Has anyone conducted a continuous vs flash/strobe test for portraits and found a difference?

Discussion in 'Lighting Equipment' started by mood_lover, Sep 12, 2017.

  1. (this question is only about the visual look or appearance, not about power, convenience, features, temperature, etc)

    Howdy. I live by the motto that light is light, and regardless of the source they all [generally] are guided by the same principals and laws of physics. However, I was speaking to a well known lighting expert in my city and he told me that continuous/hot lights actually look slightly different. "It has a subtle nuance to it, a subtle glow or smoothness because the quality of light is different at the source". I found this hard to believe if the bulb whether continuous or flash is modified the same way, under the same power.

    So I ask, has anyone actually conducted a test on this topic? I wish I could, but don't have continuous lights at the moment. Why is it that flash "looks like flash" and continuous light doesn't "look like continuous". Is it because the key light on the face is usually too strong when people use strobes? Where does the "looks like flash" idea come from if light is light after all?

    Why is it that the extremely powerful hot lights used in cinema don't look artificial?
    Last edited: Sep 12, 2017
  2. This question is best answered if you do the work and test the lights yourself. You will learn more by doing than asking. That said there is a difference in color temperature. The difference in look usually refers to the hot light having a fresnel lense. If you put a strobe in a fresnel housing the quality of light will be the same but the temperature will not. A hot light will also cause you to shoot with higher ISO or shoot wide open and slower shutter speeds which all account for the look. Do your self a favor and explore this for yourself it will be a wonderful learning experience.
  3. William Michael

    William Michael Moderator Staff Member

    Maybe the photos made under Flash which do not have that “subtle nuance to it, a subtle glow or smoothness” are that way, simply because many Photographers are not as skilled in Flash Lighting Techniques as are Cinematography Lighting Directors.

    Also, a typical (good quality) Cinematography Lighting Rig required for a scene, even for a medium budget movie, would easily be in order of tens if not hundreds of thousands of dollars; plus this Rig would be under the aegis of a comprehensive skill base of the: Electricians, Riggers, Lighting Techs, Lighting Director and Director of Photography and the Director probably would have have a final input.

    My guess is that if your friend the lighting expert is an expert, and I don’t question that claim, it is more likely that his comparison is being made between a final Cine Product where there was an high level of skill, staff and gear used, to a Stills Photo-shoot where there might have been one or two staff; limited time; (relatively) less amount of Flash gear which is likely less sophisticated.

    I reckon in this comparison a good/experienced eye could nail some differences in the “look” of the lighting – but that appears to me to be a broad ‘apples to oranges’ comparison – and not really a scientific or logical approach which can make the definitive conclusion that the difference is solely because of the source of the light, being Professional Cine Lighting :vs: Professional Studio Flash.


    On the question of have I made the comparison – well sort of, but not directly: I have been involved in Cine and Stage Lighting.

    I think to address your general question, it is necessary to note that Stage and Cine Lighting, both have a basic difference of purpose to the purpose of Studio Flash.

    In the former, typically the lighting must carry and allow for both: (multiple) Subject Movement AND (multiple) Camera Movement.

    However when setting a rig for Studio Flash the purpose is for that one shot or series of similar shots that rarely account for any, or only minor: Subject Movement and Camera Movement.

    I think that this might more easily be argued as one major reason “why” your keen eyed friend can see a difference between Cine Lighting and Studio Flash and why he sees Cine Lighting with “a subtle nuance to it, a subtle glow or smoothness.

  4. Why do hot lights look natural to us? I would guess that the reason would be because we live in a world of continuous light sources. The hot lights blend with the environment. It creates our environment and sets the mood. The warm tungsten temperatures are soothing. There is a soft quality as the light is bouncing of the walls and ceiling.

    The flash temperature is much cooler. The term flash look which many refer to is the non blending or non balancing of flash to the environment or ambient. We all have seen shots where the background it 2 stops or more under from the flashed subject. It is an unatural look. It does not mean it's bad. Many fashion and commercial photographers do this.
  5. Way back when I started a professional education in photography (late 70's) studio flash was an expensive luxury, the use of which was reserved only for the higher classes of the photography school I was attending (the nowadays Royal Academy of Arts in The Hague, the Netherlands)
    The lower classes had to make do with Philips Photoflecta lamps (500W oversized lightbulbs), even for product and pack shots, which in combination with the in those days held at the highest acceptable 27 DIN/400 ASA (back then ISO was a less widely used term) films and slow lenses of the day (and I'm not even talking about the much slower large format camera lenses) made taking a picture quite a challenge

    So studio flash, even the basically quite limited BEAM units of those days (about as technically advanced as the Balcar units of the same era), was a real step forward:
    - no more slow speeds with wide open lens,
    - no more slow tungsten films ( