Are you seeing microscopes claiming to provide magnification up to 2500x for a compound microscope, and 180x for a stereo microscope? The highest useful magnification for a compound microscope is 1000x, and most routine stereo microscope zoom up to 45x magnification - so how is this possible?

The answer is quite simple, the claim is misleading, and tricks  the customer into buying into false / empty magnification. Yes you will still get 2500x magnification, but the information you gain under 2500x is quite useless. In fact 1000x magnification provides you with the maximum amount of useful information.

These websites give you more magnification by giving you multiple sets of eyepieces (15x & 20x). In order to gain the 2000x magnification you will need to swap out the eyepieces. This will lead to you dropping eyepieces, making the lenses dirty, getting confused as to which eyepiece is in, but most importantly empty magnification.

Why is false magnification bad?

Yes putting in those 20x eyepieces will give you 2000x magnification, but what these sites do not tell you is that you will not be able to see the detail you need to see. You are increasing magnification but decreasing the optical resolution. The image will become blurry and useless. This is the same concept as if you were to zoom in on a picture on your phone. As you zoom in closer and closer the picture becomes blurry to the point that the picture is useless.

In addition the filed of view (area you see) is greatly reduced when you put in higher magnification eyepieces. Most 10x eyepieces have a 20mm field of view, while most 20x eyepieces have a 12.5mm field of view. Therefore the end result is that you see roughly half the area, with poor resolution. 

So why do they make 15x & 20x eyepieces?

There are a very few limited applications that require higher magnification eyepieces. 99.9% of the microscopes we sell are with standard 10x eyepieces.

The reason some models advertise 40x-2000x magnification is simple- marketing. They rely on an uneducated customer buying into their products. They mislead the customer into thinking they need 2000x magnification, when they really don't. Take a look at all of the major brands, and you will find that they do not advertise false magnification.