You can almost always get more out of an image if you shoot in FF mode and crop, I have many 30 MP crops that are still 6MP more than a 24 MP K-3. Rupert had his squirrel shooting setup done for APS-c. I believe he used a Sigma 50-500. He shot his K-1 images in crop. Because he had the FL he needed to fill the frame at 500mm on APS-c there was no benefit for him to use the full frame mode. He would have just cropped it in any case. Smaller files for all the required info. To get the same FoV with a K-1 he would have needed a 750mm lens.
That probably seemed a bit excessive for squirrel images.
Originally posted by pxt At this field only disadventage of wide angle lenses are that if you want AF are limited to 15-30 and as it is without filter mount it is useless for photography. Buying adapter for about 20-25% price of lens is not way which I want to go. You have right that usins sensor is only possible with full frame lens, but now I am looking for the most rational use of K1 II crop mode if you do not buy APS-C lens earlier.
I'm laughing. go to the one of the threads with 15-30 images. It's hardly useless. Your choices are hardly limited to the 15-30. There are many legacy options. As I pointed out with the FA 50 macro and DFA 50 1.4, if you want edge to edge sharpness, the macro is sharper at the edges anywhere in it's focal range than the DFA 50 1.4 is at it's best. The smooth out of focus areas of the DFA are what it was designed for. That has absolutely no use for landscape. Lenses like the 20-35 are still quite functional on FF. This attidue that the advent of new lenses means you should throw out all your legacy glass is complete nonsense and unsupported by any scientific comparison. It's the attitude of a few folks who were being paid to promote Pentax.
My own take on filters in general is that they aren't worth the bother. Tess went through a filter phase, so, I've done many image comparisons, hers against mine. She got some nice images, but with the DR increases, K-5 and on, filters became largely irrelevant, as did shooting HDRs.