Scarlet 4K Crop Factor

[Ryan Lightbourn]

So is it 1.73 as stated here?:
http://www.red.com/tools/crop-factor

or 1.62x as stated here?:
http://www.reduser.net/forum/showthread.php?66210-Scarlet-X-Data-Sheet

 

[Phil Holland]

My crop factors are created relative to the aspect ratio of the maximum Red sensor resolution in relevance to the comparison format, in this case FF35 with the aspect ratio 1.9:1 applied. Mostly because we don't typically shoot movies in 3:2.

It's more of a "general" idea as every aspect ratio, format, and resolution "funtastic" variables that make it difficult to standardize things.

The three big reasons I post info on crop factors are:

- Expected lens coverage
- A predictable approximate field of view change across the various formats/resolutions found on Red cameras
- A point of relevance for those familiar with other systems and mediums to know what to expect at various formats/resolutions

For VFX purposes, I just deliver the actual frame size of the format so whatever aspect ratio a production is working on it can be extracted from that to match the footage.

 

[Neil Cronin]

So is it 1.73 as stated here?:
http://www.red.com/tools/crop-factor

or 1.62x as stated here?:
http://www.reduser.net/forum/showthread.php?66210-Scarlet-X-Data-Sheet

The geometries are different, so there isn't a universal crop factor. You can get the dpi of the MX sensor (5120px X 2700px / 27.7mm by 14.6mm) and compare the ratio of your target resolution to your preferred dimension of full frame still 35mm (36mm X 24mm). You might care about the horizontal crop factor, or the vertical, or the diagonal.

My guess with the two numbers you asked about is one horizontal, and one is diagonal. But it's just division depending on what you are looking to measure.

-n

 

[David Mullen ASC]

I tend to just compare the horizontal view since the aspect ratio affects the diagonal. A Full-Frame 35mm sensor is 36mm wide, so divide 36 by the width of the 4K area of the Scarlet sensor to get the crop factor compared to FF35.

If the Scarlet pixel size is 54 microns, I think 4096 pixels comes to 22.12mm, so that comes out to a 1.627X crop factor (for horizontal view) compared to FF35 (personally, I don't understand the need to compare everything to FF35 when most filmmakers are used to the field of view of 35mm cine / Super-35 focal lengths.)

 

[Phil Holland]

I tend to just compare the horizontal view since the aspect ratio affects the diagonal. A Full-Frame 35mm sensor is 36mm wide, so divide 36 by the width of the 4K area of the Scarlet sensor to get the crop factor compared to FF35.

If the Scarlet pixel size is 54 microns, I think 4096 pixels comes to 22.12mm, so that comes out to a 1.627X crop factor (for horizontal view) compared to FF35 (personally, I don't understand the need to compare everything to FF35 when most filmmakers are used to the field of view of 35mm cine / Super-35 focal lengths.)

I'm the same way really. I do provide relative crop factors in relation to FF35 and S35, but it's all really just for a general understanding.

I actually map out my wide, medium, and telephoto lenses "mentally" this way. Where I might want to shoot 35mm on one format, I may want 25mm on a different format. It's effected me in relationship to those focal lengths that I'm "mentally" trying to hit because I have my "things".

200mm has been fun with Dragon 6K, but I'm attracted to 180mm-ish for my personal way of working on that format size. This might be because of what 200mm looks like on FF35, this might be because I'm insane. I'm not looking to answer those questions at the moment, so I just shoot

 

[Ryan Lightbourn]

Thanks guys. Your wisdom is appreciated. I'm trying to match a BMCC to Scarlet 4K FOV as closely as possible via one of the two Speedbooster options.

On an unrelated note, Phil are there specs floating around for the speed increases Mini-Mags will provide for Epic or Dragon?