Originally posted by DanielT74 Maybe it could be a little cheaper but I don't think "a lot cheaper". You cannot beat this lens for image quality. It will put everything else (except perhaps it's younger brother FA* 300/2.8) simply to shame.
Anyone who is after the ultimate in quality and doesn't mind the bulk and the MF should jump at this lens, IMO.
the value to me of this lens (and I have one) is its support for a converter. Indeed I rarely use it without a converter. With the higher ISO's supported credibly by the K5, I who cut my teeth on photography when ISO 160 was called "High-speed" don't find a lot of conditions that you would call 'daylight' where F4 and a modest tweek of ISO, and shake reduction won't combine to produce a usable image in most condtions. Indeed I have both an Pentax A* f/4, and a DA* 60-250 f/4 available for those occasions, and neither comes in a hard case big enough to hold a trumpet.
However converters eat F stops like candy---1 or 2 for the converter depending on which one you choose, and another 1 or 2 to make up for the IQ loss, and by then you are in trouble unless you had some spare F stops to feed the animal.
Likewise, although I own an AF adapter as pentax calls the converter that is suppose to auto focus while functioning as a converter as well, it's real easy
put it on a lense too slow for it to get enough light to work, in which case it doesn't and turns into a focusing barrier instead of a focusing help.
My favorite combination is the Pentax 1.4-L converter. It's a good enough combination that I don't worry about feeding thte animal an bonus f/stop for IQ so it really gives you a 40% focal length gain at the cost of 1 fstop. That is a very real
if modest bump over a 250 or 300 (that I have) with the same effective speed.
By the same logic however, I will smash my piggy bank and start counting pennies if I ever see an 400mm f/2.8 on the market.