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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 :)

Sekonic Profiling

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Irri

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I managed to get hold of an exposure profile target and I'm going to run a test this week.

I was thinking of Setting the metre to 320, pulling back 0.4 exposure in Red Alert and exporting tiffs. I'll do one for daylight and one for tungsten.

Have I forgotten anything?
 
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yes, I would want one for each new build. Maybe one for 320, one for 400 and one for 500 too.

I guess Weirdcrew has a point about metres being out from each other, but I hope they aren't too far out.
 
I read somewhere in the manual that you should calibrate your own camera and meter. No 2 cameras or meters are alike there for it won't be accurate. How accurate? That is the question.
 
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Well, I have found that people with little experience of RED who rely on their metres can be a couple of stops out in terms of exposure. I hope Sekonic metres are more accurate than that, considering what they cost.
 
Be sure to download the latest version from their website. The CD that ships with the meters might be out of date. My meter came with 1.n while 2.n is now on their website.

They also have a new profile chart, but it is not available yet. The new manual shows how to use either profile chart.
 
I will use the latest software. I have the 1st exposure profile chart. The second one looks like an easier, quicker way to do the test, but no more accurate. It just has more shades of grey.

I'm happy to post the profiles, but bare in mind they will be specific to my Sekonic, the lens I use, the settings I use in Red Alert etc. I'm not sure how something like DRX will affect the profile if you are using tungsten for example.
 
I took a look at this and the manual suggests shooting an 11 stop range of exposures using the camera's exposure time. I couldn't work out how to do that with a RED. I also thought the sensor may vary at longer exposures times.

I was think of doing something like the following 1/25 to 1/1600 and using the lens stop for the rest. Any thoughts?
 
Irri said:
I took a look at this and the manual suggests shooting an 11 stop range of exposures using the camera's exposure time. I couldn't work out how to do that with a RED. I also thought the sensor may vary at longer exposures times.

I was think of doing something like the following 1/25 to 1/1600 and using the lens stop for the rest. Any thoughts?
Click to expand...

Thats the way to do it, read the manual for the v2 software and there is a description of what to do when shooting flash photography which also is limited in the available stops like you are.

To the point: I just did this for my still cameras and you should definitely run the v2 software, (download from sekonic.com), and remember you need exactly 11 jpg/tiffs from each color temp and every ISO (and flash for stills...) exposed under exactly the same lightlevels (<1/10 of a stop precision). I had to shoot 132 images and had to manually align them in the software - I'm an idiot for not seeing that comming, so please do not move anything around between shots as it takes ages to align the shots in the software if you move anything around. You need to consider what you would normally do in Red alert or Red Cine before rendering out the tiffs. If you use some shadow lifting curve or highlight retention function this should be tested and stored as a possible seperate profile. You can then compare profiles and visually move the limits in the meter around to make a profile wich works for you. When a couple of people has done this, sharing would be beneficial as it is a lot of work to shoot, test and process all the shots.

One very important aspect though is you need to define clipping points and DR clipping points and middle gray level in the software before starting making the profiles. This means you should decide at what RGB level (!) the absolute clipping point and the visual white threshold should be at and what your 12/14/18% gray should be at. Sekonics suggested values might not be suitable for you motion film guys. This decision will decide where those small clipping points on the meter is located relative to the middle gray point.

The whole process is so complicated and full of trapdoors that I'm very tempted to in the future do the calibration process manually based on what I see in post directly on the meter and forget the custom target and software. The problem with this is that it is not possible to back up all those data if made directly on the meter. And you need to do it for every ISO step as clipping points move...

I found that using the measured exposure and using highlight and shadow retention in post the 11 shots were not enough. The darkest shots where not dark enough and several more shots is needed to get below the noise threshold on my still camera, but it is not possible to extend this in software and it is not possible to manually extend the DR clipping points beyond the measured values in software, you have to override it after the profile is stored in the meter and then loose the possibility to save it.

All this will be very clear to you when you do it yourself and I wouldn't expect to get everything 100% in the first go when using the RED as it is a few assumptions to be made before the tiffs are ready for analyzing.
its very late now and I might explain the process better when awake.
MHO
 
Thanks for all the tips Robin. I guessed this would be the sort of thing where you need to do it once to get a feel for it. I'll do one this week and then do it again next week when I have some Master Primes to play with. I get the feeling they will have very accurate T-stops.
 
Man, this is a pain in the arse!

It wants spot and incident readings for everything, it wants shutter in fractions like 15th 30th 60th, and it says line up the crosses to the ones on the profile chart. There are none on the chart!
 
Red staff out there. ATTENTION. Robin's comments seem very informed. What is Red's position on this exercise. I know some companies, and I belive Abel Cine is one, will take your camer in for adjustments. I have no idea of what this costs. Can Red do this as a new profit center and service for owners? Seems pretty inportant to me, but my time might be better used elsewhere.
 
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