Originally posted by Vylen Stupid.. maybe or not really.. just checked B&H Photo... the cheapest non-mirror non-T-mount 500mm+ lens is the Sigma 500mm f/4.5 for $4,999... cheaper than the Pentax 560mm, but definitely not weather sealed.
Next up from the competitors is a Nikkor 500mm f/4 for $7,999... Canon's offering is $10,499.... Sony's is $12,998...
So, the Pentax wins out in terms of relative affordability doesn't it?
No, the Sigma 150-500 and 50-500mm will remain the favourite 500mm lens for Pentaxians, due to the sub $2k costs, other lenses with TC offer better bang for buck, and the Sigma 500 f/4.5 is amazing for the price, granted not quite as long or weathersealed, but faster and I'll bet sharper wide open, and also a bit cheaper 2nd hand.
Also why not a DA* designation?
I would certainly like to see some images from it wide open, but at that cost it won't be getting me away from my 50-500mm anytime soon.