Parabolic Flash Reflector

[ben_mcree]

Can anyone explain the advantages (if any) of using a flash with a parabolic reflector head (as found on the Sunpak 120J, for instance) over a conventional electronic flash head? Are there disadvantages?

[derick_miller1]

I just ordered one (so I can't speak from experience :)

 

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The reason I decided to get one is that it can be used bare bulb, which gives a different quality to the light. It also gives you light in all directions, which can be useful, depending on how you want to light the background.

 

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I have seen others post that the quality of light using the parabolic reflector is different, but I don't have experience to comment.

[rick_massarini]

The Round reflector gives a more even drop off in light at the edges, instead of the sharp cut-off of conventional square reflectors. The 120J uses the same type of reflector as the Lumedyne and Norman 200B units. It gives a much nicer lighting pattern on the edges. I've been using Lumedynes for years and have recently obtained the new hasselblad D flash 40 which is made by Sunpak (probably a modification on the 120J, actually, but in any case, this is the only type of reflector i use...

[timber_borcherding]

Parabolic is a mathematical formula which determines that light will be evenly reflected from the edges of the reflector forward in a straight line. Think of a finely focused, expensive flashlight. The result is a fine spot of light 100 yards away! A non-parabolic reflector has a "hot" spot in the center, the edges are "gray area". The result here is that the reflector "operates" smaller: effecitvely it is a "smaller" refector with that hot spot. The result is an out-of focus spot of light 100 yards away.

 

The parabolic reflector will give you about 1/3 to 1/2 f stop more light on your subject matter than a non-parabolic reflector. I use a Lumedyne reflector on a Norman 200b/200c/400b for this efficiency. However, I prefer Norman for the powerpack.

 

A parabolic reflector does not give "bare bulb" effects as the person above stated. What he neglected to say was that this particular reflector can BE REMOVED, thus making it into a bare bulb. Both the Lumedyne and Norman have heads which can have removable reflectors.

 

Parabolic reflectors must have a light which can be exactly placed, focused, in place. If the light is not perfectly placed, the light will become "O" ringed. In a non-parabolic reflector, the light does not have to be focused and a "O" ringed light will not occur.

 

So, Parabolic reflectors must be used with care and focused. Adding a dimpled, rough surface to the reflector reduces the need for focussing--but it also reduces the efficiency of the light output.

 

Timber Borcherding

[timber_borcherding]

Response by Timber Borcherding timberborcherding

 

Also consider 1/2-of-an-ellipse type reflectors. Speedotron has these. They are focusable. Their strength is evenness of wide angle light, and the ability to focus the bulb by using a movable bulb inside the reflector. In a parabolic reflector, the bulb cannot be moved, or it will create a "O" pattern light. Non-parabolics can have a bulb placement with some latitude as to focusing it. I would say there are three camps: Non-parabolics, parabolics, and 1/2-of-an-ellipse. Non-parabolics can take alot of jostling around. Parabolics must stay stiffly in focus to create even lighting.