The size/distance fallacy...

[sk66]

There is a lot of information out there that says a larger light source is "softer" and a smaller light source is "harder." And that the "size" of the light source is also dependent on it's distance as that affects the "apparent/relative/effective" size. This is all true, but it is also rather misleading/oversimplified.

A light source is "hard" when the rays reaching the subject are effectively parallel. This occurs at ~5x size distance. Moving it farther away will *not* make it "harder." It only makes it "smaller" which will be evident in catchlights/reflections, but not in the "quality of light" per-se (you can't really make the light rays "more parallel").

And the same is true once a light source is "soft," where the rays are coming from many angles and are able to "see around corners" to provide "wrap." This starts to occur at ~1x distance for an equal size illuminated area. Moving the light closer does not make it "softer." It again really only makes it "larger" which will be evident in catchlight/reflections, but not in the "quality of light" per-se (or not to a great extent).

For example, a 2ft softbox from 2ft is equally as soft as a 4ft softbox from 4ft away (for a 2ft illumination area). But a 4ft softbox from 2ft away isn't really significantly any "softer." What the larger softbox primarily gives you is additional control within that 2ft to 4ft range where the smaller modifier cannot provide the same softness. I'm not sure I can explain it easily/well without getting overly technical, but think of it this way... there is no real/major benefit or softness to be gained by lighting "farther around a corner" if there is nothing additional there to be lit.

The primary control you gain with a larger modifier is control over falloff/contrast, which is *huge* when it comes to controlling what an image is.
You additionally gain the ability to "feather" the light while still providing the light to the same area, this is because you have the ability to light a larger area to start with. And this is also *very* significant in creating/controlling a gradient and therefore what an image is (by "feather" I do *not* mean changing where it is pointed).
And this is where grids come in… when you want the falloff from placing the light source closer, but not the softness due to the size.

The real problem with small modifiers is not that they are "hard." The main problem is that they must be close in order to be "soft," and that severely limits your ability to control falloff/contrast/gradient. And smaller modifiers limit you to smaller subject/illumination areas to start with.
And the real benefit of larger modifiers is not that they are "softer." The real benefit is in the ability to control falloff/placement/gradient while *also* being/remaining soft.

In other words, it is not simply distance ='s size ='s softness. Rather it is size ='s softness, and distance ='s falloff; and these two factors must be balanced for the desired result.



** just to clarify, "feathering" the light in order to create/manipulate a gradient *does* affect "softness" to an extent. I chose to keep it separate for simplification and because it is more of a "refinement" than a primary factor.
*** the gradient/feather I mention is due to the relative distances of the modifier's surface... the feathering is more of a "lateral shift" rather than an angular one.

 

[sep9001]

Thank you for your post.

 

[Garry Edwards]

You're not wrong. But I think that the real problem is here is the use (or mis-use) of terminolgy such as "soft" which is really little more than a marketing term that has no defined meaning, and which is often used in a deceptive way, for example when advertising silly, overpriced bits of plastic that fit over hotshoe flashguns and which are claimed to produce "beautiful soft light" when, in reality, they can only produce soft light when they are no more than a few inches away from a tiny subject

Softness and hardness are just subjective terms. To make sense of this term, we need to think instead about relative size, which is based on a defined formulae. Relative size is the relationship between the size of the subject, the size of the light source and the distance between the light source and the subject. If the light source has a diameter of 1m and is at a distance of 1m from a subject that has a 1m size, then moving the light source twice as far away requires, in order to get the same level of "softness", either the light source needs to be 4x larger or the subject size needs to be 4x smaller.

