RiceHigh's Pentax Blog: KP

Showing posts with label KP. Show all posts

Tuesday, November 02, 2021

The K-3 III Image Corner Blur Issue Strikes Again

Camera-gear YouTuber Kobie M-C tested the K-3 and K-3 III side by side and here is his report:

https://www.youtube.com/watch?v=pH2eQD6fpA0

And, his quick textual comment follows, quoted:

"Some interesting things occurred during the shooting for this test. It seems the K-3 Mark III sensor out resolves some lenses including the DA 50 1.8 which surprised me. It's a good lens, nice and sharp, but just not on the K-3 Mark III. I tried live view, electronic shutter, Focus fine adjustments from -10 to +10 and it was still soft. F/1.8, 2.8, 4 (when the lens is sharpest) and still the same result. This might be what some professional reviewers are experiencing when they mention soft images."

The below quick snapshot refers for easy reference:

(Click to Enlarge)

In fact, Kobie's finding is exactly the same as what I found last time with my new K-3 III when it was tested against my KP side by side.

As the increase in the total number of pixels of the K-3 III against the K-3 and KP is really marginal, I think there exists another factor to cause the decrease in resolution in image corners for images produced by the K-3 III, even for the same old lenses, which used to be optically good.

I suspect the (different) design of the micro-lenses and (different) assumed incident angle of light should come into play. Indeed, the new 26MP Sony sensor was first used in the Fujifilm X-T4 which has a much short back focal distance. Later on, Ricoh got this sensor and put it into the K-3 III. However, the new sensor is not that highly compatible with many of the old glass in optical sense, especially at the image corners and edges, and that wide angle lenses suffer more than standard and tele ones.

I have verified this with the latest glass marketed by Pentax, in particular, like the D-FA* 16-50 PLM, which shows a much lesser problem for the aforesaid issue and phenomenon.

Saturday, June 12, 2021

Image Corner Blur Issue with K-3 III (Head-to-head Comparison with KP)

Have had my K-3 III for over one month now and tested it with my various DA/FA/DFA lenses (mostly primes) but there is a strange issue discovered.

It is all about the unexplainable corner (or simple off-centre) softness in the images taken with the K-3 III. To illustrate the problem, here we go with the sample set below, with a pair of images taken using my K-3 III and KP with the same lens (which is a HD-DA 40mm Limited), at almost the same time and with the same exposure parameters.

Let's see the 100% centre crops of the pair of images, which are perfect in focus. I captured also the EXIF data on screen for our easy reference (Click pictures to Enlarge):

Then, here are the left side of the images in 100% crops:

And then, here are the right side of the images in 100% crops:

This problem really drives me nuts. I really didn't expect the new flagship camera would produce much lower resolution at off-centre in images than its predecessor model of 2017. It's really much frustrating after all.

It seems that the new sensor of the K-3 III has some kinds of incompatibility with the existing Pentax lens lineup optically, which is a hardware issue but not a software one, I believe. Note that I had already turned off all the lens correction functions as well as the AA filter simulator to rule out the possibility of the issue is being caused by software or other factors.

Thursday, April 15, 2021

New Firmwares for K-1/II, K-3/II, KP and K-70

http://news.ricoh-imaging.co.jp/rim_info2/support/

To support better focusing operation for the three FA Limited lenses, include both the old and new versions. But it is unknown that if focusing speed and/or focusing accuracy is/are improved. I shall try it out anyway.

Tuesday, March 02, 2021

KP Discontinued

http://www.ricoh-imaging.co.jp/english/products/#digital-slr

Whilst the K-3 III hasn't arrived yet and there is no expected delivery date of any, the KP is now discontinued. What's Ricoh doing in the meantime? They really do not want to sell other APS-C DSLR bodies but only the dated and low-end plastic-built K-70, which also had the infamous aperture-blocked problem for long? :-(

Sunday, July 26, 2020

What is the LCD Screen Size of the K-New?

Since Pentax (Ricoh) has yet not told us more specs of the K-new, in order to estimate the rear LCD screen size of the K-new, which they told us that it was "huge", I took a much similarly angled picture of my KP and then measured the dimensions of the same different parts.

In particular, I measured the dimensions of the rear wheel/dial openings, and then the diagonal lengths of the screens, calculated and got the ratio for each camera and then calculated again the ratio between the two ratios. :-)

It is found that the K-new's screen is about 1.13X diagonally larger than that of the KP. Hence, since the KP's screen is in 3 inches, it is estimated that the K-new's rear LCD screen should be in about 3.4", case closed.

Read Also: 100% Bingo! I Derived Exactly Correctly for the 645D Actual Sensor Size!

Friday, May 29, 2020

Prediction: What New Features of the K-New Would Have?

Presuming that they have the same APS-C sensor, and then going through the specs of that Sony sensor and then the set of features of the X-T4. Here we go, for the possible new features that had never been offered by Pentax before, in their upcoming new flagship:

- 26MP BSI CMOS sensor (for its high ISO performance, this sample at ISO 10000 may shed some light)

- 18.82 fps maximum frame rate with 12-bit RAW (which will be converted to 8-bit JPEG anyway, limit of the sensor for the read-out bit-depth and rate combinations)

- If 14-bit RAW is implemented (KP and K-1/II have 14-bit RAW), the frame rate for continuous shooting still picture will be in between 6.84 (for highest 16-bit readout of the whole picture) and 18.82 (as mentioned above) - the above brief marketing sheet of the sensor does not mention about the 14-bit readout modes and rates

- 10 fps is possible (considering that the XT-4 offers 15 fps continuous shooting with mechanical shutter, unless Pentax's latest mechanical engineering plus image processing speed are yet not up to there. And, the Pentax has a mirror but the Fuji does not. )

- 425 point on-sensor phase-matching AF in Live View mode, which the X-T4 has

- 10-bit full-frame 4k video in 30p (limit of sensor) or 12-bit 2k video at high frame rates (55 to 111 fps which is the limits of the sensor); Or 10-bit 4k video at 60 fps is possible with the 1.18x crop factor of the centre

- 4:2:0 colour sub-sampling for H.264 codec (which is a bit too much for the dropping of the colour data) and 4:2:2 for H.265 (Pentax may have a different codec and implementation, though)

But since that the K-new will not have any articulated screen / flipped monitor, the video capability of it will not be too strong anyway?

Other sample images of the production X-T4 in DPR's latest full review of the camera can be found here. Also, a quick glance with the comparometer at the DPR, it seems that the ISO performance will be improved from the KP's by one to two stop(s), and which will undoubtedly exceed the IQ of the K-1 II.