Page 1 of 1
Realistic Lumens
Posted: Wed Mar 12, 2014 10:28 pm
by CodyKallas
Does anyone have like a website or a list of what are some realistic lumen values? I know I should always use realistic values, but don't really know what realistic values are...
Thanks
Cody
Re: Realistic Lumens
Posted: Wed Mar 12, 2014 10:51 pm
by AlexP
Look for bulb's lumen/watt and lumen power. 60W incandescent bulb is about 700lm and 12lm/W.
Re: Realistic Lumens
Posted: Thu Mar 13, 2014 4:53 pm
by CodyKallas
AlexP wrote:...12lm/W...
Okay, which obviously makes sense. If it is a 60 watt light bulb and is 700 lumens, 700/60 is like 11.6. Does the watt directly effect the lumen though? (Sorry I am no electrical engineer but have learned the hard way that I almost need to be for this program.) Or can you have like a 60 watt 700 lumen light bulb or a 60 watt 900 lumen light bulb etc?
Re: Realistic Lumens
Posted: Thu Mar 13, 2014 8:39 pm
by Mihai
You exaggerate....it's really not that complicated. The watt/efficiency setting was added simply because this is usually what some manufacturers supply. But it's still about lumens - of amount of light being emitted. There isn't only a watt setting, without also specifying the efficiency. Check the Luminance paragraph in this page:
http://support.nextlimit.com/display/mx ... m+emitters
which is the page that explains to you what the "Luminance" setting is.
Luminance
Specifies the intensity of the light. There are several options to specify luminance, like Power & Efficacy, Lumens, Lux, Candelas and Luminance:
Power and Efficacy
This option allows you to specify how much electricity a light source consumes (Watts) and how efficiently it converts that electricity into visible light (Efficacy). The efficacy number specifies how many lumens are emitted per watt. For example, a common 40W incandescent light bulb will have a rather low efficacy of 12.6 lumens/ watt. This information is usually supplied by the bulb manufacturers. A more efficient energy saving bulb which is also rated at 40W will have an efficacy of perhaps 17.3 lumens/ watt, so for the same amount of energy consumed, it will emit more light.
The watts/efficacy way of specifying an emitter’s intensity is useful if you would like to mimic common light sources, where the manufacturer provides the watt rating and the efficacy rating. In the “Output” row you can see how many Lumens a particular watt/ efficacy setting will create.
Really, I'm not sure how this could be explained any plainer. Which part of that text did you have problems understanding?
Re: Realistic Lumens
Posted: Thu Mar 13, 2014 11:15 pm
by CodyKallas
Okay, maybe what I was screwing up in my scene was not having enough light sources then, even with my shutter down to 1 it was dark. But it was a larger room and most likely needed more light. I have come to find in something like a hanging light over a workstation, that there is sometimes 2 or 3 florescent, so I will make 3 separate meshes with the lumen of 1 florescent, to keep it accurate.
Or do I go ahead and make one source the power of 3 lights? So is it better to have 3 2000 lumen bulbs or 1 6000 lumen bulb? Because the 1 bulb would be less realistic.
Thanks for your help.
Re: Realistic Lumens
Posted: Thu Mar 13, 2014 11:31 pm
by Mihai
You need to also think more of your camera settings. It's not just the shutterspeed, but also ISO and fstop that influence the amount of light falling on the "sensor". If it's a large interior and you have few common lightbulbs, then even a shutterspeed of 1 with an ISO of 100 will most likely be very dark still. You don't have to get too careful with the amount of lumens for an emitter, just don't create a bulb that's 200000000000 lumens which many people still do
Re: Realistic Lumens
Posted: Fri Mar 14, 2014 5:05 pm
by CodyKallas
Ahhhh okay. Yeah I know enough about photography to not crank the lumens that much. I just wanted to make sure a couple thousand off would make a HUGE difference. But I guess it won't when it comes to noise levels and render speed.
Mihai how do you blend your exposures? Like in Photoshop with erasing seperate layers or use something like photomatrix (I think thats what its called). As I narrow down my maxwell path, I am coming to find the environment is giving me the most trouble wether that is noise or exposure, and I know we have talked about blending exposures, we do it in photography a lot, but didn't know if that would make a difference in maxwell.