September 17, 2014, 10:07:24 PM

Author Topic: Question about color temp of strobes  (Read 2395 times)

EOBeav

  • 7D
  • *****
  • Posts: 405
    • View Profile
    • My Landscape Photoblog
Question about color temp of strobes
« on: October 14, 2012, 12:05:39 PM »
What is the standard color temperature that most strobes put out? I'd like to balance the CT of a strobe to match some cloudy, filtered sunlight conditions. I'm thinking that a 1/4 CTO gel might get the job done. Am I thinking about this correctly?
In landscape photography, when you shoot is more important than where.

Gear: Canon 5DmkII, 17-40mm f/4 L, 50mm f/1.4, 70-200mm f/4.

canon rumors FORUM

Question about color temp of strobes
« on: October 14, 2012, 12:05:39 PM »

drummstikk

  • Rebel T5i
  • ****
  • Posts: 103
    • View Profile
Re: Question about color temp of strobes
« Reply #1 on: October 14, 2012, 01:33:30 PM »
All lighting manufacturers aim for 5200K daylight balance, and about all of them I've ever had my hands on were very close if not right on. If you want to balance with cloudy conditions, 1/4 CTO will take you in the wrong direction. It will increase the color contrast between your ambient light, which will appear cooler, and the flash's warmer light. This can be a good look if not overdone, but from what you say, you are looking for a more natural look. Trial and error is called for get you a good color of gel for your lighting equipment, but you will want to start in the blues. (Or, get a color meter for big dollars.)

You can probably get a book of sample gels at a well stocked photo store that sells studio lighting equipment. Usually the samples are about 1" x 3" which is just the right size for filtering a portable speedlight. I don't know if you are talking about battery portable speedlights or studio equipment, but you can most likely do your testing with the speedlight and then buy full size sheets of gel material if you need to cover larger studio reflectors. (Suggest marking the color number on the sample gel in sharpie before you cut/tear the out of the sample book, so when you find the one what works best, you know what it is.)
"Focused. Or focused not. There is no 'almost.'"

                                                          --Yoda (paraphrase)

EOBeav

  • 7D
  • *****
  • Posts: 405
    • View Profile
    • My Landscape Photoblog
Re: Question about color temp of strobes
« Reply #2 on: October 14, 2012, 07:57:16 PM »
I've got the Rosco Strobist collection of correction filters, sized and cut for my speedlight. So in cloudy conditions, instead of using a warming filter, I want to go the other way and use a cooling filter?
In landscape photography, when you shoot is more important than where.

Gear: Canon 5DmkII, 17-40mm f/4 L, 50mm f/1.4, 70-200mm f/4.

Ryan708

  • EOS M2
  • ****
  • Posts: 225
  • Less bickering, more shooting
    • View Profile
Re: Question about color temp of strobes
« Reply #3 on: October 14, 2012, 08:22:16 PM »
Yup If your flash is matched to daylight, it will be a warmer feeling (cooler on kelvin scale) than cloudy. I think daylight is about 5200, and cloudy is about 6000, and shade can reach about 7000! a subject in the shade with a flash fill light will have a pretty cold feel to the background. On an interesting not, I was looking at the metadada on a bunch of flash-fired shots, and on "auto white balance" with flash activated the temps were all over. Not sure how AWB decides on the temp when using flash
60D, Sigma 17-70 2.8-4, Tamron 70-300 4-5.6 VC, EF 50mm 1.8II, and a Sigma EF-610 DG superflash

dmills

  • PowerShot G1 X II
  • ***
  • Posts: 68
    • View Profile
Re: Question about color temp of strobes
« Reply #4 on: October 14, 2012, 09:17:58 PM »
The reason it works to use a cooling gel when you want to warm the background becomes clear only AFTER you white balance your subject. You make your subject more blue, then have either the camera or your software white balance. It looks at the scene and says "This subject is too blue," and pulls blue out of the entire scene, making the clouds more orange at the same time as it "adds orange" to your subjects skin tones.
Photos | 5D3 | 60D | GoPro Hero3 | 8-15 | 10-22 | 24 1.4 II | 24-105 | 85 1.2 II | 70-200 2.8 IS II | x2 III | 600EX-RT x2 + ST-E3 | lighting accessories, umbrellas, etc

