K20 D review on stevesdigicams shows awfull lot f hot pixels

Started May 24, 2008 | Discussions
TOMSDPR Contributing Member • Posts: 912
K20 D review on stevesdigicams shows awfull lot f hot pixels

Hi,

I also discovered two hot pixels on my K10 but on the studio scenes of Steves review there is at least half a dozen visible hot pixels.
Is this still acceptable?
--
Thomas - mjdundee

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jackbw Senior Member • Posts: 1,702
Re: K20 D review on stevesdigicams shows awfull lot f hot pixels

I don't see any coming from my K10d, but you're right, the studio shots in Steve's samples appear to have some wayward green pixels. Strange how it only appears in the studio samples and not the others. Could it be that it makes an appearance after the camera is on for a good number of hours?

gazonk Veteran Member • Posts: 3,070
Re: K20 D review on stevesdigicams shows awfull lot f hot pixels

jackbw wrote:

Could it be that it makes an appearance after the camera is on for a
good number of hours?

I don't have the K20D myself, but I downloaded the manual a while ago, and noticed that the K20D has a temperature warning on the display, which will appear if the camera is used in a hot place with live view.

Also, I noticed the following: If Slow Shutter Speed NR is set to AUTO, "the camera determines the conditions such as the shutter
speed, sensitivity, and internal temperature, and automatically

reduces noise as necessary", whereas when it's set to ON, it "reduces noise only when shooting at slow shutter speeds (under 0.3 seconds)."
--
Espen

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gazonk Veteran Member • Posts: 3,070
Re: K20 D review on stevesdigicams shows awfull lot f hot pixels

mjdundee wrote:

Hi,
I also discovered two hot pixels on my K10 but on the studio scenes
of Steves review there is at least half a dozen visible hot pixels.
Is this still acceptable?

I can't find that many in Steve's review, but I haven't looked very closely. The ones I find in the ISO 100 and ISO 200 shots, seem to be located in the same place in both shots, so they look like plain old hot pixels that can be mapped out with the K20D by the user.
--
Espen

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OP TOMSDPR Contributing Member • Posts: 912
Re: K20 D review on stevesdigicams shows awfull lot f hot pixels

OK - I took a look at the ISO 800 sample where they are visible very clearly in the full size view.
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Thomas - mjdundee

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jackbw Senior Member • Posts: 1,702
Re: K20 D review on stevesdigicams shows awfull lot f hot pixels

gazonk wrote:

jackbw wrote:

Could it be that it makes an appearance after the camera is on for a
good number of hours?

I don't have the K20D myself, but I downloaded the manual a while
ago, and noticed that the K20D has a temperature warning on the
display, which will appear if the camera is used in a hot place with
live view.

Also, I noticed the following: If Slow Shutter Speed NR is set to
AUTO, "the camera determines the conditions such as the shutter
speed, sensitivity, and internal temperature, and automatically
reduces noise as necessary", whereas when it's set to ON, it "reduces
noise only when shooting at slow shutter speeds (under 0.3 seconds)."
--
Espen

I just checked my camera (K10D) and found out why I haven't been seeing hot pixels. It only seems to appear when NR is OFF and at long exposures. Lately I've done some product shots with 10-15sec exposures with NR OFF and haven't noticed any hot pixels, but just now with a 30sec shot I did see some green dots.

But with NR turned ON the camera removes the hot pixels after doing a dark frame reduction. So it's really up to me how I want to use the camera. If I'm shooting RAW then I can turn off NR so the camera doesn't have to do the dark frame. If I'm shooting JPEG at longer exposures (maybe > 20sec) I'll turn on NR to avoid hot pixels. No big deal.

If NR is OFF by default in the K20D then the hot pixels may become an issue with reviewers who only review at the default settings. If it's something that can be removed by changing the NR settings then I don't see any problem in it. Other manufacturers may very well be applying NR by default anyway, knowing that some reviewers only use defaults. On the other hand if it can't be removed by changing the settings, then I'm glad the reviewers are working with Pentax to resolve it.

tsk1979 Senior Member • Posts: 1,186
Wasn't this expected?

On K20D you cannot turn of long exposure noise reduction. Why??

Because there are hot pixels galore. Noise reduction is a workaround. There is something seriously wrong with that sensor and pentax is using NR to hide it.

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gazonk Veteran Member • Posts: 3,070
Re: K20 D review on stevesdigicams shows awfull lot f hot pixels

mjdundee wrote:

OK - I took a look at the ISO 800 sample where they are visible very
clearly in the full size view.

Ok, I only had a look at 100, 200, 1600 and the 3200 pictures...

Indeed, there are a lot more in the 800 shot, both green, blue and red variants.
Some of them seem to be in the same location as I spotted them in the 100 and
200 shots.
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Espen

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gazonk Veteran Member • Posts: 3,070
Re: Wasn't this expected?

tsk1979 wrote:

There is something seriously wrong with that sensor and pentax is
using NR to hide it.

Well, this "seriously flawed" sensor has FF-class detail rendition at ISO 1600, so at least they implemented a good NR algorithm...

Just look at the comparision to D300, a700, 5D and more here:
http://www.akam.no/artikler/pentax_k20d/51057/4

And if you go down to the statue picture with mouse-over samples at all ISOs, they comment the hot pixel issue and don't regard it as serious. They say: "We found at most 3 pixel errors per shot (two of them are visible in the ISO 800 JPG shot below)".
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Espen

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Tom__Brown Senior Member • Posts: 1,345
Oh my God! What if there is no conspiracy?!!!

Just the thought is blowing my mind, man!

lol!

This situation helps put the pro-Pentax hype into perspective. I have no doubt the K20D is a world class camera, perhaps one of the very best on the market today, but it's tough to get past a hand full of posters in here who can't accept that something Pentax has done might not be perfect.

Tom
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bobmax Veteran Member • Posts: 6,380
Very nice review!
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Bob

OP TOMSDPR Contributing Member • Posts: 912
Re: Very nice review!

YES - indeed and the outdoor sample pictures of the boat hire are the fnest Steve has ever shot - no matter what camera was used.
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