Exactly what is RAW1 doing? is it using complete sensor/what does raw2dng do?

[Alvin123]

ok, 5Dmk3 has like a 5400 x 3600 pixel sensor. not exactly correct numbers but something like that.
22 megapixels.  1080P is almost 2 megapixels.

so when I use ML raw version 1 I get a raw file comprised of image sequence of raw files.  after I use raw2dng, i get dng photo files each about 2.1 megapixels.

so did raw2dng convert a 22 megapixel raw photo to a 2 megapixel dng photo?

so if we are using the whole sensor, should each raw photo be 22 megapixel?   which is  quite a large file in megabytes.

when i'm recording, it is about 87 megabytes per second. my understanding is a raw photo can be up to like 30 megabytes.  so something isn't adding up here...

take 87 megabytes per second divided by 24 frames per second, you get about 3.6 MB per image photo.
doesn't seem like its using the complete sensor to me...

hoping Alex or someone at magic lantern can tell me how the entire sensor is being used if the files are actually alot smaller...are we sure line skipping is not occuring?

maybe everyone already knows the answer but I haven't seen it anywhere...  Thanks in advance!!

[dmilligan]

Of course it's not recording the entire sensor. That would require insane card write speeds (and insane internal bus speeds for that matter).

are we sure line skipping is not occuring?

Line skipping is occurring, since recording the entire sensor is impossible for a number of reasons (including write speeds). There are really only two "easy" ways to reduce the amount of data: line skipping and cropping. Often, both are happening. In "crop mode" you can avoid the line skipping, but you will end up with a small crop of the center of the sensor, so the FOV will be much smaller. If you record at the max res from the ML raw video menu, there won't be any cropping, but there will still be line skipping. The line skipping is actually already being done by Canon. The camera sensor electronics actually aren't even able to read every line of the sensor at 24fps, so line skipping occurs. Reading each line takes some finite amount of time (rolling shutter) and reading all 3000+ of them in 1/24 of a second is not possible and it pretty well seems to be a hardware limitation (if the electronics were faster at reading lines, we wouldn't see as much rolling shutter).

"RAW" here simply refers to the fact that the data is linear and bayered. It's raw data from some of the pixels, not necessarily all of the pixels.

[Alvin123]

Thanks so much for taking the time to explain!

so I guess I could get a super wide angle lense and use the 5x zoom?

I am using raw 1 and it is very nice!

[chmee]

is line skipping approved? there's a third possibility: binning. in the case 5DIII not impossible. pixel-comparisons arent made yet..

[Alvin123]

Chmee,

can you clarify your comment?  bining?  not line skipping?

[dmilligan]

There is some speculation/debate that the 5D3 actually doesn't do line skipping, (on other cameras it's quite clear that's whats going on, but it's hard to say for sure on the 5D3). Instead the resolution is reduced via pixel binning (or even perhaps something else). There is not conclusive evidence either way that I am aware of.

[chmee]

binning in case of a sensor means you recalculate/merge to "superpixels". 1 pixel from 3x3 pixels in case 5DIII. Thats the reason, the 5DIII has 3 times fullhd (1920x3=5760) pixel-width. But its strange, the 5DIII behaves in terms of antialiasing and moiré quite good, but the raw-sharpness (noCrop-Mode) is not higher than in h.264 - i assumed, that the detail-decrease would come from the jpg/h.264-encoding). so, theres absolutely no evidence for one or the other technique..

a real rescaling of all pixels in the lower price-segment is only done by the new sony A7s.

regards chmee