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Noisy Pictures
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Hi…
I’ve a quick question.. I’ve noticed when I’m taking pictures in low light where I’d have a low shutter speed that my pictures come out with a lot of noise or look really grainy in parts.
Can anyone tell me why this is happening and how I can overcome it?
Cheers..
I’d say you are using a very high ISO.
ISO lets more light onto your sensor in low light conditions.
Patlousyphoto wrote:
I’d say you are using a very high ISO.
ISO lets more light onto your sensor in low light conditions.
PatWould ISO set at 1600 do that?
ISO of 1600 would definitely introduce more noise. Try lowering the ISO down to 400 and using a tripod for longer exposures if necessary. That should reduce some of the introduced noise.
I tried a couple of shot with different ISO settings and thats what I was seeing.. So that confirms it..
Another thing I noticed while taking photos in the dark with long exposure times were tiny white spots appearing. Is this dust? Would I use Dust Delete Data to sort that out?
Cheers..
Low light, might mean a slow shutter speed, if hand holding could also be camera shake!
Stephen.
Can you post up an image with the white spots in it ?
It could simply be lights reflecting on the glass itself. What sort of a shot were you taking ?Hi Mark..
The shot is absolute crp so I’d prefer not to post it.. :oops: It was an experiment… gone wrong..
I was taking the picture at night so it was pretty dark..[Edit]
I’ve taken another photo against a black backdrop and cropped it.. You can see it at the bottom..
[/Edit]
The part of the picture where I can see the white dots is completely black so the dots are really visible.
The dots are only a couple of pixels in size.
Here is some data..
Tv(Shutter Speed)
25Sec.
Av(Aperture Value)
F20
Metering Modes
Evaluative metering
Exposure Compensation
0
ISO Speed
400
Lens
EF-S17-85mm f/4-5.6 IS USM
Focal Length
35.0 mm
Flash
Off
White Balance
Auto
AF mode
AI Servo AF
Dust Delete Data
No
Drive Mode
Low-speed continuous shootingI’m thinking maybe it was dust on the sensor or something like that..? Or do I have a more serious problem?
Cheers[/img]
Does your camera have a long exposure noise reduction feature? what usualy happens is the camera takes 2 pictures of the same duration one is your desired shot the other is taken with the shutter closed and this is used to remove the hot pixels (faulty pixels) from your photo.
Its called black frame subtraction i think
edit i cant believe the 40d hasnt got this feature have a read of the manual my canon G3 does it as does my nikon D80.
Thorsten wrote:
No, that’s not dust, it’s a hot pixel.
Yep, thats it. Thanks..
I’ve tried the tests mentioned in the article and you can barely see the hot pixel at 2 seconds and at 4 seconds its pretty clear when you zoom in.
The camera is a Canon 40D which I bought from new five weeks ago.
It sounds common. Is it something I should I just live with it or should I return it for a replacement?Cheers..
Return or accept it? Good question. I don’t know to be honest. My take on it would be to live with it, because I doubt you will find the perfect sensor. In theory you could have such pixels mapped out (i.e., the in camera processing software is programmed to ignore these pixels) but I really don’t think it’s worth the effort. But then again I rarely shoot at anything slower than about 1/15s so it matters less to me than it might to you.
Thorsten – I think I’ll live with it.. It really is hardly noticeable.
I tried the method suggested in the is link to try and fix it..
It didn’t fix it but it did improve.
Thanks for your help.. :D
/s
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