Page 1 of 1

Yes, another lighting question - Exposure

Posted: Sun Jan 19, 2014 6:49 pm
by CodyKallas
I just don't want to be confusing myself, and really want a grasp on this because I know how important lighting is.

When I am lighting a large room, I set all my lights inside the room to typical light settings, like wattage is correct, then I turn my sun on and leave that at normal.

But in order to get this right, I have to turn my shutter way down to like 8 to light the inside, then like 1000 to adjust my sun correct?

Like technically, I shouldn't be able to have my sun on and my lights on at the same time to act correctly right? Because if my exposure is set to like 8 then my sun will blow out the room, but if I set my exposure to like 1000 to see the sun, my inside lights will look like they are doing nothing. Then I combine the two in photoshop or a program like photomatix correct?

So basically in fire, I should never be able to see the true final product until it is rendered out and combined for lighting?

I am just asking this because when I use to just do stuff in modo, we always did it all at once, and I think that is why are lighting was so difficult. And I want to be taking my renders to the next level.

Thanks for any input on this.

Cody

Re: Yes, another lighting question - Exposure

Posted: Sun Jan 19, 2014 11:46 pm
by CodyKallas
I can expose for the outside easy, then save, but when I try to expose for my lights (Turn the shutter way down) the outside just blows everything out and when I try to blend them, it won't pick up the tonal range of the inside lights, the outside just blows everything out. But I thought in real life to expose for inside lights, you only need to change the shutter.

Would that mean that my interior lights arent strong enough compared to the sun?

Re: Yes, another lighting question - Exposure

Posted: Mon Jan 20, 2014 2:36 am
by photomg1
In maxwell you have tone mapping options you can alter the gamma to make the image flatter less contrasty plus pull in the highlights with the burn . I almost always see what I can do with burn first before I look at gamma .
In all honesty I try to avoid both , as long as my scene is built to scale . In your case , see what you pull in with burn whilst your exposure is set on the interior lights.If that doesn't give you what you want (or its too far out of range) I would turn the power down on the exterior sun/sky first to try and find a balance of what I was after . Its all a bit of a taste decision on what you do , but I try and get as close to my final look in maxwell as possible rather than comping two images together. I'm sure we will all vary on that decision , I'd rather output a file from maxwell (16bit) with all the tones I wanted as its so easy to add contrast back in photoshop for example .I also prefer the look of tone mapping in maxwell rather than exporting a 32bit file and tone mapping photoshop or elsewhere.

Edit:
Also in your case what would be the real world scenario ? What time of day is it , would the room at this time of day be lit mainly from daylight for example from large windows.. Then the overheads wouldn't contribute much anyway as the daylight would be lighting most of the room flooding through the windows .So in that case you might be exposing for that and not the overheads . The overheads would just look they are on but not be really contributing much to the scene .Hope that makes sense as it's really scene dependant/final look requirements on how you tackle it.

Re: Yes, another lighting question - Exposure

Posted: Mon Jan 20, 2014 10:29 am
by tom
CodyKallas wrote:I set all my lights inside the room to typical light settings, like wattage is correct
Amount of light is measured by lumen. Lumen = Watts x Efficacy. So, wattage alone is not enough to describe your lights. Also pay attention to their efficacy values and finally the resulting lumen.
CodyKallas wrote:Would that mean that my interior lights arent strong enough compared to the sun?
You're right.

Re: Yes, another lighting question - Exposure

Posted: Mon Jan 20, 2014 4:26 pm
by Mihai
CodyKallas wrote:but when I try to expose for my lights (Turn the shutter way down) the outside just blows everything out and when I try to blend them, it won't pick up the tonal range of the inside lights, the outside just blows everything out. But I thought in real life to expose for inside lights, you only need to change the shutter.

Would that mean that my interior lights arent strong enough compared to the sun?
You need to start thinking about how this would work in the real world - forget about rendering for a minute.

If I'm photographing lets say a beach house with giant windows in the middle of the day, and also direct sunlight is shining into the space. You take a first photo exposed for the bright day light. Now I turn on a 40W lightbulb that puts out say 700 lumens. How do you expect this to make any change in your photo? 700 lumens compared to a bright sunny day is absolutely NOTHING as far as the cameras sensor is concerned. Even your eye (which together with your brain compensate really well for differences in brightness, giving humans a very large dynamic range, much larger than a typical camera) would have trouble seeing the difference. Try this example: Take a 40W lamp outside on a bright sunny day, look directly at the bulb and turn on the light. See much difference?

So in this particular situation, you can't really raise the exposure any more, so that little light is more visible because you have too much influence from the day light - it would just blow everything out.

What can you do in real life to fix this? Well, maybe wait until later in the day when the sun is a lot weaker. Now you can start raising the exposure and get a better balance between your indoor lights and natural light.

What can you do in Maxwell? Well since you can alter the strength of the Physical Sky and Sun, you can also do that, instead of re-rendering with other settings. So I would first of all just mute Sun/Sky. Then change the cameras exposure so I see a little bit of the indoor lights, then turn on Sun/Sky again and lower their strength a lot.

But in my opinion you want to avoid these situations where the interior is perfectly exposed with incandescent lighting, while the exterior is a bright sunny day, and also perfectly exposed. It just looks weird. Why? Because all the architectural photos we've seen are just that, PHOTOS of reality, not reality. It's how a camera captures reality and that's what we are used to. Even the human eye would see the outside a little brighter if let to adjust for the much weaker indoor lighting for a little bit.

So in my opinion, have the interior properly exposed, and the outside bright, with a hint of what's going on. It's ok if the exterior is a bit bright, it doesn't also have to be perfectly exposed! Look at any interior photographs since....forever. Is the exterior overexposed? Is it really a problem? This HDR craze trying to mimic what the eye/brain sees is many times simply ridiculous - with resulting photos that are really just crappy and weird.

Re: Yes, another lighting question - Exposure

Posted: Mon Jan 20, 2014 4:37 pm
by CodyKallas
Awesome answers guys. Exactly what I was looking for.

Thanks again for the time put in to answering all my questions. I am really getting a handle on this.

Cody