Maximum Exposure permitted is not enough

I measured the light levels in my real living room with my camera, In bright sunlight I get 245Lux. In my render a nice bright sun lamp looks exactly right.

If I then measure my real room in lamp light its at 20 Lux. If I set my scene bulbs to the correct light wattage output everything looks dark as it should. I then turn up the exposure as your eyes do and as you would on a camera, except it only goes up to 10.

245/20 is more than 10. I need to turn the exposure up to 12.25 to achieve the same dynamic range as I see in reality. Is there any answer to this other than to turn all my lights up artificially?

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So, just to be clear, your ultimate goal is to get Blender’s rendering system to function with real-world values as effectively as the human eye? If so, I believe that is an unrealistic expectation. It may take thousands of dollars worth of camera gear to begin to capture enough data in order to recreate a scene close to what the human eye sees*. You will need to make compromises either in the use of real-world, accurate values, or you’ll need to accept the limitations of the system.

A more realistic goal would be to get Blender to be able to image your scene similar to a consumer digital camera sensor.

That being said (and without being in front of Blender at the moment), have you tried manually typing 12.25 into the exposure value setting? Blender sliders may have a default maximum value but quite often you can manually type in a value above that maximum. Give that a shot, and let us know how it goes!

* Raw sensor capabilities rather than post-processing techniques like exposure bracketing.

Isn’t that a soft limit meaning that you can type in higher numbers than the slider initially permits?

No it won’t let me type in higher than 10. It corrects anything over 10 back to 10.

If I install the photographer add-on I can get the exposure up slightly more, so it’s not some sort of hard limit. The box just won’t accept higher numbers.

Are you talking about the exposure in the Color Managment tab? Because I just tried and I can type in numbers ranging from -32 to 32

No. Exposure in the Colour Management Tab is applied post render. It has no effect on ray-tracing noise.

Exposure that effects the render is under the Film tab.

You made two assumptions before deciding the slider is wrong.

“. . . in bright sunlight I get 245Lux. In my render a nice bright sun lamp looks exactly right.”

". . . If I set my scene bulbs to the correct light wattage output everything looks dark as it should . . . "

How are you measuring the 245 lux in Blender? It seems like you’re arbitrarily choosing something you like the look of and assuming it must have real world value.

  • Have you tried increasing the light strength?
  • Is your monitor profiled? Try changing the brightness/contrast and see how that looks.
  • It might look better viewed in lower ambient light levels . . .

I’m labouring the point, but you can’t assume it must be right because of how it looks.

I have never touched the film/exposure to set anything. Only color management/exposure. There is no manual setting in my version of Photographer addon that adjusts film/exposure. If you use Nishita sun & sky texture at strength 1, that is your reference light. My version may be outdated, but when I set sunny/16 rule (f/16, 1/100s, iso100), Photographer sets the film/exposure to -6.64, and anything under direct frontal clear sun & sky light should not be overexposed. I think mine gets underexposed, but I think I used a version pre Nishita where other assumptions were made.
The issue is that in vanilla Blender nothing (yet) is measured in photometric units (nor can we measure received light), but in some “weird” watt measurement that has nothing to do with a lamps electrical watt usage - this “watt” term has caused insane amounts of confusion. There is an addon that gives you extra lights in the light menu, the free one does come with a few reference lights that provide a good enough starting point for almost anything artificial (not LPS or other “pure” sources, Cycles can’t do those). An 800 Lumen A19 LED lamp translates to 2.1308 watts.

In real life you can capture a lot of exposures and assemble them into an HDR and work from there. In rendering, you get everything there is in a single render as long as you save in some HDR format and work from there. The most common and no brainer approach is to use filmic - it simulates more how a analogue film emulsion camera works, in that more bright actually appear more bright, at the loss of saturation. The next thing is tone mapping, which you can do in blender or externally although I could never get acceptable results (I know it can be done) and use sRGB instead of filmic. While some may want to go ACES and apply LUTs, corrections, and other grade work in i.e. DaVinci Resolve (too complex pipeline for me, but I don’t do things for “art” either). Personally I just use filmic and call it a day, it works for my purposes and I don’t have to involve my brain. :smiley:

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Thanks, this was what I was half expecting. I had assumed the “wattage” had a vaguely real world relationship. Silly me.

My point about Photographer was that I could push the rendered exposure a bit beyond what the default 1-10 slider allows, which shows it’s just an arbitrary limit.

Now I know its all arbitrary I’ll just change the light values.



I can’t do that with my version. Here the addon EV value drive Color Management Exposure, whose value I can set manually from -32 to +32. Addon sets it to -8 to (EV 16) to +14 (EV -6). It does not touch the Film Exposure value which for me is hard coded from 0 to 10 (I’m always using 1).
Wattage is a real world value. It’s just not a value you can easily find anywhere.