Pentax K-5 Preview

A cut model of the Pentax K-5 as shown at Photokina 2010
"The engineering masterpiece" (photo © 2010 Falk Lumo)
 

The Photokina 2010 has just closed its doors and I am compiling my findings regarding Pentax into this article. I posted my first impressions a week ago.

Pentax K-5

The most exciting part (besides trying out the 645D) certainly was to find out about the new K-5 camera. I gathered a lot of material from various sources and wrote a full Pentax K-5 hands-on preview report. A short blog article turned out to be the wrong format and therefore, I posted it on my website. Here you go:

-> Pentax K-5 hands-on preview

Don't miss the exciting news. Moreover, I tried to answer as many questions I received as possible in the report and to skip as much redundant info as possible too.

However, a small number of questions didn't fit the K-5 context so I am putting them here:


Lens questions:

DA 35mm f/2.4:

The new DA 35/2.4 introduced short before Photokina is specified here:

• DA 35/2.4 press release by Pentax Japan (English version)

The production capacity is 2/3 of that of the 18-135 lens and will be available as a kit lens for the K-5. Early reports about the 35/2.4 have been very positive (sharpness wide open, bokeh, very fast focussing, maybe 35mm image circle) and as a kit, may have a very attractive pricing.
The kit will be black only and non-black versions are said to be unavailable (at least outside Japan).


DA 18-135mm f/3.5-5.6:

This lens was announced together with the K-5 at Photokina and is specified here:

• DA 18-135 press release by Pentax Japan (English version)

The lens was received with much interest and will be offered as a kit lens for the K-5 too. A number of features I could clarify:

1. The aperture ranges are as follows:
   18-19 mm f/3.5
   20-29 mm f/4.0
   30-79 mm f/4.5
   80-135 mm f/5.6
2. DC focus motor:
   "DC" stands for direct current according to one source, and for dual current according to another. That needs further clarification although my bet is with the direct current camp ;)
3. Focus motor noise:
   The focus motor almost certainly is not ultrasonic. I tried to listen despite the show's background noise. It sounds different than an ultrasonic motor (it's more motor-like, less twitter-like) but isn't necessarily (much) noisier.
4. Focus motor speed:
   The focus motor appeared to be about as fast as a DA*16-50mm ultrasonic motor. Which isn't fast exactly. The DA 18-55 WR kit lens is a lot faster!
   Pentax missed a chance to deliver a higher speed focus motor (e.g. ring type) rather than a lower production cost one.
5. Image quality:
   I don't know. From the specs, it could be better than that of a usual floating aperture lens.

Teleconverters:

Pentax showed its 1.4x autofocus teleconverter at Photokina 2 years ago. It has disappeared. I asked what happened to it. The response I obtained was hard to accept: Pentax Germany requests production of the teleconverter but Japan denies saying that teleconverters aren't required anymore in the digital age. Pentax Germany tried to explain that a digital magnification may actually have a negative impact on image quality (as we all know) but obviously it did not help much. What shall I say...?


Post Photokina Pentax strategy (as I guess it):

Overall, Pentax is a bold performer in 2010: 645D, K-5 and K-r seem to be 3 winners. And the company itself is making profit. So what else should it take to make a Pentaxian a happy Pentaxian? Not much should one think. Esp. as an Olympus E-5 (good-bye gift?), Canon 60D (downgrade?) and Nikon D7000 (Pentax clone?) are not particularly exciting. But the grass never is green enough ;)

It's because many Pentaxians are addicted to their hobby. They want to invest further in their system and are imaginative enough to foresee "their" camera and lenses in one or two years time.

Therefore, it's a bit irritating that all signs emanating from Pentax at Photokina (foremost but not only from Pentax Germany staff) cry out: we're not going upstream with the K mount. Not now. The 645D digital medium format is as professional as one may actually desire. "Unfortunately" however, cameras in the tradition of the *istD or the higher end film bodies attracted quite a few rather professional photographers into Pentax. Over the last couple years, their fraction is shrinking though and this Photokina won't halt it. It's no fortunate coincidence either that no new Star-lenses are announced and FA Ltds. are tagged "end of life" (whatever that means...) in Germany. Personally, I also don't expect a revival of non-standard lenses (like 85/1.4, 135/1.8, 300/2.8, 600/4, maybe not even a 400/5.6), based on a statement that the rarer lenses aren't currently profitable for Pentax to make. And I hear a bold "no" to full frame. Pentax doesn't see their enthusiast user base go full frame.

To be fair, nobody knows about the future prospect of mirrored cameras. On the other hand, Pentax seems still to be in an evaluation phase with respect to mirrorless cameras and meanwhile anticipates to sell the K-r against mirrorless cameras from other vendors. This worked out fine in the past (with the K-x) but Pentax may start to realize that this won't continue for too long. So, it may be understandable that in this atmosphere of change, Pentax may not invest in the $1500+ segment in order to re-establish their share in that market segment. On the other hand, Pentax learns that what was the $1500 segment (K-7, D300) now is the $1200 segment (D7000) and soon will be in a region with aggressive price competition. As will be mirrorless cameras.

