So the conditions did not need an aperture of f5.6 but you decided to 'test' it at that anyway. Why?

You would normally set the widest aperture if the conditions require it or a particular effect will be achieved by using it. You will not get the best out of the lens at full aperture.

If you want the lens to produce good results, give it at least half a chance by stopping it down to f8/11/16.

I don't think the lens has been made yet that will produce it's best results wide open. If it has, it'll cost an awful lot more than you paid for your 400mm.

. . . and if it doesn't ? ? ?

Nice series, but you have dust on your sensor. There are two distinct grey blobs in the sky of the first image.

Sorry, here.

Yes he does. Attach the longer of the two lenses to the camera and reverse mount the stacked lens using a dual male filter thread adapter, otherwise known as a stacking ring.

Fine selection, thanks. Have a look at #3 which shows your sensor has a lot of dust spots on it.

Not a comparison, but have a look at my images on the first page of this thread. Taken with the K20D + DA* 300mm @ ISO 6400.

I think it shows quite clearly that high ISO works quite well, certainly in bright daylight. I appreciate however that high ISO performance at lower light levels as you will experience may not be as good.

The K200D sensor is the same as the K10D, a CCD 10.2Mp sensor. In the K20D, Pentax changed to a CMOS construction 14.6Mp sensor which has a much lower operating temperature.

CCD sensors can be prone to overheating during heavy use, like indoor sports events, and excessive noise can become an issue.

The lower operating temperature and improved noise immunity of the sensor in the K20D would make it more suitable to your needs IMHO.

If you are going to buy one, there are plenty of little used bodies available. Stocks of new ones will fairly soon become very scarce I think.

You might also consider the Samsung GX20 camera. It's the same camera as the K20D but with different firmware, a different badge on the front, and slightly different ergonomics. The GX20 can be bought for less money than the K20D, usually.

Any lenses you have for your K200D will work on either a K20D or GX20 body.

Walking before running springs to mind.

A3 printers and decent inks are not cheap to buy, or cheap to use. Why not get a decent A4 printer and have any A3 prints that you might want produced professionally by ProAm or Photobox.

You can spend the money you save on more lenses.

Sorry to hear of your loss Yves. Time is a great healer.