Double Diffusion Studio Lighting Questions

[smoke665]

Looking at my next learning project, and curious about the effects of using double diffusion. I have a diffusion cover on my octabox, and a large frame with white nylon rip stock to use as the secondary.

1. In reading so far it seems that using double diffusion increases the color saturation and fine detail. Is this a correct statement and why or why not???
2. Are there any recommendations as to the distance between the subject and the second diffusion panel, or would it follow along the same lines as a large softbox?
3. Are there any recommendations as to the distance between the light and the second diffusion panel? Or is there a point of diminishing return?
4. If I'm using my large octabox as the primary, and diffusion panel in between, I'm assuming it will pretty much eliminate catchlights. Should I try a second light to supply the catchlights or just add them post? Seems like that might be the easiest.
5. I've read several articles on it so far, any good recommendations for further reading?

 

[fmw]

It looks to me like you misunderstand diffusion. The purpose of diffusion is to enlarge the light source relative to the subject in order to soften the light.

Hard light outdoors occurs when you have direct sunlight. Hard light, harsh shadows, small light source (the ball of the sun). On an overcast day you have soft light, little or no shadow, huge light source (the entire sky). The larger your diffuser and the closer it is to the subject, the softer the light. The smaller it is and the further from the subject, the harder the light. Having two diffusers only reduces the light on the subject. It is the larger diffuser than will determine the softness of the light.

A diffuser shouldn't affect the catchlight other than to soften it and enlarge it. It should only have the catch light look like the diffuser. Hope this helps.

 

[smoke665]

It looks to me like you misunderstand diffusion. The purpose of diffusion is to enlarge the light source relative to the subject in order to soften the light.

Though my OP probably didn't convey it I am aware this. What I was unclear of is how it appeared in the examples to highten saturation and fine details.

Also wouldn't the distance between my octabox with diffusion and second diffusion decrease catchlight size? Or intensify

 

[Designer]

Also wouldn't the distance between my octabox with diffusion and second diffusion decrease catchlight size? Or intensify

You may have already seen this, but here:

Double Diffusion Lighting Technique is Helping Photographers Fix Tough Reflections | Expert photography blogs, tip, techniques, camera reviews - Adorama Learning Center

 

[Derrel]

So many questions, so little time to respond. It's Saturday AM, gotta get out to Silver Creek Falls soon.

I've used double and even triple diffusion at times over the years. I am a huge fan of Speedotron snap-on mylar diffusers for metal parabolic reflectors, and often use 1,2, or 3 of them over 11.5-inch or 7-inc metal reflectors on my flash units. Diffusion can come in many forms, not just from panels.

I like umbrella boxes in which the light hits a DULL-colored, white VINYL interior (not the shiny rayon type stuff), and then goes through THIVK ripstop nylon. Lastolite Umbrella Box...thius is why the quality of the light is better than the cheaper, $29 per pair Steve Kaeser Enterprises umbrella boxes. This is double diffusion...once off the inside, again thru the fabric...doubly-diffused....Ad a mylar diffuser over the flashhead and it's triply-diffused light...

Panels/scrims and fabrics/silks/mesh can all be used as second diffusion sources, and there are MANY setups....you can even use two fabrics/silks over a panel (scrim) and shoot raw light off to one side, and force the other part of the beam to come thru the fabric(s) so it is diffused. Limitless arrangements possible using a diffuion scrim aka a panel.

This type of lighting has been covered in the old Dean Collins "Finelight" videos; search YouTube for some SUPERB videos. Diffusion can be used to both increase the size of a light source and/or to reduce its hardness(its shadow-causing potential) or reduce its specularity (look it up). Diffusing light can be done with opal glass, mylar, metal or fiberglass screening,tracing paper, coffee can lids, Visqueen window plastic, and factory-made stuff like TuffSpun (a Fibreglas [trade name Fibreglas,one s,e before g] material, and so on. Same with ripstop nylon, thule, silk, gauze, whatever.

Diffusion and using more than one diffuser has a set of optical rules. The closer to the panel the light is, the more it diffuses; the farther away the light is from the diffusion panel, the harder the light is. The material itself also has an effect: window screen or wire diffusers diffuse LESS than say, ripstop nylon material does, at the same setup. Larger panel = larger source =softer liught at closer distances. Beyond 25 feet or so, the physicval size of the source of the light becomes almost the same in most cases.

