Thanks Pete - it seems as thought he Pentax 1.4X is to blame then - must be manual only
Donut

I have managed to pick up a set of Vivitar Automatic Extension tubes, a Soligor 49mm reversing ring and a Aico Pentax mount bellows to go with my existing kit of: -

K100D with kit 18-55
Tamron 70-300 Macro
SMC Pentax A 1.7 50mm
Vivitar MC 24mm f2.8
2X KAX Macro teleplus MC7 (which is a great piece of kit) and
Pentax 1.4X-S Converter.

Now I'll get to the point.

What is my best bet for Macro photography. I guess the extension tubes and bellows would produce similar image quality as neither have any additional glass. If these are going to be worth a try how do I deal with setting apetture and shutter speed as clearly the camera won't have a clue what's happening with the lens. What about the reversing ring on the 50mm? I will get round to experimenting - which is easy to do with the digital but a few quick pointers would be useful.

An unrelated question - should I be able to get my kit lens to autofocus using the 1.4X-S converter or is it too old to allow this function. I appreciate it won't work with the tamron due to a lack of light getting in.

Thanks for any advice.
Donut

I use a Tamron 70-300 which I get pretty decent results with on my K100D. If you hunt around they are <£90. The advantage of this over many of the older lenses is that it is light and has a 1:2 macro.
Donut

I didn't really want to go for the 18-250 as it would mean that I wouldn't use my 70-300! Maybe I could part exchange it.
How does the 18-250 compare with the 18-55 kit lens. Does the large range mean that it is too much of a compromise?
I certainly want as good but preferably better optics than the 18-55 kit lens.
I am interested in the 24-135 - niblue how much do you expect to get for yours?
Cheers
Donut

I'm looking to get a lens to use as a general purpose walkabout lens. I would like to be able to replace my kit lens with it. I already have a Tamron 70-300 macro to cover the long telephoto end.
Ideally I'd like a 18-135 ish lens. could go to 24-135 or 18-120. You get the general idea. Do any Pentax K mounted lenses exist that could fit the bill.
I've considered the Sigma 17-70 but would lile something that goes a bit longer.
Cheers
Donut

Thanks all. Very new to Linus/Ubuntu. Impressed so far but not quite as easy and transparent and Windows XP but much much faster.
Any good "idiots guides" available for Linus especially Ubuntu. Sorry to get off the photography track - may be I should post this somewhere else?
Donut

I'm thinking of installing Linux Ubutu on a home pc and was just checking if any of the RAW convertors (such as SilkyPix) will work with it.
Anyone any experience of using a Linux machine for photo manipulation/editing
Cheers
Donut

Thanks photo*ist - that's exactly what I meant - I knew that being red/green colourblind would be a problem It is the hexagon that I am talking about
Donut

Peter, I've used a couple of mf lenses and know exactly what you mean. However if you partially compress the shutter release and focus the lense you will get the red dot and bleep confirmation of a focus fix - at least I do with my K100d. I would like to use a better focus screen in the future but find that the above method works OK - especially if the aperture is not to wide.
Regards
Donut

Sounds like a great lens but even if it were available it is well above my budget.
Now considering the Sigma 17-70

Donut