ISO measurements?

[anchoricex]

Can someone explain like I'm 5 how the ISO is measured on the fs700? I'm not familiar with the db unit, I'm guessing this comes from more traditional serious video cameras and I've moved from a DSLR.

Any help is appreciated, thank you!

 

[nyvz]

Can someone explain like I'm 5 how the ISO is measured on the fs700? I'm not familiar with the db unit, I'm guessing this comes from more traditional serious video cameras and I've moved from a DSLR.

Any help is appreciated, thank you!

On the FS700 you have the option of displaying gain as db or ISO. db is basically just a generic measure of relative strength/power/intensity and is used in many fields in a lot of different ways, but all you need to know is that for cameras, every 6db is one stop or double the signal strength. Gain is displayed on the FS700 relative to base 0db gain, so 0db is always the lowest possible level no matter your gamma curve. ISO, however is determined by the middle grey value of whatever particular gamma curve you happen to be using and is arbitrarily defined by the manufacturer. For CINE4 0db is ISO640, I believe for CINE1 it's ISO500 and CINE2 is ISO400 and SLOG2 is ISO2000. At all those base levels, the gain amplifiers in the camera are at their lowest level and any change in brightness in your image is simply the camera processing the data with a different gamma curve, but the same signal gain is applied and the RAW data coming through the ADC should be identical. From those base levels, every doubling (one stop) of ISO number, the equivalent gain goes up +6db.

 

[Stuart Keasley]

On the FS700 you have the option of displaying gain as db or ISO. db is basically just a generic measure of relative strength/power/intensity and is used in many fields in a lot of different ways.....

What a great explanation, thank you for that!