Well it still sounds to me like a Foveon type sensor (with improved low-light performance), is the way forward.......perhaps for a 14+MP K1D!

Seeing as I raised the question of Foveon sensors recently, I find this thread particularly interesting and wonder how well that type of sensor would handle this situation.
Perhaps the in-camera processing can be designed to recognise these symptoms and somehow compensate for them but if it really is a limitation of the Bayer-pattern system, then at least pro-spec. cameras should have something better.

I agree with Mongoose entirely.

Pete, it was perfectly reasonable for you to perform your own test and it's given you an opportunity to compare the two cameras side by side, with regard to handling and ease of use etc.
In terms of performance, your test is by no means conclusive and we all know that both cameras are very capable. Under most conditions, it would be nigh on impossible to tell which camera took which image and so a more controlled and demanding set of tests is required.
How well does each camera cope with tricky lighting conditions, moving subjects and using flash etc. etc.

For optical performance, using the same lens is an excellent idea because that would eliminate the biggest potential variable. A good alternative to the Takumar lens would be a Tamron adaptall 2 lens, they are generally very good and will only cost you a few pounds plus whatever mounts you require.
The two kit lenses that you tested might be similar in terms of focal length etc. but the glass/coating and the construction (groups/elements) might be very different.

Despite the lack of any really useful result, I quite liked your test and if you are satisfied that it has proven to you that the K10 is as good, if not better than the E400, then it's served it's purpose - well done!

Blimey .....and I thought mine was 'a bit of a result'

You're quite right Pete, not so many 50mm lenses are appearing these days and you certainly didn't pay a bad price for one of the finest standard lenses ever produced.

Ebay is an excellent source (I've only made a few disappointing purchases over the years) but for lenses, don't be too specific in your searches. I mean, don't restrict yourself to the lens only section and tick the 'include the description' box.
Many sellers split their kit into seperate lots but quite a few sell complete outfits. You might not be interested in an old SFX or SF7 but there might be lenses and accessories that would cost you more if you bought them seperately.

A while ago, I got myself an SFXn and SMC-F 1.7 (both in excellent condition) for £58, which if I remember correctly was the opening bid plus p+p.
I can only assume that potential buyers were put off because they didn't want the camera

Pete, I'm a little disappointed that you asked for some idea of prices, after I went to the trouble of including the following in one of your earlier threads - re: the A series F2

..... this was the cheapest of the 50mm lenses because it had the smallest maximum aperture but is still a very good performer.
I picked one up for £10 a few years ago but because genuine Pentax lenses have grown in popularity recently, you probably wont find one that cheap. I certainly wouldn't pay too much more though because you might strike it lucky elsewhere and bag yourself an F1.7 (F1.4 versions tend to be rather costly these days - often in excess of £60).
The F1.7 is the one to go for as it does perform slightly better than the F2, as well as being 'faster'.

Consider the price carefully because the F2 should be less than £20, the F1.7 less than £50 and the F or FA series (auto-focus) F1.7 between £50-£75.

Those are the figures I'd be looking for, although they can go for really silly prices!

So you managed to get an SMC-F 1.7 for £79, a tad high in my opinion but I've known them to go for quite a bit more.

AF is nice but you'll pay a premium for the luxury, so don't forget to look for MF wide-angles and telephotos but as Matt said, they were designed for 35mm cameras and even a 24mm lens is hardly wide-angle at all on a K10D.
MF telephotos of 125mm or 135mm and even 200mm are often available quite cheaply. They are usually very good performers because they are optically quite simple and easy to produce, have reasonably wide maximum apertures and have an even greater 'reach' on a DSLR because of the 1.5x crop factor ie. a 200mm lens on the K10D is equivalent to a 300mm lens on a 35mm film camera.

I've no idea why Pete still claims to be confused, surely we've covered everything between us!

In a nutshell, Pete get one of these:

either SMC Pentax-A 1:1.7 (manual-focus)

or SMC Pentax-F or FA (optically the same) 1:1.7 (auto-focus)

Pete, that lens would be an excellent choice.
As it's A series (with electronic contacts), it will enable full program exposure and multi-pattern metering. The only thing you lose is AF because it's a manual focus lens.

