Lighting Ratios

[Digital]

Back in the 90's I took a portrait class and this is what I remember about lighting ratios: you can use the aperture setting for a lighting ratio, e.g. if your main light is at f/8, and your fill light is at f/5.6 you have a 2:1 ratio.
You can also use distance to determine a light ratio, e.g. if your main light is 8 feet from your subject, and your fill light is 4 feet from the subject, you have a 2:1 ratio.
Did I remember correctly or am I all wet.
Thanks

Bruce

[xpatUSA]

Back in the 90's I took a portrait class and this is what I remember about lighting ratios: you can use the aperture setting for a lighting ratio, e.g. if your main light is at f/8, and your fill light is at f/5.6 you have a 2:1 ratio.

Interesting terminology, Bruce. Not having ever used lighting in that way, how exactly does one determine the f-number of a light? Seriously interested and just asking.

You can also use distance to determine a light ratio, e.g. if your main light is 8 feet from your subject, and your fill light is 4 feet from the subject, you have a 2:1 ratio.
Did I remember correctly or am I all wet?

Bruce

Not so sure about the distance ratio. The illuminance (lux) at the subject depends on several more factors than just the distance:

http://kronometric.org/phot/lighting...20handbook.pdf

It's all in there.

[Digital]

Thanks for your response Ted. The usual way to determine the output of a light is a flash meter.
Your point on the distance, I believe is correct; however I believe it still can play a role in lighting ratios.

Bruce

[xpatUSA]

Thanks for your response Ted. The usual way to determine the output of a light is a flash meter.

Ahh ... flash lighting. Now it is clear, thanks Bruce ...

"you press a button on the side of the meter which makes the little square indicator flash, indicating that the meter is ready to take a reading. Then you hold the meter up to your subject where the light is going to be illuminating them. Then you fire the flash. In doing that, we get an F reading on the meter"

https://selfhelpphotographer.com/how...erfect-photos/

I suppose that for continuous lighting, one could spot-meter the lit-in-turn surfaces of interest in shutter priority with no EC and use the metering's f-numbers the same way. I think there's a mode on my Gossen Starlite II that does something like that ...

Your point on the distance, I believe is correct; however I believe it still can play a role in lighting ratios.

Maybe so.

[Manfred M]

Bruce - in terms of concept, you are right. If my key light meters at f/8 and my fill light at f/5.6 I am shooting at a 2:1 lighting ratio. If the fill light is metered at f/4, and the key light is the same, then the lighting ratio is 3:1.

Yes one can move a light closer or farther away and change the lighting ratio, but one has to be aware that this will also impact the quality of light. The farther from the subject, the smaller the light source and the harder the light (although that might be what you are trying to achieve). I was taught that one generally does not place the light more than twice the diagonal (for a rectangular modifier) or twice the diameter (for a round one) from the subject in order to maintain the quality of light. This primarily refers to the key light and potentially the fill light. Once you start working with a hair light of a rim light, sometimes we are trying to push some hard light at the subject.

[xpatUSA]

Bruce - in terms of concept, you are right. If my key light meters at f/8 and my fill light at f/5.6 I am shooting at a 2:1 lighting ratio. If the fill light is metered at f/4, and the key light is the same, then the lighting ratio is 3:1.

Would that be 4:1, Manfred? Based on the ratio (F-key over F-fill) squared.

[Manfred M]

Would that be 4:1, Manfred? Based on the ratio (F-key over F-fill) squared.

What I have written is the most commonly used based on the number of stops difference between the key light and fill light.

Different photographers measure it differently too. Some point the meter at the light (which is the way I was taught) and others point the meter at the camera. With a 180 degree measuring dome over the metering head, that compensates for a lot of issues.

[xpatUSA]

What I have written is the most commonly used based on the number of stops difference between the key light and fill light.

So, if understand correctly: if the fill light is metered at f/4 and the key light is metered at f/8, then the number of stops difference between the key light and fill light is 2EV. Where does the "commonly used" lighting ratio of 3:1 instead of the obvious 4:1 come from?

I'm asking so that Bruce doesn't get confused by our divergent responses.

I would really like to know where that "3:1" comes from and the rational behind being 25% low compared to the actual ratio.

Anybody?

[William W]

Re Flash Lighting Ratios / Flash meter measurements of Key and Fill Light -Certificate and Ad. Cert (Photography) Sydney Tech College Curriculum, circa 1973~1990 in AUS, taught:

equal F/stops = 1:1Lighting Ratio
1 Stop difference = 2:1 Lighting Ratio
2 Stops difference = 4:1 Lighting Ratio
3 Stops difference = 8:1 Lighting Ratio

I am fairly certain same was taught at City and Guilds London and most European Colleges.

