Five Stops of exposure for video
- Thread starter Amos Kim
- Start date
zoostory
Well-known member
what do you mean keep it at five stops? You mean you want to keep everything within the latitude of your digital camera, or you want to shoot something five stops over or under key? If the latter, I don' think many digital formats have that much lattitude, definetely not to go 5+
If you're talking about keeping things within bounds, in the video and digital world, it is usually typical to use a waveform monitor and the IRE scale, not the F/Stop Level style of shooting. So you would want to keep your blacks above 0 IRE and your whites under 100 IRE (typically). If you have a mac laptop and FCP, then you have a built in waveform. You can connect the firewire of your camera to FCP, open capture tool, and click the wave form button. I'm sure there are tons of tutorials out on the web for how to read one.
You can also use zebra stripes, which a lot of cameras have these days. You set them to an IRE, say 100, then everything at 100 IRE will have stripes, and you know you will need to stop down to be within bounds. It's not as specific as a waveform, but if you get good at using them, they can be quick invaluable tools.
Or, you can get a grey card from a film color chart evenly lit, zoom in and focus your camera on the card and turn on auto iris (make sure you don't have anything else set to auto, no gain, etc). Your camera will adjust to an F-stop, lets say for example, a F/2.8. Then, take an incident meter, set the frame rate to the same rate as your camera (use 30 for 29.97). Hold it in front of the gray card and toggle the ASA until the F-stop is 2.8. Then you have an ASA rating for you camera. For example, my Z1U comes in around ASA160 (low!) at 25fps. You can then use your meter like you would for a film camera. However, keep in mind that if you change any settings on your camera, like gain or shutter speed, it will alter these readings. Also, the IRE scale and F/stops do not directly correlate, so two stops above on your meter won't land exactly where you'de expect on a waveform... still, it's pretty close, and it's a good tool for discerning contrast ratios and spots that are out of your cameras latitude.
me personally, I tend to stick to zebras for typical smaller indie shoots. For daylight caucasion skintone I try to hit my actors at 70, for nighttime around 40 or 50 (trust your eyes!) Also, another trick I do in the day sometimes is I set my zebras at 100... I let a small part of the sky blast out over 100, and I keep that consistent. So yeah, I am losing that piece of sky, but as I adjust for sun level throughout the day, things stay pretty consistent.
Also, make sure to do some tests and get your cameras LCD screen to a more realistic brightness. Like on my Z1, when I first used it, the brightness was at full, I relied on my eyes, and was shocked to see how dark things were on my TV at home.
hope this helps!
If you're talking about keeping things within bounds, in the video and digital world, it is usually typical to use a waveform monitor and the IRE scale, not the F/Stop Level style of shooting. So you would want to keep your blacks above 0 IRE and your whites under 100 IRE (typically). If you have a mac laptop and FCP, then you have a built in waveform. You can connect the firewire of your camera to FCP, open capture tool, and click the wave form button. I'm sure there are tons of tutorials out on the web for how to read one.
You can also use zebra stripes, which a lot of cameras have these days. You set them to an IRE, say 100, then everything at 100 IRE will have stripes, and you know you will need to stop down to be within bounds. It's not as specific as a waveform, but if you get good at using them, they can be quick invaluable tools.
Or, you can get a grey card from a film color chart evenly lit, zoom in and focus your camera on the card and turn on auto iris (make sure you don't have anything else set to auto, no gain, etc). Your camera will adjust to an F-stop, lets say for example, a F/2.8. Then, take an incident meter, set the frame rate to the same rate as your camera (use 30 for 29.97). Hold it in front of the gray card and toggle the ASA until the F-stop is 2.8. Then you have an ASA rating for you camera. For example, my Z1U comes in around ASA160 (low!) at 25fps. You can then use your meter like you would for a film camera. However, keep in mind that if you change any settings on your camera, like gain or shutter speed, it will alter these readings. Also, the IRE scale and F/stops do not directly correlate, so two stops above on your meter won't land exactly where you'de expect on a waveform... still, it's pretty close, and it's a good tool for discerning contrast ratios and spots that are out of your cameras latitude.
me personally, I tend to stick to zebras for typical smaller indie shoots. For daylight caucasion skintone I try to hit my actors at 70, for nighttime around 40 or 50 (trust your eyes!) Also, another trick I do in the day sometimes is I set my zebras at 100... I let a small part of the sky blast out over 100, and I keep that consistent. So yeah, I am losing that piece of sky, but as I adjust for sun level throughout the day, things stay pretty consistent.
Also, make sure to do some tests and get your cameras LCD screen to a more realistic brightness. Like on my Z1, when I first used it, the brightness was at full, I relied on my eyes, and was shocked to see how dark things were on my TV at home.
hope this helps!
once you determine your F stop ( based on incident reading or on grey card for reflective) figure 2 1/3 stop over and 2 2/3 stops under that reading ( based on NTSC set up black at 7.5ire ....
figure once you do take a reading off grey card and if you set your Fstop at that reading - flip grey card over to white side and that should be around 2 stops over ...
figure once you do take a reading off grey card and if you set your Fstop at that reading - flip grey card over to white side and that should be around 2 stops over ...
taubkin
Veteran
The DVX in cinegamma has 7.5 stops of lattitude. And it's more like 2.5 up and 4 down. But thinking in f-stops is not very good in video, because an f-stop in a DVX is a lot of contrast. Thinking in IRE, at least by the 10%'s will give you a much better control.
Anyway, this is how I expose in video:
Shooting a gray card:
F16_________10%_________-4 Stop
F11_________13%_________-3 Stop
F8__________22%_________-2 Stop
F5.6________36%__________-1 Stop
F4.0________51%__________Diafr.
F2.8 ________70%__________+1 Stop
F2.0 ________86%__________+2 Stop
F1.8________98%__________+2.5 Stop
Anyway, this is how I expose in video:
Shooting a gray card:
F16_________10%_________-4 Stop
F11_________13%_________-3 Stop
F8__________22%_________-2 Stop
F5.6________36%__________-1 Stop
F4.0________51%__________Diafr.
F2.8 ________70%__________+1 Stop
F2.0 ________86%__________+2 Stop
F1.8________98%__________+2.5 Stop
Barry_Green
Moderator
A spot meter is of very limited value in video. If you're going to spend that kind of money, spend it on a waveform monitor (or a software waveform, like DV Rack). That will give you precise, usable information about your exposure.
HekCentrik
Member
taubkin said:
could you explain the chart above a bit better please? Do you mean to set the zebra at those values when the DVX is set to the different aperture settings? Are these with grey card calibrations or always? What's the HEX value for this grey card and should it have any reflective properties at all?
I use DVRack also and usually ignore the waveform (perhaps I shouldn't
) I usually do 80% for facial CU and 100% all other times, guestimating everything by eye. This produces various degrees of acceptability so clearly not flagrant overexposures isn't the thing to watch out for.school me please! :crybaby:
HekCentrik
Member
not if it's a rubbish, inconsistent look they woulddjgvinny said:this is exiting i smell a fight :evil:how about just shoot the dam movie ,if its good story and focused, nobody give f about the f stop