As stated above, this was the cheapest of the 50mm lenses because it had the smallest maximum aperture but is still a very good performer.
I picked one up for £10 a few years ago but because genuine Pentax lenses have grown in popularity recently, you probably wont find one that cheap. I certainly wouldn't pay too much more though because you might strike it lucky elsewhere and bag yourself an F1.7 (F1.4 versions tend to be rather costly these days - often in excess of £60).
The F1.7 is the one to go for as it does perform slightly better than the F2, as well as being 'faster'.

Consider the price carefully because the F2 should be less than £20, the F1.7 less than £50 and the F or FA series (auto-focus) F1.7 between £50-£75.

Those are the figures I'd be looking for, although they can go for really silly prices!

Incidentally, it's very easy to be confused because 1:2 or 1:2.0 means F2 as opposed to 1:1.2 which means F1.2
The 1.4 lens states "SMC PENTAX-A 1:1.4 50mm" and obviously Pentax didn't feel it necessary to include the decimal point on the F2.0 model.

Hope that clarifies things

I think lenses can be explained quite simply, although it was even easier in the days when 35mm film ruled.

SLRs were traditionally supplied with a standard lens (50mm focal length), because this lens gives approx. the same angle of view as the human eye and images therefore looked natural.
Lenses shorter than 50mm, ie. 28mm are known as wide-angle and give a wider angle of view, making them ideal for group shots and landscapes.
The wider the angle, the more unnatural it can look because straight lines can appear curved - like looking through a goldfish bowl and the space between nearby objects and distant ones appears greater.

Longer than 50mm, ie. 70mm and above are known as telephoto and like a telescope, enable you to fill more of the frame with a distant subject.
Telephotos compress the perspective - the distance between nearby and distant objects appears reduced.
Short telephotos (70mm to 100mm) are often considered ideal for portraits.

Zoom lenses have a variable focal length and are designed to have the characteristics of fixed focal length lenses within the stated range ie. 28mm to 80mm or 80mm to 200mm etc.
Certain optical compromises have to be made but modern zooms are nevertheless very good, although they do tend to have smaller maximum apertures than prime (fixed focal length) lenses within the same range.

The aperture (F stop) is the hole through the center of the lens that the light passes through. It's not necessary to know how the value is calculated but suffice it to say that F22 is a smaller hole than F4 - think of it as a fraction ie. a quarter (1/4) is smaller than a half (1/2).
Faster lenses have a larger maximum aperture than slower ones which make them better for low light situations (there's a bigger hole for the light to get through) but they contain larger glass elements and are therefore heavier and more expensive.

Shutter speed ie. 1/60th of a sec. determines how long the hole (aperture) is open for and therefore how much light reaches the film or sensor. The correct combination of aperture and shutter speed gives the correct exposure.
Fast shutter speeds 'freeze' moving subjects.

Depth of field is the amount of the scene in front of and behind the subject that appears to be in focus. Smaller apertures increase the depth of field - excellent for landscapes, large apertures are ideal for still life images where you wish to isolate the subject by blurring the background.

The final exposure is determined by many things - how bright the subject is, the lens you have chosen, the depth of field that you want, the amount of action blurring, the film speed (ISO setting) and other incidentals such as whether you want to use flash.

With regard to lenses, a 50mm lens is a 50mm lens no matter what camera it is fitted to but most digital SLRs use APS-C sized sensors which are smaller than 35mm film. This effectively means a 50mm lens acts like a 75mm short telephoto.

General rules:
For group shots and landscapes use a wide angle lens and set a small aperture (wide angle lenses have more depth of field at any given aperture) - this will ensure that you get as much of the scene in the shot and as much in focus as possible.

Use a large aperture and/or a telephoto lens to isolate the subject from the background.

Use a fast shutter speed to freeze the action or a slow one to blur it.

Ensure that the shutter speed is at least equal to the focal length ie. 1/60th sec. for a 50mm lens, to avoid camera shake for hand held shots.

Use flash/external light sources or increase the film speed/ISO setting when the ambient light is too low to otherwise achieve the desired exposure. Increased ISO speeds raise the amount of grain, so a long exposure with the camera steadied on a tripod might be preferable.

Phew, that should cover the basics.

Where'd you get the 2.8 from?

That is an M series F1.7 lens (manual focus, manual aperture control) and was originally designed for cameras such as the MX and ME.
It does not have electronic contacts and therefore is not fully compatible with modern program cameras and you will not have access to multi-pattern metering.
Thanks to the standard K-mount, this excellent lens can still be used albeit with some restrictions on all Pentax K-mount 35mm SLRs and the DSLRs.