How do you know when to use 1/8, 1/4, 1/2 or full CTO?

[TMR Design]

I'm beginning to understand the use of gels for balancing flash and ambient light outdoors. I also know that I love the look of having my man light warmed up a bit and would like to do that with a gel as it's being shot. I don't want a warming filter on the lens because I typically don't like the whole shot with the filter but find it to be very pleasing on skin tones. This would also save me a step in post processing where I add a warming filter.

Is it more trial and error to determine which CTO gel is going to work the best or is there a science to it?

[pcunite]

Is it more trial and error to determine which CTO gel is going to work the best or is there a science to it?

I am not an authority on this but I offer my experience.

Like you I use gels for artistic purposes from time to time. If I am photographing a staged scene I just use the colors I want and that is based on ART not science...

But your question I assume is in areas outside your studio and areas you don't have total control over. You and I need to buy this:

Sekonic Prodigi Color C-500 Color Meter

Most of the time doing weddings and the like I don't gel. As I walk from room to room it is to hard to get exact because of flash angle and bounced heights. You can only get close... The only time I would gel in these scenarios is when my flash lights the room I am in but not the room behind the subject lite with tungsten. In those scenarios just put a CTO 1/4 and it will be close.

[TMR Design]

Thanks man,

I should have specified that this is only when I'm doing portraiture.

[pcunite]

I should have specified that this is only when I'm doing portraiture.

One note I will add. There is a recent thread in which someone thought I should have used a CTO gel to balance a scene. However the resultant shot I took was because I was bouncing off of a certain color wood not because tungsten bulbs where in use (they where but my flash was over powering them).


When I am doing event photography I don't get paid to case the venue like a full production movie crew would do. Yes I should have color tested what the wood would do to the subjects. I just don't get paid to do that...

[Gentleman Villain]

Thanks man,

I should have specified that this is only when I'm doing portraiture.

I kinda think CTO gels are a bit too orangey/redy for shooting people and have always preferred these rosco gels:

Cinegel #3444: Eighth Straw 1/8 CTS
Cinegel #3443: Quarter Straw 1/4 CTS

However, I love CTOs for non-human subjects...especially food shots and architectural interiors. Generally, I'll use a full CTO for those kinds of subjects....it's much more fun to go all the way when warming up a strobe rather than going halfway or 1/8th of the way :)

Just an opinion...I'm sure others will certainly disagree

[TMR Design]

I kinda think CTO gels are a bit too orangey/redy for shooting people and have always preferred these rosco gels:

Cinegel #3444: Eighth Straw 1/8 CTS
Cinegel #3443: Quarter Straw 1/4 CTS

However, I love CTOs for non-human subjects...especially food shots and architectural interiors. Generally, I'll use a full CTO for those kinds of subjects....it's much more fun to go all the way when warming up a strobe rather than going halfway or 1/8th of the way :)

Just an opinion...I'm sure others will certainly disagree


Interesting. Thank you. I'm going to have to play around with the Rosco swatches to get a feel for the differences in these gels.

[Hermes]

I posted on the subject a little while ago on this thread:

http://photography-on-the.net/forum/showthread.php?t=518707

Essentially it is a combination of experience and trial & error. There is little point spending money on a colour meter as you will generally only be choosing between three gels, 1/4, 1/2 and full CTO - with a little bit of practice, making the choice will be second nature.

As has been mentioned, CT Straw is also useful on occasion although personally I prefer to reduce the amount of CTO on the flash when shooting people rather than switching to straw, as it does give a yellow cast which does not suit everybody.

[jrsforums]

I'm beginning to understand the use of gels for balancing flash and ambient light outdoors. I also know that I love the look of having my man light warmed up a bit and would like to do that with a gel as it's being shot. I don't want a warming filter on the lens because I typically don't like the whole shot with the filter but find it to be very pleasing on skin tones. This would also save me a step in post processing where I add a warming filter.

Is it more trial and error to determine which CTO gel is going to work the best or is there a science to it?


There is a science to the light shifting of gels. However, I do not know how to apply it....selectively...the way you want to. It is much easier to apply it to a masked layer in Photoshop.

[TMR Design]

Thank you for the suggestions guys.

I just did some testing, and although this won't help me in terms of balancing flash with ambient light, it does show me the warming effect on skin tones (well, fake skin, that is).

