Just Google them one at a timne with +review on the end.

Some others have already done the research on this in case anyone is tempted.

See Here

I wonder if this would affect the second hand - or even new - value of Pentax models?

Yes, very good point and what I was missing.

As a side issue, I understand that the professional places like Oxford solve the distance/ movement problem by catching the unfortunate creature and putting it in the fridge for a while. This slows it down somewhat!

About the longer focal length macros and keeping your distance - I came cross this stag beetle which had strayed into my conservatory. I did some pix close to with my 35mm DA macro and became quite absorbed.

The beetle seemed to get somewhat annoyed and suddenly lunged rather closer to me than I was comfortable with or needed. This pic is not cropped! A little more distance would have been better. It then launched itself in the air as they ponderously do and flew off.

Basically, with practise and good eyesight, your eyes are a better judge of focus than a computer.

It's much quicker, too because you can focus anywhere on the screen instantly.

Business wise, I'm not so sure. I bought my Hasselblad outfit, 2 bodies, one electric, 50, 80, 150 and 250 Sonnars in 1978. It did cost me a small fortune.

In 1993 I sold the lot. Apart from servicing every couple of years, they cost me nothing in repairs. But what was amazing was that I got near enough the same price for them in '93 as I paid for them in '78.

That made them the cheapest cameras I had ever had - though inflation had taken its toll of the price, of course.

I still struggle to see the point for an amateur though. Where would that extra quality show up? Not on the web, for sure.

My GX20 enables me to make prints at top quality 300dpi at 16 inches across. I can't imagine many people would need more than this. But obviously many people do and I'm interested to know what I'm missing.

The 70mm f2.4 DA is a great lens, razor sharp wide open and tailored for the DSLRs.

For amateur purposes, I don't see the point. For professional purposes, you'd just buy the Hasselblad.

Pentax wouldn't sell to professionals because they don't have a professional service setup (they could if they wanted to but plainly they don't find it worth while, ditto Olympus). The professional market is quite small compared to the amateur one and generates little profit for Nikon and Canon other than its great marketing value.

Assuming a 39 megapixel sensor, for even the biggest monitor screen you're throwing away most of your pixels and even for a top quality commercial print at 300dpi, you'd be discarding pixels until your print measured 2 feet across. It's true you could crop more but in practise you don't use a medium format camera for the type of subjects you can't control.

Since I am a happy amateur now, I find even the pixel count of my GX20 too many. It only comes into its own for my contributions to my agent's stock library, though even there 8megapixels would normally be more than enough.

Maybe I'm missing something - I usually do.

This is interesting. My 60-250 is very fast focusing (GX20 body) - and very impressive in follow focus mode. No matter what anyone's expectations of speed, they would never be able to describe it as slow.

Yours would seem to be a faulty item because I'd have thought the 300 would have the same motor and mechanism.

I do have my doubts about Pentax's quality control sometimes.