Thanks for all your encouragement.
I'll go thru some of the questions now, trying to help out where I can.
Originally posted by opiedog seems like this is a function of the higher FPS of both cameras. k20's much less affected and i haven't notice that on my k200.
I'm not sure why this is. The faster shutter by itself shouldn't cause more blur than a slower one. But a heavier one should (effective weight of moving parts). We don't believe that the shutter is this much heavier. Something else is involved. So, it isn't the faster FPS. Just bad luck.
Originally posted by RonHendriks1966 Would putting the SR to off have any influence or is that not blocking the sensor at his place?
By the way do you have the report also as a pdf-download in Deutsche Sprache?
Switching SR on or off has no impact on the effect itself. We don't recommend to switch off SR as it does still reduce blur due to free hand shake.
To help understand: the movements due to SR are slow and large compared to the movements of the camera body during the time the shutter moves (fast and small).
Sorry, report's original is English language. Would be German if Leica had the problem though
Originally posted by philbaum Of course, what Wikipedia doesn't address is the impact of the shutter motion on the SR behavior of Pentax like cameras. But it certainly supports Falks report conclusion that shutter motion is involved in the problem.
Questions:
1. It seems to me that Pentax's decision to go to higher shutter speeds (which of necessity would speed up the first and second curtains as a constant, i think) contributed to this problem - am i right on that?
K20D: max shutter speeed 1/4000
Kx: max shutter speed 1/6000
K7: max shutter speed 1/8000
2. If Pentax wanted to eliminate this nick blur problem, could they issue a firmware change that would reduce maximum curtain speed and of course, reduce maximum shutter speeds. (On the Kx, this would also have the likely side effect of reducing curtain noise as mentioned by Wikipedia)
3. Is it practical to use Live View as a way of eliminating first curtain vibration and mitigating this problem as suggested by the Wikipedia article. The K20 doesn't have good Live View implementation so i can't address this. I'm so used to a good optical viewfinder, not sure i would want to use Live View for framing.
Thanks again, real progress of course in understanding the problem.
Ad Wikipedia: The K-7 and K-x don't use an electronic first curtain in Live view (LV) or mirror lockup (MLU). In LV, the shutter is closed first before the actual exposure starts with opening the first curtain again. So, the Wikipedia article does not apply.
Ad 1. Maxiumim shutter speed is controlled by the accuracy of the slit size, not the travelling speed. A higher speed shutter simply is more high quality precision engineering.
What requires a higher travelling speeds is a faster flash sync time (1/180s in all three cases). And possibly a very high FPS rate.
However, as said above, the travelling speed cancels out of equations. Mass and distance are the only parameters which matter. At least as fas as the effect of body movement is concerned. The non-linear effect is ... non linear. So here, speed and accelarations may indeed play a role.
Ad 2. In any case, we don't advise to change shutter curtain speed and BTW, it wouldn't be feasible anyway.
Ad 3. Like SR, LV and MLU have no impact on the effect.
Originally posted by Gimbal One "non-linear term" that might cause problem for the SR is mechanical friction in the suspension of the image sensor plate. It can very well lead to small "jumps" when the SR system wants to move the plate a very small distance.
And there are friction as we can easily test by tilting the cameras and listen to the sensor sliding around, some cameras even needs to be knocked a little before the sensor starts sliding, "Starting friction" in action.
Unlikely but not impossible.
Originally posted by dlacouture What could be done by firmware would be to counter this curtain-induced sensor shake (taking into account the actual orientation of the camera), by mapping this shake with accelerometers and overlaying this to the SR loop...
As it seems to be quite repeatable and constant from one camera to the next, it could work (if the SR loop is not hardwired!), but at the expense of a huge work by Pentax...
And even then, it will greatly depend on what you have on the camera at the time, I think : additional weight (think Grip, Flash and Lens here) will surely lessen the curtain effect by decreasing the curtain/camera weight ratio...
So, as much as I'd like to see this solved on both models, I don't have much hope...
I wrote something similiar elsewhere.
This is actually a nice aspect about SR: it could be programmed to counteract the shutter effect (cancellation approach). As you write, only perfect for a single body weight/lens combination. But should still help in general.
Let me complement with this thought:
If the body moves in counter reaction to the travelling masses of the shutter, then the magnetically floating sensor could just "slide" to not participate in body movement. The magnetic forces could be changed to just G-force with the feedback loop switched off (during the time a curtain travels). This should still be better than to try to follow the kick-n-stop body movement and to possibly overshoot afterwards (if this is what is happening).
So, a camera with a mechanical focal plane shutter and a floating sensor
could be the perfect camera free of
any shutter-induced perturbation.