SR stabilisation

Pareto,
The K20D auto ISO algorithm differs slightly from the K10D, and tends to aim for lower ISO overall.

However, in both cases, by far the easiest thing to do is to assign ISO to the front wheel and use Av mode. You'll have to go into the custom menu and look for the e-dial section.
In that mode, pressing the green button reverts to Auto ISO, and moving the e-dial will override that and force a manual ISO.

Then you have the immediate choice of auto ISO or manual

Takes a little while to get used to examining three values - Av, Tv & ISO - but the Pentax is unique in this

Matt

Matt,

thanks for that! I nearly always use Av but hadn't realised I could put the ISO on the front wheel. Now to start digging in the menus...

Best wishes, Kris.

Kris,
All firmware versions beyond 1.01 can. (Only the original 1.00 could not).
It's a real bonus!
NOTE: Since the VF shows ISO and not remaining shots, to see how many shots remain on the card, hold the OK button down
Matt

Thanks for your input. I always shoot in Av mode and I was aware that I can override auto ISO with the front dial. I'm just lazy and wanted to stop bothering about ISO at all.

My/the need to raise ISO manually is only determined by the two formulas I mentioned above, so I would prefer to just set them inside the custom menu, instead of relying on a mysterious default formula and keeping in mind to override it each time it differs from my requirements.

It leads to a workflow where you set your own shutter limits beforehand and auto ISO works to provide them for you. You don't have to examine Av, Tv and ISO, but you can concentrate on DOF (Av), focus and composition.

However, as I said, my urge might be related to my own lazyness and my unwillingness to process additional data in my head. No need for Pentax to act on it, if their users prefer to do it the manual way. But it could attract new customers, as it is a unique feature for someone who upgrades from a lower class and it underlines the value of in body SR.

In situations like that described by your scenario 2. I tend to decide on what Shutter/aperture combo I would like, then program those with TAv mode and watch the ISO. If it starts to climb too high I nudge my settings, if it drops low enough I might boost the shutter speed.

I agree your additions would make Auto-ISO much more useful (hint hint Pentax!!), just passing on how I deal with the situation described.

I've been following this thread with some interest.

I can think of a way of testing it, but not without additional equipment.

What it needs is the camera on a shaking platform, where the amount of shake is consistent, at a level where pictures taken with stabilised SR are obviously more shake-free than SR-off pictures taken on the same platform.

Then all that's needed is to take pictures with the camera on the shaking platform, with SR on, but before 'SR-lock' has been obtained.

Then compare the pictures with the two control sets to see if they're better, worse or neither.

The amount of shake from the platform would ideally be large compared with the amount of finger-induced shake (to allow influences from the latter to be discounted), but not so large that stabilised SR can no longer cope.

I suppose in the absence of the shaking platform, maybe sitting the camera on a washing machine (on something soft, probably) would do if it was quite a shaky one (possibly on the wash cycle rather than the spin cycle if the shake frequency in the latter case is too high).

Then if the pre-SR-lock results are grossly different from both the SR-off and the SR-lock cases, it may still be possible to draw some useful inferences from the experiment. But in the absence of the precision engineering solution that Don might provide, proving that the amount of shake was consistent enough might be difficult.

tape a playstation game controller to a flinsy tripod and run some (controlled) dc current into the "Force Feedback" motor in the controller to get a consistant, (and variable) amount of shake to the camera.

Nice one, Don. That was the kind of precision engineering I had in mind

Not, sadly, that I have either of those.

Actually, at work I have a rather large speaker and an audio oscillator... that just might do the trick
Matt

even better!
while you're at it, set a glass pie plate on there and fill it with a goey mix of cornstarch and water, and get some macro shots for us ok?

Will it do very low frequencies? At a guess you'd need less than about 10 Hz.

Ooh! That reminds me of stuff Peter Gabriel was doing - had all this stuff showing at his gig. Really cool. Forgotten the word... have to go and find it
Oh yes
Matt

hydrodynamics? neutonian viscosity flow?

I don't know...I'm just a gradeschool drop out...

Interesting topic this.

Don,
It was something to do with the strange way that viscous liquids form regular patterns when vibrated at certain frequencies. They'll start out all random, then all of sudden will form a regular pattern. At different frequencies there'll be a different formation. It's really quite bizarre!

Just been Googling... it's called "cymatics". (All I could remember was it reminded me of the word gymnastics! LOL!)
e.g. http://www.rmcybernetics.com/projects/DIY_Devices/homemade_cymatics_display.htm


Matt