Jump to content

Lux, ND and Colour correction information


Don

Recommended Posts

Posted

Does anyone know of a web site or book that can explain.................

 

- What Lux is, how you work it out etc

- How you use Netural density to dul light down by how ever many stops and how it is relivent to the TV industry rather that still photos.

- The different types of colour correction and how you use them, for example if you wish to correct a light by 1/4 CTO but you only have 1/2 or ands 1/8 etc

- Also any information on the different frost types and what they do would be useful.

 

Reference charts and text would be fantastic.

 

Many thanks

 

Don.

Posted

Er..... hundreds of photography web sites, forums and plenty more video ones. A google will give you all the web results you want - Amazon have stacks of photography books, but in this case, I'd just go to the local library and look through the photography section.

 

It boils down to some fairly basic stuff, really. A bit of history will show you photographers measuring in FCs (Foot Candles), Lux is the same kind of measurement, but done on the metric scale. Critical things to look up are the inverse square law and how this relates. ND filters do 'dull down' - but that's not a good choice of word as dull could imply colour correction, whereas ND simply reduces all wavelengths passing through. The main use is to allow the camera to oeprate with a wider aperture, giving less depth of field. Modern cameras are too sensitive in many cases, meaning that picking something out by having sharp focus on that, and the rest out of focus, is very difficult - Indeed, many video cameras need an ND filter just to stop the picture washing out when the lense is almost shut and there is still too much light!

Posted
Does anyone know of a web site or book that can explain.................

 

- What Lux is, how you work it out etc

- How you use Netural density to dul light down by how ever many stops and how it is relivent to the TV industry rather that still photos.

- The different types of colour correction and how you use them, for example if you wish to correct a light by 1/4 CTO but you only have 1/2 or ands 1/8 etc

- Also any information on the different frost types and what they do would be useful.

 

Reference charts and text would be fantastic.

 

Many thanks

 

Don.

 

The answers to some of your questions and some useful background reading can be found here;

http://www.rosco.com/uk/technotes/filters/index.asp

 

As far as ND filters go, .3 ND is roughly the equivalent of one stop (half the light level), .6 ND is two stops etc.

CTO and CTB can simply be added together. In other words two layers of 1/8 CTO are equivalent to one layer of 1/4CTO

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.