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Forum: Pentax DSLR Discussion
03-25-2012, 05:06 AM
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As far as I am concerned, you left out the most important aspects:
(1) Quality Control
(2) Glass
Ad (1): I would have gladly, very gladly indeed, paid $2000+ for the K-5, because IMO the K-5 would be totally worth it -- if, and that's too big an if, if it did what it's supposed to do. But it didn't, thanks to the neverending story of totally unacceptable f*ck-ups with sensor stains, focus problems, mirror flopping, etc.pp. ad nauseam.
Ad (2): Any camera is at most as attractive as the lenses available for it. I might try to score on eBay some old Made-in-Japan glass from the "limited" series, but that's not a substitute for the standard 70-200 f2.8 that Pentax simply does not offer. I don't see anything in Pentax's current lens portfolio that makes me go "wow! wanna have!"
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Forum: Pentax Medium Format
02-08-2012, 03:52 AM
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Yes, I do know.
And I also know that EV, as in "13.61 EV vs 11.37 EV dynamic range," means Exposure Value, commonly referred to as a stop.
What exactly is your point?
No, I'm not.
38.7 dB vs 36.7 dB SNR means a difference of 26%.
13.61 EV vs 11.37 EV dynamic range means a difference of 373%.
8.62 bits vs 8.15 bits tonal range means a difference of 38%.
22.2 bits vs 21.1 bits color sensitivity means a difference of 114%.
None of these differences, obviously, is less than 10%. You really need to familiarize yourself with the concept of logarithmic scales.
I have not made any such assertion. Please do try to engage in a discussion without resorting to dishonesty.
I think you know perfectly well that you are anything but polite here.
Free advice: Arrogance and derision do not make you look superior.
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Forum: Pentax Medium Format
02-07-2012, 09:21 AM
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Yes I do. The problem with your interpretation is that the 645D's seemingly superior results are based on downsampled data, to wit: print performance measurement values ... derived from a RAW image after a normalization step that transforms all images, regardless of original resolution, to an 8Mpix image.
(Emphasis is mine.) That's why I wrote "color sensitivity per pixel." The per-pixel measurements are what we need to look at, if we want to find out how a K-5 sensor in Full Format (and hence, 36 megapixel resolution) would perform. To do this, you need to
(1) look at the individual measurement graphs, rather than merely skim the (misleading) overall scores, and
(2) be sure to check the "screen" tab rather than the "print" tab.
The "print" tab shows evaluations from downsampled data as explained above, while the "screen" tab shows the measurement values and graph derived directly from a RAW image when displayed on a computer screen at 100% magnification (i.e., one image pixel corresponding to one screen pixel).
And here we find out that on the pixel level, the K-5 bests the 645D in every single dimension:
38.7 dB vs 36.7 dB SNR
13.61 EV vs 11.37 EV dynamic range
8.62 bits vs 8.15 bits tonal range
22.2 bits vs 21.1 bits color sensitivity.
Therefore, my assertion still stands: If the D800 sensor performs, on a pixel level, as good as the K-5 sensor, then it will perform better than that of the 645D.
As far as I'm concerned, absolutely not. I'm totally promiscuous, so I couldn't care less whose label my camera bears.
Which of course means that I am totally lacking any brand loyalty. If that is a crime around here, so be it.
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Forum: Pentax Medium Format
02-07-2012, 07:18 AM
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Of course Nikon's D800 has a much higher pixel density (i.e. pixel per square inch) than Pentax' 645D.
On the other hand, Pentax's own K-5 has also a much higher pixel density than the 645D. Does that affect the K-5's picture quality on a per-pixel basis? No, the 645D has only more megapixels, its pixel quality is, if anything, worse:
If you look at DXOmark.com, you will find that the K-5 produces actually less noise than the 645D at its lowest ISO setting, but more dynamic range, more tonal range, more color sensitivity per pixel.
