ASA ratings for a video camera
Posted 17 January 2007 - 11:49 AM
But, I would like to establish an ISO rating on some of my video cameras (they are standard definition NTSC cameras with the gain set at 0 db) and I would prefer to use the method outlined by Harry Mathias in the ?American Cinematographer Video Manual?.
To test the cameras I have a well-lit chip chart, a Spectra Pro IV-A and a Macbook Pro laptop running a software (?Scopebox?) waveform monitor.
My question is what should I set my set my meter at?
Spectra Cine?s site suggests 25fps. I have seen other websites say 1/30 of a second (which seems close enough to the NTSC frame rate). My instincts tell me to set it at 1/60 of second because of the fact that it is an interlaced image and I think it might be prudent to err on the side of lower sensitivity.
What would you do?
Posted 18 January 2007 - 12:44 AM
I am a little confused as to why Spectra's site would recommend 25fps. That would only be the case if you were shooting PAL progressive.
Posted 18 January 2007 - 01:20 AM
Some websites seem to give directions on this issue without specifying which format they are talking about.
Posted 18 January 2007 - 12:08 PM
I mosted wanted to know the sensitivity of the cameras in order to help me determine how many extra lights I would need when scouting a location. At 1/60 of a second, I cannot make the mistake of over estimating the cameras abilities.
During the actual shooting I am more trusting of the Waveform and the Zebras, than the Spectra Pro.
P.S. The MAC OS X users might want to look at the free demo of the "Scopebox" software. It is a very nice Mac alternative to the Windows only "DV Rack" waveform/vectorscope monitor program.
Posted 23 January 2007 - 10:24 AM
a PD-170 and you should see the look I get in 4:3. I'm using monitor,zebra and of course
I can send it to post for the desired format. Now I agree the PD-170 is a toy compared to
what most dp's are using here. I believe at one time that I had my ASA figured out for the
PD-170 and I think it measured out to be ASA 400. Like everybody else here I left my Spe-
tra IVa in the bag and relied on the monitor,zebra.
Posted 23 January 2007 - 12:18 PM
The single most accurate way of reading video levels is with awavefomr. If not that then zebras will do you justice. Setting your faces at between 75 and 85 will pretty much garuntee you non overexposure in that area. I have an article on zebras that I thought was on my website. I see it is not. I'll put it up in the next day or two.
Posted 23 January 2007 - 12:52 PM
I have an article on zebras that I thought was on my website. I see it is not. I'll put it up in the next day or two.
Thanks Walter! I look forward to reading your article.
Posted 23 January 2007 - 10:13 PM