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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 :)

Redspace vs. Sekonic

Manuel Wenger

Manuel Wenger

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I just tried to figure out what Redspace is about and shot a 11 scale grayscale with a dynamic range of 6 stops. I overexposed up to 2.5 stops and could recover detail up to +1.5 stops, i underexposed up to 2.5 stops and i could bring it up to a (for me) acceptable noise level of -2 stops, so I´m getting about 9,5 stops of latitude, have to say the test was not very scientific, i did it on my balkony, so light could have changed slightly. so i think there is maybe a 0.5 or 1 stop more possible

BUT what raises a question mark is the following.
I set exposure of the greyscale using the false color function, which in this case indicated a T11 for neutral grey (green in the False Color) Exposure done using Redspace 25fps 1/50s shutter ASA 320.
If i set my Sekonic to 320 ASA 25fps i get a reading of T22 for neutral grey ???

Any advice where these 2 stops difference are coming from ?

Manuel
 
RE false color temps V/S metering

RE false color temps V/S metering

Isn't the green false color set for Caucasian skin exposure? This is slightly off 18% grey - I would check that with an 18% grey card and your sekonic in spot meter mode in controlled lighting conditions (remember to use a daylight color temp or exposure will be slightly off) and then do an ambient reading for comparison. You have probably done this, but just to make sure... I'd be interested in hearing what your results are!
Best,
Drew
 
Hi Drew, the green is 18% neutral grey, caucasian skin tone is pink in the false color mode. Did a spot meter reading and an ambient reading they´re both 2 stops of from what false color meter tells me. I posted somewhere else, if i do a spotmeter reading at the false color green i get a reading of 56-58 IRE for neutral grey, which in my opinion is too high, I´d consider Neutral Grey somewhere at arround 45 IRE depending on the curve.

Manuel
 
Hey Manuel,

Maybe this will help evaluate the false color signal... There are three exposure guides available: false color, RED spot meter, and zebra value. It would be interesting to compare the response of each of these, along with a waveform monitor, and reference that to the light meter. I have not yet tried this...

Karl
 
I shot a grey card and got the same result. I used the spot meter in camera set to320 ASA and 50 IRE and used my sekonic at 320ASA for an incident reading and spot reading and the Red came out to be 1 and 1/2 stops slower than my reading.
 
Further up to go away from "native", and I believe more the penalty.
I need more details from " Native" SPACE than REDSPACE.

Stewart
 
framework said:
Hey Manuel,

Maybe this will help evaluate the false color signal... There are three exposure guides available: false color, RED spot meter, and zebra value. It would be interesting to compare the response of each of these, along with a waveform monitor, and reference that to the light meter. I have not yet tried this...

Karl
Click to expand...

WOW ! What a RED # you have on hands in states.

9.11 stops in RED ?

Sorry for my other issues with you :
Have you planned to use RED to make 911 ? No Offense but it's needed for our CHINESE WORLD to understand more about RED 911.

I can co-invest the New RED 911 films with you in both HK-China and US, and I am serious.

Stew
 
Stew ! WTF are you talkng about ??
If you can contribute to this issue, you´re more then welcome to post, otherwise please tame your fingers down, no offense. I like your attitude.

Hi Karl, IRE reading on the spotmeter was 58 for the neutral grey, didn´t try out zebra yet
 
I can confirm the same here. The DP on the feature that is being shot with our 2 Red cameras is saying the same: 2 stops difference between sekonic reading and what false color is saying. This remains a bit confusing.
 
manuelwenger said:
Stew ! WTF are you talkng about ??
If you can contribute to this issue, you´re more then welcome to post, otherwise please tame your fingers down, no offense. I like your attitude.

Hi Karl, IRE reading on the spotmeter was 58 for the neutral grey, didn´t try out zebra yet
Click to expand...

I am hearing not WTF and should be like this order " World Fair Trade "
( WFT ), and you know what I am talking about my freind.

STEW
 
I noticed the same thing when doing some exposure profile tests. The white patch on the card (+2.33 Ev) was green in the false colour display.
 
...seems, somebody from RED has to enlighten us ;) Stuard, Jarred where are you ??
 
I believe that False color is linked with Histogram and RAW. In that case, it's setting the grey card it see to the "sweet spot" at the histogram range, so it's not behaving as "visual" spotmeter, but it's tightened to camera sensor. So if there is a space in left side of histogram (no big highlights), to fill the whole range, it will push that way.

Or maybe I'm wrong and there is some bug. Or it's different philosophy of establishing exposure. Cos if I set grey card, measure it with spotmeter and get response that the reflectance is 8EV (100ASA Calibrated Pentax Spotmeter) will set the Spotmeter's Calculator to 320ASA, set 8EV against 18% mark, the F-Stop is 4. If I set the false color that there is green cast over 18% greycard then the f-stop (actually T-Stop) on lens is 2 1/2. So that's 1 and 1/2 difference.
 
One week ago, using the Histogram and our eye (i know, I know), we noticed the same thing. We had 2 stops difference in daylight and 1 1/2 stop difference under tungsten light.
 
I have a sekonic 758DR and before "Red Space" I was having problems getting accurate exposures with the RED (I was getting good exposure, but the monitor and histogram looked underexposed). Now with build16 and Redspace its much closer to perfect as far as matching my meter (and at all iso's). I had to profile the meter for my Red again but I am extremely happy with it now. Just fiddle around with the profile start-up menu (see the sekonic instructions) record some footage, than process and check it in Red alert. I wouldnt trust the flase color too much.
 
hunterrichards said:
I have a sekonic 758DR and before "Red Space" I was having problems getting accurate exposures with the RED (I was getting good exposure, but the monitor and histogram looked underexposed). Now with build16 and Redspace its much closer to perfect as far as matching my meter (and at all iso's). I had to profile the meter for my Red again but I am extremely happy with it now. Just fiddle around with the profile start-up menu (see the sekonic instructions) record some footage, than process and check it in Red alert. I wouldnt trust the flase color too much.
Click to expand...

We were using redspace in build 16 as well and had the same issue as Jeff Deveraux.
 
I think it was posted the other day that build 15 has a 0.4 stop buffer in the stoplights for clipping, but that has been removed for build 16 to get more accurate exposure. Although that explains why the monitor looks a little dark, it doesn't explain why you'd be off 1.5 stops-ish.

Thanks for the info on build 16 being okay when calibrated.
 
From the two shoots that I've done on B16, I can also confirm the 1 to 1 1/2 stop difference between the Sekonic light meter and Red. In Redspace, which is supposed to boost the gamma for midtones, The spot meter reads f5.6 where the Red reads f2.8 1/2 to f4. This has been a disturbing finding, as we had to rate the Red at ISO 160 to get accurate results from the meter. Hopefully it is a bug that can be fixed in the release build for 16 and not related to the native response of the sensor.
 
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