Sony Fx30 crop factor

[lucai]

Hello, I'm shooting with a full frame lens sony 20mm t1.8 with focus breathing compensation enabled with a sony fx30. When I import the files in Catalyst browse the metadata say the 35mm equivalent focal length is 38.7mm, so the crop factor is 1,935! When I use the aps-c sigma 56mm t1.4 according to catalyst browse the 35mm equivalent is 94.4mm, so the crop factor is 1,686. Is Catalyst browse correct?

[SonyShahpour · Accepted solution]

Breathing Compensation feature can only be used with compatible lenses. Angle of view and image quality may change slightly when this feature is turned ON. Even with this feature turned ON, depending on the lens,

compensation may not be fully effective. Breathing compensation is not available for unsupported lenses, 120p (100p) movie recording, S&Q recording at 120p (100p), or stills

This function automatically changes the crop rate depending on attached lens and its focusing position to keep a consistent angle of view.

In the Latest Catalyst Browse/Prepare, manual compensation control and other details can be adjusted as needed.

[SonyShahpour · Accepted solution]

Breathing Compensation feature can only be used with compatible lenses. Angle of view and image quality may change slightly when this feature is turned ON. Even with this feature turned ON, depending on the lens,

compensation may not be fully effective. Breathing compensation is not available for unsupported lenses, 120p (100p) movie recording, S&Q recording at 120p (100p), or stills

This function automatically changes the crop rate depending on attached lens and its focusing position to keep a consistent angle of view.

In the Latest Catalyst Browse/Prepare, manual compensation control and other details can be adjusted as needed.

[alisterchapman · Accepted solution]

To clarify, the equivalent focal length given is a result of the crop introduced by things such as focus breathing compensation, active image stabilisation or the crops used at higher frame rates such as the 1.6x crop from APS-C when shooting at 100/120fps with the FX30.

In the case of a Sony FF lens this is added to the 1.4x crop between FF and APS-C. I suspect that for non Sony lenses the camera may assume it is a FF lens so incorrectly adds the extra 1.4x.


But I really do wish crop factors weren't applied to focal length as it has nothing at all to do with focal length. A 50mm lens is a 50mm lens no matter what sensor you put it on and will exhibit the same perspective and same DoF regardless of the sensor size. Crop factors only affect the field of view. And if you come from a cine film background your normal reference frame size isn't full frame photo its 35mm movie film which is closer to APSC-C than FF. 

[lucai]

Hello Allister, thank you very much for your reply. I come from film background so super 35 is my usual reference and it's one of the main reasons I bought the fx30.