The f/1.7 versions are supposed to be the same, optically, from the K through the FA. I know the A and F versions render identically.
The A50/1.4 is a little softer at f/1.4 than the A/F50/1.7 is at f/1.7. At f/2, they all look nearly identical, but the f/1.4 has a nicer rendering of out of focus elements. At f/5.6, I can't tell any of them them apart unless there is a specular flare reflection imaging the aperture blades in the image.
The f/2 lens is a very good performer, but doesn't meet the sharpness of the f/1.4 or f/1.7 models at corners/edges until f/4-5.6 in my example.
Godfrey
On Apr 13, 2005, at 9:07 AM, Shel Belinkoff wrote:
What's the deal with the A50/1.7?
My favorite 50 is the K50/1.4 - most especially for B&W use. Still looking
for a better sample than the one I now have. BTW, Fred, how does the K
compare to the A, IYNSHO?
Shel
[Original Message] From: Fred
Just for simplicity (to make it easier to compare the K-mount 50's), I put
the Pentax and Ricoh lens charts on a page at
http://www.cetussoft.com/pentax/xitek50/
1. My favorite 50 is the A 50/1.4.
2. The A 50/1.2 is a better lens than some people give it credit for.
3. The A 50/2 has a high "bang for the buck ratio".
4. And then there's the A 50/1.7...
Fred
