Does the Pentax K20D Perform Better with non-DA Lenses?

by Miserere


When the K20D was first announced, a collective groan went up when Pentax unveiled the pixel count of its sensor. 14.6MP sounded like too many to provide low-noise images with a wide dynamic range. Pentax were quick to calm us down by pointing out that the individual pixels in the new CMOS sensor were actually of a similar size to those of the K10D; what they had done was shrink the inter-pixel space where all the circuitry is located so they could now fit more pixels onto the chip without making them significantly smaller.

Smart...

They also improved the micro lenses that sit on top of each pixel. By bringing them closer to the surface of the pixel they improved the light-gathering capacity of each pixel because light reaching the micro lenses from different angles will now be better directed towards the pixels instead of being lost in the spaces between them.


While DA lenses have been designed so the light leaving the lens from the rear-most element is as perpendicular to the sensor plane as possible, older lenses were not designed with this requirement because film is sensitive to light coming in from almost any direction. This is one of the reasons why some older lenses don't perform as well on digital SLRS as they did on film SLRs.


All these improvements should help the K20D provide better IQ with non-DA lenses than previous DSLRs from Pentax. If this is true, it would be a very important reason to upgrade for those of us who own a lot of old lenses.

As you might imagine, I don't have a K20D, so I cannot test this myself. It would be interesting if blog readers owning a K20D and one of the other Pentax DSLRs could perform some experiments to show whether Pentax's claims are true or not. Yvon, I know you have both a K10D and a K20D; this sounds like a nice weekend project for you :-) Of course, you'd post the results here for all to see.

I wouldn't be surprised if this were true, and it's another big plus for the K20D that Pentax isn't advertising emphatically enough.

Run some tests, and post your results in the comments section.


Thanks!

Miserere

Pentax/Samsung new 14.6MP CMOS sensor.

I found these images today from a Japanese or Asian site that shows how Samsung is promoting the new 14.6MP CMOS sensor that are shipped with the Pentax K20D and the Samsung GX-20. The new sensor was developed jointly (Pentax and Samsung). From what I was told, Pentax engineers, who have more experience than Samsung with photographic equipment, designed the sensor. Samsung is manufacturing the sensor since they already had manufacturing plants and the technical experience to make this new CMOS sensor come to life.

Click on images above to enlarge.

The images are self explanatory, although technically, I don't quite fully understand the process. I have always been amazed to read, on various sites, that CMOS APS-C sized sensors were limited to 10MP. A decade ago, CCD sensors were apparently limited to 3 or 4MP while CMOS sensors were too expensive and had a lower IQ. We have surpassed these barriers many times over and I have no doubts that new technological advancements will make it possible in a not-so-distant future, to pack 20MP on an APS-C sensor with excellent IQ at all ISO.

The buzz word these days is Full Frame. The full frame sensors are a vestige from the 35mm cameras era. It was just a handy way to make 35mm lenses fit on a new digital SLR design. Yes, the 35mm lenses do fit on the APS-C sized camera but project an image circle bigger than what the sensor can capture, hence the cropped image circle that makes a 200mm lens act like a 300mm lens and a 20mm wide angle lens act like a 30mm lens. I think it's wonderful. Have you priced a 300mm f/2.8 versus a 200mm f/2.8 lately? Telephotos are much more expensive than wide angle lenses. APS-C ultra wide angle lenses are now available, at about the same reasonable price of full frame wide angle lenses, making the APS-C sized cameras getting the best of both worlds. See previously post "APS-C versus Full Frame".

Pentax may produce a full frame sensor in the future, but it will only to meet the false perception of the consumers that bigger is always better. With time, the APS-C sized sensors will have the same IQ and pixel count of the full frame sensors. Full Frame DSLR cameras and lenses will always cost more to manufacture and will forever be heavier. As example, the Canon EOS-1Ds Mark II series and the Nikon D3 are great cameras but costs between $5,000 and $7,000 US. If you have ever held one of these cameras, you know just how heavy and bulky they are.

So, from my point-of-view, I believe in technology, the same technology that brought us from silver halide film to this new digital age and to this 14.6MP CMOS sensor that the Pentax K20D and the Samsung GX-20 have introduced. It offers the greatest resolution in its class.

Isn’t technology great?

Thank you for reading. Tomorrow, I will post more about my PMA 2008 experience with the new Pentax cameras and lenses.

Thank you for reading.

Yvon Bourque