Parabolic softbox/umbrella in practice?

Started Dec 11, 2017 | Questions
Jacques Cornell
Jacques Cornell Forum Pro • Posts: 12,693
Re: Depth really shouldn't matter

Serjojeee wrote:

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Sympa wrote:

The depth of a parabolic reflector is its f/number. A deeper reflector will use more light from the flash.

Do you have a source for this claim? I find it hard to believe that this is true if you are using a reflector to focus the light so that all of it hits the interior of the parabola and doesn’t spill outside it.

Which is good but doesn't affect the quality of the light, only the quantity.

A deep reflector is more difficult to shape correctly than a shallow one.

There must be some kind of diffuser or dlurring in the system, or you will get an image of the flash tube projected on the subject. This can be a matter flash head cover, a beaded reflector, or a defocusing.

There always will be some spill, otherwise there will be some shading of the reflector in focused position. So from my point of view that statement is correct.

I have no idea what this statement is supposed to mean.

It meame that you need different spill kills for different focus positions.

If you use the right reflector, both deep & shallow parabolas get ALL the light. Deep ones don’t “use more light”.

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Serjojeee Senior Member • Posts: 1,335
Re: Depth really shouldn't matter

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Sympa wrote:

The depth of a parabolic reflector is its f/number. A deeper reflector will use more light from the flash.

Do you have a source for this claim? I find it hard to believe that this is true if you are using a reflector to focus the light so that all of it hits the interior of the parabola and doesn’t spill outside it.

Which is good but doesn't affect the quality of the light, only the quantity.

A deep reflector is more difficult to shape correctly than a shallow one.

There must be some kind of diffuser or dlurring in the system, or you will get an image of the flash tube projected on the subject. This can be a matter flash head cover, a beaded reflector, or a defocusing.

There always will be some spill, otherwise there will be some shading of the reflector in focused position. So from my point of view that statement is correct.

I have no idea what this statement is supposed to mean.

It meame that you need different spill kills for different focus positions.

If you use the right reflector, both deep & shallow parabolas get ALL the light. Deep ones don’t “use more light”.

With deep reflectors like parabolix and broncolor and chinese copies there is impossible to make a proper spill kill. Even for not that deep reflectors like profoto deep umbrellas when strobe is mounted as deep as possible with hensel 500 the strobe itself act as spill kill but there is a small spill which is not bothering me. The good thing is that all the reflector surface is working. Parabolic reflectors are good to work at a distance anyway. I mean that spill problem is exaggerated. Maybe it's a bigger problem with shallow reflectors though...

Jacques Cornell
Jacques Cornell Forum Pro • Posts: 12,693
Re: Depth really shouldn't matter

Serjojeee wrote:

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Sympa wrote:

The depth of a parabolic reflector is its f/number. A deeper reflector will use more light from the flash.

Do you have a source for this claim? I find it hard to believe that this is true if you are using a reflector to focus the light so that all of it hits the interior of the parabola and doesn’t spill outside it.

Which is good but doesn't affect the quality of the light, only the quantity.

A deep reflector is more difficult to shape correctly than a shallow one.

There must be some kind of diffuser or dlurring in the system, or you will get an image of the flash tube projected on the subject. This can be a matter flash head cover, a beaded reflector, or a defocusing.

There always will be some spill, otherwise there will be some shading of the reflector in focused position. So from my point of view that statement is correct.

I have no idea what this statement is supposed to mean.

It meame that you need different spill kills for different focus positions.

If you use the right reflector, both deep & shallow parabolas get ALL the light. Deep ones don’t “use more light”.

With deep reflectors like parabolix and broncolor and chinese copies there is impossible to make a proper spill kill. Even for not that deep reflectors like profoto deep umbrellas when strobe is mounted as deep as possible with hensel 500 the strobe itself act as spill kill but there is a small spill which is not bothering me. The good thing is that all the reflector surface is working. Parabolic reflectors are good to work at a distance anyway. I mean that spill problem is exaggerated. Maybe it's a bigger problem with shallow reflectors though...

