Focal length changes ?

[ackuma]

Hi everyone,
I have a little question, perhaps stupid,
When we change the camera's speed the resolution change too, imagine we make a shot in 4K at 25 fps and now we change the speed to 120 fps the resolution go down to 2K, that's right ?
What append on the censor ? it shut down a parts of the censor ?
So in this case, the focal length change too because we have a smaller area on the censor ?

Regards

 

[Stephen Williams]

Hi everyone,
I have a little question, perhaps stupid,
When we change the camera's speed the resolution change too, imagine we make a shot in 4K at 25 fps and now we change the speed to 120 fps the resolution go down to 2K, that's right ?
What append on the censor ? it shut down a parts of the censor ?
So in this case, the focal length change too because we have a smaller area on the censor ?

Regards

Hi,

The focal length of a prime lens does not change, however the angle of view will change due to the cropping of the sensor.

 

[Clint Lealos]

That's right. You are cropping out the center of the sensor when you shoot in 2K on the Red One. Your lens lengths will be doubled...sort of.

 

[ackuma]

The focal length of a prime lens does not change,

Yes, I misspoke.

Ok, it's the same the difference between DSLR canon 5D and 7D in fact.
So if I use 50mm field of view 24.92 in 4K 16:9 (22.1 x 12.4 sencor size ), I obtain with the same prime a f.o.v around 12.61 in 2K if I understood...

Thanks a lot for your quick reply !