Originally posted by pathdoc
I don't like your chances, but good luck anyway!
I always thought the focal length was reported by an analogue to digital conversion of some sort of potentiometer signal (or possibly very narrow discrete steps) as the focal-length helicoid was spun up or down towards narrow or wide angle. Maybe Pentax does it differently; I don't know.
I think that is exactly how it is done with the rom supplying a table of values that correspond to focal length. There are definite discrete steps.
---------- Post added 02-06-17 at 06:46 PM ----------
If you could hack enough of the lens rom up you could really change the lens to read as anything. I see no reason why the camera would know that sdm exists if it no longer thinks the lens is a 60-250. All you need to do is preserve the focal length so that SR and any focus corrections embedded in the rom still work.
---------- Post added 02-06-17 at 06:48 PM ----------
Originally posted by bwDraco
I would think that just fixing the SDM would be a lot cheaper than the cost of the 70-200 but you did at least upgrade there.
Last edited by zosxavius; 02-06-2017 at 04:48 PM.