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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 :)

Just in case you were wondering how accurate ISO 800 is on Dragon...

Evin Grant

Evin Grant

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I decided to do a quick and dirty ISO verification of my Dragon last night, simple setup using a 500W Lowel Omni and a Macbeth chart.
This is obviously tungsten only and I'll try to do a sunlight and HMI test as well but it may take a week or so.

Notes:

Lens used was a 50mm f1.8(T1.9) AFS-G Nikkor so I could show the displayed stop on the 5" touch. (any discrepancy at f8 between the f & T stop is under 1/10 stop and within the margin of error of this test.)

The 18% chip exposure was verified by a Sekonic incident and Minolta spot meters (see pic) as well as the "video" exposure mode and a Zebra set to 41-43 IRE.

The frame grab was made in RC3/RG3 but was the same result in RLF.

This is only a reference to 18% grey placement as it relates to the indicated ISO, all other tone placements above and below will be determined by the curve in use.

Dragon800.jpg
 
thanks for the test! obviously much appreciated!
 
Great info Evin!
 
Thanks for sharing
 
Evin Grant said:
I decided to do a quick and dirty ISO verification of my Dragon last night, simple setup using a 500W Lowel Omni and a Macbeth chart.
Click to expand...
I've often said that I think the standard Macbeth chart is worthless in an all-digital world. It had a meaning in a photochemical film lab, but not for digital.

If you're trying to measure exposure, get the DSC Labs grayscale chart:

Toni_050511_E2W_3ins_sm.jpg


I much, much prefer a greyscale chart to a chart with random chips of color paints that have no bearing on modern-day camera chips. The DSC people are pretty sharp.
 
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  • #7
Marc Wielage said:
I much, much prefer a greyscale chart to a chart with random chips of color paints that have no bearing on modern-day camera chips.
Click to expand...

I wasn't using the color chips, just the 18% grey chip. With the backup from both the incident and spot measurements I can say with certainty that chip is accurate.
The rest of the chart is of limited use I agree, but it is a known quantity and that gives it some bearing as a reference outside the particular electro-optical system you may be testing.

The truth is I couldn't find my 15 year old Kodak grey card and I'm not sure I'd trust it at this point anyway.
 
Evin Grant said:
I wasn't using the color chips, just the 18% grey chip. With the backup from both the incident and spot measurements I can say with certainty that chip is accurate.
The rest of the chart is of limited use I agree, but it is a known quantity and that gives it some bearing as a reference outside the particular electro-optical system you may be testing.

The truth is I couldn't find my 15 year old Kodak grey card and I'm not sure I'd trust it at this point anyway.
Click to expand...

Whoa. I have a gray card from 1982. Perhaps I should toss it. :)
 
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  • #14
Jacobo Martinez said:
Guys, is 18% grey in the exposure meter ( GREEN HIGHLIGHT ) of red cameras 43 IRE? or is it 50 IRE? When you rate at 800iso in the camera, am I suppose to see 43 IRE in RCX or should it be 50 IRE?
Click to expand...

42-43 IRE is what Red's meters considered middle grey, I believe Arri uses 45 on the Alexa but it's widely considered anywhere between 42-50 but I've not seen a camera that uses anything higher than 47.

Remember the legal IRE range is 7.5-100 and it was originally an analog video brightness scale which is arbitrary when applied to the digital space.
 
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  • #16
The "RAW" view is a bit of a misnomer, it's not linear light and still has a curve applied plus it's not tuned to the Dragon sensor. I don't use the RAW view at all, I use the histogram, a meter and a calibrated monitor for exposure. If your big concern is noise then you need to test each EI and then bring it through your specific post chain and evaluate them in your specific delivery format on a suitable display for that format. Your tolerance for noise has as much to do with how the footage is being developed, delivered and displayed as it does what EI you shot at. So far I've projected (2K) up to EI 2000 Dragon footage and been very happy with the results as long as it's properly exposed.
 
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  • #19
Marc, I suppose you missed the "quick and dirty" part of my opening sentence :toetap05:

I'm well aware of the limitations of the the grey card, but I think this is the most salient point in Ryan's article...

"1. If it ain't broke, don't fix it.
If your current metering methodology is yielding consistent, predictable results, more power to you! Don't sweat the fact that 18% really isn't 18%. In the end it is about the results you produce, not the technicalities."

The point being that Red placing their "middle gray" exposure at 42 IRE appropriately compensates for any reflectivity difference, so call it 12% or late for dinner, with all three measurements in alignment you can feel confident using your incident, spot or in-camera meter for proper exposure without compensation, assuming you have tested your 12-18% grey card.

And yes, I need to buy a new grey card, probably this one from X-Rite though, those DSC charts are bit overpriced these days...
M50103_M1.jpg
 
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