Any difference between backwards shooting in silver octagon umbrella vs a beautydish ?

I while ago I bought a beautydish with gid of 40cm which I would like to sell for a portable beautydish (foldable) of 70cm.

Then it doesn't take up too much space in bags and it's lighter.
http://www.benl.ebay.b​e …03987f:g:j9QAAO​Swvg9Xed0o

But now I'm just realising, isn't that +- the same effect as it bounces too ?
A beautydish is harsh light, but shooting inside a silver softbox umbrella is also harsh light, or is there a difference ?

CanonYouCan wrote in post #18347674
A beautydish is harsh light, but shooting inside a silver softbox umbrella is also harsh light, or is there a difference ?

Only you control how "harsh" a light is. Won't the effect depend on the size of the source & the distance it is away from the subject?

Once again, as is often the case in photography, is that the true answer is, "It DEPENDS!"

A beauty dish is classically a parabolic reflector with a center disk to reflect the light back to the dish rather than to emanate directly to the subject from the incandescent hot light or flash. The beauty dish provides a concentrated light source where the center is the brightest and the light gently falls off at the edges. The surface of the beauty dish can be silvered or white, with white yielding a 'softer' light.

So IF your umbrella was a parabolic design, it could mimic a beauty dish pretty closely, IF it was

1. a parabolic umbrella of similar diameter,
   
2. assuming both had the same surface treatment (silver vs. white) of its reflective surfaces
   
3. and the light source pointed backward at the umbrella
   

Wilt wrote in post #18347720
Once again, as is often the case in photography, is that the true answer is, "It DEPENDS!"

A beauty dish is classically a parabolic reflector with a center disk to reflect the light back to the dish rather than to emanate directly to the subject from the incandescent hot light or flash. The beauty dish provides a concentrated light source where the center is the brightest and the light gently falls off at the edges. The surface of the beauty dish can be silvered or white, with white yielding a 'softer' light.

So IF your umbrella was a parabolic design, it could mimic a beauty dish pretty closely, IF it was

1. a parabolic umbrella of similar diameter,
   
2. assuming both had the same surface treatment (silver vs. white) of its reflective surfaces
   
3. and the light source pointed backward at the umbrella
   

I don't think I've ever seen a single beauty dish that adheres to the definition of a paraboloid. In fact most reflectors sometimes described as parabolic (such as, for example, all deep umbrellas) are nowhere near a paraboloid.

Given the extreme variety of beauty dishes and the way they interact with the various flash tube designs on the market, I'd agree with you, "it depends". Just not on anything related to a paraboloid .

Beauty dishes were first used in the late 30s and 40s for glamour headshots of Hollywood actresses.
They were designed to create a tube of light, rather than a cone of light, without a center hot spot but with smooth transition from highlight to shadow.

The diameter was about twice the width of a human head so that there would be wrapping of indirect light.
The center deflector was incorporated to eliminate a center hotspot and to make all the light indirect.

The original design was for photoflood lights that extended into the dish behind the deflector.

Modern interpretations for strobe use have probably varied from the original design substantially. Regardless, in my view, there are modifiers that accomplish the original intent reasonably well. Some are collapsible.

The only way to find the one that works best is to test several with the lights with which they will be used most often.

Well said DM.

I just got a 32" silver deep umbrella type octobox and did a test vs a beautydish. This cheap umbrella box controls the spill lot better than a regular umbrella of softbox, but the focusing and quality of light are just different from a real metal beautydish.

Flash inside the 32" octobox, no difussion vs AB 22" beauty dish..

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MayaTlab wrote in post #18347757
I don't think I've ever seen a single beauty dish that adheres to the definition of a paraboloid. In fact most reflectors sometimes described as parabolic (such as, for example, all deep umbrellas) are nowhere near a paraboloid.

Given the extreme variety of beauty dishes and the way they interact with the various flash tube designs on the market, I'd agree with you, "it depends". Just not on anything related to a paraboloid .

The beauty dish might not have a parabolic profile you would expect from my earlier description, but the beauty dish nevertheless 'funnels' the light in a somewhat collimated manner to produce harsher edged shadows than you expect to get from a 'large source'. So it behaves more like a parabolic reflector than it does behave like even a silvered umbrella. Its shadow is responsible for the classic below-nose-to-lip appearance of Butterfly lighting.

Wilt wrote in post #18348896
The beauty dish might not have a parabolic profile you would expect from my earlier description, but the beauty dish nevertheless 'funnels' the light in a somewhat collimated manner to produce harsher edged shadows than you expect to get from a 'large source'. So it behaves more like a parabolic reflector than it does behave like even a silvered umbrella. Its shadow is responsible for the classic below-nose-to-lip appearance of Butterfly lighting.

