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Old Mar 17, 2008, 3:46 AM   #1
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I have another 40D question.
In the bottom right corner of the viewfinder is a number which shows the maximum burst that can be buffered before the frame rate drops to the CF write speed, ie the number of frames you can get at (roughly) 6.5 frames/sec. Out of the Box my 40D never showed a burst capacity of over 6 frames. It has taken a month to find out that a C.Fn was set to reduce noise. I have turned this off and now I can get 17 frames in the burst as advertised.
Since I shoot in RAW, why is noise reduction being applied to my images, and if it is not, why does it reduce the burst size? The manual explains nothing about this function being applied to RAW files, indeed, it states the RAW file is what the camera sees.
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Old Mar 18, 2008, 8:44 AM   #2
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Good question. People also found out that Highlight Tone Priority option also influences RAW.

Quite strange behavior after which we might say that RAWs are not only loseless compressed information what sensor sees, but a little bit more. I don't mind, since the result is what I care about, it is not matter what leads to it - pure hardware or smarter software which knows better to read info from the hardware.

I assume all of us must agree upon.
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Old Mar 18, 2008, 3:01 PM   #3
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The result is what I care about too. If I wanted the camera to alter an image i would shoot a jpeg. computer software is more powerful and more sophisticated, if i want to alter the dynamic range or noise I will do it on my computer.
so, surely RAW should be just that. At the very least, it should be clearly explained in the manual, or somewhere that the C.Fn noise reduction and HTP is applied to RAW files as well as jpeg and defaulted to off
What if the "result" had been 2 seconds into a burst? You might have caught a bunch of beautifully toned, noiseless non-results, but missed the keeper because your 6.5 frames/second had dried up after 1 second....

Does anyone have the answer? Is this a bug in the firmware or an omission in the manual and the RAW image is processed by these settings?
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Old Mar 18, 2008, 4:35 PM   #4
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if you are using the DPP, the raw images reflect ur actual settings than the raw image. U can reset all the slider to 0 and use the raw image. In case ur using ACR(ADOBE) u will actually use the RAW image instead of the changed imaged.

For somereason the DPP uses in camera settings even for RAW images. Thats where u have options to even reduce Noise etc.

I am guessing the RAW images are imbedded with the in camera settings (FOR JPEG) as an option that can be viewed using the DPP.

Now coming back to the size, i find it really strange. Lots of factor come into determining the size of an image. Some real expert in this file size matter could share his findings.


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Old Mar 20, 2008, 6:15 AM   #5
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It's quite normal that the size of the images is different according the information sensor provides. All those pictures have same size, prior compression, but the compression algorythm has different data to handle and therefore we have slight filesize difference.
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Old Mar 20, 2008, 4:21 PM   #6
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Thanks for the replies. There seems to be some confusion over image size, which I am not concerned about, and the number of images in the burst at 6+ frames per second.
While RAW image size may have some small effect on burst size, the variation in size, I guess, will have little real world effect on the number of images in the burst.
It is an interesting idea that the camera keeps the RAW file intact but uses time to calculate/write the noise reduction information or HTP info which it then saves with the image. this would explain why these C.Fn settings reduce the burst number.
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