I shot these samples using a Nikon SB-800 at a constant f/9. Custom white balance was set for the first shot with no gel. Some color is lost in the web optimized images but you can still see the effect. There is a slight difference between CTO and CTS and can really only be seen with a larger, higher resolution image.

I didn't check color temperature to see how much the temperature shifted with each one. This was just done as a visual test but I can definitely say that either the 1/8 CTO or 1/8 CTS are exactly what I was looking for and almost identical to the warming I would add with a layer mask in Photoshop. I'd much prefer to get it in camera so I think that I'm going to try the 1/8 CTO on my next shoot. The 1/4 and 1/2 are just too extreme, or at least it seems that way. I can see trying 1/4 but 1/2 or greater seems a bit much.

In my shots I'm obviously close enough to the background to see the effect but if I were shooting outside and my background was a natural setting with ambient light then I suspect the gel'ed light wouldn't have any effect on the ambient surroundings.

[pcunite]

I just did some testing...

I had my fingers crossed you would do this! I have enjoyed your other posts with this model...

The reason you might use a 1/4 is when the subject has a good deal of naturally occurring (or light bulbs) of CTO on them already. Your test show that it might be unpleasant to create it by itself.

[TMR Design]

Hi pcunite,

Thanks for that tip. I guess I'll find out where I stand once I start experimenting with real subject's outside.

[DDCSD]

I also know that I love the look of having my man light warmed up a bit and would like to do that with a gel as it's being shot.

I love to have my man light warmed up in the evenings, around sunset. :lol:;)


Here I used a Roscosun 1/2 CTO. The effect isn't too bad, but to me it is a bit strong (not mentioning the underexposure and other stuff, but its the only example I have). A 1/4 or 1/8 might have been better in this situation. This was very near sunset. It is also just a half-candid with my sister-in-law and her husband. They actually like it, but they are very pale/reddish to start with. :lol:

http://derekcecil.smugmug.com/photos/309676256_FFdHe-L.jpg

[Rudi]

I just did some testing, and although this won't help me in terms of balancing flash with ambient light, it does show me the warming effect on skin tones (well, fake skin, that is).

I see that she's had another hair makeover, Robert. :D

[Curtis N]

For outdoor portraiture, I think in practical terms the best procedure is to try to get reasonably close with the gel, shoot a white balance target so you can adjust in post to get the subject color correct, and the let the background fall where it may.

I have been known to use a 1/4 CTO in the sunshine to give my subjects a little warmth. As the sun starts to set, I think it's a matter of experience to know when to switch to 1/2 or full CTO (and I certainly don't claim to be good at it).

Artistic intent is a big part of it, too. You can use a CTO gel on your subject and then adjust the color temp accordingly, and it will make a dull sky more blue.

[breal101]

The ratio of flash to ambient plays a role. The color temp of the ambient is important to consider. It's all a crapshoot in some ways and falls into the perfect white balance or pleasing color thing. And color meters, even the best ones were a bit shaky IMO.

[TMR Design]

I see that she's had another hair makeover, Robert. :D

You know how women are about their vanity Rudi. :D

[TMR Design]

For outdoor portraiture, I think in practical terms the best procedure is to try to get reasonably close with the gel, shoot a white balance target so you can adjust in post to get the subject color correct, and the let the background fall where it may.

I have been known to use a 1/4 CTO in the sunshine to give my subjects a little warmth. As the sun starts to set, I think it's a matter of experience to know when to switch to 1/2 or full CTO (and I certainly don't claim to be good at it).

Artistic intent is a big part of it, too. You can use a CTO gel on your subject and then adjust the color temp accordingly, and it will make a dull sky more blue.

Thanks Curtis,

I have a feeling my best bet is going to be having various gels and noting time of day and type of sun and ambient light. Then I can see what works and what doesn't.

[TMR Design]

A color meter is nice in terms or seeing temperature and shift but doesn't really do much for me with regard to this topic. Either way this is a subjective thing. There is no technically correct way to do it and I think that I'm going to roll the dice and give it a shot

In the samples I shot I used both CTO and CTS gels. They look almost identical in that particular sample.

In general, is one preferred over the other? What is the exact difference between the orange and the straw?

