Originally posted by dvest please add any more info that could help me with this decision.
Some comments if I may.
You already have a very fine camera in the K-r -
see its high DxOMark ranking.
There seemed to be a view that good HighISO performance means that the Lower ISO lag - that doesn't make sense - certainly this is clearly not the case - the top DxOMark ranked cameras are both the top HighISO and LowISO performers.
At lower ISO the differences are obviously measurable as shown by the DxOMark -
but may be difficult to see visually - most of the reviews out there tend to point out there is very little difference at ISOs below 400 -
Of course YMMV - but it may be worthwhile checking the full sized test samples at Imaging-Resource.com to see how the low ISO
images of the K-r compare to
the K-5 -
I would hazard that below ISO400 there would be very little difference (I know obviously they are not the same size so it can't be a 1:1 comparison - but it is still very educational to actually compare side-by-side).
There will be some who will point out (correctly) that differences are unlikely to be seen with JPGs out of the camera (note that) -
some of the test shots do have RAW versions - so one can download those convert them and compare.
Again it may be pointed out that things like dynamic range are unlikely to be seen with a straight converted RAW to JPG -
but examining things like the shadow areas - especially when one wants to bring up the shadow details, then the difference can be seen - again note that.
If one is going to shoot JPGs
or mostly do straight conversions from RAW without too much pushing up of shadow areas -
one may not actually see much material difference.
There are other very good reasons to have a K-5 over a K-r -
but unless one is going push the boundaries, things like shadow areas -
Low ISO performance may not be one of them?
For a lot of measurements see the
ImaTest of the K-5 on Imaging-Resource.com
(there's a lot to take in there...)
however just past 1/2 way down the page is the dynamic range comparison with other cameras - from RAW - the K-5 is the top dog at 10.2 stops DR, along with the Nikon D7000 - the K-r has not been tested yet - but the K-x (similar?) is in the list at 9.33 stops DR.
JPG DR tells a completely different story with several cameras doing better than the K-5.......
BUT looking at the full sized test samples at Imaging-Resource.com one can still tell that the K-5 is a top dog the K-r and K-x images are really good too - yet these are mere JPGs - so DR does not tell the whole story either.