Originally posted by suzyq I too am frustrated. I treated myself to a sigma 150-500mm as a retirement present to myself.
I’ve never been happy with the results. The staff at my go to store matched it to my K 50 as I wanted to take pictures of birds. Reading your email I think the K50 just doesn’t support the K50. In the last year I have struggled with dark exposures when starting up the camera. It’s a common fault and yet Pentax hasn’t recalled the cameras. I’m totally disillusioned with Pentax. Apparently they used cheap components for my K50 and several others in that range.
I've only used my K5 with my 150-500.
When I bought it new, in 2011, it was the top of the line for Pentax...magnesium body alloy shell, water resistant, stainless steel frame I believe. It's been a good camera (touch wood), almost 10 years old. Initially I had some trouble with it freezing and it was under warranty. I sent it in to Pentax Canada (I'm a Canuck) and they repaired it well and I've had no issues since then...and we're talking a decade.
I also have a K10D (bought new in 2007) and it was also the top of the line then. No issues and last time I checked , a few years ago, I had more than 60,000 shutter actuations on it. My K-1 bought new in 2017 had a funny loose sound when I shook it. Sent it back to Pentax Canada, they repaired it and all has been fine. It was top of the line too.
I've been happy with my Pentax equipment, and I use it regularly.
I've generally been happy with Pentax, and I've had one (Pentax S1a) which I bought new in 1969. Over 50 years.
As far as my Sigma 150-500, I like it. I shoot pix of birds, but mostly big birds, such as American White Pelicans (I'm near where they breed), Owls....Great Grey, Great Horned, Northern Hawk , Snowy White, Barred, etc.
I've got some pretty good pix of these birds in flight , perched and sitting on rocks (Pelicans) and I find the Sigma gets some real sharp pix. It is a heavy combo, the Sigma and the K5...but I'm big guy, 6' 3", 245 lbs. so I may not notice the weight as much as a smaller person.
I use certain settings...usually set the ISO 400-1600, mostly 800. I use aperture preferred, use an F stop of between F 9 to F 11...as the depth of field of a super telephoto is narrow and birds can move out of that range fairly easily. My shutter speed is over 1000th of a second, I subscribe to the practice of if I'm shooting a 500 mm lens I use about 1/1000th or faster. I want clarity in my pix and these settings seem to work for me. I use the Sigma only during the daylight hours, as it is not a fast lens, like an F 2.8.
I take a lot of pix and I practiced a lot at a bird feeder that attracted a lot of Chickadees..small, fast songbirds. I figured when I could get a sharp pics of these little fast flyers, then a pelican or an owl would be a piece of cake.
Not ever pix is perfect, but I'm happy with the number of keepers following these methods. Also I use the Pentax Shake reduction, not the Sigma and I usually use continuous auto focus and always try to aim for the eye of the subject, If I get the eye in focus, I find the rest of the subject is usually clear.
Hope this is of help to you.
Les