I'll consider anything RobE17. It turns out the 55-300 I have is the DA L version so it lacks the quickshift, that and probably poor technique accounts for why mine hunts more than it probably should.

I'll consider 70-330. I'll consider 100-300. I've also flirted with the thought of the cosina 100-400 purely on the basis of price but I've not seen much in the way of sample photos for that so I reserve judgement.

My main aim is fast focus, good sharp results and can cope with some poor lighting.

oh I'll keep an eye out. if I get at least a 400 or better at some point, then I can always sell the TC later.

the only plus to this is at least at airshows, which is when I'll be using this combination I should have a very bright day so that might help offset the strop drop

oh well, a change in job circumstances has just settled it for me.

1.7 TC on my existing lens it is then.

when I was at Duxford in July I saw 2 other pentax cameras and I'd been wandering around all day. plenty of nikon and canon of course.

there is definite bias in the camera mags though.

I've read reviews where they always score pentax highly in a shoot out with other makes, but then when someone asks "I'm thinking of getting a camera, I need xxxxx" and then the magazine recommends a nikon or a canon and never even mention pentax.

mike-p, I can't PM yet because I haven't been a member 30 days.

the TC looks good. jessops, promaster and this, all seem to be one and the same item.

how much would shipping be? and I could pay by paypal.

well as long as it works in AF mode with the modern lenses I don't mind.

I was just leery of some teleconverters because a lot of older ones won't do AF and I 've seen some threads advising people to get a teleconverter that is marked PZ-AF to address that issue.

great, thanks for that.

if I can source one of these I think that will make me a lot happier, get a good TC to go with it and then sell my existing 55-300.

so what is the name of the pentax 55-300 with quickshift because that is my one gripe with my existing DA L 55-300 ED, it hunts......a lot.

for airshows I want a fast 300 lens to get round that, sometimes the 55-300 I have just hunts and I have to zoom right back to 55 to re-acquire and have it lock in.

the jessops 1.7 TC sounds good. is there more to the model number I should be looking for than just jessops 1.7 tc?

I had been considering the kenko 1.5 pz-af or the tamron pz-af 1.4 but am struggling to see why the tamron is double the price of the kenko.

what sort of figure should I be seeing the jessops priced at?

do you shoot moving action with your 55-300 + TC setup? because that is my main use, action ie air shows, ie fast moving aircraft.

at the moment I have the DA L 55-300 but I'm also casting around for a faster 300 tele if I can find one at a reasonable price.

thanks john,

I was aware of the tokina. it sounds like a really good lens but 'hens teeth' comes to mind. I've only found one being sold on ebay in the last six months of listings and while there is one listed at the moment, it is a broken one.

so as much as I'd like a tokina, I think I have to consider something else. if I see a tokina, I'll buy it but in the meantime.....