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Matching SENSORS in Canon 7D vs. 5D ??


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#1 Bwana George

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Posted 02 July 2010 - 07:54 AM

Since the sensor in a Canon 7D is smaller than the full size sensor in a Canon 5D Mark II, if the SAME portion of the 5Ds sensor was used to match the sensor size of the 7D, which camera would produce the best quality video ?

In other words, what I'm trying to find out is which camera would produce better over-all quality video using the exact same portion of the sensor?

Since both cameras produce HD 1080p video, it would seem to me that the 1080p packed into the smaller size sensor of the 7D would be better than the same portion of the 5Ds sensor, since its 1080p is spread over the entire "full frame" sensor.

I am going to be using lenses that WILL cause vignetting with either camera, so I'm trying to find out, since I'll have to crop in post, which camera will produce the best quality video. Don't ask my why....that's just the way I have to do it.

I hope that makes sense, and if I'm not understanding something clearly, forgive me. I'd just like to clarify this issue from people that understand digital better than I do.
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#2 Brian Drysdale

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Posted 02 July 2010 - 08:11 AM

You'll be cropping a smaller area from the 7D's 1080 frame, so best go for that.
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#3 David Mullen ASC

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Posted 02 July 2010 - 09:27 AM

Since the sensor in a Canon 7D is smaller than the full size sensor in a Canon 5D Mark II, if the SAME portion of the 5Ds sensor was used to match the sensor size of the 7D, which camera would produce the best quality video ?

In other words, what I'm trying to find out is which camera would produce better over-all quality video using the exact same portion of the sensor?

Since both cameras produce HD 1080p video, it would seem to me that the 1080p packed into the smaller size sensor of the 7D would be better than the same portion of the 5Ds sensor, since its 1080p is spread over the entire "full frame" sensor.

I am going to be using lenses that WILL cause vignetting with either camera, so I'm trying to find out, since I'll have to crop in post, which camera will produce the best quality video. Don't ask my why....that's just the way I have to do it.

I hope that makes sense, and if I'm not understanding something clearly, forgive me. I'd just like to clarify this issue from people that understand digital better than I do.


But this only works if you don't shoot in video mode on these cameras, like shooting RAW stills for time lapse. If you shoot video mode, the whole sensor is used for the HD frame, minus whatever trimming it takes to get 16x9 out of a 3x2 sensor. That area is then decimated -- line skipping, pixel binning, compression, color subsampling, etc. - to get the HD recording.

You don't have the option of only using a smaller area of the 5D sensor to get 1080P video unless you are shooting in still mode, like for time-lapse.
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#4 Mathew Rudenberg

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Posted 02 July 2010 - 12:36 PM

I don't think any one has mentioned to you yet that one of requirements of this board is to use your real name. you should go ahead and change it

Since the sensor in a Canon 7D is smaller than the full size sensor in a Canon 5D Mark II, if the SAME portion of the 5Ds sensor was used to match the sensor size of the 7D, which camera would produce the best quality video ?


If you crop both sensors to the same size you will get somewhat more resolution out of the 7D (or the T2ii which has the same size sensor and is cheaper)
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#5 David Mullen ASC

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Posted 02 July 2010 - 12:44 PM

If you crop both sensors to the same size you will get somewhat more resolution out of the 7D (or the T2ii which has the same size sensor and is cheaper)


But these Canon cameras do not allow sensor cropping pre-conversion to in-camera 1080P video...
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#6 Bwana George

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Posted 02 July 2010 - 12:58 PM

But these Canon cameras do not allow sensor cropping pre-conversion to in-camera 1080P video...


I realize that, so the cropping would have to be done after the fact, in post with Adobe Premier CS5. According to others using this software program, THAT can be done.

So, it's back to my original question: if the cropped area of the 5D "Matched" the sensor size of the 7D, WHICH would make the best quality "VIDEO"?
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#7 David Mullen ASC

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Posted 02 July 2010 - 01:45 PM

I realize that, so the cropping would have to be done after the fact, in post with Adobe Premier CS5. According to others using this software program, THAT can be done.

So, it's back to my original question: if the cropped area of the 5D "Matched" the sensor size of the 7D, WHICH would make the best quality "VIDEO"?


Obviously the 1080P video from the 7D is going to be better than the 5D 1080P video cropped to essentially 720P. And considering the 1080P Canon (whether 7D or 5D) recording only measures out to 750 lines, the rest is lost in aliasing, to lose an effective 1.5X means more like 500 lines of resolution after cropping.

And if you don't change your User Name soon, I think we're going to have to start ignoring your posts George.
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#8 Sergey Pylypenko

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Posted 07 August 2010 - 12:42 AM

But this only works if you don't shoot in video mode on these cameras, like shooting RAW stills for time lapse. If you shoot video mode, the whole sensor is used for the HD frame, minus whatever trimming it takes to get 16x9 out of a 3x2 sensor. That area is then decimated -- line skipping, pixel binning, compression, color subsampling, etc. - to get the HD recording.

You don't have the option of only using a smaller area of the 5D sensor to get 1080P video unless you are shooting in still mode, like for time-lapse.


Which comes to conclusion, that full sensor (5616 pix wide) gives more information for both .RAW and compressed .MOV images comparing to 7D's 5184 pix. I don't mention the height of the sensors, that is being cropped for .MOV, not forgetting, that full sensor is almost twice bigger then 1.6, thus has about 60-70% bigger pixels to produce less noise.

Edited by Sergey Pylypenko, 07 August 2010 - 12:43 AM.

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