Pentax K10D - Absolute Black Darkness - TEST

Has anyone tried this with Kodachrome?

so what is the final conclusion? A CCD produces noise at long exposures?
This is a well known fact and ALL CCD's will have this, no mather which brand it is or what price it costs.
The noise is mostly heat induced this is why CCD's are cooled in analytical applications like spectroscopy. And in astronomy CCD's are often cooled as well.

Hot Pixels may well be found in all makes of digital camera. In low light, noise reduction is designed to...reduce noise.

It isn't really a problem in normal use, is it?

Try as I might, I cannot find "Aktivo" to be an anagram of "Teogwin"

Erm, actually all cameras have this issue. It's to do with physics, not the camera manufacturer!

If you have a black image, the camera will still try and expose to make it 50% grey. If this involves a long exposure, then the electrons in the CCD itself (which are generating noise all the time because they are moving) start influencing the image because there are so few photons to count.

The "noise reduction" in the camera is actually "dark frame subtraction" (Google it - it's a common astronomical term). That's why the camera "pauses" for exactly the same time as the exposure - it's generating a black frame from which it works out the noise floor.

If you really want long exposures, you are better off creating a "stack" (astronomical term - Google for it) of shorter exposures and combining them in Photoshop That's what you have to do for astonomy.

Hope this makes some sense
Matt

Hi Matt,

to leave the long exposure shots out for a minute..




this is one he posted earlier. If you look at the full sized jpg (seventh post, second link) there literally hundreds, (maybe even thousands) of dead/hot pixels. It doesn't look normal, and this looks like a normally exposed image. Sensor on it's way out maybe?

Cheers

Liam

There are lots of strange things about that shot - the bright points of light, some smearing horizintally and an extreme lack of sharpness.

perhaps, singe Aktivo joined on Dec 24, & put his post in then, the one big hot pixel might be something along the lines of The Star of Bethlehem.
Happy New Year, all.
Harry

Liam,
You do make me laugh That image was:
30sec, ISO 200, f2.8, Pentax *ist-D.

So, maybe it's not "a minute", just "half a minute"

I've just tried 30sec exposures on both my *ist-D and K10D (both with and without NR). The *ist-D has a scattering of hot pixels, while the K10D is completely clean. However, both were taken straight out and used from cold, and both have Li-Ion cells.

When the dSLR body gets warmer, the electrons get more excited and make more noise (a bit like my kids ). In addition, battery noise can add to this - when using AA NiMH cells in my *ist-D I would get hundreds of hot pixels, and when I took out the batteries they were extremely warm. Doing the same thing with CR-V3 Uniross Li-Ion cells and they are still cool.

So, you have a few choices when shooting long exposures (which can be combined):
1. Wrap an cooling ice pack around the body to keep the electrons quiet.
2. Use Dark Frame Subtraction. If you have lots of shots to take with the same exposure time, turn off the camera NR and take a black frame at the end with the lens cap on. Then subtract this in Photoshop. Alternatively (and more simply), enable the camera's Noise Reduction facility.
3. Use cool and quiet batteries (the more noise the batteries generate, the more noise creeps into the image through the circuit).
4. Take fewer shots, further apart to allow the electrons to calm down.

As John rightly said, there were a few things wrong with that image - you can't push CCDs for as long as film... but once you understand what's actually going on you can do things slightly differently with digital and get great results

Matt

PS. And going back to the *ist-D makes me realise how fast the K10D is, and how small the *ist-D LCD is!!

A lot of "SHOUTING" going on in this topic, maybe the problem is noise!

Hi Matt,

I couldn't get any EXIF data off the image, and as he said about shooting in the dark, I figured that this was a normal daylight shot..

My badddddd..

Cheers

Liam

slinking off slowly to the right of the screen.......................................................................................... :arrow: :arrow: :arrow:

Thanks to all for your answers.

I was want to know - hot pixels is normal or hot pixels mean problem in camera.

Anybody who have K10D have same results or no ?
Others cameras have hot pixels ? (I don't know - it's question)

If all K10D cameras have hot pixels, then it's normal and all is ok.

If only my K10D have hot pixels, it's problem with my camera.

I don't know if hot pixels is normal or not.

I start this topic, because i need your help, experience, suggestions, etc. not for funny and not for make somebody angry.

I have some digital camera for 3 years.

I have Minolta Dimage 7i before Pentax *istD. It don't have hot pixels with Dimage 7i - with Pentax *istD and K10D i have hot pixels - i don't know if it is correct or not - it's question for you.

EXIF nothing means because EXIF can be easily changed by any EXIF editor. if i want to lie, i can change any EXIF for me. I don't do that. If i say that photo was made in darkness, then that photo was made in darkness. Timestamp nothing means - because i can change it, or time in camera is not set correctly. I don't lie.
If i want to lie, i can paint hot pixels on photo.

Hi Aktivo,

no offence meant and my apologies if I was mis-understood.

I just read the post wrong, and assumed (wrongly) that they were daylight shots, and that you had the same problem with short exposures as well.

I either say stupid things (often) or clever things (very rarely, if at all) and very little else.

Cheers

Liam

Aktivo,
You don't have a problem with either the K10D or the *ist-D. Those images are perfectly normal. Stop worrying!!!

It is like setting your audio amplifier to "no signal" and turning the volume up full - then worrying that you have a slight "hiss". You are listening to electron noise (intrinsic noise).


One reason the K10D is much better because they have cut down on the amount of electronics:
> *ist-D - CCD ---> Amplifier ---> 12-bit A-to-D
> K10D - CCD ---> 22-bit A-to-D

The K10D can do this because of the extremely wide range A-to-D (22-bit). The amplifier (that sets the ISO rating) in the ist-D will produce its own noise and add to the "hot pixel" effect. The K10D also allows a non-linear response (we've all found you can pull out information from the shadows in RAW) - it's all down to the 22-bit ADC.

However, the tests you are doing are extremely EXTREME! You are "turning up the volume" so much you are seeing the circuit and electron noise of the CCD!

My old *ist-D has three permanently stuck / hot pixels that show up even in normal conditions. In long exposures there are hundreds of them!

You say that the Minolta 7i has no hot pixels - impossible They have more of a problem since a smaller CCD = more noise. They just have much more aggressive software noise reduction in-camera. All digital cameras have noise - but their software varies. It is not a "Pentax problem".

More Heat = More noise (electrons get excited)
Smaller pixels = More noise (electron noise out-weighs the photons)
Longer exposure = More noise (electron noise out-weighs the photons)
Worse/More circuitry = More noise (circuit/electron noise out-weighs the photons)
(These are the reasons that pocket digicams are sooo much more noisy than APS-C sized dSLR cameras)


For "normal" shooting:
* Shoot RAW
* Enable Noise Reduction in the Pentax (even in RAW).
* Use Silkypix Developer Studio or Capture One which both detect stuck and hot pixels and remove them in software
* Use Silkypix, Noise Ninja, NeatImage etc to remove further image noise when using higher ISO.

To summarise - your K10D and *ist-D are okay!
And, yes, the K10D is much better and I hope to have some very low light images from it soon that I can share

Hope that helps!
Matt