DC Fan wrote in post #15661208
There's a threshold of multiple posting of identical messages that can be too easily seen as spamming or trolling.
... and we haven't had our morning coffee, have a bad case of "bed hair", and are sort of grumpy
It's really pretty simple to use... Turn the AF on, mount it on your camera, use it normally.
AF on and off is pretty self-explanatory. This is a USM lens, so you should be able to manually override focus at any time, however read the warning below.
The Focus Limiter is pretty self-explanatory and can be used to speed up AF, if needed and if all your work is being done within a particular range of focus.
The rest of the functions are relatively optional.
"Signal" selects whether or not AF "beeps" when the lens achieves focus (it's also selectable on most or maybe all modern cameras). It only works in One Shot (not in AI Servo).
"Preset" is a special focusing function, via a switch that works in conjunction with the heavily knurled ring just behind the manual focus ring. Forward position turns it off. Middle position turns it on. Rear position is momentary and you slide that to record a particular preset focus distance, after it's been achieved with AF. You then can recall that preset focus distance instantaneously by turning the knurled ring either direction. How to use it? Well, say you are photographing at a soccer match and want to set up the focus to recall focus on the goal quickly, in case some future action occurs there. Go thru the setup procedure and leave the switch in the "on" position, and you can go on with your business focusing elsewhere, but will have that distance to the goal preset for quick recall if needed. It remains recorded until you change it.
"Manual focus speed" is also pretty self-explanatory, experiment with it if you wish... Basically the reason you would change it would be when speed is the more important factor to focus more quickly with minimal movement of the focus ring, vs setting it to focus more slowly, with greater movement of the ring for a higher degree of precision. With large aperture lenses and their inherently shallow depth of field, it can be important to be able to focus precisely. Thus a lot of them have "long throw" focus mechanisms. With this lens you can choose and set it yourself, faster if - for example - you are shooting sports and want to quickly get within acceptible focus, are more concerned about speed than accuracy. Or slower if - for example - you are shooting portraits or fashion with a large aperture and need to very precisely place the point of focus, are not very concerned about speed.
If I recall correctly, the 200/1.8 doesn't have the four "AF Stop" buttons that many of the other big white super teles do, so I won't go into how those operate (they are "assignable", anyway, on some of the more recent camera models... so they can have different functions depending upon setup).
A few more specific things about the 200/1.8L...
Hopefully the one you got has both the hood and the tripod mounting ring (which might be removeable, I don't recall if it is). Take care with these... don't lose or damage them. They are virtually impossible to replace and the hood alone would likely cost about $500 U.S. if you can find one. The lens cap is unique, too... though if it's lost there are some alternatives (besides plastic coffee can lids or PVC piping caps from the hardware store)... the company that makes LensCoat also make a soft cap in a variety of sizes... I forget for certain what they call them... something like a "Hoodie".
Be carefull with the lens hood fastening mechanism too, not to overtighten or overloosen the screw that holds it in place. As far as I know, those parts aren't available separately if that locking mechanism is damaged or any of the parts are lost.
Near the rear of the lens is a drop-in filter holder. In case you have never used a lens with one of these... There should always be at least a clear or "sky" filter in this, as it's part of the optical formula. The lens orignially came with a gel filter holder, but there were optional 48mm screw-in filter holders that can be used with any common screw-in filter (a "slim" might be needed in some cases), and an optional 48mm circular polarizing drop-in filter (a standard C-Pol can't be used, there is no way to rotate it). The non-IS EF 300/2.8, 400/2.8, 500/4.5 and 600/6 lenses all also used the 48mm drop-in gel/filter holders and 48mm drop-in C-Pol . The later IS lenses and the Mark II IS lenses use a larger 52mm size drop-in that's not compatible.
Canon has no spare parts to repair some (many?) of the mechanisms in the 200/1.8,, if needed. Canon discontinued the lens in 2004 and ran out of spare parts almost immediately. The main concern is the AF system. I am not certain if Canon will even service the lens any longer. There are some third party/independent service techs who will work on it, if needed. I would recommend having it tuned up and getting it serviced every few years (depending upon how hard you use it), just to prevent any excessive wear. You might minimize manual override of AF, just as a precaution. It really shouldn't be a problem overriding a USM lens, but why take risks if you don't have to. Turn off the AF at the switch, if you want to manually focus. Also gently operate all the switches occasionally. Most switches of this type are self-cleaning, can get oxidized from lack of use.
Despite it being next to impossible to replace, always use the lens hood. It is deep and protects the huge front element of the lens very well. The front element of the 200/1.8 is plain... not convex or concave. This is partially because it is intended to be easier and less expensive to replace, if needed. Sort of like a "protective filter" (since it's too large diameter for an actual filter). However, I have no idea whether there are replacement spares of that front element available. So, if it were me, I'd use the lens hood pretty religiously to protect it... and carefully cap it when the lens is stored.
It's a great lens! Enjoy it! Whoever gave it to you, you at least owe them lunch!