Hi Paul, I've found all Sonnars have a quite unique look and the Tak 58 certainly shares it - there's no doubting its heritage or design!

Of course that look doesn't suit everybody; it's not as ultimately sharp as a double-gauss or even a Tessar, nor does stopping down yield any significant improvements. The original Sonnar design (a 180/2.8 ) was intended to be used wide open for capturing the action at the Munich Olympics back in the 30's, all subsequent Sonnars also work at their best wide open which, I believe, makes them unique among lenses.

The cheapest ways to get a Sonnar on your Pentax are the Carl Zeiss Jena S 135/3.5 or the Jupiter-9 85/2 (both M42 mount) - both plentiful on eBay. The Takumar 58 is incredibly rare and I found mine at a camera fair after a very long search - I've only ever seen one other on eBay and it was a very tatty example from Hong Kong that fetched around £300. If I were to sell mine I'd be looking to at least double that figure. For that sort of money though you could get a nice Contax II rangefinder and a 50/1.5 Sonnar...

Just-under-24-hours-to-go-bump

That Gazelle made me feel quite sad, half tempted to sneak down there with a trailer and rescue her...

I've no lack of farms around here and I'm sure most of them would yield some great photos, but I don't know of a single one that's open to the public in any way. Perhaps I should do some door knocking?

How do you find all these fabulous locations and, more to the point, do you ask the owners before shooting or do you just wait until they go out?

I'd say these are a big improvement on the last photos you uploaded, I think you're getting the right idea about depth of field and how it relates to aperture but don't forget you also need to get the focus right too (the picture of the bee has the flowers in the background as the sharpest elements).

If it were me I'd have gone for a larger aperture on the first two shots to isolate the eyes and make the background less "fidgety", and a smaller aperture on the last two to sharpen up the butterfly a bit. The closer you are to your subject the narrower the depth-of-field will be for any given aperture; hence for the macro-style insect shots you need a fairly small one to retain detail.

Keep practising and it'll all come without even having to think about it soon enough.

I have no problem focussing to infinity with my 43 but, like nearly all AF lenses, it will focus past infinity at the end of the throw. So if you were overriding the camera and focussing manually (without backing off just a smidge) then that could be the reason for your blurry shots.

Otherwise I'm not aware of any known 43 issues and it's generally regarded as being just about the sharpest lens that money can buy (in any mount) - if yours isn't then I'd suggest cleaning the contacts as John says above and if that doesn't work ask about getting it swapped. It's quite possible it's been dropped and the elements have become mis-aligned.

My money's on Clarky...

It should peel off the same as the front panels - get a sharp blade under one corner and lift carefully.

British Racing Green with bright yellow leather

M42 lenses come in three basic flavours:

1) Manual only (usually a pre-set aperture like the Jupiter-9 etc)

2) Manual and Auto (set by a switch on the lens barrel)

3) Auto only (actually quite rare but applies to later versions of the Helios-44)

If you have a lens that falls into (1) or (2) then it's quite simple to set the aperture, I'd say 90%+ of all M42 lenses fall in these groups.

If you have a lens that falls into (3) then you need to find a way of keeping the pin permenantly depressed - some use glue (which then permanently alters the lens) others may take the back off and use a spacer (reversible if the need ever arises).