Green & Red Spots on Night Shot?

[Prang]

Is there a problem with the camera if you look in the sky and water there are green and red spots , they really show up in the raw image?

Pentax K100d Super, Exposure 8s, Apeture f/8, ISO 400.




Any help appreciated.

Thanks Peter

Edit It is a bit harder to see now the image is shrunk but in the raw image they show up really bright.

[stoogest]

Do the spots always occur in the same place, or are they random (ie. different each time you take a photo)??

[NeilC]

Is it only on exposures with a long shutter speed?

Not sure about the pentax, but nikon has a long exposure noise reduction to get rid of these.

[Prang]

They are in the same spots and the longer the exposure the more there is, I have a 20s exposure that has hundreds of them.

Thanks Neil I read the manual and there is a noise reduction, I'll give it a go.

Cheers Pete

[stoogest]

If they're in the same place every time then there's a chance the sensor could have some 'hot pixels'.

[arthurking83]

....

Thanks Neil I read the manual and there is a noise reduction, I'll give it a go.

Cheers Pete

make sure you are dealing with long exposure NR and not the general high ISO NR setting too!!

If they're in the same place, sounds more like hot pixels,but considering there are many of them, it may only be long exposure NR.

easy test: body cap on and take a few multi second exposures. say.. 10, 20 and 30 sec exposures. Do one of each with long exposure NR and one without L/NR. Most important part is to use the body cap, which should be light tight. Image should be blacker than black. There's no point trying to do that at night as you may be 'seeing stars'

Does Pentax provide the user with the ability to map hot pixels? I think it was Sony that has that feature??

[Prang]

The pentax body caps are white transparent things , but I left the lens cap on and the noise reduction made a huge different s.

There is only one Noise reduction so I would say it does both?

Anyway thanks all it's another bit of info I've learned here, cheers.