Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-25-2008, 11:53 PM   #1
Veteran Member




Join Date: Sep 2006
Location: Southern Calif
Posts: 557
Native ISO of the 14.6 MP CMOS Sensor (with !shocking! attempt to lighten mood!)

Question is ultimately posed to the designers of the new sensor... Does anyone have documented, quotable source info about the Native ISO of the new Pentax 14.6 MP sensor?

I assume it to be 100 ISO -

But why ask this question when it would seem to be easily answered?

I guess it has to do more with a comparison of the Nikon/Sony sensor in the 300D.
Yes the Nikon sensor reaches a boosted 6400 ISO as does our Pentax sensor. BUT! Nikon is Native ISO 200. Nikon ISO 100 is "boosted" and is not as high quality compared to it's ISO 200.

Has Pentax gone and done something unusual and special here in developing this new sensor? Or is it clever marketing? Has Pentax made a breakthrough designing a wider native ISO spectrum base? (can I say ISO spectrum base)?



If there is a story here, what could it be?


Disclaimer: speculators must not respond. If they do respond, Igor the unofficial Perntaxx mascot will show them to the door and beat their brain silly with a large organic carrot. I kid! I kid!

And one more thing, no fun stuff allowed!

01-26-2008, 01:14 AM   #2
Senior Member




Join Date: Sep 2007
Location: Lommel, Belgium
Posts: 285
In the youtube video the guy from Pentax talks about a higher dynamic range in the ISO settings but it has a cost. The lowest ISO would be 200 but with good noise reduction (better then the K10D's noise reduction).

I don't know exactly what they mean with the dynamic range so maybe you can still manually set it to ISO 100 but then he would probably have mentioned it in the video ?
01-26-2008, 02:30 AM   #3
Veteran Member




Join Date: Sep 2006
Photos: Gallery
Posts: 5,713
QuoteQuote:
Auto - 100-3200 ISO (1, 1/2, 1/3 steps), Bulb mode up to ISO 1600, expanded range ISO available to ISO 6400; Manual - 100-3200 ISO (1, 1/2, 1/3 steps), Bulb mode up to ISO 1600, expanded range ISO available to ISO 6400
found on Pentax Imaging's own web page.

I'll point out that Pentax may change that at a later date with a firmware update.
It's been done by other companies before.
01-26-2008, 07:36 AM   #4
Veteran Member




Join Date: Sep 2006
Location: Southern Calif
Posts: 557
Original Poster
Sorry, Title Should have Read:

Unashamedly !shocking! and unsuccessful attempt to lighten mood.

Pa dum bump

01-26-2008, 08:56 AM   #5
Junior Member




Join Date: Jan 2008
Location: Bloomington, IN
Posts: 36
What is the point of an ISO 100 that is lower quality than ISO 200, is it just for marketing?
01-26-2008, 09:21 AM   #6
Veteran Member




Join Date: Feb 2007
Location: Ontario
Photos: Gallery
Posts: 630
ISO 100 is needed for bright conditions when you don't want to stop down. Given that sensors only have a limited dynamic range and available 'gain', setting the 'base' ISO at 200 means you should be able to get better high ISO performance, but requires that you use a negative gain (like -6db in my Pro JVC video camera) to get back down to ISO 100.
01-26-2008, 09:30 AM   #7
Veteran Member
jeffkrol's Avatar

Join Date: Sep 2006
Location: Wisconsin USA
Photos: Gallery
Posts: 8,434
QuoteOriginally posted by solar1 Quote
Question is ultimately posed to the designers of the new sensor... Does anyone have documented, quotable source info about the Native ISO of the new Pentax 14.6 MP sensor?

I assume it to be 100 ISO -

But why ask this question when it would seem to be easily answered?

I guess it has to do more with a comparison of the Nikon/Sony sensor in the 300D.
Yes the Nikon sensor reaches a boosted 6400 ISO as does our Pentax sensor. BUT! Nikon is Native ISO 200. Nikon ISO 100 is "boosted" and is not as high quality compared to it's ISO 200.

Has Pentax gone and done something unusual and special here in developing this new sensor? Or is it clever marketing? Has Pentax made a breakthrough designing a wider native ISO spectrum base? (can I say ISO spectrum base)?



If there is a story here, what could it be?


Disclaimer: speculators must not respond. If they do respond, Igor the unofficial Perntaxx mascot will show them to the door and beat their brain silly with a large organic carrot. I kid! I kid!

And one more thing, no fun stuff allowed!
I have yet to find the file sizes for DNG, RAW and if their compressed and you want to know about base ISO?????. One person in the know has quoted 1600 but we know that's not possible......
01-26-2008, 04:42 PM   #8
Inactive Account




Join Date: Feb 2007
Location: Gloucester UK
Posts: 441
QuoteOriginally posted by jeffkrol Quote
I have yet to find the file sizes for DNG, RAW and if their compressed and you want to know about base ISO?????. One person in the know has quoted 1600 but we know that's not possible......
DNG is uncompressed, file size (from memory) is around 22MB
PEF is compressed (lossless), file size varies due to compression, average is around 14MB

That's with firmware v 0.20

01-26-2008, 07:13 PM   #9
Veteran Member
jeffkrol's Avatar

Join Date: Sep 2006
Location: Wisconsin USA
Photos: Gallery
Posts: 8,434
QuoteOriginally posted by Richard Day Quote
DNG is uncompressed, file size (from memory) is around 22MB
PEF is compressed (lossless), file size varies due to compression, average is around 14MB

