View Full Version : How do I find out the ISO of my EX1?
02-12-2008, 11:53 AM
Is there a way to find out what the ISO is on the Sony PMW-EX1 camera?
02-12-2008, 12:07 PM
There is no such thing. It all depends on what mode you're in, what gamma curve you're in, whether you're shooting interlaced or progressive, and whether you're shooting 1080 or 720.
Adam Wilt has tested it and found it to vary from 400 to 800 depending on just the interlaced/progressive and 1080/720 factors (1080p = 400, 1080i = 800, 720p = 640 IIRC?) But that doesn't factor in the effects of gamma curves, I think I remember he tested using STD3 gamma. Changing the gamma will change how the unit processes light and renders brightness, so it will affect the "perceived" ISO.
02-12-2008, 12:31 PM
I see. Thanks, Barry. I was reading something about using light meter, and it says I have to know what the ISO of my camera for me to effectively use the light meter. That's why I am curious about what the ISO of the PMW-EX1 camera is.
02-12-2008, 03:46 PM
You can't use a light meter effectively with a video camera, it's just a recipe for getting bad footage.
You can use a light meter to rough in your lighting to some sort of ballpark, but you have to use a waveform monitor and a calibrated production monitor in order to actually know how your image is exposing.
If you want to rough in your lighting heres a tutorial with help in determining your approximate ISO.
02-13-2008, 11:51 PM
If you're trying to determine exposure your best bet is using the camera's zebras and built-in readouts such as the histogram.
That way what you see is what you get.
Otherwise, your light meter has to take into account a large number of variables including whether you have an ND filter in place, other filters in front of the lens, gain settings, precise iris setting, etc.
And after all that you still won't really know if you're getting details in shadows or highlights unless you've done extensive tests similar to what used to be done with the zone system.
The tools available in the EX1's viewfinder will be quicker and far more accurate than the best external light meter.
I worked as a news photographer and a commercial photographer for 25 years. I used to shoot commercially with a 4x5 view camera onto Ektachrome 100N -- and even with the best of care I would bracket my exposures to make certain I had it nailed. The meters I had were extremely accurate and dependable Minoltas. But regardless of how accurate the meters were, even the best photographers would shoot several Polaroids during the setup to make certain everything was just right before committing to sheet film.
An incident light meter is only making a prediction based on information that is programmed into it. If you forget to take into account filter factors, shutter speed, aperature, magnification or gain, your exposure will be wrong. And if you point the incident light meter in the wrong direction, your exposure will be off, too.
A reflective meter provides exposure info that places whatever you measured in the middle of the tonal scale. Center the needle on a black object and it ends up grey. Center the needle on a white object and that, too, ends up grey. Unless you know your imaging system's brightness range, understand the tonality of your subject, and have taken multiple spot readings, you won't know if your shadows and highlights will be usable.
Trust me, using a meter will take up valuable time and not give you any information you couldn't otherwise get through your viewfinder.
02-13-2008, 11:57 PM
Very well said, Dean.
02-14-2008, 05:59 AM
Thanks for all your suggestions. That saves me $600 buying a light meter. I'm not looking to spend any money if I don't have to, but what about a field wave monitor? Does it worth buying them or it's still best to use the camera's information showing on the view finder?
02-14-2008, 10:40 AM
The EX1 has a histogram in it, and zebras, and IIRC it has a spotmeter.
A field waveform monitor is the ultimate tool for gauging exposure on a video camera, but without one you still will have plenty of tools at your disposal to make sure that you know what your exposure is doing.
Dedicated waveform monitors are expensive and becoming less necessary; one reason the Panasonic LCD monitors have taken over the industry is because they all have waveform monitors built-in. They're not as good as a dedicated waveform but they're close enough!
The information in the viewfinder/LCD should be accurate, and it should mathematically represent the brightness values in your footage so if you set the zebras to 105% and you see zebras in your scene, that'll mean you should indeed be in danger of clipping. A waveform monitor is great because it tells you everything about your scene all at one glance; the marker function in the HVX tells you a spotmeter reading and I believe the EX1 has the same type of feature.
The histogram? meh. Some people like 'em, I guess, but I find a waveform much more useful. But, hey, at least it has a histogram and that's much better than nothing!
So don't sweat the light meter, you have plenty of tools at your disposal that should give you a pretty good way to get proper exposure.
02-14-2008, 11:21 AM
Many thanks, Barry!