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Forum: Pentax K-3 & K-3 II
02-18-2016, 03:54 AM
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Sounds like something is wrong indeed. Stop making yourself crazy and send it in for AF calibration :)
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Forum: Digital Processing, Software, and Printing
02-16-2016, 12:42 PM
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A quick example of the differences that can e.g. be seen with very saturated reds:
Pentax JPEG OOC:
X-Rite profile with RawTherapee :
DCamProf profile with RawTherapee:
Notice how DCamProf has the most differentiated reds and is better at preventing the blowing out of colors
---------- Post added 16-02-16 at 21:11 ----------
Which Raw processing software do you use?
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Forum: Digital Processing, Software, and Printing
02-16-2016, 09:25 AM
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Well, it kind of defeats the whole point of color calibration if you use the profile for a different camera, doesn't it? :lol:
But seriously, I really wouldn't recommend doing this. The results might be OK, but they might also be slightly or completely off. It's hard to predict without comparing it to a correct profile for the camera in question.
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Forum: General Photography
02-16-2016, 09:04 AM
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Forum: Digital Processing, Software, and Printing
02-16-2016, 09:03 AM
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Hi,
I created camera color profiles with an X-Rite ColorChecker for all Pentax cameras I own(ed) and am happy to share them with you :cool:
There are profiles for the K-5, K-5 II and K-3. They come in two varieties:
- created with the standard X-Rite software that comes with the Colorchecker (marked "X-Rite")
- created with DCamProf, a free new camera profiling software developed by Anders Torger
You can find more information about DCamProf here: DCamProf. It's command-line only and not easy for beginners, but IMO the results are fantastic.
The killer feature of DCamProf is the so-called "neutral tone reproduction operator" it uses for the embedded tone curve: More Info
All profiles can be found here:
{Dead Link Removed 6-26-2017}
Enjoy!
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Forum: General Photography
02-09-2016, 07:27 AM
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If you really want to know more about camera profiling, you could do worse than read the documentation of DCamProf, a free camera profiling software (which also works with the Colorchecker)
Making a camera profile with DCamProf
DCamProf
It's very technical but extremely thorough.
To cut a long story short, none of the profiles you tried strives for absolute accuracy. This is due to technical limitations of the profiles (it is explained in more detail in the links above). What is more, different manufactures (Pentax, Adobe, X-Rite...) also apply a distinctive "look" to their profiles created with their software, so they are usually far from "neutral".
DCamProf is a command-line utility and quite intimidating at first. It took me a while to master it, but it's really worth it IMO. If you can wait a few days I can upload a K-3 profile created with DCamProf so you can compare. The killer feature of DCamProf is the so-called "neutral tone reproduction operator" it uses for the embedded tone curve: DCamProf |
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Forum: Pentax SLR Lens Discussion
02-09-2016, 02:00 AM
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SDMC
Maybe not so good on second thoughts. People might believe the coating will fall apart after a few years :D
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Forum: Pentax SLR Lens Discussion
01-18-2016, 02:33 AM
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This takes pixel peeping to a new level of madness: "Look at those vast resolution differences @800%"
(SCNR ;))
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Forum: Pentax SLR Lens Discussion
01-18-2016, 02:26 AM
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I noticed that the "jumping" is also present in my DA 18-135, although to a much lesser degree. I probably wouldn't have noticed it without being alerted to this behaviour from my 16-85, but still it's there. IMO it's probably nothing to worry about, but I agree that some official comment from Ricoh to clear this up would be very welcome.
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Forum: Pentax SLR Lens Discussion
01-18-2016, 02:05 AM
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I find the 10-17 also has a pretty nice, soft bokeh @17mm. Also the DA 14/2.8. The DA 15 Limited, however, can be pretty harsh in this regard, the bokeh circles show lots of outlining and are brighter at the edges than in the centre.
