DA 300 + TC

Yes, make me an offer.

I guess that those of us on this thread have a valid interest in using a TC with a SDM lens. That`s several people, maybe worldwide thousands of Pentax users may have this need. Be champion if either Pentax or another lens manufacturer produces a suitable converter. Or maybe a forum user with electrical skills and knowledge could work a tweak. Thanks Cedric

It may take more than a tweak. This shows both MC & SHQ versions of the Kenko 1.5x TC. The MC version is on the left. Notice the missing contact!!

[IMG]http://i679.photobucket.com/albums/vv154/bforbes/IMGP1883.jpg[/IMG]

Hi barrie, This certainly draws a veil over this one then. Thanks for showing the difference. Back to the drawing board now.

Cedric

Thank you Barrie just what I was looking for, now trying to find out what the contact does

Just looked at the back of the DA*50-135 and it is the same as the TC back!

Rear of the DA*50-135



Rear of the DA 17-70



DA*55



DA*300



From which lens did you took the photo Barrie:
Also your contacts look silver while these and mine looks gold.

The missing contact on the "MC" converter if it's the same as my Bower (just took it apart) is there connecting the the back of the bayonet and the converters chip.
Spare pin contact and drill required!!

Sorry Stefan I am not sure what you mean. The photo was taken with a Sigma 105mm Macro. The photo is of the contacts on the back of the two versions of TC not the contacts on any lens. Does this help or am I not understanding your question?

Sorry I thought the right one was from a SDM lens, it looks like the collar of the DA*300mm you see in the background so I drew conclusions

But as you can see the SDM lenses doesn't even have the extra contact the SHQ TC has so that isn't the problem since the MC seems to have alll the contacts that are needed.
So somthing else is going on.

Both K100D and K10D have the full seven contacts in the lens mount. Would the TC not need to have them to carry the information from the camera?

The contact missing from the lens may be associated with power zoom.

Yes the camera has it but the lens doesn't so what kind of information would the TC need to carry if the the lens doesn't have the contact?

Nope



I believe the extra contact is the m2 (FCM contact) on a K-A mount



From bdimitrov.de link
Aparently r1 r2 r3 encode the aperture range in half stops, m1 m2 encode the minimum aperture.

Oh well - that's me blown out the water then

If r1, r2 and r3 encode the aperture and they are discretes, then only 8 settings would be available. (Grabs camera which currently has 16-50 on - 19 stops between F2.8 and F22 so that doesn't work.) The lens would have to be sending either analogue or serial data which could be done with 2 or three pins, but it seems a bit odd that they should use one of each.

At least one pin will be required for power for the focus motor (assuming it has single voltage for all functions and uses the chassis for return). I would have thought that the autofocus would require at least one pin for position demand as well.

Odd.

Don't know how the contacts really work but maybe some are multiple purpose???

The power required for the SDM goes over the PZ contacts as you can see in the first image "power-zoom power contacts"

I think the SDM and the Power-zoom motor are DC motors so the current decides what direction they turn, makes sense right?

Just to make all contacts complete.
We have r3, m2, *, m1, r2, r1 and a seventh contact.


More info about that contact here link

So what are needed for SDM???
PZ contacts - delivers power
digital information contact - At the time the KAF mount was introduced only F-lenses and newer have that contact so I assume that the camera will use the Screw-drive to focus the lens when the camera gets digital information and with the SDM I assume that is in the digital information so when the camera reads it's a SDM lens it will use SDM instead of the screw-drive. Does that make sense:
.... hmmm.... anymore contacts you think that are needed?
Focusing sensing is done inside the camera by the AF system so it simple moves the lens in focus or till it hit the focus limit and then reverse the direction. When it hits the limit you clearly hear it hit the limit and then it almost seems like it is thinking and then reverses.
This makes position demand unneeded, it simply moves between the full focus range and if it doesn't lock on it's out of the focus range.

As far as I can tell Stefan, the SDM stator requires 3 wires to it, which sounds to me as if the phase shift controls the position. Your last statement may be on to something because the focus motor always starts in the same direction. It is possible that the drive waveforms are generated within the lens body, but having got the DA*300 to focus it drives to one endstop, then returns and hunts about a point until it focuses or gives up. That suggests to me that the focus processor does have some control over the direction of the motor which would require one extra contact.

Oggy I've found these, might be worth a read.
link
link

I still need to read them but will write down my findings.