Wide Angle Built-In Diffuser

So I must ask..... if the flash's built-in, flip-down wide angle diffuser spreads the light out more, why would it not be used most or all of the time as opposed to only when you are backed out to a short/wide focal length?

I will make a couple of assumptions about what the pea-sized area of my brain that holds flash photography information is reporting back to me; I am interested to read the responses.

Assumption #1: If you were using direct flash outdoors for fill light, it would apply a gentler and less contrasty light towards your subject.

Assumption #2: If you bounce the flash off a wall or ceiling, it will spread that bounced light out even more, for the same results as #1 above.

Assumption #3: Anything you can do to take the tiny, intense pulse of light coming from a strobe and make it larger and more dispersed is usually a good thing (unless you're going for an artistic kind of "spotlight" effect).

So.... am I on, off, or somewhere in between in standby mode with these tangents?

The flash is designed to zoom to match the coverage of your lens so if you are shooting at say 105mm the flash will project more light forward and less out wide so its more efficient (or more powerful) at longer distances.
Assumption #1 is wrong as the panel does nothing to make the flash more gentle, it would seem so, but it really doesnt. It might make might changes to the specularity of the light but so little as to be indistinguishable for most purposes (only increasing the size of the light source makes it softer.

Assumption #2, it sort of depends, the wider you spread the light the less you put where its needed, you might be softer, but you might be diminishing the power of the flash already taxed by bouncing. So yes if you have a white low ceiling and walls, no if you are bouncing off of a 20ft ceiling in a conference center.

Assumption #3. If you mean increasing the size of the light source with the panel, then no. Yes increasing the size of the light source is good. But what is important to consider is the apparent size of the light source, for macro you can use a smaller light because its larger than the subject and its used closer. But more than a few feet away a diffuser only 3 times the size of the flash (something like the dreaded lighsphere) does little to create any softness. Basically to do any good the light source has to be big enough to create some wrap anound the edges of the subject.

Thanks Gonzo - that all makes sense. Can I assume that all of that would apply the same to the strap-on diffuser panel on my Demb Flip-it? It's a little flimsy plastic thing with a grid type pattern on it?

RandMan wrote in post #16411610
Thanks Gonzo - that all makes sense. Can I assume that all of that would apply the same to the strap-on diffuser panel on my Demb Flip-it? It's a little flimsy plastic thing with a grid type pattern on it?

The diffusion panel that comes with the flipit, as I understand it, is designed to help get an even spread of light on the flipit. I havent used one but if its like the diffusion screen on my rogue flashbender it probably doesnt provide any additional softness, but may affect specularity.

Assumption 1 is wrong. While the wide angle coverage is over a wider area of the scene, it is still the original SIZE...the area of the flash lens is not increased, its apparent size is the same, and only SIZE of the 'source' accounts for light being 'soft' vs. 'harsh'.

As for Assumption 2...bouncing the light over a larger area of the ceiling will make it 'softer'....but not 'the same results as #1 (since #1 is not valid). For these two shots, I put the flash in Manual and manually selected the flash coverage angle. On the left is 85mm coverage (APS-C) and on the right is 20mm coverage (APS-C), both ceiling bounce in a standard home ceiling height.

Wilt wrote in post #16411623
Assumption 1 is wrong. While the wide angle coverage is over a wider area of the scene, it is still the original SIZE...the area of the flash lens is not increased, its apparent size is the same, and only SIZE of the 'source' accounts for light being 'soft' vs. 'harsh'.

As for Assumption 2...bouncing the light over a larger area of the ceiling will make it 'softer'....but not 'the same results as #1 (since #1 is not valid). For these two shots, I put the flash in Manual and manually selected the flash coverage angle. On the left is 85mm coverage (APS-C) and on the right is 20mm coverage (APS-C), both ceiling bounce in a standard home ceiling height.

As for Assumption 3, not all photos are best done with super 'soft' lighting...you lose details that the eye uses as visual hints of texture, for example. Portraiture pros often find that somewhat 'harder' light is useful to give older men more 'character', although they use softer sources to minimize wrinkles in female subjects.

Thanks Wilt. You have two inch metal 1/6th pans at home?!

Ok, last question (maybe):

What about adjusting the flash zoom? Like say out to 24mm regardless of your actual focal length. Does that help soften/spread the light at all or is that just as ineffective as the wide angle diffuser?

RandMan wrote in post #16415969
Ok, last question (maybe):

What about adjusting the flash zoom? Like say out to 24mm regardless of your actual focal length. Does that help soften/spread the light at all or is that just as ineffective as the wide angle diffuser?

Dont confuse soften and spread. The lenses in the zoom head of the speedlites are there to maximize power to match the lens being used, and to cover the angle being used. If you are on the long end of the zoom range, it limits the wasted light off the sides of the image area, and focuses the beam more tightly which helps project it. On the wide end its about getting coverage out to the far edges of the image area. Note that the zoom only goes to 24, for wider you have the flip down panel. So no, it doesnt make light softer, just helps you manage where it goes. Just keep focusing on the idea that the only thing that makes light softer is the apparent size of the light source.

A small light source is a small light source. Wasting some of the photons by diverting them out of your field of view won't improve your images unless they bounce back into your field of view.

So let's look at your assumption #2. With typical ceiling bounce, the illuminated area of the ceiling becomes the effective light source. Changing the size of that "hot spot" on the ceiling can affect your images. As a rule, (but not always) I use the wide panel for ceiling bounce.

The fork in the images below was on a dining table. The light was bounced off an 8 ft. white ceiling directly above. In the first shot, I zoomed the flash to 105mm. In the second shot I used the 17mm wide panel.

RandMan wrote in post #16411827
Thanks Wilt. You have two inch metal 1/6th pans at home?!

Yeah, photography isn't my ownly diversion. I've got an immersion blender and a Chinese hat and a mandolin, too!

RandMan wrote in post #16415969
Ok, last question (maybe):

What about adjusting the flash zoom? Like say out to 24mm regardless of your actual focal length. Does that help soften/spread the light at all or is that just as ineffective as the wide angle diffuser?

See again my post 5 photos, for examples of spreading the light to make an even larger virtual source (ceiling), resulting in increased softness of light (less apparent shadows).

As stated by others, a wide direct source by zoom head (not bounced to ceiling) does nothing for softness, it affects only the area of light coverage.

CurtisN forks demonstrate that when you are using reflections, like with chrome forks, the area of the illuminated surface is larger and therefore you see it in the chrome's reflections...Not because the light is 'softer' but merely because the area of the ceiling which is seen within the reflection has become illuminated.