Squirrel
New member
Last edited:
Relative Focal Length, Angle of View, and CCF Chart
- Thread starter Barry_Green
- Start date
Barry_Green
Moderator
That chart is totally wrong for 4/3. It's using numbers that are somewhat close to S16 film, but nowhere near what the 4/3 sensor is.
Squirrel
New member
Thanks Barry, olof - Should read 17.3 x 13mm for 4/3 in 4:3 mode. Area and crop factor are correct though. I'll get this corrected and edit the post later!
Sorry, in this case the chart is wrong: the real dimension of the AF100 sensor in 16/9 is actually bigger: 18,8x10,6mm (it has the same diagonal than the 4/3 picture mode: 17,3x13mm).
Barry_Green
Moderator
The AF100's sensor specification has been published in the user's manual as 17.8mm x 10mm.
Well, in this case the GH2 sensor, in 16/9 mode, is bigger than the AF100 one, according http://forums.dpreview.com/forums/read.asp?forum=1041&message=36396593
Darren Levine
New member
the final specs of the sensor an the rest of the camera have been posted.... http://www.dvxuser.com/V6/showthread.php?231516-AF100-new-brochure-with-final-specs!/page5
Barry_Green
Moderator
Yes, I'm well aware of that claim. However, I don't know whether it holds true in video or not. The Gh2 does video and stills, the AF100 is video only. It's possible that the 17.8 x 10 is a mathematically-appropriate extraction which makes for better video (similar to Red's 3840x2160 mode, which is designed for 16x9 HD video). Or maybe the GH2's sensor is the same size. I don't know that for sure. All I do know is that the specs have been published at 17.8 x 10.
B&H has a nice chart for stills cameras on their site to show the relative focal length needed on various stills cameras to achieve certain fields of view. But it's not very adaptable to the AF100 or cinema cameras.
Here I've put together a chart that shows the sensor sizes of common video and film formats, their Cinema Crop Factor as related to Academy Aperture 35mm Cinema Film frame size, and normalized for 16:9 image shape. It's not all that easy to put together a field of view chart when comparing different aspect ratios, so I normalized all the sensors for their widest 16:9-shaped field of view.
Without further adieu...
How was the "Aperture change to match DOF" calculated above?
Are "Aperture change" figures for the same AOV (angle of view) or same focal length?
Is the projection screen size or magnification held constant for all the formats?
I would appreciate a look into the methodology (CoC explanations/advanced details ok)...
Thank you in advance.
PS. I am wondering if two different CoC (circle of confusion) standards for 35mm cinema were used.
In my AC manual it is 1/1000th of an inch regardless of the camera/projector aperture.
Last edited:
Darren Levine
New member
it's 2.0 crop with a 35mm lens such as an EF
Barry_Green
Moderator
It's a 1.19 Cinema Crop Factor. Comparing the AF100 to its logical alternative, 35mm cinema film.
In reference to "2.0", that's comparing it against STILL film, not movie film. And in that comparison yes the AF100 would be a 2.0.
In reference to "2.0", that's comparing it against STILL film, not movie film. And in that comparison yes the AF100 would be a 2.0.
eheath
New member
Ahhhhh ok thanks
ryankroboth
New member
Just to clarify, does this cinema crop mean that if I invest in a lens intended for a 35mm film camera (or digital 35mm), say a Red Pro Prime; that I will only inherit the crop factor of 1.19 rather than 2.0? The ambiguities are confusing me to no end, especially because the RPPs' FOV are considered with Super 35.
Last edited:
Darren Levine
New member
correct, s35/super35/digital35/35mm motion film are all analogous with the same size and those lenses on the m43 will be about 1.19 crop
ryankroboth
New member
Awesome, thank you.
Barry_Green
Moderator
Well, S35 is a wider frame than 35mm cinema film. The Cinema Crop Factor was designed around the standard 35mm cinema frame, and in that scenario the AF100 is 1.19. The S35 frame sees more, so compared to S35 the AF100 would be more like a 1.3 or so.