The Pentax K1 Pixel-Shift Comes into Focus

[Michael Erlewine]

I certainly saw this coming, at least the potential of this pixel-shift technology. Having spent years trying to work through issues with Apochromatic lens and their relation to perceived color, including the obvious fact that better-corrected lenses have less “purple” fringing, etc. than uncorrected lenses, and the perception of sharpness is determined by how well a lens is corrected and not only by acutance and sheer resolution.

So, when the Pentax K1 was announced, I was drawn to it at first just because it was a 36 Mpx sensor that claimed to do something different with color and luminance, rather than just more increased resolution, “sharpness” or whatever smart companies like Sigma, Zeiss, Sony, etc. are doing these days. That got my attention. 

I found that Lloyd Chambers (diglloyd.com) was also interested and determined to check this out. Chambers pointed out to me that this pixel-shift technology already existed in the Pentax K3 (24 Mpx), which had been on the market for some time. I ordered one and tried to scramble up some lenses that would not be too far away from what I was used to in Nikon mount.

I ended up with several Voigtlander lenses, including a couple copies (old and new) of the Voigtlander 90mm APO f/3.5, a Voigtlander 40mm, and even managed to find a copy of the legendary Voigtlander 125mm f/2.5 APO-Lanther, but it had a stuck aperture ring that would not allow “A” mode, so I reluctantly returned it. I still would like a copy.

I returned the Pentax K3 and waited for the K1 to be released. Lloyd Chambers got an early copy and dove right into checking out the Pixel-Shift mode. I had to wait for my copy and some folks are still waiting. I finally paid a little extra to get hold of one. Chambers was by this time producing results with the K1 and I am grateful for his many blogs in great detail about the K1 and pixel-shift.

I also had a bunch of health problems that set me back a couple of months, and so on. Anyway, I am finally beginning to get out in the field with the K1 and the few lenses that I have for it.

There is no doubt IMO that the quality of the color using the pixel-shift mode is more “pristine” than the muddier color I am used to as obtained from Bayer-interpolation. No question about it. It has been pointed out that one of the results of this approach is that it is equivalent to having larger photosites (or whatever the correct terms are for the little wells that gather light in the sensor). I believe it. By sampling four colors (RGB and another G) the clarity of pixel-shift technology is striking and obvious.

I am still getting used to it and I seem to find the whites blow out easier than with my Nikon D810. Perhaps someone could suggest why this might be true of the pixel-shift technology. For my work, the interface of the K1 is not as easy to use as the Nikon, to put it mildly. The Pentax K1 is not optimized to make using lenses that are not coupled to the Pentax easy or fun.

So, with that being said, here are a few images shot with the Pentax K1 and the Voigtlander 90mm APO Macro that, while not what I would like them to be, give me hope that I can wrestle this new technology into some kind of cooperation for what I need it to do. Focus stacking on the K1 is much more difficult to do that with the Nikon D810, if only because it takes time to take each photo with pixel shift, as four photos are taken and then combined, while you wait. The light, the wind, etc. can change in that time and the files are huge, as well.

So, pardon the imperfections, but perhaps some of you can see, as I am seeing, the great potential for this technology. Now, if Nikon would only bring out a 50 Mpx sensor that also had pixel-shift... soon please.

These do have a short stack using Zerene Stacker, so there are some artifacts.

[Geomiljo]

Nice images, and I would also be very much interested in this technology. 

But I suspect it will be a (very) long time until something like this is available in a Nikon... since they don´t seem to like the idea of a moving sensor.

But perhaps the same tech will be available sooner in the Sony A cameras!?

/Johan

[Michael Erlewine]

The Pentax K1 in pixel-shift mode is a game-changer for me, one not totally welcome because of the difficulties in using non-coupled lenses, i.e. all my Nikon F-mount lenses with a simple adapter. This whole system, IMO, is just shy of not-worth-it and reminds me a lot of the film days, when we didn’t know what we got when we pressed the shutter until days later.

In this case, I have no way to get the K1 to show me the amount of light reaching the shutter, but it insists on staying all the way open. Things like that. It makes no sense, but I find myself blaming Nikon for being so behind the curve as to offer nothing remotely similar, not even increased resolution. I need 50 Mpx or higher.

For me, this is compounded because I want to stack focus, at least a little, and that only makes things that much more difficult. There is the annoying camera interface (IMO), the changing light in the time it takes to run four shots through the process, and the havoc that any movement plays with the image with pixel-shift turned on, the huge files for me computer to handle, etc. I am just complaining and, as mentioned, part of me wishes I could just walk away and declare it not worth it. But it probably is worth it.

With coupled-lenses, like Pentax’s own (IMO lame) selection of lenses or the few I have been able to find in Pentax K mount, the process is tolerable, but I am back shooting with non-APO lenses, and CA still exists big time and I am not used to seeing it much any more, etc.

As mentioned, trying to bring other lenses into the picture with an adapter, I feel like Ansel Adams (only I am not him) with a large view camera and all of the guesswork he must have mastered. I am used to being able to look at LiveView and see my aperture AND shutter adjusted in real-time. With the Pentax K1 and alien lenses, I have to shoot frames until I get the light where I want it, by guess-work. And I don’t like the DejaVue it throws me into. I was done with film and its quirks, or at least so I thought.

The Nikon>Pentax adapters are all so cheaply made that the glass in them (to allow infinity) ruins any lens I might attach, so the first thing I did was break out the glass in the adapter. I don’t need infinity, and am better off without their lousy glass.

Also, color in the Pentax K1 is more sensitive on the bright side than my Nikon D810. It is far easier to blow out the whites and Lloyd Chambers (in an email) explained that at ISO 64, the Nikon D810 “leaves the top 1.5 to 2-stops unexposed due to weird metering and histogram – a bug. ... I remember reading an interview that said that ISO 64 was some kind of special hardware mode for idealized dynamic range. But see no RawDigger evidence that the Pentax K1 is less good in SuperRes mode (regular mode unclear, but it is a newer sensor).” Be that as it may, I have to be more careful at the “whites” end of the spectrum.

I must be getting old

This shot taken with the Pentax K1, and adapter, for a Nikon F-mount version of the Voigtlander 125mm f/2.5 APO-Lanthar lens at f/16, ISO 100, 1/8 sec. F/16 is high to expect no signs of diffraction, and there was a little wind, and this is stacked (two images.)