>Just out of curiosity, I was wondering how it is digital lenses don't >seem >to be very fast. I would have thought it'd be easier to produce speedy >glass for an APS sized sensor. Any thoughts?
Right now the "digital lenses" on the market tend to be ultra-wides or wide-zooms, which are not easy to produce fast for any image circle. There's not much incentive for manufacturers to make, say, a 33/1.4 DA (especially if you are one of those companies that actually MADE a 35/1.4). Personally, I'd LOVE to see a 60/1.4 DA or 20/1.4 DA to get some of my favorite focal lengths back, but I don't think it's gonna happen. Most pros can apparently now work exclusively with f/2.8 lenses and get away with it, which means mostly zooms except at the extremes. Look at the olympus E-system. The lenses are digital only, and pretty fast. Of course the sensor is tiny. >Also, unrelatedly and quite OT, anyone think it's a bit odd that Sigma >hasn't got a 50 1.4 for their own cameras? Sigma's not big into primes. Honestly I suspect they never designed one because they could never sell a Sigma 50 (unless it was a macro, or f/1, or something) for any other mount because they couldn't compete with the manufacturers at that focal length. It's been argued that the biggest fault of the Sigma cameras is the Sigma mount. NOTHING else fits. Can you see Tamron or Tokina making Sigma mount lenses? Sigma could presumably make an M42-Sigma adapter, but if they didn't really want to tie you to their lenses they'd probably just have used K-mount on their own cameras. One of my acquaintances tells me that it IS basically a K-mount, but with a different backfocus distance. Who uses a 50 any more anyway? Everybody's got 28-80 zooms. If companies were selling a lot of 50s, you wouldn't see them struggling to cut costs and quality in their 50/1.8s. >I must be in some weird why why why mood, but I was also wondering what >kind of issues stop Sigma from offering it's 120-300 2.8 lens in a Pentax >mount. Pentax people probably don't buy enough expensive lenses. The chatter on this list about 3rd party lenses suggests that most people either stick with Pentax glass or buy 3rd party zooms and macros based on PRICE. People who won't spring for a good Pentax zoom are unlikely to shell out for the (relatively cheap, honestly, even if it weren't unique) Sigma 120-300. I'll bet that Sigma's other premium lenses didn't sell well in K-mount. >I was just wondering because considering that with a 2x converter >it'd be a >240-600 5.6, it would have been an affordable alternative to anyone who >wanted a FA * 250-600 5.6. Unfortunately it is very hard to get "affordable" and "good" in super tele, especially super tele zooms. The common wisdom is not to put teleconverters on zooms, and most pros don't use 2x teleconverters because the quality loss is apparently too high. The only place I see pros using 1.4x converters on zooms is on the very highly evolved 70-200 ultrapro things from Nikon and Canon. Apparently the quality loss isn't unacceptable when using these very good teleconverters with what are arguably the best lenses N and C have ever produced. Oddly, I don't think either company makes a 100-300/4 EDIF-IS zoom. Sigma, of course, makes a 100-300/4. DJE