What does "funnelling" mean ? Sending light at a narrow angle ? If so a grid can do so, does that mean that the grid behaves like a parabolic reflector ? Or maybe you mean reflecting light rays in parallel ? In which case the form of a paraboloid really is required, as well as the possibility to place a properly designed light source at the focal point of the reflector (important !), and the proper silver material - and no beauty dish has these qualities. A cheap $50 Cactus pseudo "parabolic" silver umbrella like the one attached corresponds better to that description - and still not that well. Very few modifier can actually claim to be truly parabolic, and it might not even be a desirable quality (very few people use Broncolor's Satellites for example). Broncolor's smaller paras (88 and 133), for example, have an acceptable shape, at least for fabric reflectors, but are intentionally manufactured with a somewhat softer, satin, silver material that scatters light rays a little bit (to improve illumination evenness and reduce the occurence of multiple, stepped shadows, which are frequent with fabric silver reflectors).

In addition, I'm not sure a BD's interest lie solely in its beam angle - personally that isn't the first thing I look at when using one - and that varies considerably depending on the BD and flash tube design anyway.

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Nerdy stuff ...

I never saw beauty dish in the shape of parabolic.
If there is any then it can only gives a doughnut parabolic light because the strobe position should be in its focus point. And it will be a "deep" beauty dish (first pic).

The light can be focused parallel forward by directing the interior in proper way like Mola, but its more difficult to make and it can only give multi ring paralel light

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Another important piece of this question is placement of the modifier in relation to the subject and use of diffusers.

If you have an umbrella and beauty dish of similar diameter and they both have a diffuser on the front, they are going to be more similar.

If you are at a longer distance from the subject, they also become more similar.

At closer distances, they tend to be used differently and the quality difference tends to be more apparent.

MayaTlab wrote in post #18348982
What does "funnelling" mean ? Sending light at a narrow angle ?

As I stated earlier, " 'funnels' the light in a somewhat collimated manner'

A grid or snoot does NO true collimation, it merely masks the beam so its angle of coverage is not as wide. A collimated source creates a somewhat harsher shadow edge. But the beauty dish, in being a somewhat large (compared to subject head) source which is used relatively close to the subject, has the harsher shadow of the collimated source yet also with some shadow penumbra softening of a larger source.

To illustrate the effect (and ignoring the tangent about mathematical profile of the beauty dish!) of a somewhat collimated source, one can look at page 49 of
Master Lighting Guide by Christopher Grey, 2004. (Unfortunately permission is needed to reproduce portions of this book electronically.)

Wilt wrote in post #18349116
As I stated earlier, " 'funnels' the light in a somewhat collimated manner'

A grid or snoot does NO true collimation, it merely masks the beam so its angle of coverage is not as wide.

That we agree.

Dito. By collimated, I assume you mean what I called "parallel" in terms of light rays reflection.

Which isn't a collimated (parallel) light source at all .

BTW, I hope that we are talking about a silver BD here, because it makes no sense to talk about "collimation" or "parabolic" with a white modifier as white scatters light in all direction regardless of the angle of the light rays that strike it.

A result that can be obtained with any modifier that will give you the same light distribution when looking into the modifier from the subject's POV (in the case of Beauty dishes, often like the pictures above). That in itself is uncorrelated to whether the thing collimates light rays or not or the beam angle. If we were to put the subject in a room made of Ventablack, you wouldn't see any difference between various modifiers with various beam angles as long as they are illuminated in the same way from the subject's POV.

You aren't seeing the effect of a collimated light with the pictures shown on p49. You are seeing the effect of the effective light source's size, from the subject's POV (which may be different from its physical size) and the light intensity evenness / distribution of that modifier's interior from the subject's POV.

To go back to your suggestion to the OP, i.e. to choose a parabolic umbrella made with the same material as the BD, and the same size, the thing is in reality quite a lot more complicated.
For example :
1) most pseudo parabolic silver umbrellas will look like this from the subject's POV. That's a fairly (actually, significantly) different pattern from all hard silver BDs and the shadows will definitely look quite different (multiple edges galore in general). I've seen only one pseudo parabolic silver umbrella that avoids this bicycle wheel illumination pattern, Paul Buff's soft silver PLM. That's because it uses a silver material that scatters light a little bit more than the usually more reflective silver materials that are used with most pseudo parabolic umbrellas (you could argue that it doesn't behave like a parabolic modifier then ). That's another problem : there are a lot of different silver materials with different light reflection properties.

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