Neutral Density

[Ekij]

If you really want to be able to dim an incandescent light without it looking orange at 50% you can't just use a blue filter or it will look blue at 100%.

What you need are twice the lamps. One open white, one with the blue correction.

Then when you dim you bring down the open white lamp (further than you are dimming to) and bring up the blue lamp to compensate for the orange of the dimmed open white of the first lamp.

Really tricky to busk <_<

[teachur]

Yeh, I have been looking at LEE filters website and reading the transmission ratings - that made it click in my head!

[woody74]

...in my view they can "drain" colour from objects/faces.

 

I'd think this would be ideal for a B/W look...

 

And because no one has said it: there is no such thing as grey light. There is dim, and difuse and soft, but grey is not in the spectrum. And ND isn't for color, it's for intensity. I sometimes use one stop in the bottom half of a gel frame when the actors are too close to the lights and the intensity variation between lights is too extreme.

 

This might seem odd, but I have seen L213 White Flame Green used for a B/W look to fairly good effect.

 

-w

[teachur]

L213, I will have a look!

 

Yes, I know that there is no such thing as "grey light", I am just trying to avoid the lighting dimming to a warmer sepia effect, hence the idea of using ND to cut light - though it will still affect it somewhat.

 

I'm willing to try anything...quite important we don't cross over to the "cold" side too much as this is the main blue/cold aim for other scenes not set in the hotel!

 

But 213...I shall looksee!

[Ekij]

A variety of NDs on a scroller would be ideal to control intensity without changing colour temperature.

 

But you need lots of scrollers.

[Nick512]

There is only one way to keep the colour temperature the same and reduce the brightness of a lamp and that is by using a mechanical shutter. Correct the colour as desired using the CT range. then keep the intensity of the lamp the same and reduce the output by using a bolt on mechanical shutter. all scroller manufacturers have these which will use the same cabling and PSU as there scrollers..

 

You could also look into Arc sources or moving lights. which will automatically take care of the problem.

[woody74]

There is only one way to keep the colour temperature the same and reduce the brightness of a lamp and that is by using a mechanical shutter.

 

Not to be contrary, but I think the amount of shift in color temperature by using ND is pretty inconsequential. And also, a lot of moving lights have moved away from mechanical shutters and into gradated ND wheels because (IMO) the shutters do not provide an even dimming of the field.

 

-w

[Ken Coker]

...in my view they can "drain" colour from objects/faces.

 

I'd think this would be ideal for a B/W look...

 

-w

 

I think you'll find it's a good look if you want the cast to all appear like they're suffering from a pulmonary odaema

 

KC

[Just Some Bloke]

Out of interest, another good use for ND in theatre is when using a limited numbers of channels, requiring 2 lanterns to be paired. If you just can't get the 2 paired lamps to match (1 is brighter than the other) then a piece of an appropriate ND in the brighter lantern will give you 2 matching light sources. Obviously, you may want to try putting new lamps in both lanterns first, but there will still be times when nothing else does the trick apart from gool old ND.

[Jivemaster]

ND is the only filter that will dim the light without changing colour. Having the required number of ND'd lanterns to do a fade would be crazy though.

 

ND is mainly used to bring window daylight down in level to fit in with interior set lighting CTBlue will correct colour in that situation.

[paulears]

There is only one way to keep the colour temperature the same and reduce the brightness of a lamp and that is by using a mechanical shutter.

Nope - The whole point of ND flter is to reduce the light without changing colour temperature - that's what it is for?

 

Don't forget mesh scrims, they work pretty well too on high powered kit. A half scrim on a red head or blonde works fine for taming a section of the beam.

[Jivemaster]

B&Qs selection of punched metal sheet may give you some pretty major ND but will you be able to diffuse the pattern?

[Nick512]

I think you missed my point..

 

I was under the impression the solution you required was a lightsource that stayed at a constant colour tempriture (say 6500k which is Daylight). but could be reduced in intensity without going back to the tungsten or as you put it yellow/sepia colour range.

 

ND is designed as pointed out earlier to reduce the inensity by a set numbers of stops without changing colour temp. but with a tungsten source as soon as you reduce the intensity of the lamp (ie to fade it out) you change the colour tempriture. so a CT corrected lamp faded down using the dimmer will shift back towards the uncorrected tungesten color tempriture.

 

 

Not to be contrary, but I think the amount of shift in color temperature by using ND is pretty inconsequential. And also, a lot of moving lights have moved away from mechanical shutters and into gradated ND wheels because (IMO) the shutters do not provide an even dimming of the field.

 

-w

 

If you are referning to the glass dimmer systems in lights such as the VL3ks or the retrofit for the MAC2k Range then these do not use ND. They use a graduated wheel similar to that of the CMY system with fans of a foil around a glass wheel designed to decrease the amount of light in a smooth curve as they move in front of the beam. But I do agree this is by far the best way to fade out a fixture of this type as older mechanical dimmers do not produce an even dimming field.