[Steve.Ledger]

Yes...

[adwb]

very strange all you can do is ask yn direct and hope for a answer which probably have done already,

where on planet earth are you btw?

[Steve.Ledger]

Far North Qld - west of Cairns a bit..

No, I haven't asked Yongnuo. Might do that

[adwb]

hmm to far way to meet then

if you ever find out let me know what it was and if fixable I was going to get a MX1 but i use a lot of off camera flash and the lack of hot shoe for a trigger was a irritation that i thought i could get round till you posted!!

[Steve.Ledger]

Yes, if I ever figure out what's wrong. Very likely to be something really stupid I'm [not] doing...
But even so, the MX-1 is excellent so far - well worth having imho (and the video is actually quite good albeit a little too contrasty for my taste, but easy to fix in post).

[Steve.Ledger]

Reply from Yongnuo:

Hi Steve,thanks for contacting! Sorry we do not have the Pentax MX-1 camera you mentioned, so we could not proceed relevant test.We suggest you set the camera as below:
Turn off the red-eye reduction function;
Set the YN560-III to S2 mode;
Lower the shutter speed of the camera.
If the problem still exist, if should because the YN560-III does not fully compatible with the Pentax MX-1.

Of course, I have tried the suggested setting many times. I've probably taken a hundred photos of the speedlight as I cycle through every setting possible. It makes no sense to me unless the MX-1 is firing some sort of v.highspeed TTL pre-flash in what you'd normal think is manual mode.

But why does it work for with other speedlights ? (like the Nikon in the video @ 7:10)
Pentax MX-1 Hands On: To Review Cat Miaows for Street Photography - YouTube

[adwb]

Steve an idea, why not join and post on a Nikon flash forum and ask if any one has the yn flash ax well as Nikon one and do they have problems? Or some similar question
The other thought is to post else where on this forum for any one in your area with a yn flash that you could test with just to confirm its a yn thing and not just yours ( I know your works with others) .
I have no other idea what on earth can be the cause of this non sync it just does not make sense given that the flash works else where. It almost has to be your camera but god knows why, if it takes correctly exposed flash images the preflash must be working to set the meter
Unless there is as you say some strange flash out put but then why does it work the Nikon? Do the nik one use pttl or TTL? I though that was the reason for S1 and S2 choice ? All very very odd.
Alistair

[adwb]

Oh yes one last thing, I did think to mention this before and is yn suggested it can you set the camera on a much slower shutter speed than the max sync speed and see what happens?
It might just be the yn is out at 1/180 but would work at 1/100 or slower?

[Steve.Ledger]

lol.. Thanks, Alistair. But yeh, I tried all selectable shutter speeds on the MX-1
That I got consistently lit/exposed photos from the on-board flash must mean that the MX-1 is pre-flashing to set the power, so there is no true manual mode at all.

We need a firmware update for the MX-1!

I'm over it now.. It's not going to work, even a chimpanzee would have happened upon the right setting by chance if it existed, so there's no point in pursuing it further.