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03-10-2010, 06:39 AM   #16
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And so it begins. First the measurebators find some minutae and turn it into a fatal flaw, and then the apologists come out of the woodwork.
It's a very strange world.

03-10-2010, 06:54 AM   #17
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QuoteOriginally posted by spqr Quote
14 bit is over 4 trillion colors, I don't think that is going to pose a problem if it is getting that full range. I doubt any human eye would be able to distinguish the difference. And, as others have noted, is the additional 2 bits that the Mamiya is getting worth twice the price? Again, I doubt it.

However, Pentax hasn't been terribly active in medium format for a while, so they have some ground to catch up. There's an investment in systems from Mamiya, Phase One, etc. that are not going to be tossed away just because Pentax has a digital version of the 645 now.

As for me, I'd love it, but that's going to be way out of my price range as an amateur unless I get very lucky in the lottery.
Your point is almost valid, here we are speaking about 14bits per channel. In Raw, evey sensor dot have a color, the pattern being organized in a bayer matrix, to display the image every pixel will be interpolated from the dots and its neightboors. That's the reason why Raw readers will have different rendering on default settings.

When I say above that printers have only 8 bits color depth, it doesn't mean that it can render only 256 colors of course, but that each Red, Green and Blue colors are coded on 8 bits, i.e : 256x256x256 = 16 Million nuances

But in fact, the human eye is able to make the distinction of much more tints, that's why on a computer generated image (understand "no noise") a trained eye will be able to make the distinction between 2 tints levels.

Now back to camera, having a channel coded on more bits does have some utility:
1. Printer will progress, eventually outperforming this 8bits limit
2. This helps to have a better interpollation in the rendering engine
3. When modyfying an image, this margin allow a lot more room for ajustments, for example +1EV expostion more or less means that you multiply the value by 2, wich means that you need 1 more bit of precision.

So 14 bits vs 16 bits are indeed a disavantage in theory, but in practice, you have to the images on prints to make any comment. Even professional screens are not able to render anything close to such a color depth.
03-10-2010, 07:46 AM   #18
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QuoteOriginally posted by ghelary Quote
So 14 bits vs 16 bits are indeed a disavantage in theory.
Well, in theory, with a perfect sensor and perfect ADC, because 16 is a bigger number, but in practice it is not true even in the digital domain (i.e. before printing or looking at the picture on a monitor) unless the signal/noise ratio of the sensor is low enough that there is useful data in the two least significant bits, which I highly doubt is the case here.
03-10-2010, 09:34 AM   #19
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And since 16bits takes more space to store and more time/power to process, you actually get a problem, not a feature.

03-10-2010, 10:07 AM   #20
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QuoteOriginally posted by RuiC Quote
14 bit is over 4 trillion colors ???? How did you get that??
Maybe like this: Color are mixed from 3 basic color: Red + Green + Blue. For each channel, it can recognize 14 bit, so, the number of color could be:

(2^14)^3 ~ 4 Trillion
03-10-2010, 10:08 AM   #21
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QuoteOriginally posted by gubak Quote
Same pixel count and same image sensor size as the newly announced Mamiya MF digital. But Mamiya has 16 bit color and penatx only has 14 bit (here are the 645D specification: Pentax 645D specification ). How did pentax lose 2 bits of color if the image sensor is the same which is seems likely it is? Maybe this is how pentax is able to sell the camera for so cheap compared to Mamiya.
very good posting from Emil Martinec ( Emil Martinec )

Dynamic range and DxO - Luminous Landscape Forum

---

PS: a must read for everybody is his text on Noise/DR/etc - http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/
03-10-2010, 10:16 AM   #22
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QuoteOriginally posted by Wheatfield Quote
And so it begins. First the measurebators find some minutae and turn it into a fatal flaw, and then the apologists come out of the woodwork.
It's a very strange world.
Ken Rockwell's already put the kiss o' death on it. Ten AF points too many, too many metering zones, and it insults him with its scene modes. Also, it's not expensive enough for him.
03-10-2010, 10:34 AM   #23
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QuoteOriginally posted by lithos Quote
and it insults him with its scene modes.
It doesn't even have scene modes. I think he's offended that you can select between "bright", "monochrome", "muted" etc. Boy, I wish cameras were more like in the days of film, when you didn't have to choose.

03-10-2010, 10:54 AM   #24
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REMINDER:

Adobe CS actually processes in 15bit soooooo you lose 1 bit anyways.
15bits data 1 bit info..........
Some RAW software pretends to export in 16 but it's actually NOT.. I.E.
POentax DCU4
03-10-2010, 10:59 AM   #25
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QuoteOriginally posted by Erik Quote
It doesn't even have scene modes. I think he's offended that you can select between "bright", "monochrome", "muted" etc. Boy, I wish cameras were more like in the days of film, when you didn't have a choice.
Fixed that for you.
03-10-2010, 11:08 AM   #26
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QuoteOriginally posted by lithos Quote
Ken Rockwell's already put the kiss o' death on it. Ten AF points too many, too many metering zones, and it insults him with its scene modes. Also, it's not expensive enough for him.
So this poor fellow didn't get his facts straight and he quickly became confused, I think we can all have some empathy here and not pick on the poor fellow in his time of need. Pentax put out the 645d....cleary this was very insulting to Mr Rockwell. Just because the man "lost it" in his posting....and is clearly an idiot in the photography realm, doesn't mean he isn't a human being... I hope he gets the help he needs.

As this thread points out, it hasn't even been placed in anyones hands yet or used so people really don't know much about it, but luckily is has been proven to be a total failure and has lost some sort of a competition. If I ever get one, I'm going to put some masking tape across the front and write "Nikon" on it so it can take some proper pictures.
03-10-2010, 12:51 PM   #27
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QuoteOriginally posted by smc Quote
As this thread points out, it hasn't even been placed in anyones hands yet or used so people really don't know much about it, but luckily is has been proven to be a total failure and has lost some sort of a competition. If I ever get one, I'm going to put some masking tape across the front and write "Nikon" on it so it can take some proper pictures.
It has, actually, if you go to the actual japanese 645D website. Sadly, it's in japanese, so I cant make heads or tails of it, and the user impressions are written by photographers sponsored by pentax, so they may not be incredibly objective...
03-10-2010, 02:00 PM   #28
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QuoteOriginally posted by ghelary Quote
Mamiya/Phase One uses Dalsa sensor vs Pentax (and Hasselblad) uses Kodak sensor.

Plus on CCD sensors you get analogue signal that you convert in Digital.
Is this not the case with CMOS sensors ?
03-10-2010, 02:19 PM   #29
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QuoteOriginally posted by Jonson PL Quote
Is this not the case with CMOS sensors ?
CMOS sensor the analogue to digital converter is at the pixel level, that's basically the difference. A side effect of this is that it allows downsampling that is use for lire view and video.

On CCD, the pixels are emptied of their electrical charge one after the other and the resulting electrical stream is converted to digital. That's why CCD is mentioned as being a more "primitive" technology.
03-10-2010, 02:44 PM   #30
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QuoteOriginally posted by Terzof Quote
Maybe like this: Color are mixed from 3 basic color: Red + Green + Blue. For each channel, it can recognize 14 bit, so, the number of color could be:

(2^14)^3 ~ 4 Trillion
That's wrong. The 3 basic colour cell red blue and green are used to make up ONE colour, not 3. Each colour is calculated from the sum of the 3 basic ones. So ONE and EACH colour is made from: C=(R+B+G) So it will make (2^14)^1 not ^3
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