Guest sirvine Posted March 21, 2007 Share #1 Â Posted March 21, 2007 Advertisement (gone after registration) For a camera that puts shutter priority first, doesn't it seem odd that I have to wait up to *30 seconds* for noise reduction to be applied to my prior shot? Isn't this something that ought to be handled in the background? Â How do you studio/tripod shooters put up with that? Link to post Share on other sites More sharing options...
Advertisement Posted March 21, 2007 Posted March 21, 2007 Hi Guest sirvine, Take a look here Noise Reduction. I'm sure you'll find what you were looking for!
Guest WPalank Posted March 21, 2007 Share #2 Â Posted March 21, 2007 How do you studio/tripod shooters put up with that? In a studio (w/strobes) one usually shoots at 160 ISO. So it isn't a problem. Link to post Share on other sites More sharing options...
wparsonsgisnet Posted March 21, 2007 Share #3 Â Posted March 21, 2007 Sol, Â You must have been shooting at a slow speed. Â I find this annoying as well when it happens. Usually, it's not because it's necessary but because I have the wrong iso set and there isn't as much lisght as the camera thinks I told it there is. Link to post Share on other sites More sharing options...
Guest sirvine Posted March 21, 2007 Share #4 Â Posted March 21, 2007 I see. I guess I need to get out in the light a little more often... Link to post Share on other sites More sharing options...
blado Posted March 21, 2007 Share #5 Â Posted March 21, 2007 I think I finally discovered what that noise reduction thing is all about. The -K command line option in Dave Coffin's dcraw code (which most or many raw converters use) subtracts a dark frame (raw photo with no light) from the raw data. This also explains the processing time. Now if I just knew why... Link to post Share on other sites More sharing options...
wparsonsgisnet Posted March 21, 2007 Share #6  Posted March 21, 2007 Sol, You must have been shooting at a slow speed.  I find this annoying as well when it happens. Usually, it's not because it's necessary but because I have the wrong iso set and there isn't as much lisght as the camera thinks I told it there is.  It also happened when I did not remove the lens cover. I solved this problem for keeps: I bought metal, screw-in lens hoods, that are attached to the 486 filters. I no longer use a lens cover, instead being careful where I place the front of the lens. Link to post Share on other sites More sharing options...
dfarkas Posted March 21, 2007 Share #7 Â Posted March 21, 2007 Advertisement (gone after registration) The dark frame is an exposure of the same length as your actual exposure (30sec exposure would have a corresponding 30sec dark exposure). In this time, the sensor is active, but the shutter is closed. The camera should get a pure black image, but there is always some noise at these longer exposure times. The camera's firmware is able to examine the dark exposure, and subtract the noise it sees in the dark frame from the initial exposure. Â This is like using a a photo of a lightbox to detect dust on your sensor and then subtracting it out of the rest of your shots. Nikon Capture does this with NEF files and a referrence image. Many film scanners use technology called Digital ICE, which uses an infrared pass to detect dust and scratches on negatives or slides being scanned. They are then removed from the final scan in software. Â David Link to post Share on other sites More sharing options...
Guest sirvine Posted March 21, 2007 Share #8 Â Posted March 21, 2007 Interesting. It might be nice to have the camera keep a baseline noise profile for quicker noise reduction, and let the user choose. Anyway, it makes sense why this interrupts the shutter's availability. Link to post Share on other sites More sharing options...
stunsworth Posted March 21, 2007 Share #9 Â Posted March 21, 2007 Sol, as David says it can't be handled in the background because the camera is taking a black frame to allow it to remove noise created as part of the original long exposure. Link to post Share on other sites More sharing options...
wparsonsgisnet Posted March 21, 2007 Share #10 Â Posted March 21, 2007 Interesting. It might be nice to have the camera keep a baseline noise profile for quicker noise reduction, and let the user choose. Anyway, it makes sense why this interrupts the shutter's availability. Â Sol, I thot the same but someone posted that there are carrent variables that have to be taken into account. I guess these are iso, battery strength, temperature, and the like. Â I find it amazing that we manage to get our poor bodies thru each day without all the necessary calibration and interference-avoidance that these Things need. I think I hear my wife laughing at me still again. Link to post Share on other sites More sharing options...
dfarkas Posted March 21, 2007 Share #11 Â Posted March 21, 2007 Actually, I think the idea of having a set of built-in noise profiles is a good one. If the camera could be run through a sequence of dark exposre times to get a look up table and apply the appropriate correction on the fly, this could save a lot of time for the photographer waiting to take the next shot. The theory here is that the noise signature of the camera doesn't change with temperature. CCD sensors generally start picking up more noise the hotter they get, hence actively-cooled CCDs on Imacon scanners. Â David Link to post Share on other sites More sharing options...
AlanJW Posted March 21, 2007 Share #12 Â Posted March 21, 2007 The better solution to me is to provide a menu selection that turns long exposure noise reduction off. Sometimes you just want to handle it in post processing. The 5D allows this, and I often will simply use Noise Ninja. Its especially useful to turn it off if you are doing an extremely long exposure of many minutes or hours -- like a star trail shot, where to have the camera do a black frame could be utterly rediculous. Of course because there's no provision for an ac adapter, this is not really feasible for an M8 anyhow. Link to post Share on other sites More sharing options...
jaapv Posted March 21, 2007 Share #13 Â Posted March 21, 2007 I think I finally discovered what that noise reduction thing is all about. The -K command line option in Dave Coffin's dcraw code (which most or many raw converters use) subtracts a dark frame (raw photo with no light) from the raw data. This also explains the processing time. Now if I just knew why... Â You can see why. As the photo loads in the preview there is a brief moment when the original image shows, full of excited pixels. Suddenly that disappears and it is clean. That is the black frame substraction kicking in. Link to post Share on other sites More sharing options...
Guest sirvine Posted March 21, 2007 Share #14 Â Posted March 21, 2007 I believe the R-D1s allows long exposure NR to be turned off. There are just some times when you can't tolerate the camera being unavailable. Link to post Share on other sites More sharing options...
Guest WPalank Posted March 21, 2007 Share #15 Â Posted March 21, 2007 I believe the R-D1s allows long exposure NR to be turned off. There are just some times when you can't tolerate the camera being unavailable. Canon 5D, the same. Link to post Share on other sites More sharing options...
blado Posted March 21, 2007 Share #16 Â Posted March 21, 2007 This is all very interesting. Actually, the only thing I find strange is that the camera reports that it is working on it! I guess it's to explain the processing time. Link to post Share on other sites More sharing options...
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