I have the older version of the Bigma 50-500mm lens, so I was curious to see how it coped with the K-1 full-frame sensor. Since I also have the Pentax DA 300mm f4 lens, it enabled me to get an idea of the differing resolution offered by a old, relatively cheap zoom, and a newer, full-frame prime lens.
I must say that before using the Bigma with the K-1, was encouraged by the positive results that Rupert has posted on this forum. And my impression is also that the Bigma can produce satisfying images, especially if you do not need to crop excessively. Sometimes, it is useful to have the wide zoom range, and if you can live with slightly softer images, then the Bigma is a viable option. The first two attached images, taken in the Doñana National Park, in Spain illustrate this. The red kite unexpectedly flew overhead, so no cropping was needed (this was hand held by the way!). The glossy ibis was a fair distance away and the image required considerable cropping, but I think it is still acceptable.
The last two images show what can be done with a good prime lens. (This time in upstate New York last fall.) Both required a fair amount of cropping but the overall quality was maintained very well. You can’t beat a good prime, and with the full-frame sensor, you can crop without much concern. (These two images were also taken when hand-holding the camera.)
So the prime is obviously noticeably better, but don’t forget that old zooms can offer decent shots. My thought for the day, for what it is worth. Regards, johnmb
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