Which camera is better option and about the Crop mode also the audio.

[Hachiroku]

Hello, guys.
I'm new to Magic Lantern and I have some questions. I'm really hoping you can help me sort things out.
1. Just sold my Nikon and looking for a Canon camera, I was wondering which is the better option - to buy used 550D(T2i) or pay double the price for used 7D.I want to export my movies 1080p and as I see that 7D is far closer to that resolution with continous recording.  The main question here, is it worth it to buy 7D for better recording resolution with 24fps?
2. I've seen a lot of posts about the Crop Mode and I can't still figure it out. Does it mean, that if I use it with 550D(t2i) and then I can be capable to record higher resolution continous with 24fps? If not, then how it works?
3. The last thing I wanna ask is about audio. I've seen that ML is capable to record audio, but I don't get how. If the whole post workflow is with DNG files, then how do the audio comes together? Or you can only record with external devices like Zoom H4?

I'm really hoping for an answer from You guys because the past month I've been googling around and reading, but I cannot find the right answer and it's about I start filming, but I cant decide what to pick.  Hope you can help me.

[Walter Schulz]

Please do a little more research and look what the other brands have to offer. If you want to dive into video and you have no gear/investment to protect you might find there are real strong players out there.

If you want to understand crop mode you have to understand what Canon does in DSLR video. Here we name it "native" video modes. All cameras (excluded 5D3 and - not confirmed yet - 7D2) will use every third sensor line. All other lines are just skipped. And if you do your math you will find all DSLRs (but 5D3) will not be able to record true 1080p. We call this "native" video resolution = liveview resolution. To surpress aliasing Canon uses some image manipulation. Add some aliasing surpression, noise reduction, blow up to 1080p and add sharpening. And for most cams there is a crappy IPB ratio as well. If you ever wondered why Canon's native DSLR output does not stand that well against some modern cams ... And again: 5D3 is another game.
Now comes ML offering RAW video. It's more or less just grabbing data sent to the display. Therefore you have All-I (= no interpolated/predicted frames), no sharpening, to scaling issues and no sharpening trying to mess with your data. But those frames may have an aliasing problem because lines are skipped. You may add a customized antialiasing filter with some price tag to surpress this.
Now comes electronic zoom as introduced with 600D. Just zoom in when in video mode and you have 3x focal length, virtually. And if you put 3x and 1/3 (=ratio of unskipped to lines in total) together you get 1. As in "frame grabbing" without line skipping. Or in other words: By zooming in (electronic) you change from skipping lines to sensor readout for all lines involved. And aliasing is not that much a concern anymore.

But -as almost everything - it comes with a price. Because it is electronic zoom you can't use all the sensor area but a frame within. As in "crop". Your FOV will be reduced. And if you have aliasing you have to deal with it in post. Because there is no filter available for this mode to put in front of your lens.

And there is another culprit: RAW data means serious data streams. 720p@24fps will be around 38 MByte/s. 550D won't do that for long because it's SD interface is limited to about 21 MByte/s.
7D does better but continuous true 1080p24 is out of question now.

Audio can be recorded in cam with MLV (ML video = ML's video format). If you think you want to go there you may do so.

MLV postprocessing is not that streamlined as - for example - putting NEF into Lightroom. Some people might want to use stronger words here.


Please take your time and make your decision with care. It is not a bed of roses. Or get a 5D3 and some really fast cards.