Ergo, if one could retain the per-pixel quality of the K-5 and increase the sensor's pixel count by simply putting the same pixels on a full format area, then the resulting sensor would be better than that of the 645D.
From what we know at this time, we cannot rule out that the sensor encased in the D800 is exactly that. :eek:
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Forum: Photographic Technique
07-02-2011, 09:23 AM
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Oh my, you are right :o
I have read that Hoya shut down Pentax's factories in Japan, and assumed that all of the production was located there beforehand. My bad.
Nonetheless it seems to me that there's a broad perception that the "limited" line of Pentax lenses were of better build quality when they were still made in Japan, and people pay a premium for them when they find one.
I don't think that I said or implied that. Actually, I can't even recall to have ever heard anyone saying anything to that effect either. There's no need to start "looking at the company producing the products" because everyone does that already.
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Forum: Photographic Technique
07-02-2011, 05:49 AM
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I hope that Pentax's acquisition by Ricoh is good news, and I think it increases the probability that I will buy a Pentax camera in the future.
I believe that poor management decisions by Hoya almost killed Pentax, not least their decision to relocate production from Japan to Vietnam and the Philippines. I suspect that this is at least part of the reasons for Pentax's numerous quality control issues.
The K-5 could be a dream camera, for which I would gladly pay much more than the current asking price, if it would actually and reliably work as advertised. And, of course, if they had a decent selection of really good lenses available. Neither of this is the case, and right now, Pentax is simply a no-go for me.
My hope is that Pentax will become a viable option again, soon after Ricoh took over at the helm.
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Forum: Pentax K-5 & K-5 II
01-08-2011, 12:22 PM
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I think you are correct. Your stain looks pretty much the same as the stains shown in Falk's thread, and using the information therein, you can do the math yourself.
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Forum: General Talk
01-04-2011, 03:57 AM
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What exactly do you feel is wrong with that?
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Forum: Canon, Nikon, Sony, and Other Camera Brands
01-02-2011, 03:16 AM
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No he's not. As you can read on his web site, the "teddy" shot was taken at a closer distance, and he has then doctored that picture into a larger picture showing his living room.
Therefore he's merely speculating, in his words: "how the Teddy would look at 15.5MP foveon pixels", if he had a camera with 15.5MP foveon pixels.
Given how he presents his speculation to the public, you could say it's a bit of a prank, really. If you were inclined to be tolerant and good-natured about this sort of thing.
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Forum: Pentax K-5 & K-5 II
12-29-2010, 04:13 PM
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Nothing and nobody forces you to do anything. Apart from that, there's always room for improvement, i.e. better specs which may prove to be attractive for prospective buyers.
Pars pro toto, I would pay good money for a K-3 that flawlessly delivers what the K-5 should do, and additionally comes with a FF sensor that has the qualities and same pixel pitch as the K-5 (meaning some 40 megapixels with good dynamic range).
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Forum: Pentax K-5 & K-5 II
12-29-2010, 03:39 PM
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According to falconeye's advanced stainology, d = (H - C) * N/2, or
distance = (total spot diameter - dark spot diameter) * f-number / 2
I see a total spot diameter of 18, and a dark spot diameter of 7 pixels. For Andras' camera, falconeye's formula yields 0,58201 mm distance between light obstruction and sensor, assuming a pixel pitch of 4.81 µm.
This would mean that the replacement is flawed, because the computed distance is far too small to indicate dust on the AA filter.
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Forum: Pentax K-5 & K-5 II
12-23-2010, 02:27 AM
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Attachment 78875
100% crop from the center of the image @ f = 22, not processed in any way.
It's not quite what some here call "string of pearls", but only one such a stain is bad enough for me to not accept that.
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Forum: Pentax K-5 & K-5 II
12-18-2010, 04:44 AM
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I didn't even have a glimpse at that thread, because I thought it referred to pentaxforums' own review. Thanks for the pointer :)
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Forum: Pentax K-5 & K-5 II
12-18-2010, 03:45 AM
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The Pentax K-5 earned a "Gold Award" from that Site That Shall Not Be Named.