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Forum: Pentax SLR Lens Discussion
12-21-2015, 08:32 AM
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The obvious answer is the current dedicated Pentax lens for portraits, the DA*55/1.4
Better bokeh than the 70/2.4 IMO, sharper than the 77/1.8 and less aberrations at the same aperture. However, the 77/1.8 might have a tad smoother bokeh, but both are outstanding in this respect; the DA 55/1.4 bokeh is a bit nervous at f/1.4, but from f/1.8 on it is very smooth.
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Forum: Pentax SLR Lens Discussion
12-17-2015, 01:29 AM
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For all people wondering if this is a "mistake" of the lens that could/should be fixed: I sent my 16-85, which also exhibits the image jumping while focusing, to the Pentax repair center. I got it back unrepaired, stating they could not find an error and that it is within manufacturer specifications (whatever that means - maybe the image is supposed to jump :p).
Optically, my copy is fine (no decentering).
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Forum: Pentax SLR Lens Discussion
11-30-2015, 02:30 AM
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I think there are two possible problems here at work:
- PDAF sensors cannot see how the focus actually is at f/1.8. Older cameras like K-5 have f/5.6 AF sensors, newer like K-5 II and K-3 have f/2.8 sensors (at least in the centre). If the lens in question exhibits focus shift (point of perfect focus shifts when stopping down) the camera has to guess where the focus will be at 1.8. The LensROM may(!) contain focus adjustment offsets that tell the camera in which direction and how far to compensate the focus to work around this problem based on the aperture used. I am not entirely sure, but I think if such a problem were present it would show itself in wrong (but consistent) focus.
- Sloppy lens manufacturing. Background: I once tested three DA*55/1.4 lenses (which are also infamous for focus problems!) side-by-side with the same camera (a K-5 at the time). Two lenses showed erratic focus behavior that could not sensibly be corrected. The third lens focused perfectly everytime in any condition. I kept the third one (of course!), and it still keeps focusing perfectly with two other cameras (2x K-5 II). I suspect if lenses are put together with too little care to keep tolerances small (distance between elements, centering, tilted elements) you can run into situations where its behavior becomes unpredictable, especially when considering that lens elements are moved in relation to each other when focusing or zooming.
It's probably hard enough to build a fast f/1.4 or 1.8 prime lens that focuses reliably with PDAF systems. If you make a zoom of it, add reverse-engineered focusing algorithms and are not 100% perfect in assembling the lens (and who could pay for such rigorous manufacturing and quality control?), you are simply asking for trouble...;)
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Forum: Pentax SLR Lens Discussion
11-25-2015, 04:03 AM
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For the record, my copy of the 16-85 shows the same up/down shift of the picture when making quick focus adjustments. Otherwise the optical quality seems perfectly fine. I also didn't notice any decentering problems. I wonder if this is something that can/should be fixed by the service center? It's too late for an exchange in my case
Two other things seem strange:
1. At 85/5.6, the lens is razor sharp all across the frame when used at normal focusing distances. However, close to the minimum focus distance the sharpness deteriorates completely towards the edges; A small part in the center remains sharp but the rest of the frame is very soft. I did rule out that this is a focusing or field curvature issue; it's simply a steep sharpness drop. Has anyone checked their copy for this issue?
2. Also at 85mm, the lens sometimes fails to lock focus for no apparent reason and the Hexagon in the viewfinder blinks. Actually, this seems like the same behavior that I (and many others) experienced with the DA 17-70 at the long end. The problem is that it's not always easy to replicate and only happens in some conditions and/or focusing distances. Has anyone noticed this as well?
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Forum: Pentax News and Rumors
11-20-2015, 02:07 AM
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What's the technical reason for this magenta shift? Is it really a sensor-specific problem or could it also be a software Raw processing or camera color profile issue?
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Forum: Digital Processing, Software, and Printing
11-13-2015, 02:00 AM
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Sorry, I didn't mean to throw a bad light on your (perfectly correct) answer to that question :)
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Forum: Digital Processing, Software, and Printing
11-12-2015, 02:56 AM
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Just to clarify some misconceptions from earlier in this thread: The sRGB vs. AdobeRGB setting has no effect whatsoever on Raw files, this setting only affects the color space of JPGs. Raw files do not yet have a color space assigned to them, this is done later in the Raw converter software.
