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 Post subject: unusual question
PostPosted: Mon Dec 03, 2007 12:28 am 
I have always wanted to ask this....When you use a 12mp camera @ 6mp, or a 10mp camera @ 5mp's,
WHAT actually happens? Which pixels get "left out"?
Is there much deterioration in IQ (up to a reasonable size print...10X8"?
If file size is smaller, I assume you can fit a lot more photos/GB and also save a lot of space on the pc as well as save the camera battery by quicker processing!
If you use say a D40X at @ 5 or 6mp's...will the result look indistinguishable from the IQ from the D40?(all other things being equal...)
curious,
otto


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 Post subject:
PostPosted: Mon Dec 03, 2007 10:50 am 
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Hi Otto,

I guess you are referring to situations where the camera still provides you with the expected field of view as opposed to, say, the D3 which crops the picture when used with DX lenses.

If the pixel count had dropped by a factor of 4 (12MP down to 3MP) I would suspect that "pixel binning" was being used. The idea behind that technique is to electronically combine the signal from groups of four pixels to simulate larger pixels and so benefit from reduced high ISO noise. A number of cameras use this trick though perhaps it's more common in the world of compact cameras where the small sensors pose particular challenges at high ISO settings.

The only other way I am aware of to reduce the pixel count is by using computer algorithms to interpolate and resample. Most image editors can do the same thing so I am not clear that there are any benefits to doing this "in camera" unless you are running out of storage space on your CF/SD cards.

With memory prices so much cheaper these days I prefer to capture the full resolution by having the camera save the pictures as RAW files. Then all techniques (including binning) can be applied using the appropriate software on the computer.

Bob.

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Olympus OM-D E-M1 + M.Zuiko Digital ED 12-40mm f/2.8, Lumix 7-14mm f/4, Leica DG Summilux 15mm f/1.7 ASPH, M.Zuiko Digital 45mm 1:1.8, M.Zuiko Digital ED 75mm 1:1.8.
Leica D Vario-Elmar 14mm-150mm f/3.5 - f/5.6 ASPH.
OM-D E-M5, H-PS14042E, Gitzo GT1541T, Arca-Swiss Z1 DP ball-head.
Astrophotography: TEC 140 'scope, FLI ML16803 camera, ASA DDM60 Pro mount.


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 Post subject:
PostPosted: Mon Dec 03, 2007 11:21 pm 
Thanks Bob,
I am still interested in whether IQ remains largely intact, when a D40X, D80 or D200 captures a picture at around 6mp, compared to it's maximum capability of 10mp...same as the D40 or less good?
My guess is that it doesn't suffer, up to a certain point of enlargement in the final print...would that be right?
Therefore, I am thinking that it's advantageous to keep the file-size smaller under "normal" circumstancess and only keep a FULL SIZE file if one intended to print to 13x20 and bigger...
My idea was that when travelling...how do I maximize the no. of images I can store when I don't have access to a computer to download everything...and if I am not selling my images to National Geographic,
and generally do not print larger tha 5x7 (not too much space on my walls anymore!) it's probably to my disadvantage to take full-size files all the time...I often take 5mp-size batches with my E900 compact which has a 9mp capability. I can't seem to pick much difference on my 22"
descktop LCD....or when I print out to less than gigantic sizes...such as 4x6 or 5x7....
I am beginning to think that there is more of a demarcation(or bigger margin than at first tought), in the difference between a pro-camera and one expected to be used by hobbyists andnon-professionals.... your thoughts?
otto


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 Post subject: IQ
PostPosted: Sat Dec 08, 2007 8:52 pm 
I'm no expert, but I do know that the pixel count of a lot of compacts is greater than the ability of the lens to 'fill' those pixels - i.e the lens is not sharp enough to make the pixels worth having.

On a decent DSLR that's different though - I can certainly see a difference between my 40D and my Ixus at the same resolution. If I were you I'd invest in a few extra cards / storage if at all possible.

It would be a shame to get a really great shot and then wish you had used the higher setting ...
Cheers


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