What's your approach for managing the Physical Camera's Exposure Gain EV setting?

[tinybot]

Perhaps this is a more general question about lighting --

When observing others managing the light levels in their scenes (I'm generally talking about interior spaces), I've noticed that some people will take the approach of using the default brightness/intensity of the V-Ray sun and environment, and then modify other lights and the EV value within the Exposure Gain section of the Physical Camera to accommodate.

Probably more frequently, I've seen the reverse, where people seem to leave the EV value alone, and adjust all the lights in the scene (including V-Ray Sun) to accommodate the camera's EV value.

Is there a generally preferred approach for handling exposure for interior spaces with V-Ray? Does it make a difference if I'm trying to adopt a Linear Workflow?

I've searched around and found this from another thread here:

https://en.wikipedia.org/wiki/Exposure_value

Seems to suggest using an EV value of 5-7 for interior artificially lit scenes.

[Ihno]

Always, always keep your exposure settings "real"

The ev thing is the better approach.

But it only changes the ISO, even to pretty unreal values like 80000.
So, to learn how real camera`s work by getting one yourself and become a hobby photographer is by far the best way.
You'd then setup the shutter speed, iso and f-stop yourself.

Vray and any other renderengine is made to simulate the real behavior of light.
So, if you set your camera to something that would never work in that particular scene, you'd be forced to turn the lights to unrealistic values or even f*** up the materials. And that leads to unrealistic images and unnecessary long render times.

[glorybound]

It's best for me to keep a baseline, otherwise things get messy. I set my camera to something real world, set all my lights to a multiplier of one and adjust accordantly. If I need things brighter I adjust the camera and for the most part not the lights. If the camera starts going outside of real world settings I might turn up/down the lights slightly. The camera is my baseline.

[Alan Iglesias]

+1
Excellent advice here from both Bobby and Ihno...

-Alan

[dean_dmoo]

Just a quick check regarding this. I'm going through my template scene to try and set this up correctly for LWF. I've had PG skies as the principle till now, but then I have a 0.05 burn value for Reinhard which apparently isn't correct for LWF.

So my settings; if I place a vray sun with a multiplier of 1 my physical camera EV needs to be at 14 or 15 to look normal for an exterior. Is this correct? It's just to set up a baseline for everything else.

[DPS]

That?s about right (re EV).

If if you adjust the burn then it?s not linear.

[Ihno]

Keep an eye on your iso if you work like that. Set the ev to a proper Level (14 -15 is right for a bright day) adjust the f-stop and shutter speed to keep the iso in a 100-1200 range. F-stop changes the dof and shutter speed the motionblur.

[dean_dmoo]

Thanks for the response.

So is the principle with linear that you always accept burn in your renders and adjust in post? (I'm assuming you change the burn value in the VFB exposure adjustments whilst testing shots to check before finalizing) It seems somewhat counter intuitive to purposely have your renders look "off" in vray to then adjust back in post. This is based on one person doing everything and not having to deal with multiple people / program pipelines as then that changes the issue. The main reason why I'm going this way is to try to minimize any potential issues between commercial libraries, my own libraries and to keep value's as real/original as possible.

The PG principle works fine for exteriors for me but when doing interiors I have difficulty balancing the lighting. I've checked my materials and they are mostly correct in regards to min. black / max white values. Maybe it's mostly the reinhard setting which is throwing the interiors off.

[DPS]

Reinhardt was developed to try to mimic what your eye sees so nothing wrong with using it. Particularly if you have already have a look in mind that you want to achieve and will be manipulating the contrast anyway. It renders faster too.

The purpose of rendering liniarly is because that is what a camera captures so if you?re trying to acheive a photographic look then it?s not a bad start.

[thanulee]

Be careful though cause some real world values mess stuff up, i ve reported it to support few months back.
Eg. excessive gi bleed on RT in some cases and i was advised to not use fstop or shutter but only ISO, which made using exposure in general useless cause i couldnt use values from real camera.

If u deal with post, dont be afraid of burned out areas, although, dont go overbright in general values like more than 2.5-3 will clamp down ur overall brightness in post to get em back to normal. There are two options also there: either overbright (in some logical sense with values up to 2-3) and cleaner renders in dark areas when u finalise the post (longer rendertimes) or dull renders, a bit more noise in dark areas and faster render times. Both are a matter of preference, both go in post to whatever value u want. I prefer dull renders
As u said its a matter of convinience per user: i do lots of changes in post, i go pure linear i dont wanna lose any information. Others that do not, can clamp down images from within vfb.
A tip here, If u be subtle in reinhardt like 0.85 u can have still a lot of information in post and a bit clamped highlights from render

[dean_dmoo]

Thanks, what value do you mean with the 2.5-3 part?

[thanulee]

If u right click constant in vfb and hover over ur image u can see how bright an area is, has a color float value. Ideal situation is not to pass above 1.000 but if u save linear u can go up to 2-2.5 so it can come down later in post.
edit: speaking of all these, i must note that ur brightest white should be around the range of rgb 180 and the darkest black in around 5. This will help engine with better AA and shorter render times and the materials with behave proper.