Originally posted by gsalmins Thanks for all the input. The only reason \i posted the question is because the guy in TEmpe was so adamant about yhee difference in IQ. Though my background is engineering and science, when it comes to photography I prefer my subjective opinion of an image. Back home \i have a large shelf loaded with old glass that I have fun with. From time to time I sell some and then buy some more. I have some favourites that I'll never part with like a Series 1 Vivitar by Komine, ver 3, light falling on the sensor at an angle notwithstanding. My DA 55-300, though will be on the market.
My basic approach to photography is to have fun, take lots of photos, walk around with eyes open and then spend a little time sorting and improving in Lightroom. I've been a \pentax guy since \i bought my first SV in 1964 (still have it). So over the years \i've gone through a lot of glass. I'm still a relatively recent convert to digital and have a lot to learn, especially how to make the best use of White Balance settngs. I seem to get an unwanted amount of blue in some of my photos.
Sorry for being so sarcastic. My response to comments like the one your saleman made is that the user is the largest variable not the equipment. With your experience with a range of older glass, all in the Pentax system too!, you might be one of the people that could really appreciate any subtle differences in a lens made for digital sensors over the older film format lens.
Perhaps I am missing something but I keep reading, really, but I keep seeing that the optical formula for certain lines of lenses has been unchanged over the years. For example, I read that the Fast 50 lineup has the same optical formula from the M series through the FA series. Now, if I read that wrong or read a misinformed writers post please correct me, but if that is true how can the salesman be correct?