"Spill" usually refers to light emitted from the flash that falls outside the edges of the mod. For example, if you put a strobe head with a wide dispersion too far back from an umbrella, some of the light will go sideways from the head and never hit the umbrella. It sounds like you're using the word "spill" to describe something else, because a head with a spill-kill/reflector placed deep inside a deep para is not going to escape without being reflected off the mod.

If you use an appropriate reflector/spill-kill on your flash head, all of the light will be directed into the para, regardless of whether the para is shallow or deep. And thus, a deep para doesn't use any more light than a shallow one. By definition, a para throws light from a properly positioned source in a column. Again, it doesn't matter whether the para is deep or shallow. What affects the efficiency of the para is the reflectivity of the material, and how closely its shape matches the mathematically defined shape of a parabola.

https://en.wikipedia.org/wiki/Parabola

https://en.wikipedia.org/wiki/Parabolic_reflector

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If you think digital is hard, try slide film.
http://jacquescornell.photography
http://happening.photos

 Jacques Cornell's gear list:Jacques Cornell's gear list
Panasonic Lumix DMC-LF1 Panasonic FZ1000 Panasonic LX100 Sony a7R II Panasonic Lumix DMC-GX8 +49 more
Serjojeee Senior Member • Posts: 1,335
Re: Depth really shouldn't matter

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Serjojeee wrote:

Jacques Cornell wrote:

Sympa wrote:

The depth of a parabolic reflector is its f/number. A deeper reflector will use more light from the flash.

Do you have a source for this claim? I find it hard to believe that this is true if you are using a reflector to focus the light so that all of it hits the interior of the parabola and doesn’t spill outside it.

Which is good but doesn't affect the quality of the light, only the quantity.

A deep reflector is more difficult to shape correctly than a shallow one.

There must be some kind of diffuser or dlurring in the system, or you will get an image of the flash tube projected on the subject. This can be a matter flash head cover, a beaded reflector, or a defocusing.

There always will be some spill, otherwise there will be some shading of the reflector in focused position. So from my point of view that statement is correct.

I have no idea what this statement is supposed to mean.

It meame that you need different spill kills for different focus positions.

If you use the right reflector, both deep & shallow parabolas get ALL the light. Deep ones don’t “use more light”.

With deep reflectors like parabolix and broncolor and chinese copies there is impossible to make a proper spill kill. Even for not that deep reflectors like profoto deep umbrellas when strobe is mounted as deep as possible with hensel 500 the strobe itself act as spill kill but there is a small spill which is not bothering me. The good thing is that all the reflector surface is working. Parabolic reflectors are good to work at a distance anyway. I mean that spill problem is exaggerated. Maybe it's a bigger problem with shallow reflectors though...

"Spill" usually refers to light emitted from the flash that falls outside the edges of the mod. For example, if you put a strobe head with a wide dispersion too far back from an umbrella, some of the light will go sideways from the head and never hit the umbrella. It sounds like you're using the word "spill" to describe something else, because a head with a spill-kill/reflector placed deep inside a deep para is not going to escape without being reflected off the mod.

If you use an appropriate reflector/spill-kill on your flash head, all of the light will be directed into the para, regardless of whether the para is shallow or deep. And thus, a deep para doesn't use any more light than a shallow one. By definition, a para throws light from a properly positioned source in a column. Again, it doesn't matter whether the para is deep or shallow. What affects the efficiency of the para is the reflectivity of the material, and how closely its shape matches the mathematically defined shape of a parabola.

https://en.wikipedia.org/wiki/Parabola

https://en.wikipedia.org/wiki/Parabolic_reflector

No I meant spill in exactly that way. But I think that all reflector should be working. I'd better deal with spill than with smaller reflector cause spill kill will kill some part of the reflector. And in defocused position the spill is worse. It's ok

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