Have you ever opened the battery of the Pentax it simply has two AA shaped Li-ion batteries in them, they are only a bit shorter then the AA standard. We are now simply talking about the shape of the plastic box containing two batteries.

If your pentax battery gets weak it might be worth buying two of those batteries and simply replace them

If the weather is consistent why not use manual?
Just make some test shot till you get the exposure right and you don't need to adjust after that if the weather stays the same and the exposure is very consistent.

About the metering, the meter tries to get a grey exposure so to say so it makes black into grey and white into grey as well, if you have both it will balance them out.
If the meter first meters the dark asphalt with one photo and the bright motorbike with the next one you get a different exposure value with both shots. Matrix meters the whole frame, you could also use the other metering which meters also the whole frame but on the old way... forgot the name of that metering
It meters the whole frame but use 100% of the middle and weakens off to the edge of the frame.

This one was done with the K10D and a cokin infrared filter so it is possible.


Full version with metadata link
Shutter Speed: 1 second
F Number: F/5.6
Focal Length: 18 mm
ISO Speed: 400

This is not the standard black and white infrared but it really is a infrared photo and made it into a duotone photo. Since you only use the red pixels you lose 1/4th of the resolution

Couldn't you use any battery as long as the flash support the voltage?

You have I believe Li-ion cells the size of AA bateries so they will fit your flash but if the voltage is correct?

Most of what you said Davex is half true.
The F-number is en ratio number of the diameter of the entrance pupil devided through the lens focal length. When you use a 2x converter you double the focal length while the entrance pupil stays the same that's why the f-number is two stops higher. The extra glass of the TC slows it down a tiny bit more but not that much.

The DA*50-135 has SDM and SDM only works good with one type of Tamron 1.4x TC. The Pentax 1.7x talked above has his own AF so that means that any lens mounted on it has AF.

If a lens of 70-200 is long enough then one of the TC above might preform quite or else I would go for the zoom.

Do you have a photo for us, that would tell us more then a thousand words.

With panning and auto sport I'm around the 1/80 to 1/160 depending the speed of the cars, the faster they go the faster the shutter speed goes since it is simply imposable to pan a very fast car for long.

Opera 10 also got UK checker.

Here you go link

And a site with more explanation and limitation of each lens series link

All you need to know link

All in all not much between them but the interface and handling are different. For the handling I would go for Metz over a Sigma but that's personal.

The Metz 48 is a great beginners flash with quite some options but if you can stretch it the Metz 58 won't disappoint you either.

About the guide numbers it doesn't say absolutely which is more powerful.
The Pentax AF540 is for example more powerful over his range then the Metz 58, it's because of the extra zoom step or else it would have been called the Metz 52

Talked to my uncle but at this time no interest so all others do your bidding the K10D is a good camera.