It may be old, but it is tiny, fast and a beauty.

Yes the FA50 is quite an old design, surpassed these days by the latest (greatest?) offerings by Canon, Nikon, Sigma etc, but let us be brutal here, it is quite probably the smallest F/1.4 nifty out there for a DSLR.

It may be old, be even now it delivers on digital, whether full frame or APS-C.

Now its features. Well it is a screw AF lens, so a little noisy, but not excessively so.

Wide open you could call it dreamy with quite a lot of CA, but then again, apart from the Sigma Art lens which is designed to be spot on wide open and as a consequence very large indeed, I personally would trade this for the sheer small size of the FA.

Now, stopped down to F/2.5 and beyond, this lens comes into its own. It is VERY sharp all the way to F/11 and falloff beyond this is still good. CA has more or less gone.

Now, you are thinking, a 20 year + lens design on a digital FF body, especially 36MP of the K-1? Don't worry, this, like many other Pentax primes going back 40 odd years are superb with the demands of a 36MP full frame sensor. Sharp all over and incredible detail.

If you can cope with dreamy contrast, and some CA wide open, but stopped down gives VERY sharp images on your demanding body, then look no further than the tiny FA.

I love mine a lot.

Agree completely; the FA 50 is one of my favorites on the K1.

Dale

Dale108 wrote:

Agree completely; the FA 50 is one of my favorites on the K1.

More agreement here.  I picked mine up second hand in 2003 or 2004 and it's been my most used lens on APS-C for studio work ever since; though since getting the K1 a few weeks ago the 77 is getting more use  (that's just the perfect angle of view / working distance).  I was out shooting (normal photography - not rigorous testing) with the FA 50 on the K1 yesterday and was very happy indeed with the results - the pixel pitch of the K1 is the same as the K5 so the centre part of the image is basically what I'd get on the K5 but at the apertures I was using you can't see any fall off in quality near the edges.   It's not just compact but versatile, e.g. as a macro lens when combined with extension tubes (or reverse mounted).

The OP (and title) isn't blind to this lens's downsides: it came out in 1991, and its widely believed that Pentax made a final batch a few years ago and when those are gone they're gone. The optical design is older - AIUI the FA is optically the same as the A (with the addition of autofocus mechanism) and the only update to the A was the addition of the electronics for the camera to control the aperture, it may well be that the glass is unchanged from the first SMC Takumar 50 f/1.4 which came out it in the early 1970s - which in turn added coatings to an established combination of elements. (50mm Takumars command decent prices)
 If Ricoh add an in-lens motor and the latest HD coating  this 1960's design will be good for decades yet.