That's with firmware v 0.20
Thanks. I would have preferred that they compressed the DNG and not the PEF...
Personal preference and paranoia...
At 14mb there only a tad larger than the D files (13mb +/- a few tenths)..
Oh, and what was that other rumored file format? Someone guessed at 8bit TIFF but that seems ridiculous...
01-26-2008, 08:33 PM   #10
Veteran Member
mattdm's Avatar

Join Date: Feb 2007
Location: Boston, MA
Photos: Gallery
Posts: 2,964
QuoteOriginally posted by jeffkrol Quote
T
Oh, and what was that other rumored file format? Someone guessed at 8bit TIFF but that seems ridiculous...
It looks to me that they added 16-bit TIFF, which is a reasonable choice for a widely-supported 16-bit "developed" format.
01-27-2008, 12:02 AM   #11
Inactive Account




Join Date: Feb 2007
Location: Gloucester UK
Posts: 441
QuoteOriginally posted by jeffkrol Quote
Thanks. I would have preferred that they compressed the DNG and not the PEF...
Personal preference and paranoia...
At 14mb there only a tad larger than the D files (13mb +/- a few tenths)..
Oh, and what was that other rumored file format? Someone guessed at 8bit TIFF but that seems ridiculous...
It's an Adobe recommendation that DNG is uncompressed. All the other makes that utilise DNG (Ricoh, Leica & Samsung) only offer uncompressed DNG. So I guess we are stuck with that for now. BTW, the DNG files are 23.7MB not 22MB (just checked).

This is from a K10D Pentax presentation slide:



Hope this goes some way to explain non compressed DNG's.

I'm not absolutely sure about the TIFF option, I never tried saving any files in TIFF, I'm not sure v0.20 had this option active. However John Carlson clearly says in his youtube presentation that you can save in-camera processed Raw files as 8 bit TIFF files, but it's not a shooting format option.

Regards
01-27-2008, 12:21 AM   #12
Veteran Member




Join Date: Sep 2006
Location: Southern Calif
Posts: 557
Original Poster
yes, thank you

for everyone's replies.


I simplify my question to the bone>

The K20d - what is its native ISO?
01-27-2008, 12:34 AM   #13
Inactive Account




Join Date: Feb 2007
Location: Gloucester UK
Posts: 441
QuoteOriginally posted by solar1 Quote
for everyone's replies.


I simplify my question to the bone>

The K20d - what is its native ISO?
I don't think anyone knows for certain.

If the noise worsens at ISO 200 compared to ISO 100, then it's a fair guess that it will be ISO 100. The challenge is that the noise between 100 to 400 is very hard to differentiate, so it could be anything in that range. The fact that the noise can be clearly seen at higher ISO's definitely indicates that it cannot be ISO 1600, that's plainly clear (also, IMO, a ridiculous notion).

Personally, I would guess that it is ISO 100. But I don't understand why the native ISO should be a concern as long as noise doesn't worsen at low ISO's.
01-27-2008, 03:32 AM   #14
Veteran Member
blende8's Avatar

Join Date: Feb 2007
Location: Bremen, Germany
Photos: Albums
Posts: 1,484
I think this is a very interesting question.
I never really understood why it is only possible to amplify the signal but not to reduce it.

Where can I read more about Nikon's D300 base ISO?
01-27-2008, 03:55 AM   #15
Veteran Member
Derridale's Avatar

Join Date: Jan 2008
Location: Brisbane, Australia
Posts: 412
QuoteQuote:
I never really understood why it is only possible to amplify the signal but not to reduce it.
I think you're mistaking analog vs digital here. Of course you can attenuate an analog signal, and lower its amplitude, but a digital signal - as in the "native ISO" of a sensor - IS what it IS. It can be "amplified" although that is not really the correct term - maybe "boosted" would be a better term. It uses interpolation to add extra bits, as digital information is either on or off, a one or a zero. Analog information can be amplified by any number of means, as well as attenuated.

To attenuate such a thing as the "native ISO", by my understanding (and by no means professing to be an expert on such matters), would involve discarding bits, or reducing the amount of information, which in turn would make the "steps" between the information of one cell of the sensor and another much coarser.

Am I correct in assuming that the ISO is only an general-use description of the sensitivity of the sensor - it is NOT the same as the ISO rating of film? The term ISO is only used because most photographers are familiar with it relative to film speed. The light sensitivity of each "cell" of the sensor is fixed, and will relate to the baseline situation whereby the cell responds maximally to a given strength of light signal, and this is converted by a convoluted mathematical formula to the "ISO". This is what you are enquiring about - the actual sensitivity of the cells of the sensor.

And unfortunately, I don't know what the baseline ISO is of the new K20D... took a long time to get round to a negative answer, huh? But hopefully I answered the question about why you can't reduce the ISO without throwing away information.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
base, camera, dslr, iso, mp, nikon, pentax, photography, question, sensor, spectrum
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K7 Native ISO brofkand Pentax DSLR Discussion 9 01-16-2010 04:13 PM
Samsung GX-20 CMOS sensor seliscan Pentax DSLR Discussion 2 12-20-2009 06:31 AM
New Pentax CMOS sensor Busiko Pentax News and Rumors 26 03-28-2008 02:54 PM
New Pentax CMOS sensor NaClH2O Photographic Technique 19 02-16-2008 09:59 PM
Native ISO in the K10D Michael Rothman Pentax DSLR Discussion 5 01-11-2007 05:44 AM



All times are GMT -7. The time now is 07:33 PM. | See also: NikonForums.com, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top