A more elaborate studio setup!

[Kodiak]

Anyway, what are these 'Flags' you people mention about?

Hey Haseeb,

A flag, in this case, is an obstructive device that will stop the light from going where
it is not wished! Made of anything in any non-reflective material, a flag is positioned
between a light source and your subject… just as a curtain will pulled to shade a
computer screen.

[HaseebM]

Thank you, I should try this out.

[Mike Buckley]

A flag is also sometimes called a gobo. I think it's derivation is "go between objects" but I'm not sure. It can also be placed between the light source and the camera as a means of preventing flare and lack of contrast.

[Kodiak]

A flag is also sometimes called a gobo.

Yes… but this is not correct. The flag will stop dead the light as the gobo will
1- modify it
2- project it

I think it's derivation is "go between objects" but I'm not sure.

This is correct.

It can also be placed between the light source and the camera as a means of preventing flare and lack of contrast.

This is an other usage of the flag as its function is to block the light
from going where it is not wished.

Flags are sometimes included in gobos sets sold on the market. This inclusion
may be at the origin of the confusion.

[Mike Buckley]

Gobos aren't flags? Sheesh!

One of the things that's frustrating about the world of photography is that there is so little formal standardization of terminology. That makes it difficult to communicate.

As an example, I learned of the term, "gobo," reading the fourth edition of Light: Science & Magic, which from what I can tell is widely recognized as a Bible of understanding light. The authors define gobo on page 77 as "photospeak for anything that goes between the subject and the light source specifically to block part of the light." Yet on page 179 they explain how to make and position a gobo to prevent light from striking the lens (not the subject).

[Kodiak]

widely recognized as a Bible

I'm no bible, don't pretend to be one nor got the definition from one!

Having worked in a cinema environment, where both flags and gobos
are used at the same time on the set but for obvious different reasons,
I still use the term commonly used in both disciplines or trade.

However, for me here, the distinction is important only in the attributes
of each: one is a blocker as the others are modifiers. Once the difference
understood, I really leave to everyone the freedom to put flags in any
category they may want.

[Manfred M]

Mike - a gobo is something that goes between the light and subject and modifies the light falling on the subject. A gobo usually has cutouts or shape modification that transmits part of the light. Think of a flash travelling through the bannisters of a staircase and casting a shadow of their shape on a wall. That is more what a gobo will do. Cut some patterns in a piece of cardboard and use the light and shadows it casts. That is what I would refer to as a gobo.

I've also heard people refer to flags as a "cutter"; but there may be a subtle difference here too, that I'm not aware of.

[Mike Buckley]

Is it a coincidence that both Manfred and Kodiak have backgrounds in cinematic photography and that they make distinctions between a gobo and a flag? Perhaps those who work in that realm have a more specific or even a more accurate use of the term, "gobo."

Allison Earnest in her book, Lighting Product Photography, states on page 46 that flags are also called gobos, implying that they are one and the same.

Glenn Rand writes on page 24 of Lighting and Photographing Transparent and Translucent Surfaces that blocking [light] can be complete, as with a gobo, or partial, with scrims, grids or gels." On the next page, he describes a setup in which "the gobo acts as a flag (a dark, normally black, panel or object placed in the light envelope to absorb light and minimize reflections)."

Add to that the information in my previous post that Light: Science & Magic, which is authored by three professionals, uses the terms, "gobo" and "flag," synonymously.

In summary, I have three books that explicitly explain the use of flags and gobos and all of them seem to use the terms synonymously. So, I wonder if the professional photographers who were perhaps brought up in the world of still photography use the terms differently than those brought up in the realm of cinematic photography.

To keep things clear, I hope in the future to use a verb such as "block" or "modify" to communicate with others rather than a noun such as "flag" or "gobo."

[Kodiak]

Allison Earnest in her book, Lighting Product Photography, states on page 46 that flags are also called gobos, implying that they are one and the same.

Yes, they are also called gobos because they are! Like I said, the flag is
the only one to block the light. So when a light engineer asks for a gobo
he will also state which effect he wants… hundreds to choose from but if
he asks for a flag, one just needs to know the size because the effect is
very clear.

Sorry Mike, this will go nowhere… it's like potato and tomato… say it the
way you please, as long as you're understood.

[Mike Buckley]

say it the way you please, as long as you're understood.

That's the problem, Kodiak. Different people far more steeped in the correct usage of terminology than I use the two terms in such a way that there is no way that I know I am not causing confusion. I would not have learned this if you hadn't explained, so thank you!

[Inkanyezi]

Although my most used language is not English, I also share the thought that gobo is something used between the light and the subject - or, it could be something between the subject and the camera. I have heard gobo for both. But a flag is simpler and does not state where the flag would be used. The flag has a simple form, and can be used for blocking light from a source toward something, be it camera or subject or even something else as a reflector or difusing screen. Some lamps have flags attached, that can be used to limit the angle of their output.

A photographer I know used the term gobo for a white mesh screen with a hole in the middle, a mesh mask, which was put in front of the camera, to cause a diffuse white framing of the shot.

[Manfred M]

Mike - I think that the issue is that there is no "universal" definition for these devices and local use of the terms may vary.

In my own rather limited time in the field, I've picked up the same definitions of a gobo, as Kodiak's; although I can see where the author you quote is coming from; both devices are set between the light source and the image. The main difference is how they handle the light spilling past them.

[Kodiak]

The main difference is how they handle the light spilling past them.

…very simply! ;-)

[Kodiak]

…really makes me want to go out, buy non-alcoholic bottle of wine…

Why that???

[Kodiak]

Thank you, I should try this out.

…one more thing…

By definition, a flag will stop a light beam and prevent it to reach a scene.
This says nothing about its size… I use flags that are 3x6 feet down to a
simple piece of black paper, just a few square inches, that may have a gentle
bend to it and stands right next to the subject!

[HaseebM]

Why that???

I don't drink.

[HaseebM]

…one more thing…

By definition, a flag will stop a light beam and prevent it to reach a scene.
This says nothing about its size… I use flags that are 3x6 feet down to a
simple piece of black paper, just a few square inches, that may have a gentle
bend to it and stands right next to the subject!

I learnt a lot reading posts here and from this thread. I really want to try this out on some objects and am on the hunt to find a Gobo and Grid. Unfortunately Elinchrom only seem to sell their lights and do not keep stock of accessories. I have emailed them twice already and no reply. It is unfortunate a brand such as Elinchrom does not answer back. Anyway, I am still trying to find these items and one from eBay india has in stock but from one bad experience I had with eBay, I do not want to buy from there.

It would be helpful if someone can just post a image with the Flag in it.

[Kodiak]

I learnt a lot reading posts here and from this thread. I really want to try this out on some objects and am on the hunt to find a Gobo and Grid. Unfortunately Elinchrom only seem to sell their lights and do not keep stock of accessories. I have emailed them twice already and no reply. It is unfortunate a brand such as Elinchrom does not answer back. Anyway, I am still trying to find these items and one from eBay india has in stock but from one bad experience I had with eBay, I do not want to buy from there. It would be helpful if someone can just post a image with the Flag in it.

A flag is a usage: something used as a flag but it is not a "thing"! Don't
go out to buy flags it will cost you a fortune! … just make them.

Anything may be used as flag like in the following photo (I included some
mirrors as well):

[Inkanyezi]

As Kodiak says, it is a usage. My most frequent use of a flag is when I shade the lens with my hand to avoid direct sunlight into it when the sun is just outside the image area. The hand serves as flag.

[HaseebM]

Thank you Kodiak, greatly appreciated.