Agreed. That was what I was trying to get at, in my own roundabout way.

That just isn't relevent. Pentax implemented the system in their cameras. If we're going to start debating the inception of concepts in the context of this discussion, we might as well argue that Pentax have no input at all, because they did not invent the concept of focusing light onto a photoreceptive surface through a system of lenses.

Which is where I disagree. In a modern camera system there's a whole lot more to it than that. Most of the 'features' I mentioned can have an effect on image quality. However your definition of image quality appears to vary from mine, in which case it becomes a matter of semantics. In my experience there's no point continuing to discuss it when that's what it boils down to so with respect I'll probably bow out about now.

The camera contributes the AF system (unless you use manual focus) and metering system. In the case of Pentax it also contributions Shake Reduction. All three can make a direct contribution to the quality of your image, to a greater or lesser extent depending on the circumstances.

Additionally there are many other camera properties which might play a vital part in enabling you to capture the image you want in particular situations: Continuous shooting speed, Weatherproof body, Live view mode (when you need to be 6'2" but are only 5'6" as I discovered for one particular shot a few days ago), Electronic Level Function (yes, this can make a difference, particularly when lens distortions make it difficult to line up a shot accurately in the viewfinder), Composition Adjustment, Ergonomics as has already been mentioned. I'm sure there are a bunch more I haven't thought of off the top of my head.

Then there are the JPEG-only as-you-shoot image processing functions which are too numerous to mention. They needn't be useless to a RAW shooter, either - personally I shoot in RAW+ and use the various JPEG features as I see fit. That way if the camera produces a JPEG that's close enough to what I want (with maybe some minor tweaking), I save time by not having to touch the RAW file and I reap the benefits of these features.

Of course if you don't use these features you don't get the benefit of them, but to me that's a pointless argument. The features are there for a reason and can make a difference if you allow them to.

...I'm curious as to whether anyone here uses it. Since getting the K-5 my dial has been set to Av most regularly, but I've also used Tv, TAv, M and P modes depending on the situation. Sv doesn't strike me as being massively useful, mainly because Sensitivity can be set manually in most of the other exposure modes anyway.

If anybody uses it, in what kind of situation do you find it useful?

I like shot no. 2. It sort of gives me the strange impression that the cars are impatiently waiting for the people to stop nattering and get on with it.

This is in typical light levels in the city at night, lit by ordinary orange-coloured street lights (sodium vapour?). I'm not sure how typical this is for an up-to-date DSLR as the last DSLRs I used before I got the K-5 were 5-6 years old (Canon EOS 350D and 30D).

Interesting. I haven't seen a direct comparison. As far as focussing speed goes, I find my Tamron hunts a lot in lower light conditions. It's fine in bright light. Of course that may be as much down to the camera as the lens and I'm sure it's common with most camera/lens combinations. I wouldn't mind trying a DA* for comparison though. Problem is I like to shoot a lot in low light, which was the main reason I saved for a K-5 rather than going for the K-7, and got an f/2.8 lens rather than a kit lens. The 18-135 was quite tempting just for its range.

You have some really good shots there, cabstar. I've only had my 17-50 for a short time but if I can take just one or two shots as good as yours I'll be happy!

I have one too. I have found it excellent so far and have no complaints about sharpness even wide open. The image quality is really, really good by any standard.

I must admit, though, if I'd had the extra money to splash around I'd have gotten the DA* 16-50. It's a little over twice the price, but for the extra money you get some really worthwhile features that the Tamron doesn't have:

- Weather sealed construction
- Quick shift focus mechanism
- Silent focussing motor (the Tamron is fairly noisy)
- An extra millimetre wide

These are all objective advantages, leaving aside slightly more subjective areas like optical quality and focussing speed.

For the price, though, the Tamron is unbeatable as a standard zoom with an f/2.8 aperture.

I thought this thread was about Little Bo Peep until I opened it.