nureality wrote in post #7611369
b) The 70-200 f/4L USM debuted in September 1999. The 70-200 f/4L IS USM debuted 7 years later in November of 2006. Frankly, they take their time with updates of lenses.
the 70-200 f/2.8L USM came out in March 1995, The 70-200 f/2.8L IS USM came out in September 2001 (thats a 6 year stretch). And mind you in both cases, the IS version was a debut, not a "Mark II".
The 28-80 f/2.8-4L came out in April 1989, it was replaced by the 28-70 f/2.8L USM in November 1993, which finally was replaced by the 24-70 f/2.8L USM in November 2002. That last upgrade took 9 years.... arguably the 24-70 f/2.8L USM is due for a replacement anytime now.
Got it -- they're slow. Perhaps lenses are designed with a production run in mind, and updates will not come until that run has finished.
The price differences are an amalgam of many factors, optics, build quality (materials), labor costs to handle more precise instruments and tools for construction, and also product line dilution. Canon has over 60 lenses in their line, with many segments having clearly defined LOW PRICE, Mid-Range, and LUXE (L) models. They must keep the models separated by price. $500 bux difference between the 70-200L's IS and NON-IS models is meant to keep 4 models on the market and offer the client more options that will ultimately keep them buying a CANON-branded product as opposed to something from the 3rd parties. Although many people here do their homework and are willing to look at comparable and in many cases BETTER products from Tokina and Sigma, the average buyer is a brand-zombie. By having 4 differently priced 70-200's they give the customer enough options to almost gaurantee a Canon sale.
Time's are a'changin', though, as 3rd party manufacturers begin to pump out more and more quality glass. The primary reasons I think people may stay with Canon are not IQ, but USM and AF consistency. Sigma is now coming to understand the importance of USM in their lenses, so when Tamron and Tokina get that message, there will be even stiffer competition. But they most certainly need to address the AF issues, which, ironically enough, Canon may have addressed with micro AF adjust. Of course, that will only help for AF that is consistenly off; it won't help for inconsistent AF.