Just sayin' ;)
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Forum: Pentax K-5 & K-5 II
12-17-2010, 09:29 AM
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I don't think so. The "optical theory" is that you can calculate the distance from obstruction to sensor by evaluating the difference between umbra and penumbra at f=22 or thereabouts. If the difference is small, you have a problem, because that means it's sitting on the inside. If it's big, or no umbra at all, you have dust.
If you have "parallel" light falling on the sensor, you have no penumbra to evaluate.
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Forum: Pentax K-5 & K-5 II
12-07-2010, 03:00 PM
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I remembered this picture as an illustration for obnoxious smudges visible in "real" pictures as requested by the OP, but fortunately the camera isn't mine.
Thanks for the concern, anyway :)
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Forum: Pentax K-5 & K-5 II
12-07-2010, 09:16 AM
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While no "SOP" in the narrower sense, these here are supposedly stains that are impossible to get rid off. Doesn't look like dust to me either.
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Forum: Pentax K-5 & K-5 II
12-06-2010, 04:01 AM
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Falk,
Schraubstocks request has nothing to do with hot pixels. Some people noticed that the stains seem to multiply over time, and if that were the case, it doesn't seem far fetched either to expect that a flawless sensor doesn't necessarily stay flawless.
I'm not sure where I read the hypothesis that it may have to do with heat, but it doesn't matter either. I guess we're all stabbing in the dark here as far as the origin of that problem is concerned. :(
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Forum: Site Suggestions and Help
11-27-2010, 02:34 AM
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OK, thanks. I could swear I saw "10" when I started, and assumed this was the default, but obviously I misremember :o
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Forum: Site Suggestions and Help
11-27-2010, 02:12 AM
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I seem to recall that I started with a "reputation" of 10, which apparently has been downgraded to 0 for reasons that I do not know.
How can I find out why that happened? I already looked in my profile for clues, but didn't find anything anywhere.
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Forum: Pentax K-5 & K-5 II
11-27-2010, 02:01 AM
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I'm not sure why you wouldn't do that yourself. With a Rocket Blower you don't run a great risk to damage the sensor.
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Forum: Pentax K-5 & K-5 II
11-27-2010, 01:38 AM
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Thanks for the link.
BTW and apropos, on photoble there's a picture which I think would be a nice demo shot to illustrate what the K-5 is capable of: impressively sharp at full resolution (i.e. even for pixel peepers) without any obvious sharpening artifacts.
Assuming that the photographer had to know what he was doing to achieve this result, it probably also illustrates the old adage that it's not the arrow, it's the indian. |
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Forum: Pentax K-5 & K-5 II
11-26-2010, 09:07 AM
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Would you give a hint where to find this test chart? The download section on your homepage is empty ... :confused:
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Forum: Pentax Camera and Field Accessories
11-26-2010, 07:07 AM
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The Gitzo GT1550T tripod kit is currently on sale for £299 in the UK, and the GT1541T goes for £229.
I should probably not mention the company here, but you'll find it instantly when you go to gitzo gt1541t - Google Product Search
I bought both, i.e. the GT1541T after my wife confiscated the GT1550T
Caveat though: I have a hunch that they are not philanthropists, they merely want to clear their warehouses for the "new and improved" Gitzo traveler collection that was announced on November 2. So, if you take the bait, your cheap Gitzo may be outdated very soon. ;)
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Forum: Pentax K-5 & K-5 II
11-24-2010, 06:59 AM
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I for one thank you for that. :)
To sum it up, it seems like the best strategy to check the sensor is to take an out-of-focus picture of a white wall, using the smallest aperture (i.e. the biggest f-number) available on your lens. That should separate the wheat from the chaff, as far as this problem is concerned :cool:
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