Time to write to card

Mandi · 10-22-2007, 04:35 AM

Hi all

I'm not sure if this is quite the right place to ask this question, but I sure would like to know the answer!

When one shoots on a slow shutter speed - 30sec, say, or a very long "B" exposure, the camera takes as long to write the image out to the card as it did to take it in the first place - i.e. 30sec for a 30 sec exposure, 200sec (roughly - I've never actually timed it) for a 200sec exposure. Why??? It doesn't seem to make any sense that if you've collected "x" amount of light (albeit very sloooooowly) that you will need longer to "process" it than if you take a 1/4000 exposure which also, presumably, colects "x" amount of light only quickly.

Thanks for your input!

Peter Zack · 10-22-2007, 04:42 AM

What is happening is the NR (noise reduction) is writing a 'dark frame' that takes as long as the original image. What the camera is doing is taking that dark frame and comparing it to your picture and mapping out, then removing any hot pixels that showed up in the first exposure. You can turn off the NR in the menu. You don't see this in a faster exposure as the NR doesn't need to map or remove hot pixels then. Some do this process on the computer to speed up the shooting times, I haven't tried that myself and just let the camera do it's thing.

Peter Zack · 10-22-2007, 04:47 AM

Here's a couple of threads that discuss this further:

https://www.pentaxforums.com/forums/pentax-dslr-discussion/11546-noise-reduct...rocessing.html

https://www.pentaxforums.com/forums/pentax-dslr-discussion/11489-time-exposur...ite-times.html

Mandi · 10-22-2007, 01:22 PM

Thanks for that! I should have thought to do a search before asking - this forum seems to have the answers to everything!

10-22-2007, 04:35 AM	#1
Mandi Senior Member Join Date: Jul 2007 Location: Sydney, Australia Photos: Gallery Posts: 126	Time to write to card Hi all I'm not sure if this is quite the right place to ask this question, but I sure would like to know the answer! When one shoots on a slow shutter speed - 30sec, say, or a very long "B" exposure, the camera takes as long to write the image out to the card as it did to take it in the first place - i.e. 30sec for a 30 sec exposure, 200sec (roughly - I've never actually timed it) for a 200sec exposure. Why??? It doesn't seem to make any sense that if you've collected "x" amount of light (albeit very sloooooowly) that you will need longer to "process" it than if you take a 1/4000 exposure which also, presumably, colects "x" amount of light only quickly. Thanks for your input!

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10-22-2007, 04:42 AM	#2
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	What is happening is the NR (noise reduction) is writing a 'dark frame' that takes as long as the original image. What the camera is doing is taking that dark frame and comparing it to your picture and mapping out, then removing any hot pixels that showed up in the first exposure. You can turn off the NR in the menu. You don't see this in a faster exposure as the NR doesn't need to map or remove hot pixels then. Some do this process on the computer to speed up the shooting times, I haven't tried that myself and just let the camera do it's thing.

10-22-2007, 04:47 AM	#3
Peter Zack Pentaxian Moderator Emeritus Join Date: May 2007 Location: Edmonton Alberta, Canada Photos: Gallery \| Albums Posts: 10,643	Here's a couple of threads that discuss this further: https://www.pentaxforums.com/forums/pentax-dslr-discussion/11546-noise-reduct...rocessing.html https://www.pentaxforums.com/forums/pentax-dslr-discussion/11489-time-exposur...ite-times.html

10-22-2007, 01:22 PM	#4
Mandi Senior Member Join Date: Jul 2007 Location: Sydney, Australia Photos: Gallery Posts: 126 Original Poster	Thanks for that! I should have thought to do a search before asking - this forum seems to have the answers to everything!