I have a job on Saturday where I will be capturing a driven pheasant shoot. I will be using the K1 with the K3 as backup. I have the FA24-105 , but can't help thinking that I will want a bit more reach, so I am thinking of using the 60-250. I had read how this lens is very nearly FF and that with a modification to an internal baffle it could be made fully FF.
However, before I start dismantling a £1200 lens

The results are below.
60mm @ f4

60mm@f5.6

60mm@f8

60mm@f11

250mm@f4

250mm@f5.6

250mm@f8

250mm@f11

All I have done with these is add lens profile correction in Lightroom.
As you can see, at 60mm it is useable at any aperture but there is no vignetting at all beyond f5.6
At 250mm there is vignetting right up to f11, but can easily be corrected in post from f8 and maybe even f5.6. Of course you can crop it, but that sort of defeats the point of using it on a full frame.
I intend to see how it goes on Saturday before I consider the baffle modification (https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/304092-da-60-250-mod-ff-6.html, but if it's successful I've saved myself a fortune on the FA*70-200 and gained a bit at either end of the focal range

Any how I just thought some of you may be interested.