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Old Jun 3, 2006, 12:30 PM   #1
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When I take long exposures it takes a long time before I can take another picture.* Is this my memory card, or just the camera?* I am looking to buy a new memory card and I would like to know if I should even bother getting a fast card like the SanDisk Extreme III, or just the SanDisk Ultra II.* Thanks.
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Old Jun 3, 2006, 12:48 PM   #2
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It's the Noise Reduction causing the delay on long exposures.

Most modern digital cameras, including yourPentax, have a Dark Frame Noise Reduction System built in to mapout hot pixels (pixels that are too bright)on longer exposures. Typically, this system is automatically enabled with exposures of around 1 second or longer with most models.

Hot Pixels on longer exposures are normal. You just don't see them because of the Noise Reduction system.

What happens, is when Noise Reduction is turned on, the camera is actually taking two photos (one of your subject, and another with the shutter closed). That's why long exposures take twice as long with Noise Reduction turned on.

It then looks for hot pixels in the dark frameexposure (these are the only pixels that will be bright because the shutter was closed),and mapsout pixels in the same locations in the actual exposure of your subject (it replaces them with values interpolated from adjacent pixels). This is know as "dark frame subtraction"

But, the longer the exposure, the less accurate this type of system is. It's relying on hot pixels to be in the same place in both the actual and dark frame exposure, since the exposures are being taken at approximately the same time, with the sensor at approximately the same temperature, using the same exposure settings. But, when you get into very long exposures, you sometimes end up with pixels that are hot in the actual exposure, that didn't show up hot in the dark frame exposure. So, the system misses these.

You can turn this system off if desired (look for the Noise Reduction choice under the Custom Settings. But, unless you want hot pixels (pixels that are too bright) on longer exposures, I'd suggest leaving it turned on.

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Old Jun 3, 2006, 7:42 PM   #3
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Hi TravisG5

I have the DS. In My experiance, You Will be just fine with the Ultra 2. I personally have not noticed any increase in Read/write speed, Reg VS Ultra II.
Where i notice the difference is Unloading Pictures using My card reader. In My case I have noticed that with the ultra II, My Pictures Download Much Quicker.
I have a friend in a different Forum who swears by the Ultra III. And i have other friends that swear by the regular Cards.
I Personally only use Ultra II Cards. I figure a little extra head room cannot hurt.

So IMHO Its your call.

Hope this helps
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Old Jun 3, 2006, 9:39 PM   #4
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JimC, thanks for the explanation on noise reduction. i've not been using it thinking it was similar to what i have in elements 2 that reduces noise but also degrades the image. being somewhat lazy i haven't done tests (intended to.....) but now you've piqued my interest. lately i've been doing wild flower close-ups in the early evening when it's calm,with some2 sec, 3 sec, or longer exposures. i'll try it out now for sure. thanks again, eric
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Old Jun 4, 2006, 11:52 AM   #5
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Does anyone know how fast the *ist DL writes to the memory card?* I am looking at a card with a write speed of 5MB per second... would this be fast enough?
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