EX ASA speed?
- Thread starter mikeb123
- Start date
If you think of a digital SLR, you can make it whatever ASA you like - just dial the numbers in. But on my Canon, it is a lot noisier at 1600ASA than 100ASA.
With video cameras, measuring an ASA rating will tell you what stop you need to get correct exposure for a certain light level. But like with a DSLR, you can make the camera whatever ASA you like by altering the gain.
To use ASA rating as a sensitivity comparison with another camera, other factors must be the same, and the most obvious is signal/noise ratio. And s/n figures are not the same for all cameras at 0dB.
Best way to compare relative sensitivities is dial in gain on each camera until it just starts to be objectionable, then see what stop the cameras are for the same lighting level. Under those conditions, my own impressions were that the EX1 is substantially better than other cameras of that size/weight, and that seems to be most peoples experience.
Ryan Patrick O'Hara
Veteran
I get what you are saying but if anyone knows what the factory default setting at 0db is rated, I would like to know. Of course it would be an approximation.
Depends how you define it, and after you define it, it depends on the gamma curve you select.
Looking at where middle grey falls, i get around 400, but on most of the cine gamma curves it's closer to 250. Cine 4 is my favorite curve, and gets around 400.
These numbers are pretty typical for HD cameras. But as harddrive explains, they only tell part of the story.
Looking at where middle grey falls, i get around 400, but on most of the cine gamma curves it's closer to 250. Cine 4 is my favorite curve, and gets around 400.
These numbers are pretty typical for HD cameras. But as harddrive explains, they only tell part of the story.
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A quick and easy way to determnine your ASA on a video camera with a incident light meter.
Frame up your camera on a grey scale or similar chart.
Aim some light at the chart it doesn't matter how much.
Set the iris on your camera to give a proper exposure. Auto iris should get you in the ballpark. Note the f stop and shutter speed.
With an incident light meter set the Shutter speed on the light meter to match what you have set on your video camera.
Minipulate the the ASA(ISO) on your light meter until it matches the f stop on your camera.
Whatever ASA(ISO) you end up with on your meter is your camera's ASA.
Frame up your camera on a grey scale or similar chart.
Aim some light at the chart it doesn't matter how much.
Set the iris on your camera to give a proper exposure. Auto iris should get you in the ballpark. Note the f stop and shutter speed.
With an incident light meter set the Shutter speed on the light meter to match what you have set on your video camera.
Minipulate the the ASA(ISO) on your light meter until it matches the f stop on your camera.
Whatever ASA(ISO) you end up with on your meter is your camera's ASA.