Specifications at a glance:
Focal Length: 85mm (110mm APS-H, 136mm APS-C)
Dimensions: 2.8 by 3 inches
Weight: 15 ounces
Maximum aperture: f1.8
Minimum aperture: f22
Diaphragm Blades: 8
Lens Elements: 9 elements, 7 groups
Front element: non-extending, non-rotating
Autofocus Mechanism: Ring USM
Closest focus: 2.8 feet
Maximum magnification: 0.13x life size
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Released in 1992, Canon's 85mm f1.8 USM lens is one of the oldest in Canon's lineup. While it may be an oldie, it's definitely a goody. In any debate of canon's best non “L” lenses, this one is sure to be brought up. With its fast aperture, USM motor, and modest price tag, this lens was designed for low light, sports, and portrait shooters on a budget. Shooting indoor sports court side is exactly why I bought this lens almost a year ago. Unfortunately, it gave the dreaded “ERR 99” and refused to autofocus about half the time on my old 300D/Digital Rebel, despite working perfectly on my newer 30D. I sent it back, which, due to B&H Photo's generous policy, was no hassle at all. Below is a brief review of the lens though analyzing some of my old pictures.
Optically, this lens is a mixed bag, especially wide open. Even at f1.8, the center is sharp. Unfortunately, as one moves out, the sharpness falls off dramatically. On my 1.6x crop EOS 30D, the sharpness falloff starts about ¾ way out from the center. On a full frame camera, things in the corners must be pretty mushy wide open. Stopping down will improve sharpness across the frame. At f2.8, the center moves from sharp to razor sharp and the sharpness falloff starts to extend out further to the side of the frame. Stopping down to f4 yields virtually no improvement in the center, but the outer parts of the image continue to improve a bit. Unfortunately, the corners will never catch up to the center no matter how much you stop down. Now this may seem bad, but is it really? No, definitely not. This lens is not designed as a landscape/architectural lens where corner to corner sharpness is a must. The 85mm f1.8 USM is a portrait/telephoto/low light optic where, chances are, the subject will be in the center of the frame, where sharpness is good to start with. Chances are that, if used in its intended purpose, the soft corners of the lens won't matter anyway.
Autofocus Performance: 5
Armed with Canon's USM motor, the 85 f1.8 USM is a speed demon. Autofocus is virtually instantaneous, accurate, and to boot, just about inaudible. Needless to say, use of this lens won't be causing any heads to turn (the slap of the shutter will, though). However, be warned! With a maximum aperture of f1.8, the field of view will be razor thin the closer you are to your subject, so focus carefully. So if your images are out of focus, it may be your fault, not the lens's. Example: you do a close up portrait and focus on the end of your subject's nose. The end of the nose will be sharp but the eyes may be slightly blurry. You must focus precisely with such a fast lens. Fortunately, in well lit situations, you can stop down to f2.8 or more to achieve greater depth of field and room for error with focus.
The 85mm f1.8 USM lens is solidly built, especially considering its price point. The mount it metal and the rest of the lens externals are high quality plastics. The lens has a very dense feel about it. Shake it and there's no rattling whatsoever. The lens is inner focusing, which means that the front element does not extend or rotate during autofocus as the lens racks from macro to infinity. The focus ring is rubberized, well textured, and gives a very comfortable feel to it. Because the lens has a USM motor, the focus ring does not turn during autofocus and autofocus can be overridden by simply turning the ring at any time without the need to flip any switches. In operation, on my lens, the focus ring seemed a little snug in movement. Still, snug is better for manual focusing than sloppy. The lens takes 58mm filters.
This lens packs a lot of performance into a cheap package. It was selling for around $300 when I bought it and, with all the price increases, is now knocking on the door of $400. Still, it's a great value, especially considering it has the USM motor. With its excellent optics, USM motor, and build, this is a pro quality lens at a consumer grade price. If you choose to buy, you're putting your money to good use as this lens will deliver the goods every time.
As a short telephoto prime lens, the Canon 85mm f1.8 USM is not a general purpose optic, it is designed for low light and/or portrait shooting. When used to its intended purpose, the lens performs admirably. Images are sharp in the center (where the action should be), autofocus is top notch, and the build is good for a consumer grade lens. On top of all that, despite the ridiculous price increases, it is still a great value considering the competition. If you own a full frame or APS-H camera and want a lens to shoot indoor sports or portraits, just go out and buy one. APS-C croppers, the story might be different for you. If you're looking to do portraits, no problem, move or have your subject move. If your game is indoor sports, one of the Canon's 50mm primes may be the better choice if you're shooting court side, as the 85mm essentially becomes 136mm. Still, crop factor aside, the 85mm f1.8 USM is a lot of fun to use, as it literally opens up new worlds in the dark.