Wow really? Ok. Here's a $750 Sigma 105mm Macro lens compared to the $1200 135mm L. That's 2/3rds the price of the Canon 135mm L, it's a cheaper lens that blows the Canon lens out of the water with no hint of blurry corners or a blurry mid frame. And it has Image Stabilization. I think that's more than a fair comparison.
What a stupid comparison, a lens that is 30%, longer and twice as fast, that is equivalent to comparing a 300 f4 and a 400 f2.8 and moaning about the price difference!
Why not compare like with like, say the $769 Sigma 105 Macro with the $869 Canon 100 Macro IS L (I actually got mine new from B&H for $785 on one of their silly sales ages ago)? A far more relevant comparison. Would I pay $100 for guaranteed future function and resale value, oh yes.
So you're saying that nobody will notice 3.5 stops of noise? Because that's what the addition of image stabilization wil give you when shooting an event. You know those indoor things with very low light where especially with a 135mm you have tons of unessesary shutter speed to compensate for camera shake. I guess everyone should just be shooting at iso 4800 instead of 400, because that's what you're saying doesn't matter. There's no difference after all. Yep. None. /sarcasm
No that is not what I said, but if you want to run with that, I'd be using a 70-200 f2.8 with IS in that situation as it would give me vastly more flexibility, secondhand MkI's are superb value, I'd lose a stop in dof (which I'd want anyway, see below) but get back that and a lot more with the IS. Having said that, in your scenario how slow the shutter speed goes normally becomes the issue and not because of camera shake, people move, having f2 and f1.8 is all very well in theory, in actual real life event shooting it isn't so good, groups of people don't stand in a plane either, the fast lens might help with AF, but shooting wide open at events doesn't normally work. So at poorly illuminated functions we shoot with flash to keep our dof deep enough and freeze our subjects, any variation and skill level, from straight on camera deer in the headlights incompetence to Neil Van Niekerk "black foamy thing" mastery; from a single AB800 in a corner to four ProFoto heads everywhere. If you are shooting as a pro, act like one.
So you say, what is the point of a 1.8? Well in my book nothing, we are talking 1/3 stop here, way too small to notice in dof terms, way too small to make a difference in exposure terms. Sigma have grabbed the headlines, and the attention of some impressionable folk. I am sure many will buy it and think it is the greatest lens ever, in physiological terms we are programmed to think whatever we purchase is the greatest thing ever or a piece of shit, and people want to love their purchase as it validates their decision making process and choice.
I doubt it will affect the resale value of the Canon 135 f2 though, and that, in my mind, is the way a product is valued.
My bottom line, even if it comfortably outperforms the Canon lens, as the Sigma 35 f1.4 seems to, I wouldn't buy one. Sure I'd like the Canon to be "better" but the IQ from it has never ruined a shot of mine,
which was my original point about incessant IQ "conversations", but the real killer for me, from Sigma as a company, is they left thousands of owners with a worthless
lens door stop, that, to me, is unforgivable.