LED Bi-Color in 3200K does need minus green correction filter? at DVinfo.net

Go Back   DV Info Net > The Tools of DV and HD Production > Photon Management

Photon Management
Shine an ever-loving light on you.


Reply
 
Thread Tools Search this Thread
Old October 29th, 2010, 02:19 AM   #1
Tourist
 
Join Date: Oct 2010
Location: Hungary
Posts: 3
LED Bi-Color in 3200K does need minus green correction filter?

Hi!

I'm about to purchase a set of LED Panels 1x1 from Cinelight vendor and I would like to know if a LED Bi-Color set in 3200K would required minus green correction filter to remove the nasty green spike.
I know that the so claimed 5600K led's need some degree of minus green correction filter but how about the 3200K?
Does the 3200K led's suffer from green spike?

Thank you!
Alex
Alex Muller is offline   Reply With Quote
Old October 29th, 2010, 02:46 AM   #2
Regular Crew
 
Join Date: Aug 2008
Location: London
Posts: 70
Since they proudly give a CRI of 85 for their straight daylight LEDs (which is actually quite poor, about the same as domestic fluorescents) but don't give any info on the CRI of their tungsten LEDs, I would suggest that you will need a bit of minus green.
Robin Lambert is offline   Reply With Quote
Old October 29th, 2010, 12:13 PM   #3
Tourist
 
Join Date: Oct 2010
Location: Hungary
Posts: 3
Under key feature they mention "-ultra-efficient LED technology with high CRI level (90RA)."
CRI 85 is for the DayLED 600 led panel. All LED 1x1 models are mentioned with CRI 90.

I'm wondering how a minus green 1/4 over a tungsten balanced source will affect the color temperature ..
Alex Muller is offline   Reply With Quote
Old October 30th, 2010, 03:23 AM   #4
Regular Crew
 
Join Date: Aug 2008
Location: London
Posts: 70
Just a warning, a CRI number under the RA system is not the same as the original CRI system.

Some LED and fluorescent tube manufacturers claimed that the original CRI system didn't take into account the nature of their products and so adopted another system with different colour charts which was better for sources with spiky outputs. So a CRI number with the RA system is not the same as the "standard" CRI.

In my experience a 249 quarter minus green will have hardly any effect on the colour temperature and measurements show that it takes a 3200k tungsten down to >3100k, a mired value of about -10 to -20, less than a one eighth CTO, in other words, hardly noticeable.
Robin Lambert is offline   Reply With Quote
Old October 30th, 2010, 08:02 AM   #5
New Boot
 
Join Date: Oct 2005
Posts: 22
Minus Green Filtering with LED

I have a quick question and though it diverges from the main question, I am hoping one of you can confirm my suspicion. I have warm cards in my kit and the minus green card is, in fact, green. I recently purchased an LED light set that includes a minus green gel that is colored magenta. My question is, do I white balance with the LED light before adding the magenta gel, since it colors a white card slightly magenta and I would assume make the camera see magenta as white, whereas my minus green warm card makes the camera see green as white?
Thanks for any clarification.
Reg
Reg Carter is offline   Reply With Quote
Old October 30th, 2010, 08:18 AM   #6
Regular Crew
 
Join Date: Aug 2008
Location: London
Posts: 70
If you white balance on a green card it has the same effect as putting a magenta filter on the camera lens.

So, if you white balance on the "minus green" card, the whole scene will take on a magenta hue. If you put your magenta filter over the light source, then only that light will be "corrected".

If your LED is the only source of light, I would switch it on, point it at a white card, or piece of paper and do a white balance. If there were other sources then I would put the magenta filter on the LED to match it to the other lights.
Robin Lambert is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > Photon Management

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 03:26 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network