieces, you can easily inspect the quality of the vias for example - again, the image quality is amazing.
With the 0.5X auxiliary lens, which is what I use most of the time, the quality of the image is still very good, but does not qualify as amazing, as in the other two cases. I think this is to be expected, as it requires more light and the working distance is much higher.
The 20X eyepieces are probably the black sheep of the family. I used them once and I just felt like I was getting more detail with the 10X ones, even if the image was smaller. After that, I put them in their box and never used them again. They might work in some situations, but truth is I don't really need 180X so there's no need to compromise.
The photo port
Initially I ordered a 1/2 CTV adapter, however that didn't work well with my DSLR and I was able to procure a 1/1 adapter which seems to work a lot better. The picture quality is not what I expected, but as I learned from talking to a few biology enthusiasts, this appears to be the norm when it comes to microscopes and they said my photos look okish.
One of the two issue I had was that the left side of the photos was a bit out of focus at the higher zoom settings, so getting a well focused image might require 2 pictures, stacked together: one to get the center and the right side in focus and another one for the left side (just tweaking the focus knob and taking a second picture). The other issue was that I couldn't get the camera in focus at the same time with the eyepieces when using the 0.5X auxiliary lens. I believe this is strictly related to the adapter and to the fact that I didn't know what I needed for my setup.
After getting my expectations back in check, I was able to consistently get good photos with a bit of post processing. Good enough for documentation and measurements.
For the first picture I used 3 images, one to get the middle and the right side in focus, another one for the left side and another one to also get the top of the capacitors, the LEDs and the bottom resistor in focus. After that I used a sharpen filter to get rid of the blur. For the measurement picture, I only used one photo and applied a sharpen filter.
All in all, I think it's worth getting the trinocular head over the binocular one. The picture quality is decent and it's a big upgrade from taking pictures through the eyepiece - just pay attention to which adapter you need for your camera.
The 56 LED ring light
Simple thing, but it's worth mentioning, since lighting is very important. I always have an extra lamp shining down on the things I'm inspecting and I observed that when using no auxiliary lens, both the ring light and the extra lamp help, but when using the 2X lens, the ring light dominates and the extra lamp can't provide enough light by itself. The situation is reversed when using the 0.5X lens: the ring light can't do it by itself and the extra lamp becomes the main light source.
It wasn't apparent from the photo on their site, but the ring light also has a dimmer that gets a lot of use when zooming in and out, since the light can become too strong as you zoom out or too dim when you zoom in.
One thing I was pleasantly surprised by, is that once fixated, the ring light can still be rotated to give you better access to the on/off switch and the dimmer and the movement has a similar feel to the zoom and focus knobs, smooth and precise (not that it matters, but it's a nice touch).
Being a microscope newbie, I didn't know this at first, but the eyepieces can be adjusted such that you don't have to continuously re-focus when you zoom in/out.
A minor annoyance were the tiny screws that you can optionally use to lock the eyepieces into their sockets, so they can't be pulled out. There's nothing wrong with them, but I lost them at least 4 times while switching eyepieces, since they're so short and tiny and they fall off when you unscrew them. Now with the 10X eyepieces permanently in place, I don't have to worry about this again.
An additional thing you can and I strongly advise you to buy, is protective filters (yes, just like for your camera). Turns out you can get 48 mm to 52 mm adapter rings that can be fit on the 0.5X lens or directly on the objective and then use any 52 mm filter you wish. Personally, I got some cheap UV filters (plain glass), for a total of about $5 (adapter + filter). The filter will protect the much more expensive lens from fumes and solder/flux splatter, so it's definitely worth the investment. The 2X lens doesn't have a thread, so you can't fit filters on it, but the working distance is so tiny that you won't want to work under it anyway.
Well, I guess the tone of the review makes this less of a surprise: I love it.
In the short time I had it, I used it both for inspection, soldering and rework of 0402 components and for some soldering tasks that I would have otherwise thought to be impossible. I was surprised to learn that even cutting traces and pieces of a ground plane from a PCB is much easier under the microscope, because you see how deep your cutter is going and you can actually peal the copper off.
I think I got a great deal and I believe Yuyao Dagong Instrument is a serious company that can be trusted. If I were to need another microscope, for the same task, I'd choose them again.