I just found out.

Has anybody actually observed a problem with mirror slap, conducted any tests? I can't imagine it being noticeable on short exposures or long exposures of a few seconds or more. What's the most critical exposure time? Perhaps around 1/10 sec?

I am not so sure if it is a problem at any speed. But it makes me feel better.

Regards, Horst

There have been suggestions that there can be a problem around 1/125 sec, not with any particular marque but generally. In practice, I have never noticed it, but on the other hand some shots can be sharper than others for no discernable reason.

On a tripod I use the 2 second timer and the mirror is therefore lifted out of the way before the exposure.

Some shots can be sharper than others due to the variability of the autofocus, which still isn't great on my K5-IIs. Couple that with a lens that shifts focus with aperture and it all gets a bit hit & miss!

I made the comment because my K5 goes "clack" when pressing LV and "Ker-LACK clack" when you press the shutter. Without LV the mirror goes up and the shutter is very quiet so I assumed the racket was due to the mirror banging about. (Which surely can induce vibration?)

I think the "clack" is the mirror up and the "Ker-LACK clack" is the shutter then the mirror down when the exposure is done.

I just found out the solution to a problem which bugged me for a long time.
The problem with light entering in to the viewfinder window when taking shots from a tripod.

I had all sorts of suggestions, but they all required something to be stuck on or covering the viewfinder window.

But the other day, I was sitting on the throne and reading my K5 manual and I found the solution:

when using the tripod, after focusing, leave your eye on the viewfinder window and press the > AE-L<
button. This stores the exposure time and no matter how much sun shines in to the window, The exposure value from before is used to take the picture.
I tried it, and it works.

You know the old sayings: If all else fails, read...........................

I hope this helps others too.

Regards, Horst

That's a good idea to get around the metering problem but it doesn't prevent the other problem - light entering the viewfinder and getting onto the sensor. I think that problem really becomes significant when using large stop ND filters.

It does stop light getting in to the sensor through the viewfinder and hitting the sensor, because the mirror flips up .

Normally the light reading is taken before the mirror flips up . This way it does not matter, because the original reading is saved. Only the light which hits the sensor from the lens is used for thaking the picture.

Regards, Horst

The light still gets in and bounces around inside the camera, some of it reaching the sensor. It can reduce contrast and create streaky effects, like I said particularly noticeable when using big stop ND filters (because the light leak through the viewfinder is no longer insignificant in comparison with that through the lens). I posted here on 30/11/2015 my tests showing the effect.

I concur with Waypoints finding - I, too, have taken some where the contrast is greatly reduced with a bigstop ND on the lens; physically block the viewfinder with a cap/ glove or something and the problem goes away.

Yes two different issues going on here.
The first is the metering being off, leading to the wrong exposure settings being selected. As mentioned earlier, with big ND filters I'm not asking the camera to auto meter for me.

The second is light entering whilst the shutter is open and the shot is being taken. This gets worse on longer shots, but is an issue EVEN when the mirror is up.

It's one of the reasons I prefer to use mirrorless cameras for long exposures. If it wasn't for the looks & lack of EVF the K-01 would be perfect!.

Yes, mirrorless has distinct advantages for this type of work.

Live view is still the most precise way of nailing focus of static shots such as landscapes also - using digital zoom to punch in and focus peaking for precision.

I use mirror lock up and a cabled release. I hadn't thought to cover the viewfinder so thanks for the heads up on that.