[Music] hey everybody dr. Rowe here I'm actually gonna walk you through the microscope all the way from scanning power to the oil immersion system and I'm going to show you the parts of the microscope as we go as well as what you're seeing through the ocular inside the microscope so let's go ahead and get to it I decided to use a blood smear so we're looking at a blood smear here another microscope this is what the scanning power which has a 4x objective but the oculars up here the eyepiece has a 10x objective these can be twenty or twenty-five but you multiply the two together so right now we're looking at a total magnification of 40 X not very much when you consider how small a red blood cell is so 4x magnification here times 10 in the ocular I'm actually gonna take it out of focus I'm gonna take you all there in the beginning when I first put the slide on the stage here so I'm gonna first thing when you put when you put the slide on you want to make sure that it slides right into this little lobster claw here and then you move using these two knobs here the top knob moving the slide forward and backward bottom knob side-to-side then you're going to put the image right over your light source now the first major tip I can give you is to move the stage all the way to the top you want to start here and there's two reasons for that number one as students are often having trouble finding something on the microscope and I can see from across the room that they're never going to see it because their stage is way too far away and number two as long as you start at the top and work your way down you're not going to break your slides so that's the first tip I could give you so what I did there is I got it in focus using this here the coarse adjustment knob is how it's how you move it large distances as you can see here sorry for the psychedelics there but then now that I have it where I think it's in focus the key here with this with what's called a parfocal microscope especially where the objectives are linked together the key is to make sure it's as close to 100% in focus as possible so I will actually I call it the Goldilocks strategy I will actually purposely take it so I think it's in focus going in one direction I'll purposely go too far take it out of focus and then I'll go back and the reason I do that is because if it's only ninety percent in focus it'll probably look pretty good at this lower magnification but as we move up I'll be farther and farther away from actually having it in focus okay so once I think I have it in focus the next thing to do before you move on is to find what you want to look at which really we're just looking at a sea of red blood cells at this point but you want to find a part of the slide that you think is interesting not much to look at here but if you find something you definitely want to see you want to Center it and that's because right now we're looking through a 40 X magnification as I go to the next power which I will now the 10x magnification a low power the magnification is jumped from 40 X 200 so that means the magnification went up two and a half times which means the field of view what you can actually see has gotten two-and-a-half times smaller so something looks really interesting on the right-hand side of the field of view inside the microscope when I go to the next power I'm not gonna see it anymore it's somewhere off to the side here so all right so the same thing I get it where I think it's in focused I use my Goldilocks strategy to purposely take it too far out of focus both directions and that's why I do so I kind of like the eye doctor like is this better or this better well they both look pretty good right right have it here and then just a little bit difference but if you get it super crisp you're going to think yourself later all right so the low-power I now had in focus not really looking at anything yet we're just getting to the point where we can visualize structures but what you are looking out here just real quickly this is you know your blood is 99.9% red blood cells so you're looking at a sea of red blood cells here those little purple structures you see throughout those are gonna be your white blood cells but we'll see them in more detail as we progress now we're gonna head to the high dry power does the hydropower is called that because the highest magnification you can get without using immersion oil which we'll use when we get to the oil immersion objective the hydride power has a magnification of 40 X so you take that times the 10x magnification that's in the ocular and we're now looking at a total magnification of 400 X now you may have noticed that I had to turn the light intensity up a little bit there so this is the rheostat knob where you do that and that as you as you go up in magnification think of it this way you're basically using less of the light bulb so it does get darker so that's why I turned up the light intensity a little bit using the rheostat knob now we're starting to have some structures that I want to Center they really want to get a get a good look at here so I'll actually just annotate in the video which types of white blood cells were looking at but I have it in focus as good as I can get it so what I'm gonna do now is just scan around a little bit and let you see what some of these wet blood cells look like here at this hydropower so I'm just I'm just scanning around I'll kind of highlight things that you're seeing but we're actually gonna move on then to the oil immersion lens system so I've done other videos on oil immersion I've done other videos on why we need oil for oil immersion but now let's just go ahead and do it so the key here with oil immersion is we have to put immersion oil right on the slide so I'm gonna I'm gonna turn this half a turn so it's gonna look black there on the screen as I grab my immersion oil immersion oil works because it has the same refractive index as glass so I'm gonna put a single drop of immersion well right there on the slide and then I'm going to slowly move the objective into place and what I should actually happen is the glass with the immersion oil on it should now be act touching the oil immersion objective and now I just jumped up from 400 times magnification to a thousand but notice how that it's almost perfectly in focus and the key there is I did my work moving forward like I talked about in other videos and I made sure it was as focus as it could be at the hydropower and that made my life a whole lot easier as I moved forward so I'm just gonna tweak this a little bit I'm just gonna scan around try to find a couple things more interesting but mainly were to seeing these red blood cells here here's a handful of white blood cells there's a platelet there I'll highlight that in the video and that is how you use the microscope so now that I'm done again stage all the way down and I'll complete my cleanup I'll turn the rheostat now up down turn the power off and there we go I have some cleanup to do but that is how you use a microscope from start to finish this should be the definitive guy for how to use the microscope in the lab have a wonderful day go change the world [Music]