It might be better to ditch the word "softness" and to substitute the word "contrast", because this is really much closer to what we are talking about.
But even "contrast" is both subjective and variable...
For example, a 150cm softbox, mounted on a studio flash head and directly pointing at a 3-dimensional subject, will produce low contrast (soft) lighting provided that it's close enough to the subject.
But the same softbox used with a hotshoe flashgun will produce a very different effect, simply because the front diffuser won't be of (anywhere near) equal brightness across its entire width.
Let's forget about the hotshoe flashgun then, and go back to our studio flash head - different designs of softbox, and different thicknesses/qualities of the diffusers, will also affect the contrast.
But let's forget that too, for the moment. If we position our softbox at an acute angle to the subject (so that the light is skimming across it from one side or the other) then, even if it's a very big softbox, the light will be contrasty and far from "soft".
In fact, a softbox can, depending on angle, design and quality, produce both low overall contrast and high local contrast at the same time - is that light soft or hard?

 

[juggler]

Garry has hit the nail on the head - it's all about contrast. I find it much more useful to think in terms of shadows* rather than light. The phrase 'hard light' is often used to mean two different things - (a) hard edged shadows or (b) dense shadows. Similarly 'soft light' is also used to refer to various different things, e.g. (a) soft edged shadows / wrap / subtle falloff, (b) shadows with reduced density or (c) unfocused light.

I'm not saying all those usages are correct - they just illustrate the problem.

*and specular highlights, but that only confuses the issue.

 

[sk66]

You're not wrong. But I think that the real problem is here is the use (or mis-use) of terminology such as "soft" which is really little more than a marketing term that has no defined meaning

I've always believed that hard/soft do have defined meanings... they're just very frequently misused. Both terms relate to the transitions from lights to darks in an image. If it is sudden/distinct it is "hard," and if it is gradual/indistinct then it is "soft." If you have no shadows it is neither hard nor soft regardless of the type of light source used, it is "flat." However, the extent to which the lighting is hard or soft is subjective.

Neither term relates to contrast/falloff, although they are often combined/convoluted. And that was the purpose of the post... to separate the two factors into what actually causes/controls them.

Everything on the web seems to be about size/distance in relation to softness... i.e. there is a lot of "move it closer" type of explanations.
But the fact is that a source is either suitably large, or unsuitably small, and there is not much range in between. Once it is suitably large, moving it closer/making it larger does not make it softer, it just covers more area. And once it is unsuitably small, moving it farther/making it smaller does not make it harder. But the changes in distance *do* affect contrast/falloff.

I don't think we can eliminate hard/soft and speak only of contrast because contrast/falloff is a factor controlled only by distance. And that was the main point of the post... the real benefit of "larger" is that it gives you control over contrast/falloff over a range where a smaller source/modifier cannot. But for that to be true it has to be physically larger (i.e. *not* closer/relatively larger).


***there are a lot of "tweaks"/refinements/modifications that can be made (i.e. feathering/grids) once these two basics are set...but I was trying to avoid all of that for the sake of simplicity/understanding.

 

[sk66]

Double post

 

[sk66]

Garry has hit the nail on the head - it's all about contrast.

I can't quite agree...
You can have soft high contrast and you can have hard high contrast, but they will be very different images.

 

[Kodiak Qc]

You can have soft high contrast and you can have hard high contrast

•


+1

It's more like all about wrapping!

 

[Garry Edwards]

I don't think we can eliminate hard/soft and speak only of contrast because contrast/falloff is a factor controlled only by distance.

With respect, that isn't right. Contrast can also be greatly affected by angle of incidence.

I can't quite agree...
You can have soft high contrast and you can have hard high contrast, but they will be very different images.

But those very different images can be created with exactly the same light sources at exactly the same distances, varying either the light position, the camera position or both

 

[Terrywoodenpic]

Early portrait studio lighting was mostly done with spot lights as the main light.
These produced strong moulding, strong texture, hard shadows.
Even when refocussed to a flood similar directional light ensued... just over a wider area.
Fills were of two sorts. Small frontal directional spots often used to flatten micro skin texture such as wrinkles.
And soft dishes of various designs to lighten shadows and control contrast.
Soft panel reflectors were often used mainly in High Key lighting.
I have noticed a return to favour of the more directional "Hollywood" lighting among some photographers.
What is hard to achieve with modern studio flashes is the same texture, and micro contrast in detail so easily brought out with large spots.