I have seen on www exactly what Manfred has stated and this has been termed "Lighting Ratio".

To answer Ted's question - "where does this come from?" to me it's a representation of an "F/STEP Ratio" and personally, I don't like it because it, IMO, falls short of describing what is exact: albeit, I think, a simplified way of dealing with the topic.

In a similar manner, some descriptions of ND Filters and "Filter Factors" on the www have, IMO denuded the reality which was formerly described correctly in the (now old) text books and curricula.

Basically, I am having a little whinge about www misinformation and/or inaccuracies.

WW

[Manfred M]

Re Flash Lighting Ratios / Flash meter measurements of Key and Fill Light -Certificate and Ad. Cert (Photography) Sydney Tech College Curriculum, circa 1973~1990 in AUS, taught:

equal F/stops = 1:1Lighting Ratio
1 Stop difference = 2:1 Lighting Ratio
2 Stops difference = 4:1 Lighting Ratio
3 Stops difference = 8:1 Lighting Ratio

I am fairly certain same was taught at City and Guilds London and most European Colleges.

I have seen on www exactly what Manfred has stated and this has been termed "Lighting Ratio".

To answer Ted's question - "where does this come from?" to me it's a representation of an "F/STEP Ratio" and personally, I don't like it because it, IMO, falls short of describing what is exact: albeit, I think, a simplified way of dealing with the topic.

In a similar manner, some descriptions of ND Filters and "Filter Factors" on the www have, IMO denuded the reality which was formerly described correctly in the (now old) text books and curricula.

Basically, I am having a little whinge about www misinformation and/or inaccuracies.

WW

I agree on the lack of clarity and the underlying basis is suspect. I wonder if this comes out of the USA as the instructor that taught me this came out of the photography program at RIT (Rochester Institute of Technology) which I understand is a very highly regarded North American school.

[xpatUSA]

<>

I have seen on www exactly what Manfred has stated and this has been termed "Lighting Ratio". <>

Pardon the clips Bill.

I have this minute got back from researching "Lighting Ratio".

One has it as "The ratio can be determined in relation to F stops [sic] since each increase in f-stop is equal to double the amount of light: 2 to the power of the difference in f stops is equal to the first factor in the ratio. For example, a difference in two f-stops between key and fill is 2 squared, or 4:1 ratio."

On the same page: "In situations such as motion picture lighting sometimes the lighting ratio is described as key plus fill to fill alone. A light meter can automatically calculate the ratio of key plus fill to fill alone."

That would be 5:1 for a 2-step difference ... the plot thickens.

Jim Zukkerman, writing for Sekonic, says:

"A 3:1 lighting ratio occurs when the light discrepancy between two light sources is one and a half f-stops." ... and more:

https://www.sekonic.com/studio-lighting-understanding-ratios

Ho hum ...

[xpatUSA]

Jim Zukkerman, writing for Sekonic, says:

"A 3:1 lighting ratio occurs when the light discrepancy between two light sources is one and a half f-stops." ... and more:

https://www.sekonic.com/studio-lighting-understanding-ratios

On the other hand, a la Monty Python, here's something completely different:



https://picturestoryteller.com/categ...atio-lighting/

Here they're using EV just as OP Bruce originally recalled.

What can we say?

It seems that "lighting" means many things and that the ratio thereof is quite moot.

[William W]

. . . On the same page: "In situations such as motion picture lighting sometimes the lighting ratio is described as key plus fill to fill alone. A light meter can automatically calculate the ratio of key plus fill to fill alone."

That would be 5:1 for a 2-step difference ... the plot thickens. . .

I think your text is not contradictory, rather attempting to be explanatory.

Motion Picture (Cine) Lighting Directors usually use that formula: the same with Stage Lighting Directors.

Again, that's exactly as I was taught, I did Cine in my Advanced Diploma and I have a broad brush of Stage Lighting, though never have practiced it as a trade, myself.

The Talent, being lit, in both those situations is (a) mobile and (b) for Cine might be viewed by two three or sometimes four different cameras, simultaneously and (b) for Stage are viewed by different sections of the Audience - That's the explanation I learned that we should use this Lighting Ratio for Cine and Stage, and it be different to Stills: noted this Lighting Ratio formula gives a bigger ratio numeracy - the reason is so that the Lighting Director is always assured/reminded that s/he is aware of the 'harshness' (for want of a better technical word) which might affect the various Camera Angles or different Audience Perspective.

