Question: Use of CTO and CTB on stobes

[boywonder27]

Ok is this right, I am using off camera flashes connected with PW.

When I am set up in hotel room which has Tunsten lighting, do I strap my stobes with CTO filter?

When shooting in a room with Florescent lighting strap my stobes with plusgreen filters, and syn 1/60 or below?

When shooting out side put CTB filters on my strobes, to match daylight.

Is this right, cause kind of confussed on when and what situations to use CTB and CTO in?

[Ed Shapiro]

Your answer is on the way! Just tell me- are you using film or a DSLR with a white balance control?

Ed

[boywonder27]

I am using Digital. Have three off camera flashes, that I use to light a scene.

[Ed Shapiro]

OK 27- Here's the information!

Whether or not to use ANY filters on your flash equipment is dependent on who your a planing to do your lighting and how much ambient light is going to be mixed with the flash illumination. If all or the majority of the lighting is being supplied by your flash equipment and you are not attempting to blend it or balance the color temperatures of the ambient and the flash lighting you need no filtration on your flash heads at all. You simply set you white balance for daylight or electronic flash and shoot. If there is a great deal of daylight in the room, coming in from skylights or windows, you can drag the shutter- that means you set the shutter at a speed which will all owthe existing daylight to record at whatever f/stop you are using to accommodate your flash output. If you flash exposure is (for example) f/11 and you make an ambient light reading and find out that at f/11 you will need 1/30 sec. for the ambient light to "register" on the film or sensor- you simply set the shutter at 1/30 sec. and shoot. Sometimes I will make another exposure of, in this case, 1/15sec. as well to bring the ambient light in the background up. If a portrait subject or a model is included in the scene I try to place them in a darker part of the room so that the ambient light does not "bleed" onto the face causing overexposure or aesthetically poor portrait lighting. An overhead gobo can also be used to prevent overhead existing light from striking the subject. Filter wise- no filtration is really necessary unless the daylight and flash need to be critically balanced. This system works well with architectural interiors where daylight is the dominant source. By increasing and decreasing the flash output you can come up with an exposure that creates a very natural lighting.

If the dominant source of light in a given room is incandescent lighting such as table lamps, chandlers, wall sconces or track lighting, it is best to use tungsten lighting for architectural work where this kind of ambient light exists. By white balancing for the available light and filling in with quartz lamps, you will achieve a good balance, here gel filters can help. The color temperature of standard household incandescent lightning is around 2500 degrees Kelvin . The color temperature of professional quarts lamps is is 3200 degrees Kelvin. You may want to gel your lamps with some Rosco #3443 Quarter Straw 1/8 CTO gels. This is an amber warming filter. After that, simply set your white balance to tungsten and perhaps use a custom balance to tweak the effect to your preferences.

If you want to combine flash with available tungsten lighting you can set you white balance for the tungsten lighting and gel your flash heads with a stronger warming filter such as a Rosco #3202
(full Blue) CTB. Again, if the ambient lighting is not needed to light up the background in a portrait, there is no need to worry about filtration. If the shutter is dragged and the background is a bit warm- that is not a problems unless the job requires critical color matching.

Fluorescent- This is more complex. With a digital camera you can easily find a white balance for fluorescent and other kinds of lighting with discontinuous spectrums. Many fluorescent tubes and compact fluorescent light bulbs lack the red and magenta parts of the spectrum and, with most color films, will impart a greenish tint on the final photograph. With your DSLR this is not a problem until you use flash and wish to combine it with ambient fluorescent lighting. The problem is exacerbated by the fact that all fluorescent tubes and coils do not have the same color properties- there are dozens of different types. Your electronic flash is very close to daylight which has a full spectrum. My experience that it easier to effect a balance when U.S. Cool White tubes are in use. To balance the to light sources you may need a GREEN gel over your flash heads- maybe as much as CC30G in order to balance your electronic flash units with ambient fluorescent. Some experimentation will be necessary- once you discover how much green you need to achieve a balance you can than set a custom white balance to get the desired result. Once again, if you are not blending the flash and the fluorescent lighting you can make sure the shutter speed is fast enough to not omit any ambient light- don't forgot NOT to exceed the flash synchronization speed of your DSLR.

Nowadays, there has been some technological improvements in fluorescent lamps. The old types worked with a 60 cycle ballast (transformer)- the new ones work with electronic ballasts that produces thousand of cycles. The pulsating or flickering of old types fluorescent tubes were know to cause eyesight problems and headaches in some people. More fluctuations and and variations occur as the fluorescent tubes age and begin to falter. I haven't made any tests on the new ones as yet so I don't know if theses up to date changes have effected issues like color balance and the discontinuous spectrum.

I hope this helps- Ed

[Mr_Bester]

Originally Posted by Ed Shapiro

OK 27- Here's the information!

...

If you want to combine flash with available tungsten lighting you can set you white balance for the tungsten lighting and gel your flash heads with a stronger warming filter such as a Rosco #3202
(full Blue) CTB. ...

Wouldn't you want a CTO filter instead. The CTB would cause your strobe/flash to be incredibly blue on tungsten white balance.

Originally Posted by boywonder27

When shooting out side put CTB filters on my strobes, to match daylight.

No, your flash is very close to daylight. You shouldn't need any filter unless you are trying to change the color of the flash. The CTB filter is meant to be placed over a tungsten light to bring it to daylight.

Dug

[atomic_079]

I can't add to much but some thing to think about. In many interior lighting situations you come across would be the dreaded mixed light. Like in corporate offices. Tungsten desk lamps with overhead florescent and maybe even a window with daylight streaming in, oh wait and don't forget monitors. If you can't shut some of these off your going to have problems.

Also (since Ed's posts always get my teach on) something that has really helped me understand filters. I 'd recommend doing a little research and reading regarding MIRED (micro reciprocal degree) here are a couple of links for reference. Basically most filter vendors list their filters with a +/- MIRED value. Once you find the MIRED difference for your particular combination light, film, white balance you just add or subtract filter values to match your needs. Then it's just math.

Mired - Wikipedia, the free encyclopedia
http://www.leefilters.com/downloads/...ion_Poster.pdf