DSLR Image Crop factor to match RedOne Sensor

[PaulClements]

I posted this in another thread last night, but thought I'd post it here again. If you want to work out the crop factor for your sensor (So the field of view you see on the cropped images shot on your DSLR is what you will see on the RedOne sensor using that same lens) use the following equation (Please note your sensor's physical size must be bigger than the RedOnes in order to be able to crop the image using this equation):

Height
Ph = Pixel Height
Sh = Sensor Height
(Ph/Sh)x(Sh-22.2)=Ammount to crop Vertically

Width
Pw = Pixel Width
Sw = Sensor Width
(Pw/Sw)x(Sw-12.49)=Ammount to crop Horizontally


Sensor Sizes

The following shows the sensor sizes for RedOne and two of the closest matching physical and pixel size sensors from both Canon and Nikon.

RedOne (@35mm 4k RedCode)
Sensor Physical size: 22.2mm x 12.49mm
Pixel Size: 5.5µm
Pixels: 4096 x 2304
Megapixels: 9.5


Canon EOS 400D Digital Rebel XTi
Sensor Physical size: 22.2 x 14.8mm
Pixel Size: 5.7µm
Pixels: 3888 x 2592
Megapixels: 10.1


Nikon D40x
Sensor Physical size: 23.6 x 15.8 mm
Pixel Size: 5.89µm
Pixels: 3872 x 2592
Megapixels: 10.1


Crop Factors for Canon EOS 400D Digital Rebel XTi and Nikon D40x

If you take a picture on the Canon then crop it by 405 pixels in height (Although it'll be slightly lower resolution) it ought to give you the same field of view as that lens would when attached to the RedOne.

If you took pictures on the D40x you'd need to crop them by -230 px width wise and -543 px height wise in order to see the same field of view as the attached lens would give you on the RedOne.


Hope this of help to some (And that I got my maths right!)

Cheers

Paul

[Sanjin Jukic]

Could be.
If it fits is good for director or DP to get first impression still shots. Also it could work with DSLRs like an advanced director viewfinder.
With Canon HV20 even more for director before shooting, location look outs etc...

[PaulClements]

It'd also be kinda useful to take a DSLR and zoom out for location sourcing, though the size of the RedOne I guess you could take the actual camera.

It's more for if people have a nikon or canon at the moment they can get an accurate feel for their lenses and how the fov will appear at 4k using that same lens.

[chuck colburn]

Just saw this.

http://cgi.ebay.com/Digital-Directors-Viewfinder-for-Arriflex-PL-mount_W0QQitemZ200129000440QQihZ010QQcategoryZ4691 QQrdZ1QQcmdZViewItem