***

I think Manfred might be onto something in that the "F-Step Ratio comes from the USA: no sarcasm intended, I think it is driven by wanting to make things 'simpler'.

It is similar to the 'simplifying' the (English) language: colour = color, probably a better example is 'advice' and 'advise'; 'then' and 'than'; 'further' and 'farther'; 'less' and 'fewer', etc being simplified and by doing so, depleting their differences in exact meaning.

WW

[Manfred M]

On the other hand, a la Monty Python, here's something completely different:



https://picturestoryteller.com/categ...atio-lighting/

Here they're using EV just as OP Bruce originally recalled.

What can we say?

It seems that "lighting" means many things and that the ratio thereof is quite moot.

Ted - I have run across this view of lighting ratios once or twice. In the grand scheme of things, the main issue with the different views is that using the same terminology with a different underlying basis leads to confusion.

Back to Bruce's original question; in terms of my understanding of the term, his view is correct. I suspect that as long has he speaks with other North American photographers, we will understand each other. Frankly, I rarely go past a 3:1 lighting ratio because for portraiture, I find anything higher starts to be quite severe and much of one side of the face is dark, almost a split lighting scenario.

[xpatUSA]

I think your text is not contradictory, rather attempting to be explanatory.

Motion Picture (Cine) Lighting Directors usually use '(Key+Fill) over Fill': the same with Stage Lighting Directors.

Thanks Bill, I'm beginning to get it.

The Cine/Stage folks use '(Key+Fill) over Fill' as the first term in The Ratio and they base the numbers on EV into the bargain. See the image in my post #12. From which f/8 vs. f/5.6 comes to 3:1. And from which f/8 vs. f/4 comes to 5:1.

On the other hand, although Zukkerman mentions Cine, his article is about Stills and he uses 'Key over Fill' as the first term, based on incident light. From which f/8 vs. f/5.6 comes to 2:1. And from which f/8 vs. f/4 comes to 4:1.

Although 3:1 itself appears to be a popular ratio, the actual ratio of light itself is different between the genres, meaning that the definition of "lighting" is different! (surprise ...)

I think Manfred might be onto something in that the "F-Step Ratio comes from the USA: no sarcasm intended, I think it is driven by wanting to make things 'simpler'.

Likely so.

It is similar to the 'simplifying' the (English) language: colour = color, probably a better example is 'advice' and 'advise'; 'then' and 'than'; 'further' and 'farther'; 'less' and 'fewer', etc being simplified and by doing so, depleting their differences in exact meaning.

WW

Indeed ... may I add effect/affect and compliment/complement?

By coincidence, I looked up 'further' and 'farther' yesterday! It said that 'farther' in US "English" is usually to do with actual distance and 'further' is usually to do with extending concepts, ideas, stuff, etc.

[xpatUSA]

Ted - I have run across this view of lighting ratios shown in #12 once or twice.

Indeed, to an Engineer, the concept of using ratios to determine a ratio is quite odd:

The Ratio's first term equals the ratio of the Key light to the Fill light plus the ratio of the Fill light to itself!! Glurk ...

In the grand scheme of things, the main issue with the different views is that using the same terminology with a different underlying basis leads to confusion.

Agreed, Manfred!

[xpatUSA]

This guy explains it all very well indeed, Bruce.

He even includes explanations of all the confusion.

Especially, I like "What is the correct answer to the question: What is the differences in stops for a 3:1 lighting ratio? Since method A and method B are interchanged at random, the answer could be any of 1 stop, 1 1/2 stops, 2 stops, or 2 1/2 stops."

Well worth a read.

http://www.jeffreysward.com/editorials/ligratio.htm
.

[William W]

. .Thanks Bill, I'm beginning to get it.

The Cine/Stage folks use '(Key+Fill) over Fill' as the first term in The Ratio and they base the numbers on EV into the bargain.

Yes.

. . .

On the other hand, [Zukkerman's] article is about Stills and he uses 'Key over Fill' as the first term, based on incident light.

And yes

. . .

Although 3:1 itself appears to be a popular ratio, the actual ratio of light itself is different between the genres, meaning that the definition of "lighting" is different! (surprise ...)

And, and yes.

