November 23, 2014, 06:29:52 AM

Author Topic: Why can't the 70D be 40MP in regular mode?  (Read 4196 times)

Dylan777

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Re: Why can't the 70D be 40MP in regular mode?
« Reply #15 on: July 06, 2013, 10:08:25 AM »
When you're not using live view, will it be possible to take 40MP pics?

WHY?

What do you mean why? Are photographers still stuck on this anti-megapixel circlejerk from 2002?

40MP in crop will be perfect camera for day time-outdoor-flash mounted shooters. My 5D III has 22MP, I look forward for 5D 4 to be in 18MP range.
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Re: Why can't the 70D be 40MP in regular mode?
« Reply #15 on: July 06, 2013, 10:08:25 AM »

neuroanatomist

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Re: Why can't the 70D be 40MP in regular mode?
« Reply #16 on: July 06, 2013, 10:40:23 AM »
When you're not using live view, will it be possible to take 40MP pics?

No.

Even if you could, you'd have a 3:1 aspect ratio, not the normal 3:2...

From my other post
"Though if it's just one pixel that just collects an abstract single piece of color information I suppose the shape wouldn't matter... if it were a triangle and it read the color as R23G33B92 it could just assign that to a square shaped pixel in the picture file right?"

It's not about shape. The half-pixels all have the same orientation, so your hypothetical 40 MP image would be 10944 x 3648 pixels.

As also stated, there's one microlenses over those two sub pixels, so you'd be mucking up the aspect ratio and bloating the file size without adding real information content.

And those additional autofocus pixels likely does not have colour filters. They should not for sake of AF performance

They do.  They're not separate pixels, but two sub pixels under each microlens/color filter.
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Mt Spokane Photography

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Re: Why can't the 70D be 40MP in regular mode?
« Reply #17 on: July 06, 2013, 12:16:39 PM »
I'm not sure if this helps, but its a single pixel that is sub divided.  It was not intended to act as two separate pixels, due to the geometry.
As others noted, the Bayer Filter covers the entire pixel with one color.
 

 
 
 
Here is a schematic diagram of the photosite from Canon's Patent  Note that the tops of the two sub pixels are slightly angled so they pick up light from different directions.  This geometry allows for the phase detection AF, but they need to be combined to get light from all directions.
 

x-vision

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Re: Why can't the 70D be 40MP in regular mode?
« Reply #18 on: July 06, 2013, 12:55:45 PM »
The two "half-pixels" share the same front-lens so they probe the same spatial info and therefore are not increasing the spatial resolution. In order to double e.g. the horizonal resolution they would have to double the little frontlenses too but then they could not use it in the same way for phase contrast autofocus...

That makes sense.

Moving on, can you tell me about these little lenses? Are there literally 20million little tiny lenses?

Yes, there are.

And as already noted, these 20 million tiny lenses determine the image resolution - even though there's a 40mp sensor underneath.

The thing is, this 40mp sensor would have likely had quite poor image quality if it wasn't doing the 2->1 merging of signals.

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Re: Why can't the 70D be 40MP in regular mode?
« Reply #18 on: July 06, 2013, 12:55:45 PM »