AmScope OMAX 40X-2000X Lab LED Binocular Compound Microscope with Double Layer Mechanical Stage and Coaxial Coarse/Fine Focusing Knob

First: the highest magnification objective lens is oil immersion only. You must put a drop of oil on your slide cover and then lower the lens into the oil to focus on anything. You must NOT do that with the other three lenses.This is what allows the 2000x mag: light goes through oil instead of unsteady air. It's a fantastic feature at this price. Don't worry though, you can be happy just using the other 3 lenses, which is what I plan on using mostly.**If you didn't know what oil immersion objective meant-know is the time to research 'microscopy techniques' along with 'microscope slide preparation' and 'cell staining' techniques and 'dark field' vs 'light field'-- illumination'. Basically: this is a 'real' microscope, and you should learn how to operate it in the proper manner to use it at its fullest. With that said, except for the 4th lens they throw in (oil immersion) a little kid could easily figure out all the features. There is supposed to be a slip of paper with address to download a manual-but I didn't see it. There are tons of omax videos on you tube if you need help.I chose the LED light because: they run cold so it won't kill live pond cells like a hot halogen would. They also last longer.So, how is this scope? Well it's better than what I used in high school and Chem I in university. It's way better than my 4 cheapie Tasco-style garage sale scopes and my homemade macrobellow system.Assembly was easy: loosen knob at top to remove top cover. Remove clear cap on underside of head unit. Place head unit on top of scope and re-tighten knob. Pop in the eyepieces: my 20x were **really** tight and hard to install, but it's 40 degrees here and the metal holes that they fit into may have contracted a bit. Just be patient and they'll go in. That's it!! Oh, and plug it in for light.The objectives are parfocal, meaning when you switch between them you only have refocus using the fine-focus knobs a little. Great feature which makes using it even more of a pleasure. There is a dimmer switch for the LED, and also a diaphragm under the stage-which was half closed when shipped: slide it open for even more light. Again, if you don't know what these terms mean you should start researching 'how to use a microscope'.Optics appear flat and focused edge-to-edge, which is the opposite of many telescope mirrors I deal with~but that's another story. Each eyepiece spins for diopter adjustment, and the eyepieces slide apart for interpuppillary adjustment. Focus with one eye closed using the focus knobs, then switch eyes and focus that eye buy turning that eyepiece itself. Now open both eyes: both will be focused but you'll have double vision: slide the eyepieces further and closer apart. At some point the double vision goes away and in a snap you get a very wide-field view: a single view. It a little like those 'magic eye' optical illusion posters: once you get it-you get it. But it might take a few minutes of fiddling.Delivery: I just joined amazon prime as a guest and this was the first thing I bought. It arrived (to Detroit) in less than 48 hours. It came with all the accessories listed and a nice cover too. It comes with a green filter in case you get chromatic flaring: but that's why the scope doesn't cost **literally** 15x more (at a minimum).I love this microscope, and wished I had bought it earlier. A hearty 5 stars!!!

(UPDATED REVIEW)This is an update to the review below. I must state that, after I wrote the first review I was immediately contacted by OMAX customer support. To be honest, I am not sure how they got my phone number...I assume through my Amazon account. A "tech" called and left a message. He stated that he would be happy to try a few things to get the microscope working properly. Unfortunately, I had already packed and mailed the first microscope back to the factory so it was too late. I agree with some reviewers that the microscope needs to come with a BASIC instruction manual. I am not a first time user of microscopes so it assembled with ease. However, I am sure some people would really need a basic guide.My second microscope arrived and is working PERFECTLY. Thanks!Thanks to OMAX for the amazing customer support and for reading the reviews on Amazon. It really shows they care! I have not had the same luck with their competitor Amscope. They were quite rude to me when I needed assistance.(BEGIN ORIGINAL REVIEW)When the microscope arrived I was really exited and began to assemble it immediately. One of the FIRST things I noticed, while assembling, was that the lens at the base of the viewing scope (the one that faces down when you attach the viewing head to the base with the knurled locking screw)was glued in place at a slight angle. It wasn't flush in the hole that the lens was supposed to go in and there was a large glob of glue (optic cement) on the side.I desperately wanted this NOT to be an issue and, when I first started using the scope...it didn't seem to be. Then, as I increased magnification more and more, I began to notice that focus was IMPOSSIBLE at 1000x or 2000x magnification. I tried slide after slide and to check the focus. I could NEVER get a clean or crisp focus and I became fully aware that this lens placement was the issue.So, with a heavy heart, I decided that this microscope HAD to be exchanged.I am going to order another one of these microscopes because I am SURE that the first one suffered from human error during the manufacturing process and feel the microscope, if built properly, must be a good product from all that I have read. So, here we go again...