Sekonic and RED Adjustment

[Ergin Ozturk]

Altough i have read lots of posts regarding RED ASA and lightmeter readings i could not understand why my Sekonic reading and RED readings are different in specific ASA (ISO) values

So i decided to make a quick test with my gray card;

1.I switch my RED to false color mode
2.I evenly lit my grey card
3.Adjust ASA values in RED
4.I adjust fstop untill my gray cars is "green" in false color and noted fstop value
5.Adjust lightmeter asa same as RED and read the fstop

repeated 3-5 steps for every ASA

After i see the sekonic readings and RED reading i found the difference is consistent for each ASA value which is 1.7 ftsop. So i adjust my Sekonic +1,7 fstop now everything seems fine. For same ASA value i am reading same fstop for both RED and Sekonic.

So my question is do you think that am i making a mistake by doing this adjustment?

[Dominic Jones]

I certainly don't treat Red as 320ASA, so no, probably not...

Were you lighting with tungsten or daylight sources? That can make a difference, so I would check under both if you're planning on relying on your meter.

One thing I can't quite understand though, is why you are performing step 3 - oh wait, you're adjusting that to check that the ASA readings match across all settings, right? That should work fine...

One other thing is to check which viewing space you're in - bearing in mind that false colour is reliant on the View LUT that you're currently using, and also that apparently false colour is not accurate in View RAW mode.

But, assuming you're shooting under tungsten sources and WB is 3200K, that sounds like about the right result to me - about 2/3 stop slower than indicated by camera. I usually set my meter to 250ASA under daylight and 200ASA under tungsten, which should give almost identical readings to your system...

Hope that helps,
Dom.

[Filipo]

I usually set my meter to 250ASA under daylight and 200ASA under tungsten, which should give almost identical readings to your system...

Hope that helps,
Dom.

What are you using rec709 or redspace?

[Ergin Ozturk]

What are you using rec709 or redspace?

redspace

[Dominic Jones]

Same here, so that makes sense...

[Vance Colvig]

I am new to the digital world and to RED, but as far as I can tell so far, metering RAW seems like the best way of getting the most out of the sensor. Am I wrong?

[Dominic Jones]

That's one perfectly acceptable way to work, but there are others...

I'm personally very keen on metering when shooting with this camera, although it is by no means a necessity. For my part, I find that since the "video tap" on the camera does not really show you what you are recording, and since false colour in RAW view is apparently inaccurate (and even before I knew this, as I'm more comfortable with meters than the new false colour system on Red), it pays to have a more "film like" approach to lighting than one may take with an F-900, for instance.

I will, usually, drop into View RAW mode to check my highlights aren't clipping, but it doesn't give you so much info about what's happening at other points in the exposure range, so it's not a one-stop tool, for my tuppence.

At the end of the day though, whatever gets you pictures you are happy with is "correct" - and that will be different for different DPs, of course...

[Blair S. Paulsen]

While metering the RAW is a good reference point, in my experience there is more to the story.

IMHO the best way to get exposures that match your intent is to run a simple test. This will not be a definitive technical measurement but it will help you to learn the relationships between the various tools like false color and the histograms. Get a feel for what the monitor tap puts out versus a processed RAW image, etc.

1) Medium shot of a human subject, a test chart or gray card, the background should be a mixture of colors, have some hard light and a softer source.

2) Set the camera ASA/ISO to 320 (yes Viginia, it is a bit slower than that) and set a fat stop like F4 on the lens, remember this is only a test - seeing the effects of over and/or under exposure is good information.

3) Mess around with every exposure tool there is: light meter (incident and spot reading galore), histograms, RGB stoplight, false color, etc and repeat any on camera readings in RedSpace, Rec. 709 and RAW. (Disclaimer: the version of RAW the camera is showing you may be gamma encoded and has been reported as variable depending on which firmware build you are running. For specific information on this matter please ask Stuart English as he knows the details a thousand times better than I do.)

4) Roll short clips at F2.8, 4 and 5.6. Open the clips in RedAlert, RedCine or Scratch. Look at the histogram! Play with all the controls and see the results with your own eyes. Make some 4K TIFF stills and open them in Photoshop if that is a familiar working environment for you.

After you have taken the best exposed clip and adjusted it to suit your taste compare the processed image on your monitor to the RedSpace monitor tap live off of the camera. Using the same stop as the best exposed clip reference image, run through the various exposure measurement aids and judge their accuracy for yourself.

My personal working style has evolved to using false color in RedSpace as my primary exposure reference. While I don't care to dispute those who claim that the only reliable information is linear light RAW I work in the real world where RedSpace output is the most client friendly choice. By training my eye to know what RedSpace false color readings mean in reference to what I will have to work with when grading the RedCode RAW data in Scratch (or RedAlert) I get excellent results. YMMV.

[J. Eric Camp]

My test, approach and workflow is pretty much identical to Blair's.

[Ergin Ozturk]

I am new to the digital world and to RED, but as far as I can tell so far, metering RAW seems like the best way of getting the most out of the sensor. Am I wrong?

We spent 2 days in Cyprus for a feature test. First day i used RAW as reference and noticed that everything was overexposed. second day i swithed to Redcine and it seems more proper highlight. So ı do not prefer RAW as reference especially in highlight conditions.

[Vance Colvig]

Thank you for your offerings. I will do the exposure test method as discribed and see what I can learn.
All the best,
Vance