Question for the pros: Considering that both, the prime 100mm 2.0 and the 135mm 2.0 L lenses are great. good IQ, sharp. bright. fast. ideal for portraits...
Yes. Better background blur (due to more telephoto power), better close up capabilities (due to shorter MFD), better build, much less purple fringing wide open, and 7 % sharper (see photozone.de or old.photodo.com: 135 2 sharpness: 4.5/5; 100 2 sharpness: 4.2/5).
I love the 135mm focal length, but it is almost always too long to use indoors except for very tight head and shoulder portraits. Other than that and a tendency to flare it is nearly perfect. The 100 f2.0 is a true bargin. I have the 100 f2 instead of what I really and truely want, both the 85 1.2 and 135 2.0 and so the 100 f2 has saved me a bundle.
I like shooting tight, even indoors but that's just MY particular preference. On the 1DmkII, 1DmkIII and 40D, I prefer the reach of the 135/f2 and find its AF quicker than the (still very fast) 100/f2 and 85/f1.8. I will occasionally even use the 200/f1.8 on the 40D indoors...that's how much I like tight headshots. The 135/f2 has such great sharpness and contrast that it takes a 1.4x or 2X converter very well with an imperceptible quality loss.
I owned the 135L and sold it for the 100 f/2. The 135L is a better lens overall, but honestly in sharpness and bokeh they are very, very close. The 135L has better color and CA control, but other than that, they are more alike in IQ than different. The 100mm was just a better focal length for me...135 was just too long to use as a portrait lens, and that was what I wanted to use it for mostly.
Here are the 135L and 100 f/2 wide open at f/2, so you can see a bit of the bokeh, and the sharpness, and how very close they really are. These are 100% unsharpened unprocessed crops. Yes, my wife's romance novels were the target..they were handy and provided something with detail to shoot.
If you want a fast, fixed 135mm focal length lens then go for the the 135L. No doubt. I've owned a good copy and the sharpness, contrast and color were incredible. Subjectively speaking, my 135L looks like it was a bit sharper than JMan13's. Hard to say, though. I don't know how sharp the printing of those books were.
I think the 135L is better and has a bit more "magic" if you like, but I would buy based on your preferred FL, not on the difference in IQ or price (I prefer 100). Also, for available light, you will be able to handhold the 100 at slower shutter speeds... which may make a difference too.
In the above photos, the 100 f/2 is the first image, and the 135L the second. And no, I didn't have a soft copy of the 135L. Remember the above crops have had no sharpening applied to them...they are straight from RAW.
AS Mh2000 said, get the focal length you need. My old 100 was just as sharp and colorful as the 135 I had. I found no extra discernible magic with the 135 other than it would focus closer relative the the focal length. I found the 100 slightly sharper and colorful to the 85 1.8 (wide open) which I now have but made the move to the 85 only becasue I want to eventually pick up the 135 to give me more range when I am shooting with 2 bodies.
not a pro here, but i love shooting in the 85-135 FL range with FF and 1.3x crop cameras, and agree with the advice to buy based on need for a focal length, not the lens itself. i've owned or own the two 85's, the 135L, and am enjoying a newly bought 100/2 (thanks twistedlim!). also the 100/2.8. except for the macro lens, other than FL, these lenses are remarkably similar in IQ imho. you just can't go wrong with any of them. if another FL besides 135 will suit you, save the money ...
