I used to have this lens and subjectively it's comparable to the Pentax SMC-M 50mm f/2.

That is, not stunning as 50mm primes go, but very usable and still better than a kit zoom.

the 50mm prime is such a well known and understood lens that a bad one is a very hard thing to find unless it's damaged or deffective in some way.

135 is a bit of a different kettle of fish and I'd be inclined to go for the Pentax 135 F3.5 instead.

to do in camera B&W properly would need a way to change the filter in front of the sensor.

The K10D IS the feature stripped enthusiast version, it has only one idiot mode, everything else is creative and useful for something.

Even though I use Av nearly all the time, I wouldn't want to lose the options on my K10D.

well, I've uploaded AN avatar, not a picture of me I'm afraid.

Still, if you MUST see me, here I am

[IMG]http://img.photobucket.com/albums/v68/thatguypinchedmyname/Image0025-web.jpg[/IMG]

I'm the one on the right

Now a ball head tripod strong enough to take my Tamron would be a fine thing to own, I might even use it occasionally, but no where near often enough to justify the expense!! Weight (or lack thereof) is certainly one of the major advantages of the Pentax 300 F4

John, how facinating, I actually didn't know there was a word "Dastard" to correspond with "dastardly" (which of course I know from the Wacky Races if nowhere else!).

Argee, thanks for a revealing insight into the training of our police. It certainly explains a thing or two. Good luck, I wouldn't have your job for all the tea in China!

if it has an A setting, then it does have some electrics, though not as complex as the electronics in a current generation lens.

The aperture system works like this:

If you take the lens off the camera, you will notice a couple of levers on the back. One is moved by the aperture ring, the other sticks out further and if you move it by hand it will move the aperture blades. I will call this the aperture actuator (I don't know if that's its real name but it'll do for now).

The position of the aperture ring dictates the minimum size of the aperture. In the K and M series cameras of the 70s and early 80s, all that happened was that the aperture actuator was kept depressed (to open the aperture) until you hit the shutter. When the shutter is released the actuator springs up and the lens stops down to the selected aperture.

Later on Pentax realised they needed a way to control the aperture from the camera body for Tv and Program modes to work. They therefore made A series lenses on which the aperture actuator movement is proportional to the area of the aperture. This means that if you know the maximum aperture of a lens, you can stop down to any aperture you like by moving the actuator a specific distance. That's where the electric contacts come in, allowing each lens to tell the camera it's maximum aperture so that the system can work.

That's why the A setting is off the bottom of the aperture scale, it wouldn't do any good for the camera to request F16 if the aperture ring could be set to prevent the lens stopping down past F8, so the automatic setting needs to be beyond the minimum automatically selected aperture.

I agree George, 300 isn't long enough to need a tripod per se as long as your technique is reasonable.

I use a support with my 300 2.8 for weight reasons more than anything else!

I don't have the Pentax, but with my Tamron 300 2.8 I've been known to use a monopod or one of the old Photosniper rifle style stocks.

Mostly I just hand hold it for moving subjects, but on the other hand I don't get a very good hit rate so perhaps I would be better off learning to use my monopod better.

This has been done a lot in recent years with graphics cards and even some CPUs (Intel Celerons around the 1GHz mark IIRC). Rather than making a whole new item, they just ship the full shabang with some bits disabled and untested. The old ATi Radeon 9500 was a good example, most could unlock their extra processing units to effectively become 9700s at a fraction of the price. Then theres the Athlon MP/XP, exactly the same chip but the XP had multi-processor abilities disabled. You could turn those abilities back on with the judicious application of a small amount of silver paint!

thanks for the critique Peter, I'm always interested to hear what others would try given the same picture. I'll have a look at a squarer crop later.