Originally posted by dbpdbp Is the Pentax worth the difference in price assuming both could be found from an IQ standpoint. I'm assuming the Pentax is made better. And what IQ differences would one be expected to find? Sharpness, contrast, color, etc... ?
Thanks very much,
Bob
PopPhoto.com has a review of the sigma in their lense section. According to their test the lens is strong through 135 and then gets worse through 200. When I compared that review with the one PopPhoto did of the Pentax in the mid 1990s the Pentax scored much better at 200 and was equal to the sigma at 70 and 135. I do not own either. I briefly owned an earlier version of the Sigma, bought used from KEH. I returned it when it was noticably worse at 200 than my 70-300 4-5.6; I didn't the extra stop that badly.
Also form what I have read there are serious quality control issues with the Sigma. My guess the enhancements made to the Sigma for DSLR would allow it to close the performance gap a little.