asa ratings for sdx 900

[Allan Leader]

Hi everyone,

What type of asa ratings are operators using for their SDX 900 cameras in 24P and 60i ?

 

Thanks very much.

 

al leader

[Laurent Andrieux]

Sorry I don't esp know this camera, but if you have the camera specifications, it's easy to determine. They give you a recommend f-stop at a certain illumination, for instance (and it may be the figure for this one) 2000 lux (or 200 fc) f 11. If you have a meter that displays either fc or lux, it's possible to determine experimentally from this figure. Otherwise, do this calculation : S(asa) = f²X250/tXI where f is the f stop, t the exposure time (1/60, 1/50 and mind that deviding by t is then multiplying by either 60 or 50) and I the required illumination in lux . For instance you'll get S = 11²X250X50/2000 that comes close to 800

 

If you don't have the camera user's guide, do you have a wafeform monitor ? A luxmeter ?

[John Ealer]

Sorry I don't esp know this camera, but if you have the camera specifications, it's easy to determine. They give you a recommend f-stop at a certain illumination, for instance (and it may be the figure for this one) 2000 lux (or 200 fc) f 11. If you have a meter that displays either fc or lux, it's possible to determine experimentally from this figure. Otherwise, do this calculation : S(asa) = f²X250/tXI where f is the f stop, t the exposure time (1/60, 1/50 and mind that deviding by t is then multiplying by either 60 or 50) and I the required illumination in lux . For instance you'll get S = 11²X250X50/2000 that comes close to 800

 

If you don't have the camera user's guide, do you have a wafeform monitor ? A luxmeter ?

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Depending on how the camera is setup (gamma mode, slope, etc.) I usually find the effective ASA of the 900 is between 640 and 1000 ASA.

 

J

[Laurent Andrieux]

And the value beetween 640 and 1000 is 800...