[sfaust]

I use a color meter quite a bit, and its very helpful. It would also work well in this situation Robert, since you can measure each light independently or together, and understand the it will have on the subject. Once you get used to reading the light meter, you will know very easily that you have say a 1200K difference between sources. Then you can decide on how you want to correct that.

For example, lets say your ambient lighting was later afternoon sun and it measured at 5150K, while your strobe measured 5500K. Thats a 400K shift between the two. If you used a 1/8 CTO which is a 300K shift, it would correct the 5500K strobe to 5200K, which is still 50K on the cooler side, but barely visibly noticeable. You could also go with a 1/4 CTO and get a warmer light from the strobe on your subject.

Basically, you can take two readings, and know exactly which gel to use without test exposures or guess work. I generally like about a 800K shift on the warmer side for my strobes hitting people to add a warmer skin tone. Generally I can get that on the first shot by measuring and then using the right combination of CTO gels. The same holds true for correcting fluorescents, halogen, tungsten, etc.

The down side is that color meters are expensive. However, it was really necessary when shooting film since visual testing was really a viable option. So learning how to read a meter, and doing the basic math conversions, allowed you to get spot on with the colors. I still do it this way since is so much faster than test exposures. But I find I can usually get right on with known light sources (ie, my strobes are 5200K, bright daylight, etc) and only need to measure when the lighting varies (various stages of sunsets, open shade, different bulb types, etc).

BTW, here are the shift values for CTO
2400K Full CTO
1200K 1/2 CTO
600K 1/4 CTO
300K 1/8CTO

CTB's work in the same way, but shift colors toward the cooler side.

[jrsforums]

I use a color meter quite a bit, and its very helpful. It would also work well in this situation Robert, since you can measure each light independently or together, and understand the it will have on the subject. Once you get used to reading the light meter, you will know very easily that you have say a 1200K difference between sources. Then you can decide on how you want to correct that.

For example, lets say your ambient lighting was later afternoon sun and it measured at 5150K, while your strobe measured 5500K. Thats a 400K shift between the two. If you used a 1/8 CTO which is a 300K shift, it would correct the 5500K strobe to 5200K, which is still 50K on the cooler side, but barely visibly noticeable. You could also go with a 1/4 CTO and get a warmer light from the strobe on your subject.

Basically, you can take two readings, and know exactly which gel to use without test exposures or guess work. I generally like about a 800K shift on the warmer side for my strobes hitting people to add a warmer skin tone. Generally I can get that on the first shot by measuring and then using the right combination of CTO gels. The same holds true for correcting fluorescents, halogen, tungsten, etc.

The down side is that color meters are expensive. However, it was really necessary when shooting film since visual testing was really a viable option. So learning how to read a meter, and doing the basic math conversions, allowed you to get spot on with the colors. I still do it this way since is so much faster than test exposures. But I find I can usually get right on with known light sources (ie, my strobes are 5200K, bright daylight, etc) and only need to measure when the lighting varies (various stages of sunsets, open shade, different bulb types, etc).

BTW, here are the shift values for CTO
2400K Full CTO
1200K 1/2 CTO
600K 1/4 CTO
300K 1/8CTO

CTB's work in the same way, but shift colors toward the cooler side.

Not sure where you obtained the shift values...

For example, Rosco, for 1/8 CTO, shows a shift of 5500 to 4900 or 600K
http://www.rosco.com/uk/filters/cinegel.asp?order=so&display=12

Actually, the "Mired" shift is not linear, byt differs based on the starting (source) light temp. Without getting into forulas, you can see this using the Lee calculator.
http://www.leefilters.com/architectural/products/mired/

[sfaust]

I used my faulty memory rather then checking my notes ;) Sorry. Here is the corrected values

Full 2600K
3/4 2300K
1/2 1700K
1/4 1000K
1/8 600K

[Wilt]

Hi Robert, I just saw your thread. I have, for many years in shooting weddings, used a 1/4 CTO on my fill flash on camera while using 1/8 CTO on my highlight flash off camera. I find that it is often preferable for indoor scenes to have a bit of warmer-than-neutral look, as if shooting available light indoors, and find it more flattering to the bride. And the 1/8 CTO takes a bit of the coolness off speedlights. Just my opinion.

[Rudi]

The reason you might use a 1/4 is when the subject has a good deal of naturally occurring (or light bulbs) of CTO on them already. Your test show that it might be unpleasant to create it by itself.