Where it was once normal to have a "Hard" directional main light and "soft" fill, this has now become more difficult to achieve using light modifiers.

Large spots were more akin to point source lighting.

 

[Terrywoodenpic]

With respect, that isn't right. Contrast can also be greatly affected by angle of incidence.

But those very different images can be created with exactly the same light sources at exactly the same distances, varying either the light position, the camera position or both

Exactly... Texture and moulding are controlled by angle of incidence of the light.
but The larger the source of diffused light, the greater the wrap, the less the texture.

 

[juggler]

I have noticed a return to favour of the more directional "Hollywood" lighting among some photographers.
What is hard to achieve with modern studio flashes is the same texture, and micro contrast in detail so easily brought out with large spots.

Guilty as charged
Perhaps you could elaborate on why modern studio flashes can't achieve the same texture and micro contrast? I know a gridded reflector doesn't focus in the same way as a fresnel but I'm struggling to understand the physics of how that affects apparent texture.

 

[Terrywoodenpic]

Guilty as charged
Perhaps you could elaborate on why modern studio flashes can't achieve the same texture and micro contrast? I know a gridded reflector doesn't focus in the same way as a fresnel but I'm struggling to understand the physics of how that affects apparent texture.

In those days I mostly use large 2KW and 3KW Spotlights these were used at least 10 feet from a subject ( unless you wanted to have fried flesh) and the Light output was controlled by equally large rheostats. In effect there was no "Wrap" at all. Skin before fill was added had pores like hills and valleys. It was virtually point source lighting. We called the main light the "Modelling light"
In one studio where I worked we had no Flood lights at all and used Spots for everything, some small some large. though we did have some reflectors and flats.and numerous flags.

A modern flash simply does not create the same degree of directional lighting, Grids can only limit the degree of the spread they can never focus each ray.
Of course a flash can be focussed with a Fresnel, but it would be fairly expensive and difficult to control. I suspect the newer LED lighting units can be fitted with decent Fresnel's. but I don't know what the market would be.
But if fashion dictated Hollywood lighting the manufactures will follow.

If you squirt a Spotlight across sand paper and enlarge the result, every grain is delineated with its own shadow and you get micro reflections from every face. A softer light simply evens out the texture.

 

[Garry Edwards]

Guilty as charged
Perhaps you could elaborate on why modern studio flashes can't achieve the same texture and micro contrast? I know a gridded reflector doesn't focus in the same way as a fresnel but I'm struggling to understand the physics of how that affects apparent texture.

What an interesting discussion this is becoming - at long last we have a thread about the qualities of light, rather than about which ineffective toy is cheapest
I would also be interested in knowing why (or how) a modern studio flash can't achieve the same texture and micro contrast - because of course it can, all other factors being equal.

 

[Garry Edwards]

Early portrait studio lighting was mostly done with spot lights as the main light.

I pressed "Post reply" accidentally, so this post just replaces my last one
What an interesting discussion this is becoming - at long last we have a thread about the qualities of light, rather than about which ineffective toy is cheapest

In those days I mostly use large 2KW and 3KW Spotlights these were used at least 10 feet from a subject ( unless you wanted to have fried flesh) and the Light output was controlled by equally large rheostats. In effect there was no "Wrap" at all. Skin before fill was added had pores like hills and valleys. It was virtually point source lighting. We called the main light the "Modelling light"
In one studio where I worked we had no Flood lights at all and used Spots for everything, some small some large. though we did have some reflectors and flats.and numerous flags.

A modern flash simply does not create the same degree of directional lighting, Grids can only limit the degree of the spread they can never focus each ray.
Of course a flash can be focussed with a Fresnel, but it would be fairly expensive and difficult to control. I suspect the newer LED lighting units can be fitted with decent Fresnel's. but I don't know what the market would be.
But if fashion dictated Hollywood lighting the manufactures will follow.

