SDM hack question


Link Posted 03/02/2015 - 01:59
Hello People,

I have a question for the brave, the brave few that alter their own equipment.
I would like to know if anyone has ever disconnected SDM control of their 50-135 star lens. I have read that some have after the SDM motor fails, but I want to disconnect before...
I have read of a few hacks, but the one that makes the most sense is to just cover the two SDM contacts with tape or some other thin insulating material, thus making the camera think it's a screw drive lens.
I need to know if people have tried this - with success and if the camera still knows what lens it has mounted to it. I am the type how will alter my own stuff, just looking for opinions from those that have tried it, or of any other way of disabling it.
Hacking the firmware seems a bit dramatic.
The lens isn't particularly fast at focusing, the screw drive might actually be faster...? I have had this lens for two years, bought a four year extended warranty, no signs of wanting to die, but I like the idea of using the other drive mechanism to further prolong the life expectancy of the lens. I imagine that if the SDM is still functional, the screw drive gearing wouldn't conflict mechanically with the SDM motor and it's little gear reduction bits. But what do I know, I haven't taken mine apart and I am by no means an expert. Anyone on here that is?

Thanks in advance,



Link Posted 04/02/2015 - 20:21
As covering the contacts with tape can not damage anything - I do not understand why you are asking for opinions - why not just try it?

No matter how many lenses I have owned - I have always needed just one more


Link Posted 04/02/2015 - 20:34
Surely there is more to it than the covering of some contacts. Why would people go to the trouble of hacking the firmware otherwise?
Regards, Christopher



Link Posted 04/02/2015 - 20:58

I am not an expert. Hacking the firm ware I believe is intended to completely disable the motor. I want an easier option, less permanent option.
I was hoping to hear from those who have actually tried covering the contacts and the camera recognize the lens. I like trying stuff, but I don't fly blind. An experience or two from others that have tried it would make me more comfortable. I guess the main reason I am not trying it is that I am not sure if those two contacts actually communicate info about the lens as well. Like maybe what position the motor is in...I am not sure.




Link Posted 04/02/2015 - 21:03
Still do not understand why if you believe that just covering the contacts may work - you do not just try it - either it will work or it will not - a 10 second job!!
No matter how many lenses I have owned - I have always needed just one more


Link Posted 04/02/2015 - 21:04
covering the contacts wont make the camera think its a screw drive lens.

the lens will only work as a screw drive on older cameras that dont have the contacts.

to make it work as a screw drive you have to alter the lens LENSEEP.LNS file.

i did it to mine and it was indeed quicker than the sdm on my k3. i started a thread about it i think a while ago.

i had to use a k7 to do the mod as the k3 wont let you save and load the file to the sd card / lens.


Link Posted 04/02/2015 - 21:25
The main reason I don't try is that I don't believe everything I read. I don't want to risk frying a perfectly functional lens. Seems like it might be safe with the tape, but not about to take a gamble on spotty stuff I read on the interweb. Looking for expert opinions. Last poster has done more research than I have, maybe that is the only option. I had read from a couple of sources that the tape works, but again - the web...




Link Posted 04/02/2015 - 21:51
I've tried the 50-135 on a K-01 with tape over the SDM contacts and it does not work. the lens is reported as MF
Too Old To Die Young
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