Skew mode idea

[PaulClements]

Ok so this is one of those really weird ideas but I thought I'd chuck it out there. The skew on the Red One has always been one of it's more obvious issues. I doubt there is an easy solution to fixing it other than new sensors and faster processing with faster read/write capabilities, but I wondered about something anyway. On the camera there is little or no vertical skew which I presume is because a digital sensor writes line by line from top to bottom. So the skew is caused by vertical aligned pixels having a pause between the next in line (One beneath) being read/written as the next 4000 horizontal pixels are being recorded first.

The skew mode idea would be an in-camera option to switch between reading/writing pixels vertically (line by line across the sensor from left to right) rather than, as it is traditionally, pixels being read/written horizontally (lines of pixels from top to bottom).

If, for example, a specific shot includes a whip pan or has objects such as trains moving in the background the camera operator could switch to read/write across the sensor during the take and eliminate the skew and then switch back to normal for other shots. You could even go as far to say whether it started on the left, right, top or bottom depending on the direction of the object or pan.

I reckon this is probably something that would need to be designed into the sensor frankly and is probably quite hard, if not impossible, to achieve on the current version of the camera. But I'm curious as to whether it'd be a solution or not, after all what are the visual effects of a sensor that captures each pixel vertically rather than horizontally? (I guess chucking the camera on it's side and shooting a few scenes would be the quickest way to test lol!) And... If the visual effects are minimal to none existent why aren't digital video cameras made with sensors that read from left to right rather than top down, given that more shots are likely to include objects moving horizontally than vertically or the camera itself is being panned left or right rather than it is up and down. Maybe a square sensor than can be rotated is what's required!

I'm sure this is one of those "Aaah, I get it" moments but it's worth asking these questions from time to time .

Paul

 

[Michael Moreno]

wow Paul I always thought your avatar was awesome, I hope your right about this, because it seems like it would work. Can't wait to hear the answer to this. I also noticed the vertical lines.

 

[Paris Remillard]

I've been asking for this for a long time, for the same reasons. To me at least, the skew is a pretty big issue. I started a thread about making the DSMC sensor square for the purpose of being able to mount the camera on it's side for certain shots. Certainly the read/reset times of the newer sensors will be faster, but that won't eliminate the skew, just lessen it. From quick tests, just handholding the camera on it's side and whip panning, the difference is huge, to my eyes anyway. The expansion/contraction that you trade for the skew is totally masked by the motion blur. Some people claim that they can't see ant skew @1/48th sec shutter because of the motion blur. But when things that we recognize from our daily lives as being vertical are suddenly leaning over, things just don't feel right. Even if they are blurry. When things are being compressed by the sensor read, and then stretched out at the same time by the motion blur, we don't really register the artifact. In my personal experience anyway.

Also, if you look at the mirror shutter on any film camera where the mirror axis is below the lens, the shutter swipes in an arc from side to side. Not top to bottom as on the Red or other rolling shutter cameras.

Reorientation of the read won't eliminate the jello effect or the strobe problems or even skew. But if it can be masked by just changing the direction of the read, I can't see a reason why Red wouldn't at least explore the idea. Until the have a global shutter that can do fast frame rates. Or maybe a shutter that is global at normal speeds and rolling when it need to overcrank, if that would be possible.

 

[Sanjin Jukic]

Ok so this is one of those really weird ideas but I thought I'd chuck it out there. The skew on the Red One has always been one of it's more obvious issues. I doubt there is an easy solution to fixing it other than new sensors and faster processing with faster read/write capabilities, but I wondered about something anyway. On the camera there is little or no vertical skew which I presume is because a digital sensor writes line by line from top to bottom. So the skew is caused by vertical aligned pixels having a pause between the next in line (One beneath) being read/written as the next 4000 horizontal pixels are being recorded first.

The skew mode idea would be an in-camera option to switch between reading/writing pixels vertically (line by line across the sensor from left to right) rather than, as it is traditionally, pixels being read/written horizontally (lines of pixels from top to bottom).

If, for example, a specific shot includes a whip pan or has objects such as trains moving in the background the camera operator could switch to read/write across the sensor during the take and eliminate the skew and then switch back to normal for other shots. You could even go as far to say whether it started on the left, right, top or bottom depending on the direction of the object or pan.

I reckon this is probably something that would need to be designed into the sensor frankly and is probably quite hard, if not impossible, to achieve on the current version of the camera. But I'm curious as to whether it'd be a solution or not, after all what are the visual effects of a sensor that captures each pixel vertically rather than horizontally? (I guess chucking the camera on it's side and shooting a few scenes would be the quickest way to test lol!) And... If the visual effects are minimal to none existent why aren't digital video cameras made with sensors that read from left to right rather than top down, given that more shots are likely to include objects moving horizontally than vertically or the camera itself is being panned left or right rather than it is up and down. Maybe a square sensor than can be rotated is what's required!

I'm sure this is one of those "Aaah, I get it" moments but it's worth asking these questions from time to time .

Paul

Paul thanks for a very good idea

but I doubt that "new sensors and faster processing with faster read/write capabilities" would fix it anyway.

It is somehow in a "nature" of CMOS.

That means CMOS design has to be changed but I'm not so sure that CMOS design changes are going so fast.

Film has a skew too.

I was a little bit surprised when I saw it in a huge cinema theater on projection from a movie "The Dark Knight".

First I thought it was a digital projection but after realizing of film scratches and that the rolls are changing in circles it was obviously a film projection.

 

[PaulClements]

Paul thanks for a very good idea

but I doubt that "new sensors and faster processing with faster read/write capabilities" would fix it anyway.

It is somehow in a "nature" of CMOS.

Hi Sanjin,
Jim has gone on record as stating the Epic will have the fastest read/write of any sensor on the market , if memory serves. Reason being if you increase the speed of the read/write then the point at which skew appears becomes less. Essentially when one pixel is read, the one that sits beneath that pixel will be being read quicker if the read/write of the horizontal pixels takes less time to get to that one beneath. At least this is how I've always perceived it. It would definitely decrease the amount of skew, it's simple physics. But whether it completely irradicates it is another thing. Film has improved a lot, and I have no doubt Red's onto it for their next cameras and I hope they can do some magic and make it dissappear for good.

Parisrem, I think a square sensor is a good idea for a smaller camera like that. But a sensor that could be physically rotated behind the mount might be a better idea. Afterall cameras have typically been limited to the angle at which they capture because of the film going through it. It'd be great not to have to worry about rigging lots of equipment to have the camera horizontal or even do dutch tilt without the need of speciality heads. It'd also make underslinging on a steadicam very simple. The camera could have angles and a marker on the front that allow the operator to specify what angle they want within 360 degrees before locking off or leaving unlocked if they intend to move it mid shot. Dunno, might be a daft idea but could have some potential for unique shots and cheapening setups... might be another tool in the cameramans arsenal

Paul