If you squirt a Spotlight across sand paper and enlarge the result, every grain is delineated with its own shadow and you get micro reflections from every face. A softer light simply evens out the texture.

I would also be interested in knowing why (or how) a modern studio flash can't achieve the same texture and micro contrast - because of course it can, all other factors being equal.

In fact, the Hollywood "Glamour portraits" were largely shot with fresnel spotlights, the still photographers simply used the studio lighting that was there. The only post processing available to them was at the printing stage, although of course their large glass plates could also be retouched to some extent, and because of these limitations, and because they had a very high level of skill, they made sure that they got it as close to being right in camera as they could.
Flash wasn't available to them, and wasn't needed anyway because the glamourous stars who they photographed could cope with the extreme brightness and the extreme heat produced by the fresnel spots.
There are perhaps two factors that may make people believe that the same results can't be achieved with flash
1. Light source position can be critical, and the fresnel spots used in the movies had a built in light, ergo the filament was in the right position relative to the optics - flash heads don't all have the flash tubes in anywhere near exactly the same position to each other, and only focussing can overcome that.
2. Some flash heads (for example Elinchrom) use a modelling lamp design that obscures or partially obscures the flash tube
3. The old fresnel spots were massive, compared to modern ones. The best (fairly) modern one I've used myself is a Bron, with a 14" diameter optic, this is far smaller than the old movie ones. We used to sell one that had a 9" diameter front optic, this was nowhere near as good as the Bron but at least people didn't have to sell their house to buy it. Some other makes have them with 8", 6" or even smaller front optics - I really don't know what they're for, they're far too small for portraiture.

[QUOTE="Terrywoodenpic, post: 7361759, member: 13779"


If you squirt a Spotlight across sand paper and enlarge the result, every grain is delineated with its own shadow and you get micro reflections from every face. A softer light simply evens out the texture.[/QUOTE]

Honeycomb grids don't focus at all, they simply control the amount of light spread.
But, the standard reflector to which they are fitted does focus, how well it does that depends both on its design and on the type of finish.
A more distant light will of course create higher local contrast at any given angle of incidence, it isn't so much that a softer light simply evens out the texture, a major factor here is what happens to the light after it has skimmed across the surface - if it hits a nearby wall, or even the ceiling, and bounces back, then the unplanned fill light will of course significantly reduce the visibility of the texture. As some people know, I use hard lighting a lot, but I'm very mindful of reflected light, and I always make sure that any light that travels past my subject is then killed and not reflected back on to my subject. People who have less space than me can do the same, it just requires a black cloth or similar to stop unwanted light from hitting reflective surfaces.

 

[Byker28i]

Early portrait studio lighting was mostly done with spot lights as the main light..

I saw a really good exhibition in Rome by Arturo Ghergo, 1920's onwards photographer who used two lights only. Some stunning work of italian film stars and celebrities


http://english.palazzoesposizioni.it/categorie/exhibition-016

 

[juggler]

I was just about to say 'thanks, that all makes sense' when I re-read your reply and this line piqued my attention

A modern flash simply does not create the same degree of directional lighting, Grids can only limit the degree of the spread they can never focus each ray.

I think I can see what you're trying to say but I think introducing the concept of rays is unhelpful. A ray is notionally a one-dimensional entity and as such can't be focused on its own. Perhaps you've got a better way of putting it?

 

[Alastair]

Early portrait studio lighting was mostly done with spot lights as the main light.

Early portrait studio lighting was almost always daylight..

But I think any disagreement is limited to the definition of "early"

 

[juggler]

I pressed "Post reply" accidentally, so this post just replaces my last one
What an interesting discussion this is becoming - at long last we have a thread about the qualities of light, rather than about which ineffective toy is cheapest

Agreed!

