Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-01-2014, 06:11 PM   #1
Pentaxian




Join Date: Sep 2013
Location: Pasadena, CA
Photos: Albums
Posts: 1,113
Dpreview and K-3s ISO noise

I looked through the Exif data of their JPGs... and they expose K-3 with ~50% shorter shutter speeds than Nikon and Canon at the highest ISO settings.

Next thing you know they will write that 'high ISO noise is not quite up to par with competition'... facepalm.

Pentax K-3 First Impressions Review: Digital Photography Review

According to DXO data, K-3 does not have inflated ISO figures, unlike most other cameras. Perhaps that is the reason why so many people in user reviews complain about high iso noise...

04-01-2014, 07:51 PM   #2
Site Supporter
kiwi_jono's Avatar

Join Date: Dec 2009
Location: Christchurch, New Zealand
Photos: Gallery | Albums
Posts: 1,076
I noticed this on DXO. Pentax does a great job with ISO accuracy which does make for a bit of disadvantage on noise test reporting (if the review reporting against set ISO not actual ISO). I think it should be pointed out in reviews like this because it is relevant.
04-01-2014, 08:19 PM   #3
Veteran Member
MD Optofonik's Avatar

Join Date: Feb 2010
Location: California
Photos: Gallery | Albums
Posts: 901
Please explain.
04-01-2014, 08:59 PM - 2 Likes   #4
Site Supporter
kiwi_jono's Avatar

Join Date: Dec 2009
Location: Christchurch, New Zealand
Photos: Gallery | Albums
Posts: 1,076
Have a look at this example ISO Sensitivity of K3 versus Nikon 7100: Pentax K-3 versus Nikon D7100 - Side by side camera comparison - DxOMark

When the Nikon is set for ISO 400 its actual sensitivity is measured as ISO 279 (significantly short of 400). But if you look at the K-3 the ISO reading are pretty close to spot on (ISO 400 is actually ISO 381).
When you set the cameras to ISO 3200, the K-3 is actually ISO 2933 (around 3000) and 7100 is ISO 2192 (around 2000).
So if DPR provide comparative test images at say ISO 400 then the K-3 is achieving a higher ISO and therefore can be expected to have a higher noise component than the Nikon 7100 but people viewing the test images won't generally make an allowance for the greater error in the Nikon (which is really operating at ISO 279 not 400).

Compare other Canon / Nikon cameras and you will find that most don't achieve the stated ISO but Pentax is normally about right.

04-01-2014, 09:11 PM   #5
Veteran Member
MD Optofonik's Avatar

Join Date: Feb 2010
Location: California
Photos: Gallery | Albums
Posts: 901
Thanks!
04-02-2014, 04:45 AM   #6
Veteran Member
causey's Avatar

Join Date: Feb 2009
Location: Arlington, VA
Photos: Albums
Posts: 3,758
Honesty vs. marketing.
04-02-2014, 10:37 AM - 1 Like   #7
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,676
ISO fudging has become a pet peeve for me. From DPR's XE-2 review:

"However the X-E2's need for unusually long exposures explains much of the difference we see between it and the Sony NEX-6; in fact it's probably better compared to the performance of its peers set 1EV lower (i.e. ISO 400 on the Fujifilm compared to ISO 200 on its rivals)."


Fujifilm X-E2 Review: Digital Photography Review

DPR is aware of this issue, yet they continue to use ISO as the basis for performance comparison, allowing manufacturers to distort public perception by manipulating ISO. The only way to level the playing field would be to shoot test photos under specific standard lighting conditions, using similar shutter speeds and apertures (or better yet, light transmission). ISO could then be ignored and noise performance could be fairly evaluated.

I'm not sure why they gave Sony a pass in the quote above. I believe Sony and Olympus are fudging ISO just like Fuji does.
04-02-2014, 12:51 PM   #8
New Member




Join Date: Dec 2013
Posts: 12
wow, this ISO-tweaking was something I've never thought about. One more argument to put in the bag when friends wonder why I prefer my K-3 over a canikon alternative

04-02-2014, 12:56 PM   #9
Site Supporter
rbefly's Avatar

Join Date: Oct 2009
Location: Denver, Colorado
Photos: Albums
Posts: 2,030
More Coincidences?

Yes, DPR somehow manages to find ways to boost their favs and slag the rest. You would almost think it's intentional, but of course it's not.
Simon says.
Ron
04-02-2014, 01:11 PM   #10
Site Supporter




Join Date: Mar 2009
Location: Gladys, Virginia
Photos: Gallery
Posts: 16,008
QuoteOriginally posted by audiobomber Quote
ISO fudging has become a pet peeve for me. From DPR's XE-2 review:

"However the X-E2's need for unusually long exposures explains much of the difference we see between it and the Sony NEX-6; in fact it's probably better compared to the performance of its peers set 1EV lower (i.e. ISO 400 on the Fujifilm compared to ISO 200 on its rivals)."


