Originally posted by UncleVanya I know this seems like I’m being a pain, but your statement is the very first time I’ve seen that said. I’d like numbers not just impressions. Do we have surveys or post counts to back it up? Even though that data isn’t fully random it’s better than nothing.
I thought it was common knowledge! Certainly it's true of my K-50 (a few hundred shots then several months inactivity). Same thing in the case of my brother's K-500.
I've even heard of a possible causing mechanism: initial operations remove a protecting layer from the solenoid's plunger, which then suffers corrosion when left inactive for long periods (constant operation tends to remove the corrosion layer).
For the OP:
Never mind, there are plenty of decent Pentax-K (and M42 screwmount, which can be adapted using the proper Pentax adaptor) lenses, both manual and auto focus.
If you do eventually need to go this route, follow the aforementioned instructions regarding the green button etc. Or, you can use the following procedure: use Av mode, set the lens aperture (using its ring) and use Exposure Compensation to correct exposure, as follows: for each aperture stop closed down from wide-open, add +1EV. For example, for an f2 lens set to f4, that's 2 stops, so set +2EV. There's now no need to use the green button for the correct exposure - just shoot away.
Before anyone protests, this procedure seems to work only for cameras which are afflicted with the aperture problem. Don't know why.
Just to complete the tutorial (!), if you want to use a vintage manual-focus zoom lens, you may wonder what focal length to tell the camera when it asks the question. This is all about the shake reduction system. If you don't want to keep changing the value to match how you've set the lens, use this formula: 2*max*min)/(max+min).
For lenses with small zoom ratios (e.g. a 75-150mm), a slightly superior method is to use the average, i.e. (max+min)/2. However,
this is unsafe for ratios larger than 3:1, as you get more blur than you would otherwise induce by camera shake with SR turned off.