Noisy night shot-hot pixel?

tangcy · 24th August 2002

The skys have lots of noises. Any way to reduce them?

Setting:
f/6.3
shutter 10sec
Center weighted avg
ISO100

Not all have those noises, eg below.
f/8
shutter 8sec
Center weighted avg
ISO100

darkness · 25th August 2002

Try using lasso tool or magic wand to select the sky and smart blur/gaussian blur it? BTW, first pic seems out of focus. Accidentally shook the tripod maybe??

25th August 2002

The 'noise' here is a result of what we call 'hot pixels' on the camera CCD sensor array. This is literally 'hot', i.e. due to increased temperatures, so one way to reduce the impact of this is to take your photos while your camera is physically cool, though this isn't really that effective for extended photo shoots because most cameras heat up pretty quickly.

An alternative method that is very commonly employed (originally by professional astronomers who use digital cameras for their work) is a post-processing trick called 'dark frame subtraction'. Do a search here or on the Net for this term, and you'll probably find more info.

A far more costly option is to invest in a camera with a larger CCD/CMOS sensor, such as the digital interchangeable-lens SLR cameras. These will also tend to perform well at higher ISO settings. However, if you don't need the flexibility of an interchangeable-lens system, I wouldn't suggest going this route (because of the monetary cost) unless you really do a lot of night photography.

tangcy · 25th August 2002

If it's hot pixel, then there is little we can do abt it. Just need to cool it down b4 taking another shot.

The first shot is out of focus maybe due to the auto focus function. Seem like all the shot are not focus except for those I use MF.

Need more advise for taking night shots eg. must it be MF for night shot ? cannot rely on the camera 100%?

MaGixShOe · 25th August 2002

hi there,
i am using the same cam as urs
did u go for the pixel remapping and updating of firmware?
it greatly reduces the hot pixels and to some extend the noise of the photos taken

for night shots i use auto focusing all the way
no prob at all

27th August 2002

Try shorter exposures. Any reason in particular you were using such long exposures?

24th August 2002	#1
tangcy Member Join Date: Jan 2002 Location: Bedok Posts: 135	Noisy night shot-hot pixel? The skys have lots of noises. Any way to reduce them? Setting: f/6.3 shutter 10sec Center weighted avg ISO100 Not all have those noises, eg below. f/8 shutter 8sec Center weighted avg ISO100

25th August 2002	#2
darkness Member Join Date: Aug 2002 Posts: 757	Try using lasso tool or magic wand to select the sky and smart blur/gaussian blur it? BTW, first pic seems out of focus. Accidentally shook the tripod maybe??

25th August 2002	#3
Midnight Guests Posts: n/a	The 'noise' here is a result of what we call 'hot pixels' on the camera CCD sensor array. This is literally 'hot', i.e. due to increased temperatures, so one way to reduce the impact of this is to take your photos while your camera is physically cool, though this isn't really that effective for extended photo shoots because most cameras heat up pretty quickly. An alternative method that is very commonly employed (originally by professional astronomers who use digital cameras for their work) is a post-processing trick called 'dark frame subtraction'. Do a search here or on the Net for this term, and you'll probably find more info. A far more costly option is to invest in a camera with a larger CCD/CMOS sensor, such as the digital interchangeable-lens SLR cameras. These will also tend to perform well at higher ISO settings. However, if you don't need the flexibility of an interchangeable-lens system, I wouldn't suggest going this route (because of the monetary cost) unless you really do a lot of night photography.

25th August 2002	#5
MaGixShOe Senior Member Join Date: Apr 2002 Posts: 2,638	hi there, i am using the same cam as urs did u go for the pixel remapping and updating of firmware? it greatly reduces the hot pixels and to some extend the noise of the photos taken for night shots i use auto focusing all the way no prob at all

27th August 2002	#6
Eric Guests Posts: n/a	Try shorter exposures. Any reason in particular you were using such long exposures?