Hi Dan, thanks for that it would be a great help, unfortunately I'm going to be in Belfast that weekend at a wedding!! I've had a bit more of a play around with it, I mounted the tele on the lens and turned the focusing screw but it had no effect on the lens, also it doesn't appear that the screw protrudes from the tele far enough to engage into the lens so it looks almost definitely like the tele. Unfortunately I bought it from America so I'll have to package it up and post it home.

Great reviews from you last Fingringhoe course by the way!

This is going to be an extreme long shot, are there any users in Essex / Suffolk with a Sigma 100-300 f4 and 1.4x teleconverter who'd be willing to help out a member in distress?! I've just taken delivery of a Sigma 100-300 and 1.4x teleconverter, the AF works fine when the lens is mounted directly on the body but with the tele in between the AF doesn't function, it sounds like the screw isn't locating but I don't want to have to send both the lens and tele back, it's most likely the tele but I'd like to be able to confirm first. It's a big ask I know

There's a clue in the question! What are the favoured magazine subscriptions? I've taken a bit of a shine to Digital Photo, mainly because of the PS tutorials, I upgraded from a far cheaper ( but I still sometimes find, easier to use MS Imaging suite) to Photoshop and find the tutorials useful... although they do tend to have instructions like "Now press Ctrl-T..." with no explanation of what it's going to do for you!

K10D Pentax 18-55 @ 37mm F11 .7s ISO200

Sorry, should have said, Sigma 100-300 f4

Firstly, Hats Off to the veterans and loyal replyees who answer similar questions time after time, you're all very patient and it is appreciated, thanks!

Anyway, I posted sometime ago about which lens to buy for a trip to Africa, I've narrowed my selection to a choice of two, the Sigma 135-400 or the 100-300 with a 1.4 teleconverter, I know there's a vast price difference between the two and I'm expecting most replies to vote for the more expensive option, but how much difference do you think there would be between the 2 assuming the 100-300 has the teleconverter fitted most of the time and as such making it a "slower" lens?
Presumably to get the best of of either lens they'd would be stopped down a little, any thoughts?

That's just the choice I've made recently Gary, mine are on order from www.bhphotovideo.com
I now need to save for something to fill the gap from 50 to 100mm, the Pentax 50-135 is looking favourite but it's going to take some saving.
(And convincing if you know what I mean!)

Hello! I've recently put together a web gallery on Photium with some (probably delusional) ideas of selling some of my shots, can anyone offer some advice on advertising such a site as I've initially had a large number of hits as friends and family all have a butchers but now it's tailing off and I'm not sure of the best way to direct people my way!
I've attended a local art show and had some sales from there so that seems like a good way to go but I'd hoped the web site might do a little better...

Thanks in advance...

Simon

Can anyone offer a comparison between this lens and the 135-400? Clearly the latter is slower but how about IQ? I've been trying to find reviews of the 135-400 but there aren't many around...

I currently use a Sigma 18-125 which was a kit lens that came with my Ist DS, it's done me well as an all-rounder. Also, a Sigma 70-300 Macro APO (the old version) which came with an MZ-7 that I bought a few years ago, again its done me well although I believe the current version ha a much smoother zoom than my one.
I'm looking at upgrading to the Pentax 16-45 and Sigma 100-300 f4, not sure what I'm going to use in between though, there's quite a large gap between 45 and 100!