If candle=12 lumen in real life, lantern = 900 lumen, then real life exposure value = ??

I like how DAZ Studio uses Lumen's for lights. We know that in real life a candle is 12 lumens, and a common lantern is 900 lumens.
Based upon these values, what should the default exposure value be (under tone mapping), that represents our real world physics? I don't want to mess with the tone mapping constantly and want the exposure value set to the default, physics, universe, earth standard, that way I can just rely on setting lumens for my light sources.
Using the default tone mapping, if I set a point light to 900 lumens, it doesn't resemble the light from a lantern, even if the width and height of the sphere point light are set to what a lantern's size might be in real life. Instead, I have to set the exposure value low enough until it looks right, but that seems very imprecise. Does the tone mapping have a default setting based on real world physics? Then I can just leave it on those settings, never having to touch it again. I understand that in Hollywood they fake the lights, which means I can just increase the lumens here and there.
EDIT: so far, it seems an exposure value of 1.0 seems best, then adjusting lumens according to real life values. Can anyone confirm? This is assuming you only use Scene only lights.
Comments
A lantern of 900 lumens is very low light. I did a photography session with one light of around 700, and you need a very good lens (1.8F)
Compare the sun, which can be around 10000-100000)
Which still leaves you hanging : do you expose for indoor or outdoor? You can't have both really. This what always happens with photography.
That said, you could render with canvasses with a beauty EXR, and do the tonemapping later, since it is HDR.
The default Iray tone mapping exposure value of 13 is based on a bright, cloudy day, kind of like the default Ruins HDRI where the light of a lantern wouldn't have much effect in real life. The linked page has a chart you can guide yourself by when selecting exposure values.
Damn, this is exactly what I was looking for, thanks man.
You can render High Dynamic Range if you select the Advanced render tab, and create a canvas of the beauty type. This holds a wide range exposure you can edit with a good photo editor, e.g. Photoshop or Affinity Photo and the likes.
I'm not sure I foillow the question - the correct exposure value always varies by lighting; usually that is handled by your camera (and you can then set a +/- offset from that, which is an adjustment not an absolute value).
@Flortale
Exposure value in real life varies with camera settings and lighting. You don't need to mess with tine mapping settings all the time, you just need to understand how to light your scenes. If you light properly, you can leave tone mapping at the default.
You also cannot forget that the Studio rendering camera generally acts like a real worl camera, not human eyesight. People forget this and complain about rendering a black/dark scene with a single bulb or candle when "I can see fine in a situation like that".
Sone final advcie, to take or leave: Based on your last several posts, you seem to feel a need to manipulate every possible setting in Studio. If you concentrate on learning how to light your scenes like a photographer, you will find that the defualt render settings and shader settings gernally work just fine.