Advise please on 400mm lens

I fancy a 400mm lens to "play" with.
What is the general opinion about this

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=300336408309&ssPageName=STR...

and possibly this(is the seller a forum member, his name is half familiar)

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=180390543544&ssPageName=STR...

Thanks in advance,

Howard

He might be your Cabstar link

I've had several of the non-APO versions; they come in MF and AF variants. They're light, easy to handle, but soft and dreadful chromatic aberration wide open. Stopped down to F8-11 they're much better - reasonably sharp and less CA.

Colours not great, probably due to the CA - slightly muddy compared with the natural look of Pentax lenses. Sometimes this matters, other times not. I've had some good results, and some awful ones, the latter including attempts to photograph aeroplanes with the AF variant when the 55-300 did very well indeed.

The APO version is supposed to be better, but I have no direct experience of that.