Re: Calibrating for CCD/CMOS noise
I've uploaded some samples, so you can see what it was like. Here's one with noise reduction turned on: http://www.oksne.net/lyn/lyn_med_nr.jpg And a 1:1 detail from around the lightning: http://www.oksne.net/lyn/lyn_med_nr_detalj.jpg Here's one without noise reduction: http://www.oksne.net/lyn/lyn_uten_nr.jpg And a 1:1 detail: http://www.oksne.net/lyn/lyn_uten_nr_detalj.jpg The shot with NR is f/9, 30 s, at ISO 400. The shot without NR is f/10, 30s, at ISO 200. Conversion from raw file done with photoshop CS. I believe the noise would have shone through even with a wider aperture. What do you think? Jostein - Original Message - From: Herb Chong [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Tuesday, January 25, 2005 1:44 AM Subject: Re: Calibrating for CCD/CMOS noise how noisy was the non-flashed part of the image without NR enabled? i would guess that the reflected light from clouds and so on would overwhelm the noise signal. Herb... - Original Message - From: Jostein [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Monday, January 24, 2005 10:39 AM Subject: Re: Calibrating for CCD/CMOS noise Last summer I tried to photograph lightning flashes. With the dark-frame subtraction (DFS) on, I lost half the thunderstorm. Of course, with the precision of Murphy's Law, all the best lightnings happened during DFS. :-)
Re: Calibrating for CCD/CMOS noise
to my eyes, there is a lot of noise in the without NR that would have to be removed in Photoshop. lightning at that distance looks a lot like noise to simplistic algorithms that mostly are focused on eliminating hot pixels. i wonder if any other DSLR would far better. i think without smarter noise reduction algorithms, and there are plenty out there in other applications, that you're not going to get better. doing manual dark field subtraction wouldn't be terribly effective except for hot pixels. Herb... - Original Message - From: Jostein [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Tuesday, January 25, 2005 12:44 PM Subject: Re: Calibrating for CCD/CMOS noise I've uploaded some samples, so you can see what it was like. Here's one with noise reduction turned on: http://www.oksne.net/lyn/lyn_med_nr.jpg And a 1:1 detail from around the lightning: http://www.oksne.net/lyn/lyn_med_nr_detalj.jpg Here's one without noise reduction: http://www.oksne.net/lyn/lyn_uten_nr.jpg And a 1:1 detail: http://www.oksne.net/lyn/lyn_uten_nr_detalj.jpg The shot with NR is f/9, 30 s, at ISO 400. The shot without NR is f/10, 30s, at ISO 200. Conversion from raw file done with photoshop CS. I believe the noise would have shone through even with a wider aperture. What do you think?
Re: Calibrating for CCD/CMOS noise
Last summer I tried to photograph lightning flashes. With the dark-frame subtraction (DFS) on, I lost half the thunderstorm. Of course, with the precision of Murphy's Law, all the best lightnings happened during DFS. :-) Jostein Quoting Herb Chong [EMAIL PROTECTED]: it looks to me like the guy didn't want to use the built-in NR to get a tiny bit better performance for a lot more work. i just turn on NR on all of my digital cameras that have it and let it do what it is supposed to do. i agree that the technique of waiting a half an hour after taking the last shot to take a darkfield shot will get a better base to subtract with, but i just can't see it being worth it. Herb... - Original Message - From: Frantisek [EMAIL PROTECTED] To: Herb Chong pentax-discuss@pdml.net Sent: Sunday, January 23, 2005 2:39 PM Subject: Re: Calibrating for CCD/CMOS noise I see it now ;-) The article seems more like a proof of concept, than anything useful... This message was sent using IMP, the Internet Messaging Program.
Re: Calibrating for CCD/CMOS noise
how noisy was the non-flashed part of the image without NR enabled? i would guess that the reflected light from clouds and so on would overwhelm the noise signal. Herb... - Original Message - From: Jostein [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Monday, January 24, 2005 10:39 AM Subject: Re: Calibrating for CCD/CMOS noise Last summer I tried to photograph lightning flashes. With the dark-frame subtraction (DFS) on, I lost half the thunderstorm. Of course, with the precision of Murphy's Law, all the best lightnings happened during DFS. :-)
Re: Calibrating for CCD/CMOS noise
The Pentax DSLRs will optionally do this for you automatically once the shutter speed drops below a certain threshold. S Frantisek wrote: Hi, I don't remember this appearing here, but after some thought on how to reduce fixed noise in long exposure photos (where a lot of the noise is fixed and not random because of effects of additional circuitry and temperature), I found this very interesting article on photo.net exactly about this, reducing fixed/bias noise in sensors. http://www.photo.net/learn/dark_noise/ I will do some real world trying out, and post the results. Using GIMP or IMAGEMAGICK it could be even easier to automate the process. Good light! fra
Re: Calibrating for CCD/CMOS noise
in fact, i don't see why it has to be done on the 10D in the article at all since it should have the same type of NR firmware as the *istD. dark field subtraction of an image taken immediately afterwards will be slightly noisier and not as clean as using a dark field from after the sensor has cooled for a while, but i have not had any noise problems after taking a succession of 10-20 second exposures at ISO 200 on the *istD. Herb - Original Message - From: Steve Jolly [EMAIL PROTECTED] To: pentax-discuss@pdml.net Sent: Sunday, January 23, 2005 7:54 AM Subject: Re: Calibrating for CCD/CMOS noise The Pentax DSLRs will optionally do this for you automatically once the shutter speed drops below a certain threshold.
Re: Calibrating for CCD/CMOS noise
Sunday, January 23, 2005, 3:57:11 PM, Herb wrote: HC in fact, i don't see why it has to be done on the 10D in the article at all HC since it should have the same type of NR firmware as the *istD. dark field I see it now ;-) The article seems more like a proof of concept, than anything useful... Good light! fra
Re: Calibrating for CCD/CMOS noise
it looks to me like the guy didn't want to use the built-in NR to get a tiny bit better performance for a lot more work. i just turn on NR on all of my digital cameras that have it and let it do what it is supposed to do. i agree that the technique of waiting a half an hour after taking the last shot to take a darkfield shot will get a better base to subtract with, but i just can't see it being worth it. Herb... - Original Message - From: Frantisek [EMAIL PROTECTED] To: Herb Chong pentax-discuss@pdml.net Sent: Sunday, January 23, 2005 2:39 PM Subject: Re: Calibrating for CCD/CMOS noise I see it now ;-) The article seems more like a proof of concept, than anything useful...
Calibrating for CCD/CMOS noise
Hi, I don't remember this appearing here, but after some thought on how to reduce fixed noise in long exposure photos (where a lot of the noise is fixed and not random because of effects of additional circuitry and temperature), I found this very interesting article on photo.net exactly about this, reducing fixed/bias noise in sensors. http://www.photo.net/learn/dark_noise/ I will do some real world trying out, and post the results. Using GIMP or IMAGEMAGICK it could be even easier to automate the process. Good light! fra
