Originally posted by Confused Have read that other thread and the thread here as well. Interesting topic!

But besides the reports about experiences made, everything is just speculation. It may however, be worth the effort to find out how the Pentax SR really works.

Just a general comment: as long as the gyro sensors don't measure acceleration, the SR will remain mute and it most probably makes no difference. Stable tripoid assumed. Stable tripoids can be found in astro photography...

I do not know the following factors:

- Does the Pentax SR measure 2, 3, or 6 axes of motion?

- What is its resolution (minimal, maximum and delta in m/s^2 and 1/s^2 resp.)?

- What is the Eigen frequency of combined system gyro, electonics, sensor-drive?

- Does the algorithm apply frequency-decomposition with phase shift, or does is work in the time domain?

If I would, I could answer some of the questions. For instance, it could be that some of the tripoids' vibration frequencies are too close the SR system's Eigen frequencies. If this is the case, using SR could be very counter-productive indeed.

But even then, a tripoid's Eigen frequencies will depend on the tripoid itself, the length of legs and the weight of gear mounted. So, by knowing more it may be possible to use SR with tripoids to one's advantage -- or by educated experimentation (e.g., frequencies of shake can be measured with laser interferometers...).

To conclude, I can make one recommendation:

If the subject does not move, use a tripoid with SR off to shoot a long sequence (~ 100) of (underexposed) images and stack them together using one of those open source software packages used to stack astrophotography images. This provides SR by software.