Sensor:
The sensor is pretty much the point of the K-1. The 24x36mm “full frame”
sensor restores the full angle of view to legacy Pentax glass. Since the
APS lens lineup is rather thin in fast standard and wide lenses, this
can be a big thing for low light photography. Even on a per-pixel basis
the sensor out performs the K-3 and K-5 sensors, so on that basis it’s a
better APS camera either of the other two. I don’t know how it compares
in APS mode with the newer APS bodies (K-P and K70).
At 36 MP its pixel pitch is a bit larger than the 24 MP APS sensors,
giving up a little bit of reach when cropping telephoto shots, however
at 50MB per frame in raw, the same pixel pitch would give 48MP frames
using up 75MB per shot.
iso invariance:
One of the major characteristics of the K-1 sensor is that it is
ISO-invariant, which means that modulo clipping you will get nearly the
same result if you shoot at a high ISO as if you shoot at a low ISO and
brighten the image in post processing.
So, why not just shoot at ISO 100 all of the time? That would pretty
much make sure that you never clip your highlights. For one, it makes
it nearly impossible to review the photo you took to check for problems.
Another issue is that Lightroom has very limited range for correction,
only about five stops.
I also expect that if post processing did allow more correction the
delta between theory and practice on ISO invariance would show up as
noise, and possibly posterization in the shadows
It would be nice to be able to underexpose raw, but compensate on
previews... photographing musicians with colored backlights
Bracketing ISO effectively does nothing. While I prefer shooting Tav
mode, in Tav it only brackets ISO, it would be nice to set the bracketed
variable separately from the exposure mode.
Wide and standard full frame lenses work so much better:
My FA 31ltd and FA50/1.4 are great lenses, but they never really
inspired me on APS. On full frame however, I really quite enjoy using
them. I always had mixed feelings about my Sigma 20/1.7. Sometimes I
hated it, but only used it because it was the only fast lens I had in
that angle of view, but sometimes it really worked quite well. On full
frame it really became quite an interesting lens, although once I picked
up the Rokinon 24/1.4 I’ve rarely used it.
focus points:
They have increased the number of focus points to 33, which is a big
improvement. the narrower angle that each one operates at seems to also
help prevent the camera from focusing on the wrong thing. However, they
do not cover nearly enough of the frame. When photographing people, I
often want to compose the shot with the person's eye well out of the
area with all of the focus points. This means I cannot autofocus on the
face and eyes if the person is moving around.
The K-1 is a lot better at focusing on a musician rather than the
microphone in front of them, quite likely because of the smaller active
area of each focus point. By the same token, if I’m not careful to make
sure the focus point is on the person I’m photographing, it can do an
excellent job of focusing on the wall behind them. I should experiment
more with the select-9 autofocus mode.
Selecting focus points is not as graceful as I would like. I have heard
that on other systems, the UI for focus point selection works better.
When using manual focus, the in-focus indicator is very helpful at
focusing the lens. It works great, but for some reason, it is limited to
the center focus point. There is no reason to do this, and it makes
manual focus lenses less usable for anything but landscape work, and
even then there are problems with focus and recompose. Since there is a
very limited selection of full frame lenses available right now, and
many, if not most, of the people in a rush to buy the K-1 right away
have a large selection of legacy manual focus glass, Ricoh should drop
this restriction in the next firmware update.
One can get some reprieve from the focus restrictions by using live
view, but it is so slow to take a photo in live view, even with the
focus locked, that it is unusable for any sort of dynamic scene. This
has been alleviated somewhat with the firmware update that implemented
electronic shutter.
Auto focus speed and accuracy:
When the autofocus works, it seems to work pretty well. Not nearly as
well as Nikon. Sometimes though it just won't lock focus. This might be
due to the narrower range that each focus point uses now. I should
probably experiment more with the "auto 9" autofocus mode.
In order to photograph action, I pretty much have to prefocus and lock
out autofocus with the AF button.
Bus speed
The K-1 biggest shortcoming seems to be its bus speed. Saving files to
the SD card takes far too long, and using fast SD cards doesn’t make a
difference. I think I’ve seen that after about 40 Mbps, there is no
advantage.
buffer size
The buffer size is woefully inadequate. This exacerbates the bus speed
problem.
Lack of binning
One thing that could make a big difference with the bus speed and buffer
size problems is being able to bin pixels for lower resolution files.
While you would lose resolution, this is rarely an issue except when
cropping in extremely tightly, or printing very large prints. 2:1 and
4:1 binning would still give 18 and 9 MP files, while improving the
signal to noise ratio and the dynamic range of the data.
Yes, shooting in crop mode does give some of this benefit, but you lose
SNR and dynamic range in the final image, as well as angle of view.
size
In general, I like the size of the camera. I have rather small hands,
and I can comfortably reach the buttons on the right side with my thumb.
Some people like larger cameras, and I presume that the vertical grip
should solve this problem for them. I owned a vertical grip for my K-20
and almost never used it, so purchasing one is very low on my shopping list.
weight
The camera is pretty heavy. It feels quite solid. Going from the K-3 to
the K-5 is kind of like going from the K-100 to the K-20. The
combination of the K-1 and the 15-30 ends up being a very substantial
piece of kit.
sound
If I was not used to several years of using the K-5 and the K-3 I'd be
impressed by how quiet it is. The sound is different from the previous
two cameras, but not much louder.
Battery life
Pentax DSLR battery life seems to have peaked with the K-5. Since I
don't use the screen on the back except for brief review of images, I
could regularly get over 2000 frames on a charge. With the K-1 it is
only a few hundred.
I am, however, glad that they’ve kept the Dli-90 battery. It would be
nice if they also designed the off camera flash to use this battery
rather than AA batteries.
Processing files:
Lightroom cannot handle the dynamic range. With ISO invariance, when
shooting a scene with a lot of dynamic range, for example a musician
with colored stage lights in the background. you could set the ISO at
100 so as not to blow out the lights, then brighten the image in post
processing. Unfortunately, situations like this can require well more
than the five stops of brightening that Lightroom can handle.
In a similar vein, the wide dynamic range of the sensor means that you
have the raw information to correct for a huge range of color balance,
except that lightroom does not have the adjustment range to do so.
Raw files are 45-55MB, pixel shift files are 175-225MB. This will put a
lot of load on your system, particularly when processing large numbers
of files.
Using the camera in crop mode:
APS crop mode solves some of the issues with the slow bus and small
buffer. The square crop mode is pretty much useless because the files
are the same size as full frame. A square crop mode that stored less
data would be great, especially since it would also alleviate vignetting
on a lot of DA lenses.
Similarly, a crop mode between APS and full frame could also be nice,
particularly with lenses like the DA40 ltd and the DA35 macro which only
vignette a little bit on the K-1.
--
Larry Colen [email protected] (postbox on min4est) http://red4est.com/lrc
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