Quality of light

In another post, someone praised hammerhead flashes for "better quality of light." Quality of light is often cited as one of the big differences between inexpensive strobes and top of the line strobes. So what are the qualities of light and how does strobe/modifier design influence them:

 

Intensity

Color

Coverage and evenness

Repeatability (though that seems to be a purely mechanical parameter)

Shape of the coverage i.e., fall off, feathering, ...?

 

I have heard for years that "the quality of the light from xyz brand light/modifier is so much better than..." Where is the scientific basis for these judgements?

There probably isn't a scientific basis for most of those judgements--people have different preferences for lighting in photography as they do for most things, and styles change over time. The amount of fill flash used in some photographs shot in the 1950's looks garish today, but it was considered aesthetically pleasing at the time.

Science does a great many things extremely well but beauty is in the eye of the beholder.

When I think of quality of light I think of several things I like about my Elinchrom system. Some are measurable and part of the flash units:

Ideal and consistent colour temperature with no discernible variation over the power range and between shots and between units (packs/head).

 

Consistency in power changes and between units (packs/heads).

 

Some aspects of light quality with regards to modifiers are also measurable:

Colour temperature (poor modifiers may introduce a colour cast)

 

Even light output. My biggest modifier is an indirect Elinchrom octa measuring 190 cm (6’ 2.8”). It produces a remarkably even light with no discernible fall off. I often use it as background.

 

My smaller Rotalux octa and PortaLites also produce a very even and soft light. In part, I believe it is thanks to their internal diffuser (a set of deflectors); a translucent, white, silver and gold disc that goes just above the flash tube and thus reducing any centre hot spot. In part, I also think it is because the front diffuser is flush to the edge of the softbox. However, that is not necessarily a good thing.

 

So yes, beauty is not always about the softest and most even light. Another favourite is an old Photoflex MulitDome HV3 softbox. Compared to the Rotalux softboxes, it is terrible; it needs its internal silver reflectors to correct its slightly yellow colour cast (its white material is not and never have been pure white). Its front diffusor is recessed and I appreciate its soft fall off for portraits - especially when used with a grid.

 

With regards to previous comments about hammerheads vs hot shoe flashes in another thread; could it be that those who claim hammerheads produce a more pleasing output attribute it to the larger size of the hammerheads flash tube (roughly twice as large as most speedlights)?

heimbrant's comments also remind me that some portrait photographers love the quality of light produced by the old Hollywood-style fresnel lamps. No softness about that, hard, direct, contrasty, requiring careful fill, but still capable of stunning beauty.

The OP mentions strobes and modifiers. To me this implies studio photography. Portrait photography is also mentioned.

 

Lots of subjectivity and aesthetic preference here. Softness, or lack of it, is a strong component of "quality". Look at portrait paintings from the early Renaissance until today. Soft light from a close-to-subject large emitter is common through the centuries. One of many examples is Vermeer. Then there is small emitter lighting, a la Caravaggio with a single candle.

 

Many examples are in place today, of portrait photography that parallels the portrait painters. "Rembrandt lighting" is used today. Vermeer-style lighting is used today with large north-facing windows. Search the internet and examples of Caravaggio-style lighting can be found.

 

Strobes to me are just the engine to generate the light which is to be modified. Modifiers produce the aesthetic. Umbrella, softbox, strip box, grid, snoot, etc. all produce different effects, or "qualities".

 

Take for example a large soft box, and mount it with the appropriate speedring to a Speedotron and a Profoto strobe of equivalent output. The light "quality" will not be much different between the powerpacks because the emitter, the softbox, is the same. Color of the flashtubes will have an effect; the aesthetic effect I am emphasizing here is falloff and modeling.

 

All of the above in my view applies equally to still life photography.

In my opinion “Quality of light” is not brand dependent. I can achieve a good quality of light with any strobe and modifier you give me. You can have Broncolor lighting but that alone will not give you quality of light. The photographer must understand lighting and how to achieve a good quality of lighting on their Subject be it a hard light or soft.

With regards to previous comments about hammerheads vs hot shoe flashes in another thread; could it be that those who claim hammerheads produce a more pleasing output attribute it to the larger size of the hammerheads flash tube (roughly twice as large as most speedlights)?

 

- Twice as large as a speedlight is still a hard and tiny source. Anybody that expects direct flash to look pretty is deluding themselves.

 

Any difference is likely to come from the less axial (relative to the lens) position of a bracket-mounted hammerhead.

 

I've done side-by-side comparisons between hammerheads and speedlights. If the hammerhead is held over the camera in the same position as a speedlight, there's almost no difference in the quality of light - or rather the lack of it!

 

Same with bounce flash. If the angle and coverage (zoom setting) is made the same, then the quality of light is the same.

The catch is that most hammerheads use a less focussed - non fresnel - window, and that most speedlights automatically link their 'zoom' to the lens coverage. But if the photographer actually takes charge of the speedlight and overrides such automation, then there's no reason why results shouldn't be similar or identical.

 

I think the answer partly lies in psychology and the power of belief over evidence, rather than in any definable optical properties of the equipment.

Edited January 13, 2019 by rodeo_joe|1