Fujifilm X-E2 Review: Digital Photography Review

DPR is aware of this issue, yet they continue to use ISO as the basis for performance comparison, allowing manufacturers to distort public perception by manipulating ISO. The only way to level the playing field would be to shoot test photos under specific standard lighting conditions, using similar shutter speeds and apertures (or better yet, light transmission). ISO could then be ignored and noise performance could be fairly evaluated.

I'm not sure why they gave Sony a pass in the quote above. I believe Sony and Olympus are fudging ISO just like Fuji does.
I agree. If you are testing, you definitely should shoot manual and then comment after the fact that shooting at iso 1600 causes under exposure by 1/2 stop or, whatever.
04-02-2014, 01:18 PM   #11
Pentaxian
JinDesu's Avatar

Join Date: Jun 2011
Location: New York City
Photos: Gallery
Posts: 5,626
QuoteOriginally posted by Rondec Quote
I agree. If you are testing, you definitely should shoot manual and then comment after the fact that shooting at iso 1600 causes under exposure by 1/2 stop or, whatever.
I would rather they do that as a secondary. The primary images that show up for comparo should be shot with focal length, aperture, and shutter speed set the same, and then ISO adjusted to make the exposure equal. This should give an accurate interpretation of ISO performance. Then a second set of images can be shot at the same aperture, shutter speed, and ISO to show that one of the cameras underexposes or overexposes, etc.
04-02-2014, 01:27 PM   #12
Site Supporter




Join Date: Mar 2009
Location: Gladys, Virginia
Photos: Gallery
Posts: 16,008
QuoteOriginally posted by JinDesu Quote
I would rather they do that as a secondary. The primary images that show up for comparo should be shot with focal length, aperture, and shutter speed set the same, and then ISO adjusted to make the exposure equal. This should give an accurate interpretation of ISO performance. Then a second set of images can be shot at the same aperture, shutter speed, and ISO to show that one of the cameras underexposes or overexposes, etc.
I doubt the cameras under expose in real world situations. The issue is that they may require higher iso or longer shutter speeds to get that decent exposure.
04-02-2014, 01:56 PM   #13
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,676
QuoteOriginally posted by Rondec Quote
I doubt the cameras under expose in real world situations. The issue is that they may require higher iso or longer shutter speeds to get that decent exposure.
That's correct. They overexpose with a longer shutter speed, then lower the exposure with tone mapping. To compare a Pentax exposure fairly to Fuji or Olympus, you would need to activate Highlight correction on the Pentax.

Last edited by audiobomber; 04-02-2014 at 02:35 PM.
04-02-2014, 02:16 PM   #14
Pentaxian




Join Date: Mar 2010
Location: SW Washington
Posts: 819
QuoteOriginally posted by audiobomber Quote
That's correct. They underexpose with a longer shutter speed, then boost the exposure with tone mapping. To compare a Pentax exposure fairly to Fuji or Olympus, you would need to activate Highlight correction on the Pentax.
Er... no, using a slower shutter speed compensates for the lower ISO, giving you the same exposure.

The whole point of higher ISO is to give you a higher shutter speed when you are aperture constrained. These manufacturers are lying by not giving you the high shutter speed you expect at their reported ISO.
04-02-2014, 02:22 PM   #15
Pentaxian
audiobomber's Avatar

Join Date: May 2008
Location: Sudbury, Ontario
Photos: Albums
Posts: 6,676
QuoteOriginally posted by Cannikin Quote
Er... no, using a slower shutter speed compensates for the lower ISO, giving you the same exposure.

The whole point of higher ISO is to give you a higher shutter speed when you are aperture constrained. These manufacturers are lying by not giving you the high shutter speed you expect at their reported ISO.
Two photos, same exposure:
Fuji @ 1/50s, f/4, ISO 100
Pentax @ 1/100s, f/4, ISO 100
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!
affect, aperture, cameras, characteristics, data, dpreview, dpreview and k-3s, dslr, exposure, high iso, index, iso, k-3, k3, lens, noise, pentax k-3, review, sensitivity, shutter, test, tests
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-5 noise even with ISO 200 (was: K-5 IIs noise) lunany Pentax K-5 9 12-28-2013 06:54 PM
Pentax K-3 and 3s scheduled to appear in April JohnBee Pentax News and Rumors 296 03-23-2013 01:57 PM
K-30 banding noise, aka vertical lines at ISO 1600 and up qwertyazerty Troubleshooting and Beginner Help 10 08-13-2012 03:48 AM
DPreview K-01 RAW high ISO samples botched! JohnBee Pentax K-01 8 05-04-2012 05:08 AM
k-5 and k-r ISO noise higher than 3200? metungnasi Pentax K-5 14 12-11-2010 11:57 AM



All times are GMT -7. The time now is 02:17 PM. | See also: NikonForums.com, CanonForums.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