Not an expert in this area, so please take this with a grain of salt, but I would think that outdoors, with plenty of ambient light, the 1/4 CTO might not look quite as "in your face" as it does in this controlled test. Yes, it will shift the ambient colour balance a little more to the blue end of the spectrum, but that might not be a bad thing...

[Gentleman Villain]

Be careful with those CTOs

They can have a way of making people look like they're sitting under the french-fry heating lamps at Burger King. :)

[tim]

I only use gels when i'm trying to match tungesten, and I might use it very late in the day if the sun's seeming very orange. I have one orange gel, I use that. Honestly i'm not looking for an exact match, just to get the temp into the vauge area of the ambient light, closer than 5500K. I don't think being really precise is necessary for portraits.

[TMR Design]

Not sure where you obtained the shift values...

For example, Rosco, for 1/8 CTO, shows a shift of 5500 to 4900 or 600K
http://www.rosco.com/uk/filters/cinegel.asp?order=so&display=12

Actually, the "Mired" shift is not linear, byt differs based on the starting (source) light temp. Without getting into forulas, you can see this using the Lee calculator.
http://www.leefilters.com/architectural/products/mired/

I used my faulty memory rather then checking my notes ;) Sorry. Here is the corrected values

Full 2600K
3/4 2300K
1/2 1700K
1/4 1000K
1/8 600K

Thanks guys. I'm doing a lot of reading and taking notes. As much as I'm understanding this, I'm still a bit confused.

[TMR Design]

Hi Robert, I just saw your thread. I have, for many years in shooting weddings, used a 1/4 CTO on my fill flash on camera while using 1/8 CTO on my highlight flash off camera. I find that it is often preferable for indoor scenes to have a bit of warmer-than-neutral look, as if shooting available light indoors, and find it more flattering to the bride. And the 1/8 CTO takes a bit of the coolness off speedlights. Just my opinion.

Thank you Wilt. I think I'm going to start with 1/8 and 1/4 CTO and then look carefully at the results.

Not an expert in this area, so please take this with a grain of salt, but I would think that outdoors, with plenty of ambient light, the 1/4 CTO might not look quite as "in your face" as it does in this controlled test. Yes, it will shift the ambient colour balance a little more to the blue end of the spectrum, but that might not be a bad thing...

Hi Rudi,

I have a feeling you're right and I'm going to go easy on the gels under I know better what the effects will be in different light.

[TMR Design]

Be careful with those CTOs

They can have a way of making people look like they're sitting under the french-fry heating lamps at Burger King. :)

LOLOL Yeah, I've already seen that and I don't think it's a very good look if you're not running the deep frier :D

I only use gels when i'm trying to match tungesten, and I might use it very late in the day if the sun's seeming very orange. I have one orange gel, I use that. Honestly i'm not looking for an exact match, just to get the temp into the vauge area of the ambient light, closer than 5500K. I don't think being really precise is necessary for portraits.

Hey there Tim,

As much as I want to understand this topic very thoroughly I do want to point out that my original intent was not so much to precisely balance flash against ambient light, but rather to give my subjects a pleasing warm skin tone. In my examples above, I found that either 1/8 or 1/4 seems to give me what I want and it's just a question of whether I get those same effects outdoors or if I need to go to a stronger CTO.

Whether something is necessary, in my opinion, is a relative and subjective thing since we all see things differently and have a different creative eye with different technical skills and requirements.

[breal101]

Robert, Wilt probably has it pretty close. Naturally personal taste is a big factor so I am looking forward to another test to see what you come up with. As an aside I was wondering if you had posted your impressions of the D300 somewhere, I don't want to hijack your thread with this but if you have a link I would be interested.

[jrsforums]

I only use gels when i'm trying to match tungesten, and I might use it very late in the day if the sun's seeming very orange. I have one orange gel, I use that. Honestly i'm not looking for an exact match, just to get the temp into the vauge area of the ambient light, closer than 5500K. I don't think being really precise is necessary for portraits.

Ah....a breath of practicality..... :-)

[TMR Design]

Robert, Wilt probably has it pretty close. Naturally personal taste is a big factor so I am looking forward to another test to see what you come up with. As an aside I was wondering if you had posted your impressions of the D300 somewhere, I don't want to hijack your thread with this but if you have a link I would be interested.

