Originally posted by TB-000 I do currently have a Pentax K5. I am thinking of upgrading to either the K1 or the K3-II.
I have a number or lenses, but I find that I am mostly using my 2 favorite lenses. Almost half of my photos are taken with the Pentax DA* 300mm (sports, nature, yachting). My other favorite lens is the Pentax FA 77 mm 1:1.8 (people, close-up documentation for manuals) . I take vey few photos with my other lenses.
For the kind of photos I take with Pentax FA 77mm, I think that K1 has a definitive advantage over the K3-II.
But how would K1 perform with the Pentax DA* 300mm compared to the K3-II?
As I need the length of the Pentax DA* 300mm on the K5 and K3-II, I would need to either crop it or use the HD Pentax DA 1.4x AW AF Rear Converter with the K1.
Do you think that the K3-II or K1 will perform better in this situation?
How does a cropped K1 image compare to a K3-II image? (I can calculate the number of pixels in the cropped K1 and compare it to the K3-II, but are there other aspects to consider as well?)
If the performance of K3-II is better than K1 for the longer tele range, is the difference big enough to make K3-II better overall? Or, is the difference in the longer range small enough, to make K1 a better overall camera for my mix of photos?
As usual, it depends on what you are photographing.
I have done this comparison several times here, but the first time I did it for myself when thinking about whether I wanted to consider a K-1 for myself.
Suppose I take a picture of a bird with a lens at 300mm {currently I have a 55-300mm lens} mounted on an APS-C camera, and that bird completely fills the frame; my APS-C puts 24 MP on the bird. If I took the same picture at the same time with the same lens mounted on a K-1, the bird will fill 2/3 of the sensor vertically and 2/3 of the sensor horizontally, so the K-1 puts (2/3)*(2/3)*36 = 16 MP on the bird. Once I've cropped the FF image to show the same view, it will show less detail, because the APS-C camera is able to put more pixels on the bird. My alternatives, to put more FF pixels on the bird, are to either buy a TC {which will degrade the image, so we lose some of the FF advantage} or a 150-450mm lens {costing $2200 and having more bulk}.
If you look at what Canikon are doing, I think it is rather clear that FF is vastly preferred for landscape, portraits, etc, but APS-C is preferred for sports and wildlife. Personally, I believe a K-3iii is following which will build on what they have put into the K-70, providing better AF and better high ISO - in other words, a camera aimed more at this market and less at landscape, since the K-1 is now available for that market.