AF100: ISO or GAIN?
- Thread starter HVX-Ninja
- Start date
TheReverend
Well-known member
It's ISO labelled on this camera.
ISO is adjustable. 3200ISO as a high has been mentioned (though not final). Cam is a very low noise cam (much lower than HPX170/HMC150).
The final ISO native number rating on the cam is not final. But currently the cam is tenatively about 320 ISO.
Barry_Green
Moderator
It does both.
It is adjustable in 1/3-stop increments from 200 up to 3200. And yes, the higher you set it, the more noise you'll see. However, it still looks pretty darn good at 1600, as will be attested by anyone who checked it out at the IBC or DV Expo shows.
Rick Burnett
Section Moderator
So Barry, does that mean it has internal digital and analog gain? That you can use as you want?
Barry_Green
Moderator
Well, yes, I mean, changing the ISO is the same thing as adding gain. It's just called something different on the DSLRs. But it's the same process.
The lower ISOs are gotten at by (presumably) negative gain, and the higher ISOs by positive gain.
The lower ISOs are gotten at by (presumably) negative gain, and the higher ISOs by positive gain.
Rick Burnett
Section Moderator
Ahh, okay. Well I've read that the 7D uses both analog and digital gain, just wondering how that translated to the AF100 and how Panasonic does that. I am very familiar with the reasons why you use both, which are dependent on ALL the sources of image noise.
In other words, I was wondering if they had increased the granularity of settings, or, if they just provide two different methods for setting ISO, ie, one that video people would use and one that DSLR people would use, if that makes sense
In other words, I was wondering if they had increased the granularity of settings, or, if they just provide two different methods for setting ISO, ie, one that video people would use and one that DSLR people would use, if that makes sense
Barry_Green
Moderator
The two methods are chosen based on whether you set the camera in FILM CAM mode or VIDEO CAM mode. In FILM CAM mode, sensitivity is adjusted by specifying ISO values. In VIDEO CAM mode, sensitivity is adjusted by specifying gain in dB values.
I don't know for certain but I strongly, strongly suspect that the difference between them is simply one of labeling. I'm fairly sure that (assuming native ISO of, say, 400) that setting 6dB of gain in VIDEO CAM mode, or setting ISO to 800, would result in identical imagery. This is theory as I didn't test it, but I'd be gobsmacked if I'm wrong about it.
I don't know for certain but I strongly, strongly suspect that the difference between them is simply one of labeling. I'm fairly sure that (assuming native ISO of, say, 400) that setting 6dB of gain in VIDEO CAM mode, or setting ISO to 800, would result in identical imagery. This is theory as I didn't test it, but I'd be gobsmacked if I'm wrong about it.
Ryan Patrick O'Hara
Veteran
Barry is completely right. That's how it should be. Setting a camera's ISO higher than it is natively is the same as gain. To me, it's a matter of labeling, such as video shutter being in fractions and film shutter being in degrees. 180* at 24fps is the same as 1/48 shutter at 24fps. Same thing different terms. Every film stock and video camera sensor has ONE and only one manufacturer set sensitivity. How you personally rate it is a matter of taste, but regardless there is only one sensitivity level. Setting the chip at a higher ISO is boosting the signal. It's gain.The two methods are chosen based on whether you set the camera in FILM CAM mode or VIDEO CAM mode. In FILM CAM mode, sensitivity is adjusted by specifying ISO values. In VIDEO CAM mode, sensitivity is adjusted by specifying gain in dB values.
I don't know for certain but I strongly, strongly suspect that the difference between them is simply one of labeling. I'm fairly sure that (assuming native ISO of, say, 400) that setting 6dB of gain in VIDEO CAM mode, or setting ISO to 800, would result in identical imagery. This is theory as I didn't test it, but I'd be gobsmacked if I'm wrong about it.
groveChuck
U-matic Member
Barry- how else, other than ISO or Gain, do the settings vary between FILM and VIDEO mode?
Barry_Green
Moderator
The major things between FILM CAM and VIDEO CAM operation type are:
1) FILM CAM provides for variable frame rates, VIDEO CAM doesn't
2) FILM CAM sets the syncro scan shutter in terms of degrees (like 180.0 degrees), VIDEO CAM sets it in terms of absolute exposure time (such as 1/48.5). When in FILM CAM mode, using the syncro scan shutter will automatically track with the frame rate and adjust the exposure so that you get film-style motion blur at whatever frame rate you've chosen
3) On the HVX/HPX cams, VIDEO CAM allows access to features like Pre-Record and Interval Recording, which are disabled on FILM CAM mode. Not sure if the AF100 works the same way.
4) FILM CAM sets sensitivity in terms of ISO, VIDEO CAM sets sensitivity in terms of dB of gain.
That's all I can think of offhand. There may be more changes between the two modes, but I can't think of what they are at this time; I'd need more time with the camera to know for sure.
1) FILM CAM provides for variable frame rates, VIDEO CAM doesn't
2) FILM CAM sets the syncro scan shutter in terms of degrees (like 180.0 degrees), VIDEO CAM sets it in terms of absolute exposure time (such as 1/48.5). When in FILM CAM mode, using the syncro scan shutter will automatically track with the frame rate and adjust the exposure so that you get film-style motion blur at whatever frame rate you've chosen
3) On the HVX/HPX cams, VIDEO CAM allows access to features like Pre-Record and Interval Recording, which are disabled on FILM CAM mode. Not sure if the AF100 works the same way.
4) FILM CAM sets sensitivity in terms of ISO, VIDEO CAM sets sensitivity in terms of dB of gain.
That's all I can think of offhand. There may be more changes between the two modes, but I can't think of what they are at this time; I'd need more time with the camera to know for sure.
groveChuck
U-matic Member
:thumbsup:
