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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

Latitude in Tungsten & Daylight - downloadable charts

geoffboyle

geoffboyle

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I expect to get a ton of abuse again but anyway.....

http://www.cinematography.net/BKK/index.html

The images were shot during a Santa Fe Worshops Digital Cinema class in Bangkok

The camera was build 20 and rated at 320 ISO at 5600 Kelvin

The images were rendered from the R3D files with SpeedGrade XR 2009

Software was set to 250 ISO and 5600 Kelvin detail at max everything else off

Images were rendered to HD DPX files and then converted in Photoshop to small GIF files

As usual click on any of the small images to get the full res one.

Lens was a Master Prime at T5.6
 
I for one do appreciate that you shoot and post these tests for us. Does anyone know of a free DPX viewer for PC's?
 
Thanks for posting these. Can you, or someone else enlighten me on the following questions- (I'm downloading the DPX's now.)

1. On the very first daylight image at least on the small gif there is a smear on the right side- is that in the DPX and if so, what is that?

2. The base exposure is T5.6 @ 320- or the middle image. I assume that the other exposures were made via opening and closing the lens- is that correct - and are they at full stops, or fractions? If it was made another way, what was that process?
 
So it looks like there is a smear in the DPX file- what is that?

Also- is anyone else having issues with BK120059.dpx - Photoshop keeps telling me the file is bad. I'm re-downloading it now...
 
Geoff,

Can you give a bit more of a breakdown of these images?

You say the lens was at 5.6 and the camera was rated at 320.

Which of the files are the baseline? There is no what to tell by the file name or an onscreen slate.

What part of the exposure was changed? The lens? or the software?

Sorry for so many questions but I would have no reference point to evaluate these images.

David
 
OK, the blur on the initial daylight chart is the AC moving the chart out of shot :-)

As the shot is duplicated later in the series I didn't bother to re-render.

Iris was indeed used for exposure changes at half stop intervals.

As to what was base exposure, well the idea was sorta to work out what was "correct" from the frames.

That said the first in the series is nominally correct as is one that matches further down.

In case anyone wonders, I rendered out at 250 to make sure that highlights didn't clip, something that people queried last time.

I'm going to add a third strand, corrected tungsten.

If I ever get the files I'll also add scanned film-out frames from these charts.

I'm putting these charts up for people who don't have cameras of their own or easy access to kit so that they can see what happens in controlled conditions.
 
I'm in the process of uploading a third set of charts.

Shot in Tungsten but rendered out at 5600.

So we now have Tungsten lit rendered at 5600, tungsten lit rendered at 3200, daylight lit rendered at 5600.

Interesting differences in sensitivity and noise.
 
Geoff,

which gamma curve did you use? Rec709, RedSpace (probably not)? If you used Linear, then I guess you added a log-like curve in SpeedGrade, ASC Power for instance. RedLog is not supported in SpeedGrade.

I'm not sure which SDK build is used in SpeedgGrade 2009. It may be the old one, prior firmware build 20, which is not utilizing the new colour science. The new colour science produces warmer looking pictures in a daylight environment and has less noise in white balanced tungsten lit pictures when the colour temperature is set to 3200K.

I find it much better to process under tungsten light shot R3Ds at 5000 ASA and WB them later than using Red's SDK for this task.

Your 250 ASA approach is meaningful until someone at Red confirms that at 320 ASA the absolute white is set to 1023 and not one bit higher. Otherwise we must assume that at 320 information in the highlights will be cut off by the SDK.

Thanks for posting,

Hans
 
Thanks for the answers, and for the tests. :)
 
Hans von Sonntag said:
Geoff,

which gamma curve did you use? Rec709, RedSpace (probably not)? If you used Linear, then I guess you added a log-like curve in SpeedGrade, ASC Power for instance. RedLog is not supported in SpeedGrade.
Click to expand...


Camera RGB and Redlog which is certainly supported in SpeedGrade XR 2009 and also SG DI, it's not supported in On-Set but I'm fairly certain that it will be in the next version.


The SDK as far as I know is 3.3, the latest release.
 
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