A while ago I picked up a well maintained used Sigma Non OS 50-500 for my K-1 and I liked it a lot, used it at airshows, and all around use including some astroimaging. A bit more recently I came across a sale on KEH and they had a Pentax 150-450 for about $1100 and I grabbed it up. That was to me an amazing steal.
Last Sunday during the lunar eclipse, I decided to try them both out as a direct comparison at the long end. I'm aware of the better range on the Sigma especially at the low end 50mm vs 150 is a big jump. not as much 450-500. and the Pentax being a little bit of a faster lens.
I was much more interested in IQ at the long end so while I was settled at the top of a hill overlooking L.A. waiting for the eclipse, I decided to compare the two. My target was the downtwn Los Angeles skyline. With the K-1 set up on the tripod and both lenses at hand I shot some pics. Both under the same conditions. Manual focus with LV focus peaking, ISO 100 Aperture (Sigma f/6.7, Pentax f/6.3) SS (Sigma 1/80, Pentax 1/125)
Both were processed with LR and the settings were the same (cropped a bit different)
Here's the results. to me the Pentax is a lot sharper and crisper than the Sigma.
A
B
Let me know what you think. I'm not revealing which is which yet I want to hear your opinions.