Does difusion enhance fine detail? Uh...not necessarily; Usually detail's appearance is due to shadow,specularity, and contrast, so in general, I think saying diffusion "enhances detail" is not the right way to state that. HARD, crisp light raked across wood can show "detail", same as it can in hair....so, I have no idea who said that diffusion enhances detail, because that's not an accurate statement; I think it's like saying, "Hard liquor enhances sexual performance." Ummmm...yes. And no. It all depends on how it is used. Not sure why diffusion would enhance color saturation either...but it CAN allow you to under-expose things like color transparency film, which DOES appear to enhance color saturation. On a foggy, diffused-light day, color transparency film can be UNDER-exposed, a LOT, and can deliver deep,rich-looking 'chromes; I think perhaps the above idea is a holdover from film days.


Re:catchlights. If you have a BIG panel, a Dean Collins-like very big panel, say 72 x 72 inches, it CAN make catchlights disappear if the panel is placed close enough that the eyeball or product reflects the entire panel's lighted surface. For example, put a P-22 panel 48 x 72 inches very close to a human; the panel can be so close that instead of a rectangular catchlight, what forms is a reflection that covers the entire eyeball's surface. SAME THING happens allllll the time with wine bottles, or jewelery, or Plexiglass tables: move the panel into CLOSE proximity to these items, and the "catchlight", the shaped-one, disappears, and is replaced by a big, honking overall, shapeless, lighter-colored reflection...

On products...see the Five Things You Can Do With Just One Softbox video on YouTUbe, by Tony Corbell....watch his jewlery segment in that video, you'll see what making the liught soure VWERY large in relation to the subject, can do.

Disatance from source to panel: No rulkes. Close=softer, farther=crisper. Size of original and modifier size and nature both affect the relationship and effect. A metal 7 to 16-inch diameter refelctor works wayyyyyyy differently than a 28-inch softbox, when shot thru the same sized panel. NO fixed rules: depends on desired effect,lights,diffusion materials.

1. If I'm using my large octabox as the primary, and diffusion panel in between, I'm assuming it will pretty much eliminate catchlights. Should I try a second light to supply the catchlights or just add them post? Seems like that might be the easiest

I'm not sure that's anywhere near correct. It depends on how close the panel is. Dean Collins: our job is to create and place the diffuse highlight. Post-applied catchlights can be done pretty easily these days....buuuuut...what does the lack of catchlight reveal on the subject? How close the panel is and how big it is will determine the catchlight and the diffuse highlight patterns.

There WAS an internet-sold book on "Scrim Lighting", some years back.... The Dean Collins Finelight videos are worth their weight in gold. Search them out on YouTube.I downloaded every one I could find.

 

[fmw]

It looks to me like you misunderstand diffusion. The purpose of diffusion is to enlarge the light source relative to the subject in order to soften the light.

Though my OP probably didn't convey it I am aware this. What I was unclear of is how it appeared in the examples to highten saturation and fine details.

Also wouldn't the distance between my octabox with diffusion and second diffusion decrease catchlight size? Or intensify

Soft light tends produce less contrast and lower saturation. It has no effect on details. Since it reduces the hardness of shadows, some people get the impression that it causes a loss in detail. But it doesn't. I have no idea what you saw wherever you saw it but maybe these guidelines will help interpret what you saw.

There is no point at all in using a second diffuser. A catch light is nothing more than a reflection of the light source from the eye. If the light source is larger, the catch light will be larger. It isn't any more complicated than that.

 

[smoke665]

Thanks for the replies. It's given me some things to think about as I proceed with the project. I'm in a low signal area with family till the end of the week but anxious to get started when I get back.

@Derrel I'm guessing part of what I was seeming in the example was an increase in shadow detail brought on by the softness of the light, but depending on the material used for the diffusion material couldn't it also cause the light deflect?

 

[Derrel]

@Derrel[/USER] I'm guessing part of what I was seeming in the example was an increase in shadow detail brought on by the softness of the light, but depending on the material used for the diffusion material couldn't it also cause the light deflect?

Not quite sure what you meant by light deflect in that last part. I suppose it's possible that the lower-ratio of the more-diffused lighting setup could show more shadow detail, and that additional detail could be literally seen more easily, and thus it gave the visual impression of "more detail" than compared to higher-ratio,more-contrasty lighting. Makes sense.

Hope you're having a great time there.

 

[smoke665]

Hope you're having a great time

We are. In a log cabin in the Smokies. Great views.

I may be wrong but my assumption was that double or triple diffusion would scatter and redirect the light changing the angle that it strikes the subject.

 

[Derrel]

It does not change the angle of the light very much; the front of the last diffuser/scrim becomes the de facto angle of the light.