Hot Pixels

[jsecordphoto]

For those of you doing long exposures (1 minute+) at night, using long exposure noise reduction, do you still get hot pixels in your images? I do a lot of long foreground exposures, usually around ISO1600, f2.8-f4, 6/8/10 minutes with the LENR on. I still notice a ton of hot pixels in my RAW files once I bring them into LR. Most of my photo friends are fellow astrophotographers, some using a 6D as well, but also Nikon D800's and D610's, and they said they barely see any hot pixels when using the in-camera NR.

Is there something I'm missing here? I am able to clean up most of the hot pixels using LR's noise reduction, but I don't understand why I am the only one having this issue. Is my sensor compromised somehow? My 6D is only about 5 months old.

Any help would be greatly appreciated

 

[runnah]

Noise reduction only works on the jpeg side of things.

Wait until this winter, go out and take some long exposures when t is in the 20-30's you'll see a lot less hot spots.

 

[jowensphoto]

Dead vs Stuck vs Hot Pixels

You may already know this, but that link may help determine whether the pixels are actually hot, or if they are stuck or dead.

 

[jowensphoto]

Noise reduction only works on the jpeg side of things.

Wait until this winter, go out and take some long exposures when t is in the 20-30's you'll see a lot less hot spots.

I didn't know this. I've been researching some long exposure stuff and all the articles say to turn this on, but shoot in RAW. That makes a whole lot of sense... not!

 

[jsecordphoto]

Noise reduction only works on the jpeg side of things.

Wait until this winter, go out and take some long exposures when t is in the 20-30's you'll see a lot less hot spots.

If that was true, then I wouldn't notice a difference between 2 photos taken one right after another, one with NR and one without. There are less hot pixels but still a bunch with the NR. I shot the other night with my buddy, both using 6d's, and he didn't have any hot pixels with NR. I don't think they are dead because they aren't consistently in the same spots

 

[runnah]

Noise reduction only works on the jpeg side of things.

Wait until this winter, go out and take some long exposures when t is in the 20-30's you'll see a lot less hot spots.

I didn't know this. I've been researching some long exposure stuff and all the articles say to turn this on, but shoot in RAW. That makes a whole lot of sense... not!

I dug a bit more and it seems like it does affect RAWs for some cameras and not for others. Also it seems like it makes things worse in some cases.

Honestly tho I just keep all those little in-camera images processors turned off.

 

[Overread]

Long Exposure Noise reduction is different to normal noise reduction.

For LENR the camera takes two exposures. One with the shutter blades open and one with them fully closed. Otherwise all settings are the same (including the exposure time - ergo shutter speed). The camera software then takes the photos and subtracts points of colour from the dark photo (blade shut) from the normal one and produces a single outputted photo from that. This way it aimes to remove noise spots caused by the long exposure because the only points of colour in the shot with the blades shut should be from noise generated (and hotspots should appear uniform - at least within the same similar period of time).

As such this method works for both JPEG and RAW photos



Note as mentioned the noise generated in a long exposure is from heat - so keeping the camera cool does help. Really serious astrophotographers taking long exposures will make use of custom stups sometimes using things like liquid nitrogen casings so keep the camera and sensor cool through a long exposure.

 

[jsecordphoto]

I understand what the LENR does, just don't understand why I am having such a problem with hot pixels that my comrades are not.

 

[runnah]

I understand what the LENR does, just don't understand why I am having such a problem with hot pixels that my comrades are not.

Can you post examples?

 

[jsecordphoto]

I deleted the frame without LENR because it was completely unusable. This is a 100% crop of a frame that was at ISO1600, f2.8, 8 minutes with the NR.

 

[runnah]

Well I am not sure what exactly is happening but I think what you are seeing is the limitations of the camera.

Not just your camera but all camera have a limit as to what they can do even with a very long exposure.

 

[jsecordphoto]

I don't think that is the problem here. My buddy was 20 feet away from me, using the same camera and exposure times, and not getting hot pixels like this at all. My other friend uses the d800e and does 20 minute exposures sometimes with only a few hot pixels making it through.

 

[Overread]

Few thoughts/ideas

1) Is your default noise reduction in your editing program set to a lower value than theirs

2) Is your default in-camera setting set to add brightness to more than theirs (that might account for a more noisy photo in review and might also apply for RAW as well if your RAW converter is reading your cameras settings and using them as its default starting point).

3) Have you enabled any other exposure aids or other features upon the camera. There are a few more of them around now which can result in problems in less than normal situations. They are mostly if not all editing changes for JPEG but could affect RAW if its being read from the RAW file default settings (and would certainly affect the JPEG back of camera review).


If the cameras are identical in model and make and the settings are all the same and you're getting worse performance whilst shooting in person at the same subject with the same settings - then the only other options is a defect on your unit.

 

[runnah]

I would do the "reset to default" option and try it out again.

Then turn off all "helpers" and try it again.

If things still presist, i'd seek help.

 

[jowensphoto]

I would do the "reset to default" option and try it out again.

Then turn off all "helpers" and try it again.

If things still presist, i'd seek help.

Agreed. This is mostly noise. I can only spot one actual hot pixel, but my contacts are kind of dry this morning.