SR stabilisation

I'm starting this thread partly in response to the comments made by ChrisA and Don regarding SR.

Shot a wedding on Saturday with the K20D - something like 6.5Gb of RAW files
There are a few images (and I mean a few) that were blurred when the shutter-speed/focal-length would dictate that it should've been fine.

I've been looking at the RAW files with PhotoME - which shows all kinds of interesting EXIF information

Turns out that the majority of the blurred shots had SR turned on, but SR had not stabilised... for example, the shutter had been held for only 0.28s (sometimes much shorter). This is interesting because I only ever use the "AF" button for focus.

Now, I'm aware that it is possible to get camera shake even when the shutter speed is faster than the focal length "rule-of-thumb". However, I do have a very steady hand But added to that was the fact that there were a lot of shots, and it was a very long day...

On the positive side, I have a number of pin sharp shots taken at slow shutter speeds using SR.


Maybe the thing is to remember to give SR time to work out what's happening - so it doesn't "misread" shake that isn't there!

Any thoughts or evidence?
Matt

I did read somewhere (although I have no idea where) that SR needs time to work and you are supposed to hold the shutter button for a certain (short) period of time.
Not sure how that would work in continuous mode though.

Mike,
You are correct, SR does need stabilisation time. In continuous mode all is well - the camera will track any shake.
My problem was probably that I'm quickly putting the camera to my eye, knowing that the focus is correct (because neither I nor the subject had moved and I was working at f/11-ish), and then firing the shutter. I'm wondering if SR in these situations may be the cause of the shake - perhaps if I'd had SR disabled then these shots would've been ok.

But I suppose I'll never know!

Matt

FWIW: On the wedding theme - I really, really could have done with the SMC-DA* 50-135, and probably the 16-50 too But the 50/1.4 and 100/2.8 filled in at f/2.8 and f/3.2, plus the 24-90 as the main lens.

I've noticed the same thing with my handheld 300mm shots - you have to wait for the "hand" symbol to appear in the viewfinder, which indicates that SR is ready.

Like you, I've been looking through my blurred shots in PhotoME and they almost always have "SR: Not Ready". PhotoME tells you how long you half-pressed the shutter button and on my K20 it would seem you need to hold it for around half a second for SR to be ready.

On the other hand, I haven't seen any correlation with SR Not Ready and an increase in shake. Some "Not Ready" shots have been pin-sharp

R

Thanks Reuben!
The shots I'm referring to were around 45mm, 1/80s and still blurred... but as I said, it could've been partly down to the spur of the moment.

Wonder if there is an objective way to test this out
Matt

that could be an issue with my observations.

in low light I switch af and exposure to manual, and I'm usually faster than the camera could be on auto, so I would never have bothered to wait for any kind of sr lag if that's what you might call it...

I focus with the shutter button, so SR is almost always on when I "fire". I originally had it set to the rear button, but that didn't give SR enough time to go on. And, focusing with the rear button and then waiting for SR to kick in gave enough time for the subject to move. Now, I have the rear button set to "cancel AF", so it will "kill" the AF when on AF-C.

As there is a function to prevent shutter release if AF is not locked, I'd have thought it'd be relatively simple to impose the same restriction if SR is not ready (as an option, of course).

That's a good idea

My question, I suppose is: when SR isn't ready, does the K20D/K10D disable SR, or does it make a stab at it. If it's the latter - that would certainly explain the shots I'm seeing.

Matt

Would explain mine too.
easy enough to avoid though....
if you think you need it, try it, if you see an noticible improvement, great, if not turn it off, and grab your tripod.

Absolutely agree with you Don

It was something that I meant to do, but I forgot to disable SR for shots outside - giving this weird little crop of blurriness

Perhaps it's another thing to commit to habit
i.e. - keep SR off; when you need it, make sure you check the "hand" sign in the VF before pressing the shutter; then turn SR off.

Matt

Well I'm used to people thinking I'm crazy..(in fact I'd go so far as to say THINKING YOU"RE NOT CRAZY is the first symptom of insanity.).. but thanx for sharing your observation.... makes me look a little less crazy....

I just registered to express my full support for that idea. I have been suggesting such a "force SR mode" for a potential firmware upgrade on Pentaxforums, but nobody seemed to be interessted, back then. It is especially valuable, if you hand your camera out to older people/mothers/etc, who have shaky hands, but no sense for only tipping the shutter and waiting for the SR-signal to pop up.

If someone here has contacts to Pentax, please pass this on! It should be less than an hour of work for the camera software department.

Passed on already
Along with a few other things too
Matt

Wow, thank you. If I may add another suggestion which is not too off-topic as it also relates to SR:

Auto ISO allows to set the upper and lower ISO limit. But the algorithm which chooses the respective ISO is not quite transparent and might be inadequate in many cases. I think that is one reason why many people refrain from using auto ISO. But with only two further settings auto ISO can be a very powerfull facilitation.

1. relative shutter limit (vs. camera shake)
This resembles the classical rule of thumb, but takes SR into account and allows for individual customization. The lowest ISO is used. It is only raised, if shutter speed is slower than 1/focal lenght*X seconds. Adjusting this X allows the user to consider his own hand holding skills in combination with SR. If you're steady X=0.4, if you're shaky X=2.

2. absolute shutter limit (vs. motion blur)
If camera shake is not the problem, the other reason for lifting the sensitivity is the movement of the subject. Steadiness is of no use here, as a fast shutter is needed anyway. As this limit varies from occasion to occasion, it should be possible to custumize it for the respective photo session in the term of 1/Y seconds. If you're shooting a still life Y=1, friends in a restaurant Y=30, playing kids Y=125.

ISO is only raised if the low light leads to shutter speeds that conflict with either of these rules. And only as far as necessary to stay within these limits.

The purists might say that they prefer to adjust everything manually. I can agree with that in regard to focus and aperture as they are artistic decisions. But in most cases sensitivity has no artistic influence, but is only used to fight the problems of camera shake and motion blur. I believe that the two settings I suggested above could explicate the algorithm behind auto ISO and should, in most cases, allow for adjustments that eliminate the mentioned problems and let you concentrate on the artisic part of photography.

I'm happy for everyone who wants to comment on this. And even happier for everyone who can pass this on to Pentax, so they can consider implementing it in a firmware upgrade.

Thanks.