I have no intention of contradicting JR, Smeggypants or others who have offered advice, as they are all much better and more experienced photographers than me, but AF does vary with light levels/wavelengths, so you might want to consider setting up for the lighting/lens combo you would use most often, but have the adjustments for other lighting conditions/lens combos noted and to hand.

So, if you mainly shoot in studio conditions, that's what I would adjust AF for and leave as my standard setting, BUT, I would then adjust AF accordingly and as required when shooting in other situations.

Ok, I know we would all like to do it once and forget it, but I don't believe that's possible with ANY DSLR camera regardless of make/model.

Of course, I don't know what you want to use it with, but I'm sure it only has a CF card slot and mini USB port?

As an up-date. I've found and loaded an exif reader into Lightroom as a plug-in....and it correctly identifies the lens!

So, my conclusion is that the camera gathers and exports the meta-data, and in my case the lack of full lens identification was down to PhotoMe.

Kept me quiet for a few hours

Thanks John. I suspect the answer to my question may be partially in the link - 'Note that newer series numbers may not always be properly identified by cameras running older firmware versions.'

It appears, then, that some form of meta-data translation is done in the camera's firmware, but whether the various exif readers also 'translate' is soemthing I'll continue to explore.

But, I'll need to look for a newer exif tool, as PhotoMe states that the latest version is dated '2009/05/03'.

Thanks John.

I use PhotoMe to read exif. Updated it to-day. Not sure where it gets the lens specification - from the camera or from within it's own internal database. Others lenses I used in the same shoot were older models, but precisely described.

PhotoMe declares the lens to be 'Unknown DA or DA* lens Id: 7 58'

I was looking through some exif data - as you do - when I realised my K20D doesn't recognise my Pentax 100mm WR macro lens as such.

The camera 'knows' it's a Pentax lens, and the exif shows 100mm, but reports it as 'Unknown DA or DA* lens Id: 7 58'.

I assume there's an internal database in the camera body, updated via firmware? Anyone know? Or is it that the exif software can't 'translate' the lens data into a name/model?

Doesn't seem to affect the ability to find tune AF fortunately.

Still haven't used it! Took it out Saturday, but only used 100 WR and 50-135 'cos of the weather.

PM sent.

PM sent re Pentax-DA 35mm F2.8 Ltd macro. Boxed £275

Not sure it they are identical, but here's a link to an article involving repairing a 50mm 1.2 M lens> http://grantharg.tripod.com/CameraRepair/M50mmfixa.htm