Did this get resolved?

How are you getting on with that new K-50 body?

A FF K-1 test photo with the Pentax 150-450mm @ 450mm plus 1.4x converter = 630mm (hand held.) The number sign is approx 87 metres way.
Full image



100% crop (actual pixels) clearly showing screw heads holding up the number sign.

FWIW third party forum user comparison here:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/341671-pentax-...

Have you spotted this: https://www.pentaxuser.com/forum/topic/fs--sigma-150-500mm-f5-0--6-3-zoom-lens-5... ?

and this https://www.pentaxuser.com/forum/topic/for-sale--pentax-60-250mm-f4-58169 ?

Looks like this: Shaded Broad-bar
Lovely selection of photos of them all.

400mm f5.6, they're around: https://www.pentaxforums.com/userreviews/sigma-400mm-f5-6-apo.html
One here on eBay at under £200: Sigma 400mm f5.6 MC AF prime lens for Pentax.

As to the comments regarding the 600mm lens, that was in response to RobL's post. (As I said in my post in response to yours, I wasn't sure then what you were really after.)

A 400mm lens is pretty specialist, there will be times you'd wish the lens wasn't so long! If you have two bodies in use together as some do then that's not so much of an issue.

i'm pretty sure you'd hit the same issues changing systems only with Pentax there's more older lenses available which should work just fine. With other brands, old lenses aren't always compatible with current cameras having mount and firmware issues. You might only find out once you've bought the lens (a possible costly error.) Then even if it proves compatible currently, buy a new body and the problems begin. One can't criticize Pentax for doing that to users.

Great to be able to take all of those in the space of a week. Well done.

At least it is built with a screw drive.
Actually sounds like a faulty capacitor rather than motor. The motor would either work or it wouldn't. Capacitors can do odd things and it has been suggested that is often the problem with the 16-50's. Is it that the lens works after it has been installed on the body for a while (i.e. after the capacitor has had a chance to recharge itself?)
The fact you can't repeat the problem suggests that once the capacitor has recharged itself all is well with the lens, which would be normal.

A 600mm f4 would likely cost circa £10K if Canikon pricing is anything to go by. Pre-orders anyone?
Weight? 4-5Kg. Just pop it in the rucsac when you go hiking!!
(Personally I'd pass on one of those even if I could afford one.)
At least the Pentax 560 f5.6 is only 3Kg !