Just to follow up on the aside...
I never did a review of the D300 but it's an incredible machine. If you want more detail just send me a PM.



And n ow back to our regularly scheduled program. :D

[tim]

As much as I want to understand this topic very thoroughly I do want to point out that my original intent was not so much to precisely balance flash against ambient light, but rather to give my subjects a pleasing warm skin tone. In my examples above, I found that either 1/8 or 1/4 seems to give me what I want and it's just a question of whether I get those same effects outdoors or if I need to go to a stronger CTO.

Whether something is necessary, in my opinion, is a relative and subjective thing since we all see things differently and have a different creative eye with different technical skills and requirements.

You can just drag the orange saturation slider to the right in Bridge/Lightroom if you want to do it the easy way :)

[TMR Design]

Hi Tim,

I'm really not looking for alternatives. Not trying to be rude but I know how to use Photoshop and Lightroom and can do all these things easily. I process when I have to or need to but when I don't have to process in software I don't care to do that.

Adding a gel is simple and it gives me what I want in terms of the subject lighting. Moving a slider in any software will adjust the entire image, so that means I'm creating layer masks and painting. I do enough of that.

If those other methods work for you then that's great but I'm all about capturing images as best as I can in the camera.

[pcunite]

Adding a gel is simple and it gives me what I want in terms of the subject lighting. Moving a slider in any software will adjust the entire image, so that means I'm creating layer masks and painting. I do enough of that.

It is more interesting to do things in "real life". I wonder what will become of photography when PhotoShop makes masking and layering even easier...

[TMR Design]

I think we'll always see 2 schools of thought. There will be the old school photographers and purists that work on capturing the image as they envision it, and they will take the extra time in setup, metering, composition, etc.

The other school will capture the image as is, shoot in RAW, and fix and change whatever is not to their liking, adding the things that they didn't get in the image as shot. Software will get increasingly more powerful, as will the cameras we use.

[tim]

Just suggesting an option. I have a set of gels in my camera bag that I use, my aim is to reduce my PP time as much as possible.

[jrsforums]

I think we'll always see 2 schools of thought. There will be the old school photographers and purists that work on capturing the image as they envision it, and they will take the extra time in setup, metering, composition, etc.

The other school will capture the image as is, shoot in RAW, and fix and change whatever is not to their liking, adding the things that they didn't get in the image as shot. Software will get increasingly more powerful, as will the cameras we use.

You make it sound so "polar"....as if only one is right and the other wrong.

Seems to me that one uses the tools available and/or which work for them.

Ansel Adams was "old school"....most often, his prints have significant difference to his negatives.

[Gentleman Villain]

I think we'll always see 2 schools of thought. There will be the old school photographers and purists that work on capturing the image as they envision it, and they will take the extra time in setup, metering, composition, etc.

The other school will capture the image as is, shoot in RAW, and fix and change whatever is not to their liking, adding the things that they didn't get in the image as shot. Software will get increasingly more powerful, as will the cameras we use.

Yeah, I think you're right TMR. I learned photography the old fashioned way but was young and assisting during the switch over to digital...so I have a good grip on the two schools of thought.

To be honest, I think the real differences are still format. Generally, the 35mm shooters are heavy into PP and medium and large format shooters are usually more traditional.

Just an observation, but the lower resolution of 35mm files often requires some PP tricks to jazz them up....while the higher resolution of medium and large format can still look interesting using the more traditional methods

Hope that makes sense...I guess my point is that the real separation for me is still format....35mm shooters are often heavy into PP tricks while medium format shooters are usually a bit more tradition. (not always true, but a good general observation)

I really want to get into medium format...but just can't afford an H3 right now...maybe next year :)

[form]

Color matching for me has been hit and miss. When I use gels it's to match my flashes with available light for candids, photojournalism and (now) real estate photos. In the latter, I'm finding the nvision daylight balanced fluorescent 5500k light bulbs to be of great assistance, and I'm not even needing CTOs on my flashes to get a very-close-to-perfect white balance, matching daylight, flash and lamp lights.

My opinion about portrait use of CT gels is that most people I have worked for do not prefer the extra warm tone, and neither do my eyes. When I have used a blue background it causes their skin to have a more pinkish appearance by dint of contrasting colors, which is great. When I use a grey background there is less color contrast, and any extra orange seems to turn the photo in the wrong direction. I also have to whiten eyes and teeth (more) if the balance is off.