2. Some flash heads (for example Elinchrom) use a modelling lamp design that obscures or partially obscures the flash tube
3. The old fresnel spots were massive, compared to modern ones. The best (fairly) modern one I've used myself is a Bron, with a 14" diameter optic, this is far smaller than the old movie ones. We used to sell one that had a 9" diameter front optic, this was nowhere near as good as the Bron but at least people didn't have to sell their house to buy it. Some other makes have them with 8", 6" or even smaller front optics - I really don't know what they're for, they're far too small for portraiture.

The size and focusing qualities of those old spots as described suggest to me that the best common modern equivalent would be a smallish silver beauty dish with a very narrow grid. Which happens to be what I've been using lately. Or is there something else I should try?

 

[Phil V]

So, whilst the debate is live! Something I've been considering is buying a cheap fresnel to rig as a spot enclosure.

Any of you bright fellas tell me whether it might work? Or do I have to do the experiment?

 

[Garry Edwards]

Bright fellas... well, that rules me out but I'll bite anyway
What are you trying to achieve?

 

[Phil V]

Bright fellas... well, that rules me out but I'll bite anyway
What are you trying to achieve?

In short, the classic '30s Hollywood look
Well...
There are several 'high end' fresnel focussable enclosures, and some tungsten / led modern versions (the cheaper ones don't have a very large lens though), I started searching a well known auction site for a stage spotlight to cannibalise, but then I spotted fresnel lenses designed for other uses, I've no idea what sort of effect they might produce, is it worth a punt?

 

[Garry Edwards]

Well, as I said earlier, those Hollywood ones were pretty massive, that IMO was their main quality.
Bear in mind that if you can find something similar, and assuming that you have your own electricity sub station to power it, can you find models who will be able to cope with the heat and the dazzling light? Can you access makeup that won't melt?
The design of the fresnel lens is itself quite critical, I don't know what you've managed to find but if they are cheap enough and big enough it must
be worth getting one to try it out.

But I would have thought that stage lighting is probably the best answer, although you'll still be inflicting virtual torture on your poor models Mind you, there are plenty of models to choose from...
Back in the 70's I had about 10 of these continuous light fresnels, which I used for furniture photography, they will have zero or very low value today, might be worth trying to find one.

 

[Terrywoodenpic]

So, whilst the debate is live! Something I've been considering is buying a cheap fresnel to rig as a spot enclosure.

Any of you bright fellas tell me whether it might work? Or do I have to do the experiment?

You will be horrified by the price that old mole richardson spots fetch even with out their correct stands and barn doors (per ebay) but they are fairly useless without. The 500w versions were only used as wrinkle fillers, bashers, and for effects .
You will find that they are a fraction of the price in the usa, where they are not bought as fashion lighting. (Again ebay)
even 1000w ones were bottom end for portraiture.

I am sure Led powerd spot lights are going to be the answer in the longer term. If only because of the less heat and power consumption.

 

[sk66]

With respect, that isn't right. Contrast can also be greatly affected by angle of incidence.

But those very different images can be created with exactly the same light sources at exactly the same distances, varying either the light position, the camera position or both

(I believe) You're essentially talking about feathering a light that is already suitably/excessively large for the goal. I was trying to avoid that...

Feathering does one of two things. By changing position (laterally) it changes distances to the various parts of the surface/modifier which affects the contrast. By changing the angle it also changes the distances to the various parts of the surface/modifier while *also* reducing the apparent size of the source... distances controlling contrast and size/apparent size controlling hardness.

A large/soft light source doesn't really have an angle of incidence because there isn't a singular direction of light... One might say there is a "primary" angle of incidence, but that again is due to distances, with the shortest being a straight line between the surface and the subject.

Unless I am missing something, the contrast is always due to distances in some way, and the hardness is due to size/apparent size. Regardless, you do not have these options/refinements available unless the source is suitably physically large to begin with. Which goes back to the point, you cannot move a smaller modifier closer in order to make it suitably/effectively larger... because that *will* increase the contrast and there is *no way to avoid that.

