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Micah Mahaffey

Samsung should add a 2:35 crop mode on the NX1 to fix rolling shutter

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​The sensor reads lines (not columns). The rollingshutter skew comes from the difference in readouts between lines, so the difference lies between consecutive lines, so it doesn't matter if you skip lines on the top and on the bottom, the difference between consecutive lines will still be the same.

At least from what I understand, if a video was grabbed using a sensor crop (which would be both vertical and horizontal to maintain the aspect ratio of course), the entire line is not scanned, but rather only the portion of the line that forms part of the cropped frame. So a sensor crop could indeed decrease the readout time between individual lines, meaning the perceived skew would decrease.

This is I guess why the GH4 has a better shutter than the NX1?

Line skipping could work to, that way the entire frame area can be maintained but fewer lines are read so the angle/degree of the skew is significantly less.

But why is it that 1080p has almost no perceivable RS yet it is so bad in 4k if both are reading the full sensor then downscaling?

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Guest Ebrahim Saadawi

If the 1080p on thre nx1 came from a full 7K pixel readout and downscaling it would have looked like the 4K scaled down to 1080p in post, it doesn't, there's a SIGNIFICANT loss in quality, in fact it's the same league as the Nikons, Canons, and normal 1080p cameras that don't quite resolve 1080p, and it shows moire. The 1080p on the nx1 given how it looks in quality and how much rolling shutter there is, it's definitely not doing a full sensor readout and downscaling, it's absolutely pixel binning or line skipping to throw away pixels and get faster read out. 

 

Anyhow the point is, what can reduce rolling shutter is two things, by cropping a smaller area, then the pixels are less, and it's faster to read less than read more of course, this shows mostly on the A7s FF vs s35 crop, and on the t3i s35 vs s16 crop, all cameras reduce rolling shutter skeweing when the sensor is cropped to a smaller window (well most cameras) 

and the other way is skipping lines, not reading the entire pixel sheet, thus making it much faster, this shows on cameras like the 1DC in 4K vs 1080p, GH4 4K vs 1080p, nx1 4K vs 1080p. And this is a bad option in my opinion as the hit on IQ that comes from lineskipping is worse than rolling shutter. 

 

The only thing you can reasonably ask from Samsung officially is a sensor crop mode, the same one on the nx500, around s16ish size window with the same 4K image quality yet with less rolling shutter and of course with a deeper dof and a s16 aesthetic. It would be a great addition for both rolling shutter sensitive scenes and for use as a teleconverter when we need a longer reach with a flick of a switch, it would be very helpful for prime shooters and for telephoto lovers, and to everyone honestly, 

You should all pour emails on Samsung about this native 4K crop nx500 mode. They do listen. 

 

Also pour emails on giving the NX500 the s35 2.5K mode back instead of the s16 4K mode that went into the final production model. It was absolutely beautiful. 

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I think you need to reduce horizontal resolution to make the lines roll faster off the sensor.

Cropping the sensor vertically would have same effect on rolling shutter as doing the crop in post.

In the end, a line of 4K is 3840 or 4096.... that's a lot of pixels compared to 1920.

So does that mean a 4:3 anamorphic crop would fare better? Because that sounds like a win/win. =]

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At least from what I understand, if a video was grabbed using a sensor crop (which would be both vertical and horizontal to maintain the aspect ratio of course), the entire line is not scanned, but rather only the portion of the line that forms part of the cropped frame. So a sensor crop could indeed decrease the readout time between individual lines, meaning the perceived skew would decrease.

This is I guess why the GH4 has a better shutter than the NX1?

Line skipping could work to, that way the entire frame area can be maintained but fewer lines are read so the angle/degree of the skew is significantly less.

But why is it that 1080p has almost no perceivable RS yet it is so bad in 4k if both are reading the full sensor then downscaling?

​But the idea behind the 235 crop mode is to use the whole width of the sensor.

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Guest Ebrahim Saadawi

Does't it already use the whole width othe sensor? Having a 2:35 mode on the nx1 would mean nothing but throwing away pixels at top and bottom, which can done be in post anyway. 

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