5d mk iii Raw, cropped/zoom 2k+, digital zoom or what is happening?

Started by DavidP, February 12, 2016, 01:11:31 PM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

DavidP

I'd just like to better understand the zoomed in, extra high resolution shooting capabilities of the camera. Is it a poorer quality digital zoom? Is your sensor turning into a super 35 cropped sensor like the a7s can do? Whats happening here?

Thankyou :)

Walter Schulz

Standard in RAW movie mode (and in H.264) uncropped:
Whole sensor area is used, but only every third line is used (line skipping). 3 Pixels (in sensor lines used) are binned ("merged").
-> You have to use antialiasing filters or fight aliasing in post.
-> Full sensor area used -> FOV not affected.
Exception: 5D3 is using binning for lines. 7D2 is reported to do this, too.

Crop mode:
Every pixel in cropped area is used.
-> FOV reduced
-> No line skipping

DavidP

Thankyou very much for your reply! So it sounds like you're saying, apart from reduced FOV, the quality of crop mode should be better? Does this apply to reduced resolution crops also?

Walter Schulz

Quote from: DavidP on February 12, 2016, 01:30:49 PM
Does this apply to reduced resolution crops also?

Mu.
Example with real numbers, please. You do not expect 640x480 in crop mode to keep up with 1920x1080 uncropped, I hope ...

DavidP

I just meant, is it the same, no line skipping etc if you crop to a smaller resolution? Bit strange though they would make it line skipping only for 1080p!

dfort

The issue is that the sensor has the capability of shooting images at 5760 x 3840 so how can you get a 1920x1080 image? You can either use a tiny portion of the sensor or skip every 3rd line horizontally and vertically, 5760/3=1920, the vertical is cropped slightly because the full sensor's aspect ratio isn't exactly 16:9. Line skipping introduces aliasing and moiré patterns on fine details so Canon went a step further on the 5D3 by having a group of pixels behave as a single pixel.

If you want to know more about how it works:
http://www.magiclantern.fm/forum/index.php?topic=16516

DavidP

So sorry to dumb it down but im not quite sure I got an answer there or I'm too stupid to understand lol!

So just to clarify 2 questions, firstly, if you zoom in and shoot cropped 1080p, is that gonna mean no anti aliasing and less/no rolling shutter?
2: When shooting regular raw 1080p and/or you lower the resolution to use less of the sensor, are you still getting the above benefits?

Thankyou :) P.s I just shot a few macro shots of some watches if anyones interested.Waiting for them to encode!

Walter Schulz

Where did you get the rolling shutter bit? Never came across such a claim in crop/non-crop discussions.

And nobody (I hope) ever told here there will be no aliasing in crop mode. But it's much, much worse when line skipping is used.

DavidP

I'm just presuming as on certain cams such as the a7 range, when you put it in crop mode the rolling shutter is reduced. So you think this doesnt happen here? may have to test it!


DavidP

Thankyou very much, very nice link :)

btw, I just tested out the cropped mode with my macro lense if anyone is interested.

SORRY, removed that link as I just realized the MLVeiwer to slog2 pro-res then grading in premier looks like dog shit compared to the DNG files opened in after effects. Re-making and will post soon!

DavidP