Instruction: Answer the given question using the supporting document.

Input:
Question: Will this lens work properly with the Canon 50d?
Document: This is a Canon lens in the Class with the Legendary 200/1.8. It provides vivid color and contrast with a razor thin DOF. If you are serious about your photography and like to work in low light or do lovely detailed work this is must have. I don't know why I waited so long for mine.
I got this lens for portraits, weddings and for shooting flat art work. ~~ For now I'm favoring my Canon 55mm f/1.4, over the 85mm f/1.2L. for portraits and weddings. ~~ This may very well change when it comes to shooting more weddings inside under particularly dark conditions and evening receptions where lights are set way low and candles are lit for the ambiance.
By the way, the weight of the lens by itself is quite heavy, but mounted on the Canon EOS 1D Mark III, it's well balanced in my hands. The auto focus was slower than all my other lenses, but not unbearable like some had noted. Fast enough for portraits, but maybe slow for sports photography. Looking past the sticker price, I'm thrilled to work with this lens and hoping to get eye-catching images.
This lens is an elegant choice for intimate photographic work. It's everything you'd expect and they DO MAKE YOU PAY $$$ FOR IT. Get over the cost and you'll LOVE this lens.
For a work I prefer 50mm but image quality is simple better from 85. It's awesome lens so if you have enough money - buy it.Note: Don't try compare 85/1.2 with 85/1.8 - those are completely different lenses
don't try to use it as one.funny quirk about this lens is the electronic focusing motor. it is kind of unique that there is no full-time-manual override, so you can't focus then tweak it a little. you'll have to click the switch on the body over from AF to MF. it is electronic focusing, so when the camera "sleeps", the focusing ring doesn't work.
LOVE this lens. This is great for the type of work that I do (weddings). It's my favorite lens and the best for portraits by far for the money (the next best is probably $6,000). As you'll see in other reviews online, the auto focus is VERY slow in a dark situation. Outdoors and in well lit rooms, this isn't a problem though.
This lens has the highest learning curve of any lens that I've used. The quality of the IQ depends on the quality of the photographer. If you don't take the time to learn how to work the 85L, you'll never realize its fullest potential,  Once you do, the IQ is second to none. Only lens that I have that requires no adjustments in post. None. ** AF Speed - okay, how slow is it? Well, that depends.
Female subjects will especially appreciate the dreamy DOF this lens can produce. If you do portraits or wedding work, this lens MUST be in your bag. Mark it up as a necessary business expense and start saving now. If you actually happen to have the $4000 previously mentioned, you may wish to consider the 200mm f/1.8L or the 300mm F/2.8L.
)once you get beyond these (minute) setbacks, you really are able to appreciate this thing for what it is.it is by far the crispest lens that i have ever played with.this thing demolishes portraiture like nothing else. opened up it has the most beautiful bokeh, and i find myself able to take handheld portraits at night at isos below 400. so that is definitely something.not to mention, that the lens itself is a beautiful piece of work.
Answer: The EF 85 mm lens will indeed work.  However, Mr Nieman should remember that the 50D does not have a full-frame sensor.  It has a field of view conversion factor ("FOVCF") of 1.6 times.  This means that the camera's sensor only reads the central area of the image projected by the lens.  The FOVCF ratio is the ratio of the size of the image projected by the lens on the camera's focal plane to the size of the sensor.  The sensor is in this case 1/1.6 times, or 0.625 times (five-eighths) the size of the lens's image.  This means that three-eighths of the light available from the lens is lost from the resulting image.  Another way of considering this effect in the adjustment that this implies to the effective focal length of the lens.  The lens will behave from the perspective of its field of view as though it were a lens of 85 mm times the FOVCF.  In other words, it will behave on the Canon EOS 50D as though it were a telephoto lens of 136 mm focal length.   I hope this helps.