Why Can The Scarlet 2/3" Shoot at Higher FPS than S35/FF35?

[Tom Wardrop]

I'm planning to buy a RED Scarlet as a hobby-type camera for still's and video. One attribute of the Scarlet that really attracts me is the 120fps capability, however I notice that the larger format Scarlet's (S35 and FF35) can't match the the 2/3" Scarlet on the FPS-to-Resolution ratio. Is this simply because the larger CMOS chips are less responsive or something? Can anyone explain.

Thanks

 

[J Davis]

3k is less data than 5k - greater throughput

 

[Tom Wardrop]

From the FAQ's and datasheets I've read, that is true, but look at these figures...

Scarlet 2/3"
3K @ 120 FPS

Scarlet S35"
5K @ 30 FPS
2K @ 72 FPS

Can you now see why I'm asking. The 2/3" shoots 3K at a higher speed than the S35 can shoot at only 2K. Why is that?

 

[bernd katzmarczyk]

From the FAQ's and datasheets I've read, that is true, but look at these figures...

Scarlet 2/3"
3K @ 120 FPS

Scarlet S35"
5K @ 30 FPS
2K @ 72 FPS

Can you now see why I'm asking. The 2/3" shoots 3K at a higher speed than the S35 can shoot at only 2K. Why is that?

If I were you I would wait for the final announcement.
Speculation: the S35 will likely be more a photographers tool than a filmmakers tool.

 

[Tom Wardrop]

Hmm Ok. Slow motion is something I've been interested in for a long time. 120 fps scaled to 24 fps will make the Scarlet the most affordable HD slow motion camera available. It would just be nice if the larger format Scarlet's had the same capability.

I'll definitely be awaiting final (or at least updated) specifications.

 

[David Rasberry]

Hmm Ok. Slow motion is something I've been interested in for a long time. 120 fps scaled to 24 fps will make the Scarlet the most affordable HD slow motion camera available. It would just be nice if the larger format Scarlet's had the same capability.

I'll definitely be awaiting final (or at least updated) specifications.

What you are asking for is called an Epic.

2/3" Scarlet only needs about 1/3rd the processing power for the same frame rates compared to S35. Probably has more to do with how the data paths to the processors are mapped than the sensor itself. Even at a 2k crop the processors are still seeing the 5k data bus and there is a more limited amount of processing per pixel.

 

[Tom Wardrop]

I would have assumed that when shooting at say 2k, on a 5k sensor, that only every nth pixel captured by the CMOS sensor would be sent through the pipeline. I guess the question is, when shooting at 2K, at what point does the native 5K capture become 2k?

 

[Joseph Ward]

What about a Windowed 3K on Scarlet S35/FF35 VS Scarlet 2/3 3K?

 

[Steven Hammer]

From the FAQ's and datasheets I've read, that is true, but look at these figures...

Scarlet 2/3"
3K @ 120 FPS

Scarlet S35"
5K @ 30 FPS
2K @ 72 FPS

Can you now see why I'm asking. The 2/3" shoots 3K at a higher speed than the S35 can shoot at only 2K. Why is that?

I'm guessing it's because the sensor for the S35 is 5k, so, to get it down to 2K, it has to do some processing, which slows down the maximum frame rate. For the 2/3, it's just pushing 3K of data straight down the pipe without having to downsize it.

Just a guess.

 

[Alexander Ibrahim]

The sensor on the Scarlet is 5K.

Windowing means that you read out only part of the sensor... but ostensibly that you can do so faster.

This is NOT pixel skipping, like the DSLR cameras use.

In any case, the readout from a 5K sensor is slower, even when windowed, than it will be from a 3K sensor. This disregards any differences in the design of the sensors themselves, and merely look at the the fact that you have to address each pixel and read it out... this process of addressing the pixels will take longer on a larger sensor that is otherwise identical.

In addition, the specifications for these systems are old. RED is very likely to change the final specifications when they see what they can actually achieve. What we have now are essentially design goals, what we will get later will be engineering results.

Finally... we don't have a complete picture. The S35 Scarlet records at a higher data rate, 80MB/s compared to 42MB/s on the the 2/3" versions. It may be that these figures represent that higher data rate... Scarlet may already be faster if you drop the data rate.

I expect that advances in computing technology will allow RED to offer frame rates at lower resolution that compare better with the 2/3" imagers- especially now that they are upgrading the boards in Scarlet for HDRx™ & Magic Motion.

If you truly need high speed photography though, the only no compromises way to get it is with Epic or 35mm film.

If you need "ultra high speed" photography (i.e. faster than 300fps) then Phantom is the only game for digital.

 

[David Rasberry]

Actually the maximum data rate for all the Scarlets was raised to 100MB per second some time back. The 42MB figure is out of date.
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