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F23 ASA & F900 ASA


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#1 rory hinds

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Posted 18 August 2007 - 08:27 AM

Does anyone know what the F23 and F900 ASA ratings are?

I've read 2000 ASA for the F23 with added gain and I'd like to know what the sensor is rated at.
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#2 Stephen Williams

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Posted 18 August 2007 - 08:48 AM

Does anyone know what the F23 and F900 ASA ratings are?

I've read 2000 ASA for the F23 with added gain and I'd like to know what the sensor is rated at.


Hi Rory,

I was testing the F900R recently. I estimate 320 asa with -3db. I was also shooting film, the T stops I used were identical on Kodak 5218 which I usually rate at 320 asa.

Geoff Boyle has posted some tests on CML
http://www.cinematog... 2007/index.htm

Stephen
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#3 Shaun Joye

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Posted 20 August 2007 - 01:31 PM

I was at a presentation a while ago where they mentioned they kept the ASA rating the same for the F23 but the redesigned CCD gives it a better signal to noise ratio. I didn't do any real tests with the F23 but I could definately tell that it was less noisey than the f900.
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#4 jan von krogh

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Posted 20 August 2007 - 02:01 PM

I was at a presentation a while ago where they mentioned they kept the ASA rating the same for the F23 but the redesigned CCD gives it a better signal to noise ratio. I didn't do any real tests with the F23 but I could definately tell that it was less noisey than the f900.


Hi,

same here, when i asked about the rating of the F23 in 2006, i was told approx. the same as 900/750.
F900/750, who share the same optical block were described to us as 600/300 in i/p when we bought the 750.
Our experiences so far indicate that these figures are realistic.

However, with the slowshutter option on the 900R and 750/790 (not on the discontinued classic 900), you can reach >20000 asa without gain or noise.
Its no problem to push 16 stops that way - however, at a very slow framerate then.
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#5 Michael Nash

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Posted 27 August 2007 - 05:58 PM

I was testing the F900R recently. I estimate 320 asa with -3db. I was also shooting film, the T stops I used were identical on Kodak 5218 which I usually rate at 320 asa.


Sounds about right. At zero db gain it's usually about 400 ASA. 3db = approximately 1/2 stop change in luminance, so +12db gain puts you about 1600 ASA, with noise of course. I haven't tested the F23 yet.
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#6 Matt Workman

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Posted 13 November 2007 - 05:45 AM

Obviously you can just use a scale/meter/waveform to actully derive a rating for the camera but the specs Sony were dropping at ProTech were:

@ 0db

400 ASA Dynamic Range Normal
530 ASA Dynamic Extended

Changing the color space from ITU to DCU and using SLOG/HyperGamma will effect what you rate the camera at. He also mentioned that because the camera can see into the blacks about 2 stops before film DP's rate it much higher. Then you get into Gain etc.

12-13 stops shooting with SLOG. Cinetal monitors and SpeedGrade demos were helpful, but trying to bring around all the tech gear on a shoot just sounds like a headache.

He mentioned that HyperGamma 1/2 I believe were designed with -3db. There are a lot of improvements on this camera for sure, but there are also A LOT of new things to keep track of.

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#7 David Mullen ASC

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Posted 13 November 2007 - 11:54 AM

Yes, the Sony literature seems to suggest that the sensitivity at 0db is the same as before -- around 320 to 400 ASA -- but that the noise is so much better with the F23 that a faster rating using gain is possible with less noise problems.
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#8 Jerry Doran

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Posted 13 November 2007 - 12:45 PM

Obviously you can just use a scale/meter/waveform to actully derive a rating for the camera but the specs Sony were dropping at ProTech were:

@ 0db

400 ASA Dynamic Range Normal
530 ASA Dynamic Extended

Changing the color space from ITU to DCU and using SLOG/HyperGamma will effect what you rate the camera at. He also mentioned that because the camera can see into the blacks about 2 stops before film DP's rate it much higher. Then you get into Gain etc.

12-13 stops shooting with SLOG. Cinetal monitors and SpeedGrade demos were helpful, but trying to bring around all the tech gear on a shoot just sounds like a headache.

He mentioned that HyperGamma 1/2 I believe were designed with -3db. There are a lot of improvements on this camera for sure, but there are also A LOT of new things to keep track of.


I'm confused about HyperGamma. Can anyone explain exactly what HyperGamma is doing and the differences between the 4 settings? When do you choose one over the other? How much does it change the effective ASA?
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#9 Shaun Joye

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Posted 13 November 2007 - 02:25 PM

I'm paraphrasing Jeff Cree's explanation. Hypergamma follows the regular itu 709 curve for the toe, but then gives you more latitude for the highlights. So it gives you more dynamic range than the standard curve but doesn't give you that washed out contrast look of uncorrected log. As for the differences between the 4 I really have no idea.
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#10 Jerry Doran

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Posted 13 November 2007 - 05:25 PM

I'm paraphrasing Jeff Cree's explanation. Hypergamma follows the regular itu 709 curve for the toe, but then gives you more latitude for the highlights. So it gives you more dynamic range than the standard curve but doesn't give you that washed out contrast look of uncorrected log. As for the differences between the 4 I really have no idea.


So, unlike S-Log, Hypergamma doesn't require image correction in post?
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#11 Michael Nash

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Posted 14 November 2007 - 04:25 AM

So, unlike S-Log, Hypergamma doesn't require image correction in post?


Yes, that's the basic idea.

http://bssc.sel.sony.../F23_FAQs.shtml
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#12 Shaun Joye

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Posted 14 November 2007 - 05:35 PM

Speaking of hyper gamma curves, I remember from talking to Jeff Cree that they're designed for different white levels and different gain settings, does anyone know where I could get this specific information? Unfortunately I wasn't taking notes.

-
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#13 Michael Nash

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Posted 14 November 2007 - 05:52 PM

http://www.dv24p.net...l1stEdition.pdf . Page 47.

I wasn't taking notes either, and there are sooo many particulars that are unique to this camera. I'll take a trained AC or DIT with me the first time I use it!
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#14 Dave Perkal ASC

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Posted 15 June 2008 - 11:45 AM

i just used it for a commercial airing during the NBA playoffs. I rated at 320. These are the Get Smart promos.
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