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comparisons of a Contax ND Raw file and a Sigma Foveon X3 file

Thanks for the reply DJ,

You said, > You need to be wary of these comparisons in DPReview. For ex&le, in > the Sigma vs, EOS-D60 detail comparisons, the EOS image is very > visibly larger than the Sigma image, as it ought to be as it's twice > the megapixels. If viewed at their relative natural size, as is > obviously done here, that in and on itself, all else equal, will make > the Sigma image appear sharper being smaller. The only test they did to try and equalize this issue was to use a tool in the Foveon processing software that doubles the image size through interpolation. It then yields an image which is just a bit larger than the D60's, so they shrunk it down to the same dimensions, for their final comparison. That variable alone left me wondering what's going on in the background there in Foveon's software when they blow it up to that size. Who knows what sort of algorithms they've used to boost their image sizes, and it was my guess that some sort of sharpening was involved. Hence my questions to this forum. It's always better to get info, IMO, from the professionals that are out using the gear with practical applications. I hadn't even considered the JPEG compression factor issue; good point! Thanks!

will
 
Will - the biggest print - done by a company in England for a show - from one of my own ND images, was 24x36 inches with no quality problems(shot at 100 iso in RAW).
I do a lot of prints at A3+ size on my Canon S9000 and the again quality is excellent. When you see a print from an ND, look particularly at the dynamic range which in my view is better than the other full frame 35mm slr digicams.

Andy
 
Will, as I said in the post above, the D-60 is history. There are some left on dealer shelves, but who would buy one at $2,200 when the superior D-10 costs $1.500.? If money is an issue the D-10 is the answer.
 
Long exposures and digital noise...

Astrophotographers keep their CCD quantum noise down by cooling the CCDs. This would be difficult to do in a digicam. Because the noise is unpredictable it would be nearly impossible to write software to filter it out, so I believe there must be a true maximum time exposure limit for any uncooled digicam.

This also means that the hotter the electronics in a digicam run, or the warmer the day, the noisier the CCD.

Has anyone experimented with a cooled digicam vs a room temp digicam to see if there is any difference in the noise level of an exposure? I think this would be a REALLY kewl experiment.

Take a digicam down to a decently low temp, say with a dry ice pack and cooler, then shoot quickly at the max ISO of the camera in a night scene vs that same digicam at a 45C temp?
 
The problem with cooling is that unless the whole system is designed properly you're going to have condensation problems. Interesting proposition. How much can you cool before condensation is a problem? Retorical question, of course
happy.gif
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DJ
 
Dana,

Astronomers also record successive images, and stack them. This is easy to do in a digicam and the improvement in dynamic range is theoretically unlimited. I have performed quack medical experiments with Canon RAW files on terrestrial subjects to great effect. Note that JPG cannot be used because the low-order data, starting with chroma, is wiped out at even modest compression.

For those with money and physical access to the CCD, active cooling will reduce the frames needed in a stack (to one, subject allowing).
 
I didn't know jpeg killed the chroma info off so quickly... Not every digicam will let you do RAW files, ummm... What do you think of TIFF? Is it TIFF or TGA files that digicams do? Can you define stack please?

Ok, so... Since we can't easily cool the CCD below ambient in a portable digicam and maintain a good battery life (every way I know to cool the CCD will eat batteries), do you see a limit in timed exposures that cannot be overcome, or a theoretical maximum in ISO?

Dana

"Posted by Rico Tudor on Monday, May 19, 2003 - 11:29 pm:

Dana,

Astronomers also record successive images, and stack them. This is easy to do in a digicam and the improvement in dynamic range is theoretically unlimited. I have performed quack medical experiments with Canon RAW files on terrestrial subjects to great effect. Note that JPG cannot be used because the low-order data, starting with chroma, is wiped out at even modest compression.

For those with money and physical access to the CCD, active cooling will reduce the frames needed in a stack (to one, subject allowing)."
 
If you are new-ish to digital cameras, this is a nice article that explains some of the basics.

http://www.aacug.org/MUG/showker/pixels.html

Quoting the beginning of the article:

"So many people have been asking which digital camera to buy, how many "megapixels" do I need, and 'What's a megapixel?' You would need to read an entire book to get the real, in-depth answers to these questions, and after that you'd still be in a quandary about which camera to buy. I'm going to share some quick, simplified, rules of thumb for making your own decisions"

The article was written by: Fred Showker is Editor in Chief of "MUG" the AACUG Mac User Guide, and the User Group Network News service, and a founding Apple User Group Advisory Board (UGAB) member.

Hope this is helpful.
-Lynn L.
 
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