[TMR Design]

You make it sound so "polar"....as if only one is right and the other wrong.

Seems to me that one uses the tools available and/or which work for them.

Ansel Adams was "old school"....most often, his prints have significant difference to his negatives.

Hi John,

In no way did I intend to give you or anyone else the impression that I was stating right and wrong. My observation in these and other forums is just what I said. I see 2 schools of thought. I never said anything about one way being right or better.

I prefer to get it right in camera. It's that simple. Since I started the post asking about using CTO gels I wanted to get answers and input about that topic. So, to talk about layers and masks in Photoshop and moving sliders in Lightroom is all well and good but does not address the question posed. I stated that as well but never make any comments about it being wrong... just not what I would like to be doing.

[Wilt]

On the topic of schools of thought, let me put it this way for everyone...

Black and white shooters would try to expose the negative 'right on', then they adjust contrast and brightness in the printing process.

Zone System shooters would intensively analyze the scene, then shoot it to capture the shot in a manner conducive to compensating certain areas of the scene, process the film in a manner different than the developer manufacturer's instructions, then they adjust contrast and brightness in the printing process.

And most people would simply shoot, take the film to the store processor, and look at the prints that came back, balanced by the machine!

So how does ANY of the preceding sound any different than today?...

Conventional dSLR shooters would try to expose the negative 'right on', then they adjust contrast and brightness, etc. with photo editing software like Photoshop .

Shoot-to-right shooters would shoot, intensively analyze the histogram, then reshoot it to capture the shot in a manner conducive to better capturing the shadow areas of the scene wihtout blowing out the highlights, process the RAW to raise shadow area to have a bit more detail and reduce the highlight areas to show more detail, then they adjust contrast and brightness in the RAW conversion to JPEG process.

And most people would simply shoot in JPEG, and look at the images that came out, balanced by the camera's processor (and might never use a photo editor program)


The digital world is NOT unlike the film world in most regards, apart from how many shots go thru cameras of so many users, wearing out the shutters in a year or two.

[TMR Design]

Thank you Wilt. That makes a lot of sense. :D

[Wilt]

I do think that digital photography is helping to create a large bunch of fussbudgets (to use cartonoonist Charles Schultz's Peanuts comment about Lucy).

All off this fuss about White Balance and shooting to the right. In the past, a color shooter would pick a film for its color pallette, then accept what the drugstore machine provided (which often was quite wrong!) or accept the end result of what the pro lab thought was right. Seldom (relatively speaking) would people shoot Macbeth charts and gray cards, and then ask the lab to exactly match the swatches for color balance. Now people agonize about white balance, selection of suitable white or neutral gray in each photo to adjust, exactly matching artificial light to ambient (rather than merely making an aesthetically pleasing photo), or simplistically trying to shoot to the right with a 9 f/stop range of scene fitting into a 7-8 f/stop scale (when the top of the range does not matter to the shot!).

People should first try to make AESTHETICALLY good photos, and worry about the technical tweaks as a secondard consideration, IMHO. The average viewer does not know what to look for, in the technical garp, they know what pleases them! And that is how I arrived at my choice of 1/8 CTO and 1/4 CTO...the electronic flash is cooler than daylight, so I neutralize it (Key light) first with 1/8 CTO. Then I try to flatter the bride with a touch of warmth, adding another 1/8 CTO to end up with 1/4 CTO on my Fill. My Dynalite studio lights in softboxes give me the same touch of warmth without the supplemental use of gel. I didn't try to match the warming from the softbox with a specific CTO value. Artistically motivated adjustment, not technically cold clinical approach to things.

[TMR Design]

And again, thanks. I see it as you do. I want to warm up my subject lighting and I'm not all the concerned about matching flash to ambient color temperature.

[breal101]

Back in my lab days printing custom enlargements for professionals, I found that the large majority of people prefer the warm look. I agree with Wilt, WB was a crapshoot with film, even slide film processing was different from lab to lab. Out of control processors were not uncommon. It's all about getting what looks best to you and your customers.

[TMR Design]

I've got a sheet of Rosco 1/8 and 1/4 CTO coming on Friday. I'll let you know how I make out.