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Old 16-03-2010, 12:18 AM
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dhein (David)
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Join Date: Nov 2009
Location: Adelaide, Australia
Posts: 22
Hi all,

Thanks for the feedback. To answer some of the questions -

  • I started off taking 1600 ISO shots of 30, 60, 120 & 240 secs and placed them in the marked folders. However someone suggested that ISO 1600 wasn't the best setting to test noise, so I then took 800 & 400 ISO equivalents of each. Because the film speed was being 1/2'd in each case, I had to double the exposure times to compensate so that the dark frames had the same overall exposure. These make up the other 2 files in each folder.
  • My high speed noise reduction was set to default. However I've previously tried all the settings including "disabled" , which provided minimal difference.
  • Also for reference I do of course have the camera's in built dark frame subtraction routine disabled as this will be handled by DSS.
  • These examples are straight JPG's from camera in fine quality mode. Not RAW converted to JPG. I know RAW is better, but I've already been emailed some dark frame samples in native JPG format from a Canon 40D that's virtually all black bar a few pixels @ around 2 mins. Look at my ISO 1600 2 min shots (or the 800, 400 ISO equivalents) and you'll see heaps of noise.
  • Shooting temp was around 24 degrees c. I shot these indoors with the Aircon set as this temp, no lens, just a cap over the lens opening, and subdued lighting.
I've heard a few comments that the Canon 40D was the last decent camera, before the pixel density on the newer (same size) chips caused these noise issues. That seems to make sense, and seems to be backed up by dark frame samples I've been emailed. However the one niggle is the article link I orginally posted which specifically tests the 500D's dark frame abilty with long exposures up to 5 mins, and shows very cleans results.

Cheers
David
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