EOBeav

  • 7D
  • *****
  • Posts: 405
    • View Profile
    • My Landscape Photoblog
Re: Question about color temp of strobes
« Reply #5 on: October 14, 2012, 10:23:29 PM »
So let me get this straight. Cloud-filtered sunlight and shade are cooler than standard strobes, so you want to cool your strobe to match the ambient. Similarly, sunlight and evening light are both warmer, so you want to warm up your strobe light to match that of the ambient. I shoot RAW, so I can get it close in-camera, but as long as I match the strobe color to the natural light color I can get both to look right once I get it in the computer. Am I thinking about this correctly?
In landscape photography, when you shoot is more important than where.

Gear: Canon 5DmkII, 17-40mm f/4 L, 50mm f/1.4, 70-200mm f/4.

Ryan708

  • EOS M2
  • ****
  • Posts: 225
  • Less bickering, more shooting
    • View Profile
Re: Question about color temp of strobes
« Reply #6 on: October 14, 2012, 11:44:15 PM »
2000 degree kelvin light is very warm looking- like a candle, or fire.
3800ish degree kelvin is like light bulbs (with a filiment)
5200 kelvin is about high noon light- and most flash's
6000 kelvin is about equal to a cloudy day
7000 kelvin is a sunny day in the shade

now, if the WB is correct, the subject will look the correct color, whether they are in shade, or lit by a candle. A camera will only apply one WB however. So if your subject is in the shade,(blue, cold light) and you use a lightbulb to light their face (warm light), the camera can only get one right. so the shaded background will look normal and they will have an orange face, or a normal face and blue background/body.

a flash in daylight is about correct.
in indoor lighting it will appear more blue than the room,(and should have an orange filter)
in the shade the flash will appear more yellow/orange than the ambient.(and need a bluer filter)(supposedly at least. I never notice this scenario, but perhaps It is because I prefer people's faces to look warm'ish)

some more confusion: notice I listed the light in degrees Kelvin. The warmer "feeling" light is actually colder on the scale, and vice versa.
think of it like this, a match is a warm light, but a cool temp. A blow torch is a blue light, but a high temp.
60D, Sigma 17-70 2.8-4, Tamron 70-300 4-5.6 VC, EF 50mm 1.8II, and a Sigma EF-610 DG superflash

canon rumors FORUM

Re: Question about color temp of strobes
« Reply #6 on: October 14, 2012, 11:44:15 PM »

drummstikk

  • Rebel T5i
  • ****
  • Posts: 103
    • View Profile
Re: Question about color temp of strobes
« Reply #7 on: October 15, 2012, 02:39:09 AM »
So let me get this straight. Cloud-filtered sunlight and shade are cooler than standard strobes, so you want to cool your strobe to match the ambient. Similarly, sunlight and evening light are both warmer, so you want to warm up your strobe light to match that of the ambient.

Exactly. Or as I like to put it, "Make sure the light coming out of your flash is f-ed up in the same way as the ambient light." Then, when you make corrections in post, both the ambient lit parts of the image and the flash-lit parts correct equally, and the result should look fairly natural.

I work fairly frequently in rooms lit with tungsten light, about 3200K. The full-CTO is a frequent flyer under those conditions. Also remember that balanced colors are only half of the equation. The other half is to soften or diffuse the light and have it coming from a believable direction. Somewhere off camera is usually much better, depending on your situation and the look you want.
"Focused. Or focused not. There is no 'almost.'"

                                                          --Yoda (paraphrase)

canon rumors FORUM

Re: Question about color temp of strobes
« Reply #7 on: October 15, 2012, 02:39:09 AM »