***

In 'real world' terms it probably doesn't matter much at all. We here are discussing much like we would be discussing in a classroom: on a Cine Set; Sound Stage (i.e. interior Television Set) or Stage, I think and from my experience the Lighting Director, Lighting Riggers, Lighting Panel Operators, don't sit around discussing “Lighting Ratios”, instead, the instruction is something like "one more on Stage Right fill, close the door a bit." and it's taken as read that the 'one' is 'one EV'.

Possibly because there is so much 'learning' for STILLS done via On-line Tutorials, the presenters follow a pattern (which they themselves follow from on line tutorials) of mentioning ‘Lighting Ratios’ – it doesn’t take much of a stretch to think that some on-line presenters will use ‘tech talk’ as a validation of their credentials, ergo the necessity to use and refer to ‘lighting ratios’.

I think that the course Manfred mentioned (RIT) and similar are very likely in a different category: I expect that there when Lighting Ratios are mentioned this is part of the procedure of a structured curriculum and its purpose is to form a basis of theory, before proceeding to the practical application.

In that instruction of theory, provided that the measurement terms and values are clearly defined, and the Student learns that, then, in the real world it would be easy for the Student to notice that in some work situations, the measuring is different to what was learned in the classroom.

WW

[William W]

Expanding -

So, in answer to Bruce's OP, (recalling that he is discussing STILLS and using FLASH) Manfred's Post #5 nailed the answer IN PRACTICAL TERMS, for Bruce's situation, i.e. the main points being:

1. Measure Key and Fill, etc with Flash Meter, note the different Apertures indicated (ISO stays constant), the Apertures (F-numbers) are the 'comparative units' to be used in whatever formula you choose to use.

2. You can record the adjustment of the Lighting Ratio using the indicted Apertures as the measurement units.

3. You can move the Flash Heads in and out to and from the Subject - that indeed will change the Lighting Ratio: but in practical terms that's not usually the best way of doing that - because moving the Flash Head changes to QUAILITY and TYPE of the light.

***

As one simple guide (my simple guide) to using Key and Fill with two Flash Heads for Portraiture Lighting, in procedural steps:

1. Determine and Set the Pose
2. Determine and Set the Camera Viewpoint
3. Determine the Key Side
4. Set the Key Side for
(a)Aspect i.e. angle and height relative to Subject
(b)Type i.e. use of filters/diffusers etc
(c)Quality i.e. hard/soft - this also interplays with DISTANCE of Flash Head from the Subject as per Manfred's reference
(d)Intensity (rule of thumb start at F/8)


5. Set the Fill Side as above, a, b, c
6. Adjust Fill Intensity
7. Run Test Shots
8. Review Test Shots
9. Adjust if necessary

That done, it's kind of irrelevant how the "lighting ratio" is recorded, either that record being in the Photographer's head or on paper or in a digital file.

***

I have been pondering this and - remembering I did my first Tech Course around 1972, and we were taught Stills Portraiture using Photo Floods and 5x4 Rail Cameras: the (the pen and paper note pad) records I made certainly did, at the beginning record numbers of the "Lighting Ratio" - that was because the Instructor and the Practical Examinations required us to do that.

I can't remember recording a "Lighting Ratio" ever since I passed the exams and left the classroom - what I have often recorded about a Lighting Set is:
1. Aspect
2. Distance
3. Description (meaning Type and Quality)
4. Intensity

Apropos the recording details of a Flash Lighting Set, I'd record the 'intensity' simply as F/Stops, as indicated from the Flash Meter.

In all of this my records would not typically comprise sentences, but be a diagram.

This is a recreation of a (paper and pen) notepad entry which I made to record an a-typical Flash Lighting Set, for future use should I have been required to recreate similar Employee images for the company's records:



WW

[Manfred M]

I have been pondering this and - remembering I did my first Tech Course around 1972, and we were taught Stills Portraiture using Photo Floods and 5x4 Rail Cameras: the (the pen and paper note pad) records I made certainly did, at the beginning record numbers of the "Lighting Ratio" - that was because the Instructor and the Practical Examinations required us to do that.

I remember having to shoot with a Mole-Richardson "hot" light during my studio course; 1500W if I remember correctly. It was late fall and quite cool in the studio, until the light was turned onto a subject (we all took turns being the subject). Blindingly bright and incredibly hot; everyone broke out in a sweat. We had to use really thick, heavy duty leather gloves to move and adjust the head.

The instructor was trying to make a point about how much better the technology has gotten, versus what was used in the past. The old power packs with the heavy duty cables were interesting too; I had a full semester course using them too. RF controlled monolights do have their advantages....