You can change the firmware of the K10D up and down to support or not support SDM. There was also a video on youtube of SDM vs Screw in the same lens on a K10D. The SDM took longer to go end to end through the focus range.

Just posted some test shots:

https://www.pentaxuser.com/forum/topic/cactus-v5-test-shots---self-portraits-262...

Seeing as nobody else was home to be coaxed into participating in my little test I have had to use myself as a test subject.

Here are the results:
















By the way, I cannot play the guitar. Sadly it is just a prop.

It is not the most robust test of the triggers but I wouldn't be able to do this with the IR/Visible Wireless P-TTL.

Got an outdoor shoot arranged for the weekend.

I doubt I'll sell any of my equipment anyway.

My 18-55 is a backup lens just in case. My 50-200 is shockingly de-centred and produces chromatic aberrations 20 pixels wide or wider.

Lou might sell her 70-300 which doesn't get used.

Hopefully a cap will arrive in the next week and save me ordering one.

I'd rather put a DA40 on for transit, then if I need to get it out for a shot it is quick rather than then finding a lens. Why didn't I get a DA40 when they were £200ish?

I don't have the boxes for anything any more. An other thing she made me throw away. I don't have any spare rear caps either which is odd as I swear I should have one spare.

We shall have to start up a small Pentax Strobist group on here. LOL

So far the only problem I have had are my Metz flashes going to sleep if I leave them too long. The triggers won't wake them, I need to check if there is a way to disable the sleep function.

PM sent, most helpful.

The things wives make you throw away. As soon as they're gone you need them!

Looks like the lens could not be read. Fault with the pin layout of chip in the lens (if it was secured correctly)? Dirty contacts? Odd...

Cacti have arrived. I have a shoot with a volunteer model this weekend and weather looks good. Have a location planned, will do some test shots in a bit.

They work well and reliably. The cycle time is good, as is the build quality. Seem to be worth getting over the Securelink one's which are not transceivers and more expensive.

Now to find something to shoot.

As I said, it is to do with the distance the focusing group has to travel. It has a very short turn to go from infinity to close focus of about 1/6th of a turn. The 50-135 has a throw of 2/5ths and the 300 3/4rs and they all seem to use the same motor.

Oh and on dual drive lenses SDM is slower than the screw drive.