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06-30-2008, 10:24 PM   #1
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K10D vs. K20D Anologue-to-Digital Converter - Concerns

I noticed that the K10D features a 22-bit analogue to digital converter yet the K20D only has a 14-bit converter. Supposedly Pentax say that they reduced it to 14-bits for the K20D as the 22-bit converter was providing more information than necessary.

To me common sense would dictate that in the world of digital SLR the more information the better as ultimately we are looking for the best possible data collection by the Sensor.

Why have a 14.6MP sensor but cripple it with such a low A/D bit-rate?

Just a concern of mine, feel free to add your own thoughts.


Nick

06-30-2008, 10:45 PM   #2
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Data transfer speeds for one. A 22 bit file will be larger. I tend to agree that a 22 bit A/D converter is overkill on a 14 bit sensor.
More bit depth is nicer for keeping pretty histograms during editing, but ultimately, the print you hold in your hands is an 8 bit, and if it was made on colour photographic paper, it fits nicely into an RGB colour space
06-30-2008, 11:00 PM   #3
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Awesome that puts it into perspective for me.
07-01-2008, 04:11 AM   #4
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Nope, the K20D's ADC is better

The K10Ds' ADC is actually of only 12 bit output, whereas the K20D's one is 14 bit. So, there is *real* improvement.

RiceHigh's Pentax Blog: The Secrets of the K10D (Part 2 of 3) - The Bridge: A to D Convertor

QuoteOriginally posted by NicholasN Quote
I noticed that the K10D features a 22-bit analogue to digital converter yet the K20D only has a 14-bit converter. Supposedly Pentax say that they reduced it to 14-bits for the K20D as the 22-bit converter was providing more information than necessary.

To me common sense would dictate that in the world of digital SLR the more information the better as ultimately we are looking for the best possible data collection by the Sensor.

Why have a 14.6MP sensor but cripple it with such a low A/D bit-rate?

Just a concern of mine, feel free to add your own thoughts.


Nick


07-01-2008, 06:46 AM   #5
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QuoteOriginally posted by RiceHigh Quote
The K10Ds' ADC is actually of only 12 bit output, whereas the K20D's one is 14 bit. So, there is *real* improvement.

RiceHigh's Pentax Blog: The Secrets of the K10D (Part 2 of 3) - The Bridge: A to D Convertor
Think you are mixing things up a bit. K10 used a 22bit ADC, K20 uses a 14bit ADC.
BOTH output a 12bit RAW file.
Do not believe the K10D ADC processed in 12bit (believe it was higher).
22bit ADC was deemed unnecessary by Pentax.
Are you sure you are an engineer????
..............
FWIW, the DNG shots from the K20D are uncompressed 12 bit files and are usually 23.2MB (a 14 bit file would be significantly larger). If you convert a PEF to DNG in Pentax Photobrowser, it produces a 16 bit DNG file where the unused 4 bits are not discarded, as in the "in-camera" DNG's, those files are in the region of 30.5MB, I would guess that if the files were 14 bit they would be in the region of 27MB each.
https://www.pentaxforums.com/forums/pentax-news-rumors/19149-k20d-dynamic-ran...rgement-3.html

Thanks to Richard..

Last edited by jeffkrol; 07-01-2008 at 06:52 AM.
07-01-2008, 06:54 AM   #6
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QuoteOriginally posted by jeffkrol Quote
Are you sure you are an engineer????
No, he's an injenear
07-01-2008, 07:01 AM   #7
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QuoteOriginally posted by Tom M Quote
No, he's an injenear
With a 6th grade ejimucation.... gollee....
(Sorry folks, was just thinking of the Beverly Hillbillies)
07-01-2008, 02:58 PM   #8
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I can't believe I'm agreeing with him, but RH is mostly right. Yes the K10D has a 22-bit ADC, but it only functioned at 12-bit. I can't remember exactly where, but when someone at Pentax was asked about this, the answer was basically since it only ran at 12-bit anyway, what was point of keeping it. It's just I guess, but Pentax probably had some plans for it that just never materialized.

07-01-2008, 03:09 PM   #9
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My source for the information was a camera review in Amatuer Photographer which also raised the issue.

From reading their article they implied the K10D 22-bit ADC was actually processing at 22-bits. They claim the reason for the reduction to a 14-bit ADC with the K20D was due to the fact that the 22-bit ADC supplied more data than necessary and also in order to reduce file size the K20D was limited to 14-bit.

My post was a question based off something I read why would I claim to be an engineer?
07-01-2008, 03:11 PM   #10
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The engineer comment was for RH. Got a link to that article?
07-01-2008, 03:15 PM   #11
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QuoteOriginally posted by Jodokast96 Quote
I can't believe I'm agreeing with him, but RH is mostly right. Yes the K10D has a 22-bit ADC, but it only functioned at 12-bit. I can't remember exactly where, but when someone at Pentax was asked about this, the answer was basically since it only ran at 12-bit anyway, what was point of keeping it. It's just I guess, but Pentax probably had some plans for it that just never materialized.
I'd like to see that info. Both cameras output 12bit. Sensors outputs an analog signal. No sense in using a 22bit ADC if you instantly truncate data to 12 bit. I do belioeve some of this depends on the sensor design and can be modified.
still the point is there is a difference between input, processing and output. The k10 was rumored to be eventually supplied w/ a 16bit raw Output firmware. which would be pointless if the adc already trucated data at the source to 12bit.
07-01-2008, 03:27 PM   #12
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Like I said, I have no idea where on earth I saw it. It was from one of the bazillion articles that were out there at the time of the K20D release. And for all I know, maybe it was wrong. I only remeber it beause it's the only one I recall giving an answer as to why the changed. Is it possible that the firmware update the would allow 16-bit RAW's could also flip the switch so to say on the ADC?
07-01-2008, 04:19 PM   #13
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I dont think the article is online as it came from a consumer magazine. I would scan it and post it but that would probably get me sued for Copyright infringement. Not sure what to do to get the article to you?
07-01-2008, 04:34 PM   #14
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I'm so glad, I didn't know anything of all the technical stuff you brought up here when I bought my K20D-camera! Do you mind?
07-01-2008, 04:49 PM   #15
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I read that even in the K20 the ADC only works in 14 bit for the extended dynamic range mode and runs in 12 bit otherwise. I miss film.
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