Canon 550D Really Bad Noise on Long Exposure

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Cranky

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Took a couple of longish exposure pics last night yet looking at them this morning they seem to have really bad noise issues.

This is a 100% crop from a 4 minute exposure:

noisec.jpg


I have never had this on my old combo of 400D and 17-85 but with that not allowing me to go more than an f4 aperature I had to use the kit 18-55 lens.

For info:

Camera: 550D
Lens: 18-55is
Mirror Lockup: Enabled
ISO: 100
Aperature: f16
In Camera Noise Reduction: Off

Is this due to the cheaper lens getting hot? or is it a problem with the camera?

Cheers Si
 
It wont be the lens getting hot - the lens never generates heat as once its focused etc it just sits there on the camera effectively just letting light through.

At 4 minutes, I suspect the sensor is getting hot, though I've not had any experience using the 550D...
 
BandyQuill said:
could also be noise reduction turned on in the camera, that tends to cause noise when used for really long exposures...
?
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So noise reduction creates noise???? defeats the point of it. I would guess noise reduction is off, hence the noise
 
BandyQuill said:
i was under the impression that it will try and compensate for what it thinks is noise, or am i thinking of image stabilisation...
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In camera noise reduction reduces the noise, but takes as long as the exposure to do (ie a 4 min exposure would then take 4 mins to reduce noise = 8 mins total time)

IS is compensation for camera shake, different kettle of fish
 
yea, turning noise reduction on helps. Also when processing you'll find most software is good at removing chroma-noise (probably not the correct word/spelling) which is all those coloured specks. Without the random colours you will find the noise is much less noticeable.
 
Ive just run the image through noise ninja - removes the dots fine but not the lines
 
NR was off as I would prefer to do that later on, but what I can't understand is why is it doing it on the 550 when i've done 10minute exposures on my 400D with no noise at all
 
Cranky said:
NR was off as I would prefer to do that later on, but what I can't understand is why is it doing it on the 550 when i've done 10minute exposures on my 400D with no noise at all
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More megapixels on the same size sensor is inviting noise to occur - but I wouldnt of thought that much!
 
Dave450 said:
More megapixels on the same size sensor is inviting noise to occur - but I wouldnt of thought that much!
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Thats what I thought, fair enough the 550 has a lot more pixels on the same sized sensor but the technology should also have improved along with the MP rate surely.
 
Cranky said:
Thats what I thought, fair enough the 550 has a lot more pixels on the same sized sensor but the technology should also have improved along with the MP rate surely.
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Need someone else with a 55D to do a a similar shot to compare! No idea if its a fault with the camera, wouldn't like to guess either way.
 
I got similar 'lines' in underexposed shadow areas on my Nikon D2x - was a bit of a shock as the previous model - the D1x - had better noise characteristics due to the lower pixel density.
I sent it back via Calumet (our suppliers)...Nikon said it was fine...:shrug:

It may just be one of those things that occasionally crops up with digital shooting - sensors are arranged in grids, so any shortcomings are pretty noticable.
 
i can try it tonight on my 550d if you want
what were you taking the long exposure picture of and anything else i need to know
 
Arkady said:
I got similar 'lines' in underexposed shadow areas on my Nikon D2x - was a bit of a shock as the previous model - the D1x - had better noise characteristics due to the lower pixel density.
I sent it back via Calumet (our suppliers)...Nikon said it was fine...:shrug:

It may just be one of those things that occasionally crops up with digital shooting - sensors are arranged in grids, so any shortcomings are pretty noticable.
Click to expand...

I don't think its the lines that are the issue, I think they were actually there in front of the camera! I think its the large amount of what appear to be hot pixels in the image thats the issue here...
 
Oh yeah I should have taken a crop from the sky not the jetty :D
 
Cranky said:
Oh yeah I should have taken a crop from the sky not the jetty :D
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ah - those are planks?
:lol:

Well then that noise is about what I'd expect to see without Long-Exposure NR switched-on TBH...
 
Arkady said:
ah - those are planks?
:lol:
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All makes sense now!!

Image is fine, as Rob said, noise is about right, and those lines are now justified!
 
You need to use the in camera noise reduction unless you are going to shoot your own dark frames at the end of the session and subtract them in software when processing the raw's.
 
Hmmm, i'll go and try it again tonight with the NR on and see what happens, I must admit though I never used NR on my 400D or had to get rid of excess noise in photoshop.

Fingers crossed it will work
 
Try taking the same shot, but with the lens cap on. This will give you some idea of what the hot pixel levels are really like, (this is a dark frame, and is effectively what ICNR subtracts from the image if you have it on).
 
Good plan i'll do one without NR and one with and post the results should anyone else search for a thread like this :thumbs:
 
Cranky said:
Good plan i'll do one without NR and one with and post the results should anyone else search for a thread like this :thumbs:
Click to expand...

When you do try it you will see all is well and the horrid hot pixels are gone. I dont have my camera handy but I think you can set it to AUTO or ON, one thing you will notice is the in cameras processing will take a good big longer than with it off.
 
There's noise reduction (which is used on high ISO shots for example), and then there's dark frame subtraction (which is used for long exposure shots)

When you take long exposures, the sensor heats up, thus generating more noise - on any ISO setting. Some cameras employ a technique called dark frame subtraction - where the camera then also takes another shot of the exact same duration (shutter speed) immediately after the first long exposure one, but this time without actually opening the shutter. It then uses this image to attempt to remove any noise generated from the original shot. Hence it being called dark frame subtraction.

:)
 
I've noticed more noise in long exposures from my 7D compared to my 40D too. Like half a second or longer exposures generate noise on the 7D where I never used to notice it on the 40D. I was surprised at the difference! (mostly noticed when shooting macro from a tripod)
 
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