So, some kind of either upstream or innovation strategy was expected and missed from Pentax at this year's Photokina. That's the one complaint. But I hear it from many, from Pentaxians and all over the press watching the market: "where is Pentax heading?".

As a side note, there has been staff from Hoya visiting Pentax and Photokina. E.g., Ned Bunnell was spotted at Photokina and Eguchi Kazumichi (head of marketing imaging systems division) gave an interview. So, if anybody (not me) had a chance to meet with Hoya Int'l management at Photokina and exchange some ideas, please drop a comment... ;)


Summary and verdict:

• K-5: Very solid and satisfying performance. (as known so far) 
• Hoya Pentax: In good shape but tight on resources. Communication skills leave some room for improvement.

P.S.
I activated some ads on my blog. It enables a certain guy to pay reparations:) (just joking!)

LumoLabs: Busting the alignment myth

This will be a special feature for hard core falconeye followers ;)

It all started with the exciting new feature of the Pentax K-7 camera which can produce true HDR images in-camera (it takes 3 shots, 3 exposure values apart from each other, and creates a single, tone-mapped or blended image from the sequence). It does it so well, esp. in the medium setting (as opposed to strong) that a limitation of the feature does actually hurt: you require a tripod to use the function.

The general opinion why Pentax left out the alignment step from their HDR function is that it is a processing power-hungry computation not easily done in-camera.

Not my opinion, though. I felt that Pentax has left out 10% of the implementation which reduces 90% of the functionality. Shouldn't it be the other way round?

Now, opinion isn't proof.

So, I implemented my own alignment operator, benchmarked it and compared its quality against the state-of-the-art in HDR.


The algorithm

The implementation is based on an algorithm whose computing time increases linearly with image size and is constant with amount of distortion. Note that I did not attempt to cope with the alignment problem known in panorama stitching, i.e., I don't do SIFT key extraction, I don't correct for lens distortion, I don't project onto a sphere before alignment, etc. pp. However, what I do is correct for shift and rotations which is a mathematical first order approximation to the latter and rather exact for small shifts and rotations.

The implementation uses a monochrome quad tree and high bit depth. The coding is in Java. It isn't based on anybody else's intellectual property.


The benchmark

I benchmarked the algorithm with a 5 image HDR from Munich Siegestor. It had distortions of up to 20 pixels and needed rotation as well. The source images haven't been ideally sharp (e.g., 1/25s and wide open with 15mm). And no program created a perfect alignment. So, I considered this example be adequate. The images were 14.6 MPixel JPG images.

The processing times on a Mac Mini (Early 2009), one processor used, are as follows:

• Single alignment: 175 ms
• Alignment of all HDR images: 700 ms
• Reading of all images from disk into Java heap: 16 s
• Shift-turn and write images to disk: 34 s
• Total, disk to disk (70 MB transferred), 5 images: 50 s

The K-7 has a dedicated image DSP and can certainly rival this. E.g., it can JPG-compress a 14.6 MPixel image in about 100 ms only!

Because the HDR function within K-7 already has created the required image structures in its 2 GB memory, it would be conclusive to assume that addition of an auto-alignment feature to the HDR function would add less than an extra 1/2 second to overall operation time.

If processing speed isn't the reason, so maybe it is quality? This must be looked at. In particular as some of the alignment operators I compared with took several to nearly 10 minutes to complete.

The quality

I've run several alignment operators and come up with the following ranking:

1. Photoshop CS3; PhotoAcute ("normal alignment")
2. Falk Lumo Operator (as of this blog article); PhotoMatix 3 ("by matching features")
3. PhotoMatix 3 ("by matching features"; "reduce ghosting")
4. PhotoMatix 3 ("by correcting horizontal and vertical shifts")
5. No alignment

All pre-aligned images have been read into Adobe Photoshop CS3, either by HDR merge (without further alignment) or by opening the 32 Bit .hdr-file written by PhotoMatix. Tonemapping was done in Photoshop CS3, using the "Equalize Histogram" method. The latter isn't best but as it has no parameters, I thought it would make for a good option in a comparative study. Finally, the result was studied to derive the above ranking. Which is entirely subjective!

Below are the two samples from category #2. Please, visit the gallery to view the other samples, too. Note that all sample images have been resized to 6 MPixel.

Fig.1 No alignment


Fig.2 PhotoMatix


Fig.3 Falk Lumo Alignment Operator (as decribed here)

Take me to the gallery

Conclusion

The myth is busted. There is no reason to not include auto-alignment into the next firmware release of the K-7 HDR feature. In less than an extra second of processing time, about PhotoMatix quality can be provided. Make it so!