Light issue

rk786gi · January 30

When I am creating a new light in my render scene it has temperature limit and when I untick the limit light does not work and no light falls on the character headlamp is off and scene only selected please help me I'm really new to this...

Richard Haseltine · January 30

So whata re you setting the temperature to, that you need the limit off? Temperature controls the colour of the light frequencies - turn it up too high and there may be nothing left in the visible spectrum.

rk786gi · January 31

Richard Haseltine said:

So whata re you setting the temperature to, that you need the limit off? Temperature controls the colour of the light frequencies - turn it up too high and there may be nothing left in the visible spectrum.

I'm setting the temprature to 85K and the limit set by default is 10K when I change it in parameter settings the light no longer works and everything remains dark after that I tried everything but it seems please guide me what to do :)

Richard Haseltine · January 31

That's way into the O-class star range (temperature sets colour, not brightness) so I am not sure why you would want to go that high, but it renders OK for me.

felis · January 31

What have you set Luminance and Luminance Unit to?

Highland · February 2

Here's Fred with 15,000 Lumens and 500,000 degrees Kelvin spotlight.

Scene only, headlamp off.

felis · February 2

You are getting a bluish color dur to the temperature.

What are you trying to achieve?

rk786gi · February 2

I'm not getting any light at all 10000 kelvin is set limit temperature and when I select no limit then light doesn't work at all everything remains dark only

crosswind · February 2

We couldn't reproduce the issue you have even if we set a very high value with Temperature. Temperature has nothing to do with the value of Lumens. You better post a screenshot, with the settings of light as well as the Draw Style...

Fishtales · February 2

rk786gi said:

Richard Haseltine said:

So whata re you setting the temperature to, that you need the limit off? Temperature controls the colour of the light frequencies - turn it up too high and there may be nothing left in the visible spectrum.

I'm setting the temprature to 85K and the limit set by default is 10K when I change it in parameter settings the light no longer works and everything remains dark after that I tried everything but it seems please guide me what to do :)

There is no such temperature of light as high as 85,000.

https://www.westinghouselighting.com/color-temperature.aspx#:~:text=What is color temperature?,scale from 2000K to 6500K. 

Richard Haseltine · February 2

Fishtales said:

rk786gi said:

Richard Haseltine said:

So whata re you setting the temperature to, that you need the limit off? Temperature controls the colour of the light frequencies - turn it up too high and there may be nothing left in the visible spectrum.

I'm setting the temprature to 85K and the limit set by default is 10K when I change it in parameter settings the light no longer works and everything remains dark after that I tried everything but it seems please guide me what to do :)

There is no such temperature of light as high as 85,000.

https://www.westinghouselighting.com/color-temperature.aspx#:~:text=What is color temperature?,scale from 2000K to 6500K. 

That doesn't apply universally, stars can go higher (O starts at 30,000K as I recall). Colour temperature (the emission from a black body at the given termperature) is open-ended, as far as I know.

Gordig · February 2

Fishtales said:

rk786gi said:

Richard Haseltine said:

So whata re you setting the temperature to, that you need the limit off? Temperature controls the colour of the light frequencies - turn it up too high and there may be nothing left in the visible spectrum.

I'm setting the temprature to 85K and the limit set by default is 10K when I change it in parameter settings the light no longer works and everything remains dark after that I tried everything but it seems please guide me what to do :)

There is no such temperature of light as high as 85,000.

https://www.westinghouselighting.com/color-temperature.aspx#:~:text=What is color temperature?,scale from 2000K to 6500K. 

You're citing a source that makes light bulbs. They don't need to think beyond 6500K, but that doesn't mean that nothing goes higher than that.

felis · February 3

rk786gi said:

I'm not getting any light at all 10000 kelvin is set limit temperature and when I select no limit then light doesn't work at all everything remains dark only

I still don't understand what you are trying to achieve.

Attached 4 images lighten with 1 spotlight at15000 lumen, and at temperatures at 2500, 4000, 6500 and 10000 K.

If you get different results, you must describe what you are doing.

Fishtales · February 3

OK! There are stars above 10000 Kelvin but that is the surface temperature, they are still only white not brighter. Brightness is controlled by Lumens which is a measurement of the amount of light coming from the source, the higher the Lumens the brighter the light. That though is when looking at the surface of the light, the amount of light illuminating an area is measured by space to be lit and the distance of the surfaces from the light source, measured in foot-candle lm/ft², or Candela per square metre cd/m², or Lux, Lumens per square metre lm/m². I am old enough to have used the lm/ft² when working out the lighting for workspaces but I now use lm/m² or cd/cm² in Studio :)

OK! I take it all back I didn't think it would make a difference but it did :) This is an old scene I had with the lights set at 7500 the second image is at 85000. Quite a difference :)

7500K

Click on image for full size.

85000K

Click on image for full size.

Richard Haseltine · February 3

Yes, temperature is a measure of colour not luminosity (though in the case of main-sequence stars they go hand-in-hand).

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