(*yes, you can fill with other sources)

 

[sk66]

It's probably been a few years now, but I had an acquaintance who spent a lot of money on a fresnel light and was raving about how great and special it was.

I spent a good bit of time studying the results and I could not see anything that I could specify as being due to a fresnel lens specifically. His opinion was that I'm an idiot, my opinion was that he spent a lot of money on a beast of a light for no good reason...

Fresnels *do* create "rings of light," but I suspect distance negates the effect. The only fresnels I have used personally are pin-spots... and a lot of their benefit comes from a variable aperture/masks.

 

[sk66]

So, whilst the debate is live! Something I've been considering is buying a cheap fresnel to rig as a spot enclosure.

Any of you bright fellas tell me whether it might work? Or do I have to do the experiment?

I tried to DIY a focusing fresnel speedlight attachment to make a pin-spot. It didn't really work. I used a telescoping tube arrangement but I think the tube diameter/min-length became the limiting factors. That and the lack of a variable aperture.

I think it might be possible if the main tube was large enough for the light to move inside it in order to reduct the minimum lens distance... I might try that eventually.

 

[Phil V]

I tried to DIY a focusing fresnel speedlight attachment to make a pin-spot. It didn't really work. I used a telescoping tube arrangement but I think the tube diameter/min-length became the limiting factors. That and the lack of a variable aperture.

I think it might be possible if the main tube was large enough for the light to move inside it in order to reduct the minimum lens distance... I might try that eventually.

The the lens I've found is 11", my idea is to mount at the end of a square tube which will fit over a mounted AD360 with a shallow bowl reflector behind the flash tube. The focussing would be done by sliding the tube back and forth.

From what I understand of a simple theatre focussing spot, that's about all that's required, though obviously I could add an aperture too

 

[juggler]

The the lens I've found is 11", my idea is to mount at the end of a square tube which will fit over a mounted AD360 with a shallow bowl reflector behind the flash tube. The focussing would be done by sliding the tube back and forth.

From what I understand of a simple theatre focussing spot, that's about all that's required, though obviously I could add an aperture too

A complete aside.. but I can't wait to see the results

 

[Terrywoodenpic]

The the lens I've found is 11", my idea is to mount at the end of a square tube which will fit over a mounted AD360 with a shallow bowl reflector behind the flash tube. The focussing would be done by sliding the tube back and forth.

From what I understand of a simple theatre focussing spot, that's about all that's required, though obviously I could add an aperture too

A studio spot was rather different to a stage light and gave a far more perfect and even beam.
Both the mirror could be focussed, as well as the lamp to fresnel distance. This meant you could increase the spread, as well as maximise the light from the mirror. For portraiture is was normal to use the beam partially spread, but controlled with the barn doors. None of them ever had apertures.
the intensity was controlled by a rheostat. Unlike a flood, a spot does not follow the inverse square law.
Your 11inch fresnel is about the same size as you would find on a 500w spot.. however fresnels differ dramatically with quality.

 

[Terrywoodenpic]

It's probably been a few years now, but I had an acquaintance who spent a lot of money on a fresnel light and was raving about how great and special it was.

I spent a good bit of time studying the results and I could not see anything that I could specify as being due to a fresnel lens specifically. His opinion was that I'm an idiot, my opinion was that he spent a lot of money on a beast of a light for no good reason...

Fresnels *do* create "rings of light," but I suspect distance negates the effect. The only fresnels I have used personally are pin-spots... and a lot of their benefit comes from a variable aperture/masks.

A properly constructed and set up good quality fresnel spot does not produce rings of light, it will only do so if miss focused.
had they done so they would be useless for studio work. Masks can be used to throw shadows. Variable aperatures only reduce the diameter of the size of the spot (coverage) not the quantity of light.

