Pentax K10D - Absolute Black Darkness - TEST

- Set (Green) Mode to: Manual
- Set Aperture to: Maximum
- Set Speed to: 30 seconds
- Adjust EV Compensation to: +3EV
- Set Sensitivity to: ISO100
- Set Selft-Timer Shooting 12 secs.
- Set Format to: RAW

Put camera to absolute darkness and press the shutter release button.

Open image in some editor and you will see some "stars" (pixels).
Why ?

Try this test again with ISO1600 - more pixels you will see.
Why this pixels are there ?

Try this test again, but remove lens - without lens.

If don't see any pixels - use gamma correction up to 10.0.

It's called "noise" and is present in all electronic equipment.

There was even some mathematical work done in the 1950's to try to find a way to get rid of it. Google "cantor dust".

No can do. But it can be reduced, thus programs like Noise Ninja and the like.

When you take an image the signal of each pixel is greater than the background noise level that you are, for whatever reason, trying to photograph. The difference is the signal-to-noise ratio and it will equally apply to audio equipment where it manifests itself as hiss.

As long as in practical use the noise is not visible that's fine. It's no worse than grain on film, especially when, like myself, some people would use fast, grainy films.

May I ask how the heck you discovered this???

Look this photo by my old Pentax *istD:
http://rapidshare.com/files/8830939/_IGP2086_C.jpg

What do you mean about it ?
It's correct or not ?

Lens: Sigma 24-70mm F2.8 EX DG

Aktivo,

that´s far from normal. Too many 'hot pixels' (or should I say hot areas?). Definitely something wrong with the camera.
Have you sent a picture like this to Pentax? Propably the best people to judge what's wrong (although some of the folks here on the forum might have an idea as well if they are inclined to get to the hosted pic (with that dodgy-looking website that needs time to get to your download if you don't pay up)).

Hope this helps,
Prieni

Dead pixels ?

On this photos is noise reduction OFF

Crop: 220 KB
http://aktivo.limic.com/images/_igp2086_c_crop.jpg

Original: 5.5 MB
http://aktivo.limic.com/images/_igp2086_c.jpg

If i set noise reduction ON, "dead" pixels are hidden (no visible).

Photos from Pentax *istD:
------------------------------

ISO200, No Lens, 30sec, noise reduction: OFF, in absolute darkness:
TOO MANY PIXELS ARE VISIBLE WITHOUT GAMMA CORRECTION.

Converted PEF to PNG: ~700 KB
http://aktivo.limic.com/images/imgp4224_x.png

Original PEF: ~12.5 MB
http://aktivo.limic.com/images/imgp4224.pef

Photos from my new Pentax K10D:
----------------------------------------

ISO100, F22, 30sec, in absolute darkness:
ONE PIXEL IS VISIBLE IN CENTER OF PHOTO. IF YOU ARE USE GAMMA CORRECTION - TOO MANY PIXELS ARE VISIBLE WITH GAMMA CORRECTION GREAT THAN 3.0

JPEG: ~320 KB
http://aktivo.limic.com/images/imgp0024.jpg

PEF: ~6.4 MB
http://aktivo.limic.com/images/imgp0024.pef

--------
ISO1600, F22, 30sec, in absolute darkness:
TOO MANY PIXELS ARE VISIBLE WITHOUT GAMMA CORRECTION.
(only blue or silver ???)

JPEG: ~1.3 MB
http://aktivo.limic.com/images/imgp0025.jpg

PEF: ~8.8 MB
http://aktivo.limic.com/images/imgp0025.pef

--------------------
My Pentax K10D have same problem as Pentax *istD, but Pentax K10D is more better. THIS IS SYNTHETIC TEST ! IN NORMAL PHOTOS (IN DAY) - NO 'HOT PIXELS' ARE VISIBLE !
I DO NOT TRY NIGHT SHOT FOR NOW, but i will try it.

I just wonder how you came upon this-do you use the camera in total darkness?

I keep cover on lens. At night, i set drive mode to: self-timer (12sec).
I press shutter release button and put camera in the box with wall thickness more than 1 cm. I close that box. After 12 seconds elapse, camera start shooting. i wait to end of shooting.

If you have Pentax *isD or K10D, try this test and share/post your results to me.
This problem may be only with my camera, no others. I need some results from others K10D - if it is common problem or problem with my K10 only.

Well, the camera isn't really intended for taking pictures when there is no light, so I wouldn't be at all surprised if the poor thing didn't throw up a few unusual results as it desperately tried to understand what it was doing.

Perhaps a few tests in normal situations might be more revealing?

Or perhaps even black cats in coal cellars?

Hi John,

if you have a look at the 7th post in the thread, there are a couple of pictures taken in daylight, and it does look as though maybe the sensor is faulty. Ther noise reduction removes them, but then it's meant to.

Cheers

Liam

I'm surprised that Pentax didn't consider the the coal mine landscapers out there, shame on them.

I suggest that you invest in a "radar" camera if you intend to shoot in pitch darkness.

Get a grip man.

Andy

HELLO MR. FUNNY
DO YOU HAVE PENTAX K10D CAMERA ?
SWITCH OFF NOISE REDUCTION AND USE TIME GREAT THAN 30 SECONDS WITH ISO800 OR MORE AND MAKE SOME NIGHT SHOTS AND SEND ME YOUR PHOTOS. I WANT TO SEE IT.

What do you mean about this:
Example No. 1:
---------------------------------------------------------------
NOISE REDUCTION: OFF !!!
ISO 100, F4.0, 30sec, +3.0EV:

http://aktivo.limic.com/images/imgp0082_crop.jpg

ONE BIG HOT/DEAD PIXEL FOUND ON MY K10D.
(On my old Pentax *istD, I FOUND MORE THAN 30 VISIBLE PIXELS!!!,
K10D IS BETTER)

Example No. 2:
---------------------------------------------------------------
NOISE REDUCTION: OFF !!!
ISO 1600, F16, 30 sec, 0.0EV
AMBIENT LIGHT: 0.5~2 LUX max.

http://aktivo.limic.com/images/imgp0114.jpg

MORE VISIBLE HOT/DEAD PIXELS FOUND.

Example No. 3: Logitech Laser Mouse G5 - Nice
---------------------------------------------------------------
NOISE REDUCTION: OFF
ISO 400, F4.0, BULB 44.52 sec
AMBIENT LIGHT: 0.5~2 LUX max. - VERY NICE SHOT FOR "NO LIGHT"

Resized 1/16:
http://aktivo.limic.com/images/imgp0109_hex.jpg

Full size:
http://aktivo.limic.com/images/imgp0109.jpg


---------------------------------------------------------------
Conclusion:
Pentax Cameras have problem with hot pixels, if you are not use NOISE REDUCTION and you are use long time.
MORE TIME, MORE HOT PIXELS.

Note: Noise reduction increase time to save image to memory card, but remove hot pixels.

If you have Pentax Camera - try it.

PENTAX K10D IS MORE, MORE BETTER LIKE MY OLD PENTAX *IST D.
I LOVE K10D.

I'm having serious trouble understanding the point of Aktivo's "experiment."
More specifically, WHY would it occur to anyone to do such a thing?

I've been a photographer for a mere 40 years, but hey, ain't no tellin' what a man can do with a camera if he puts his mind to it.