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Forum: Flashes, Lighting, and Studio
11-12-2015, 01:17 AM
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and that assumption is.....wrong ;)
TTL fires a pre-flash and measures the light reflected back to let the camera calculate the ideal flash exposure. It does not matter if you have direct, indirect or even off-camera flash.
That said, please be aware that some cameras (specifically K-5 und K-5 II) have given users some trouble with bounced flash exposure (probably due to a hardware bug). You can read about it here on this forum. I don't know if the K-50 is affected. It is fixed for sure in the K-3.
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Forum: Pentax SLR Lens Discussion
09-12-2015, 12:58 PM
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AFAIK the starburst effect is reduced because of the rounded aperture blades of the HD versions, it has nothing to do with SMC vs HD coatings
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Forum: Pentax DSLR Discussion
05-20-2015, 11:45 PM
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This has nothing to do with the sensor but with how the sensor raw data are processed. Depending on JPG settings and especially the color profile (i.e. how raw data are translated to RGB values) you can get dramatically different results with the same Raw data.
When shooting JPG or Raw using the Pentax software you cannot change color profile settings but only fiddle with the JPG settings. In proper Raw development software (Raw Therapee, Lightroom) you can also use different DCP color profiles, even create your own if you have e.g. a Colorchecker24.
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Forum: Pentax News and Rumors
04-23-2015, 03:46 AM
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So we won't get a single 24MP Raw file that contains the full Pixel Shift resolution but get several Raw files that can only be processed in-camerato get a JPG or with the ugly Pentax Utility? That limits the usefulness considerably IMO.
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Forum: Pentax SLR Lens Discussion
02-03-2015, 03:19 AM
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I think the issue (reported e.g. by the Lenstip and dpreview reviews) was more to do with corner softness, not general softness at the wide end. It was also reported for other mounts, not specifically for Pentax. That said, I found my copy to be very sharp throughout the range, even wide open, including the wide end. Yes, the corners are not perfect at the wide end, but I found them more than "good enough". This Sigma Contemporary was definitely one of the sharpest zoom lenses I've ever handled and I would never have worried that it would be lacking sharpness in any situation I could imagine.
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Forum: Pentax SLR Lens Discussion
01-23-2015, 02:07 PM
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Good news!
Today I received a notification from Sigma Germany that Sigma HQ acknowledged the problem and has already provided a fix:.
 Quote: 2015.01.23
Dear SIGMA 17-70mm F2.8-4 DC MACRO HSM | Contemporary PENTAX Users - Firmware Update of the Lens
Thank you for purchasing and using our products.
We have found that the SIGMA 17-70mm F2.8-4 DC MACRO HSM | Contemporary PENTAX does not function properly when the image stabilizing system on the camera body is used.
For those who own the lens, we are going to provide the firmware update free of charge.
Please note that all lenses shipped from our factory from now on will have the latest firmware.
We appreciate your continued support for our company and products.
[Product]
SIGMA 17-70mm F2.8-4 DC MACRO HSM | Contemporary PENTAX
[Phenomenon]
When the image stabilizing system on the camera body is used, the degree of image blur becomes bigger.
For further information, please contact your nearest authorized subsidiary / distributor of SIGMA.
For those who own the SIGMA USB DOCK, it is possible to update the firmware through SIGMA Optimization Pro 1.2. Source: https://www.sigma-photo.co.jp/english/new/new_topic.php?id=491
I must say I'm surprised how well Sigma has handled this issue - I didn't expect a solution so fast (and was worrying if it would be forthcoming at all...)! Many thanks to the diligent people at Sigma!:)
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Forum: Pentax SLR Lens Discussion
01-14-2015, 06:49 AM
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Thanks for sharing your findings! Is it possible for you to upload one of your pictures (e.g. on filebin.net) that show the correct SR focal length at 17-21mm? Out of camera JPEG or Raw, if possible. I'd like to take a closer look at the metadata to find out what's going on here.
You do have the "Contemporary" version of the 17-70 and not one of the earlier versions?
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