 

[sk66]

The the lens I've found is 11", my idea is to mount at the end of a square tube which will fit over a mounted AD360 with a shallow bowl reflector behind the flash tube. The focussing would be done by sliding the tube back and forth.

From what I understand of a simple theatre focussing spot, that's about all that's required, though obviously I could add an aperture too

I think an 11" fresnel will be a pretty large spot.
I picked up one of these, but haven't played with it yet.
http://www.ebay.com/itm/131612166892?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

[sk66]

Variable aperatures only reduce the diameter of the size of the spot (coverage) not the quantity of light.

Size of coverage is what I was after (very small for product work)... Bowens and ProPhoto both make fresnel spot attachments with variable apertures (about $1k+), I'm sure others do as well.

 

[Terrywoodenpic]

Size of coverage is what I was after (very small for product work)... Bowens and ProPhoto both make fresnel spot attachments with variable apertures (about $1k+), I'm sure others do as well.

In the day, people were more likely to use pre cut holes in slide in adapters than camera like apertures.
A few slides with movable arms like printing easels were available, they could rotate and be set to any retangular shape, so were good for product photography.
I am sure film studios still have every variation possible.

The most useful of all is a regular barn doors , which can be used to do about everything.

You can always cut your own mask slide from kitchen foil wrapped on a simple wire frame. But dont try anything flammable.

 

[juggler]

The the lens I've found is 11", my idea is to mount at the end of a square tube which will fit over a mounted AD360 with a shallow bowl reflector behind the flash tube. The focussing would be done by sliding the tube back and forth.

From what I understand of a simple theatre focussing spot, that's about all that's required, though obviously I could add an aperture too

I've got access to a follow spot. It's quite small but it's got to be worth a try..

 

[Terrywoodenpic]

Size of coverage is what I was after (very small for product work)... Bowens and ProPhoto both make fresnel spot attachments with variable apertures (about $1k+), I'm sure others do as well.

A 500w mole richardson with barndoors was the go to tool for product photography. There we also a large variety of large and small diameter floods with various polished and shaped surfaces that made excellent fill lights. It was not till the 60,s that large soft lights were introduced to most studios. Before that only reflectors were available for soft fill.

 

[Garry Edwards]

In the day, people were more likely to use pre cut holes in slide in adapters than camera like apertures.
A few slides with movable arms like printing easels were available, they could rotate and be set to any retangular shape, so were good for product photography.
I am sure film studios still have every variation possible.

The most useful of all is a regular barn doors , which can be used to do about everything.

You can always cut your own mask slide from kitchen foil wrapped on a simple wire frame. But dont try anything inflammable.

In the day, people were more likely to use pre cut holes in slide in adapters than camera like apertures - or, in other words, Waterhouse Stops, which of course were the first to be used in cameras too. But manufacturers such as Bron had variable apertures, slightly more convenient but not strictly necessary.
inflammable is fine, just don't make them from anything that isn't inflamable

 

[Garry Edwards]

I've got access to a follow spot. It's quite small but it's got to be worth a try..

Yes, I agree - well worth trying. But we're now straying from fresnel spots to focussing spots, not the same thing at all.

 

[Terrywoodenpic]

I've got access to a follow spot. It's quite small but it's got to be worth a try..

Stage follow spots often have simple lenses rather than fresnels. This produces a less even light with a lot more fringing. But they usually have a simple mechanism for adjusting the size of the spot on the go.

 

[Terrywoodenpic]

In the day, people were more likely to use pre cut holes in slide in adapters than camera like apertures - or, in other words, Waterhouse Stops, which of course were the first to be used in cameras too. But manufacturers such as Bron had variable apertures, slightly more convenient but not strictly necessary.
inflammable is fine, just don't make them from anything that isn't inflamable

Nice one I will edit that.
we rarlely used the term waterhouse stop for lights, we mostly just called them slides or vignettes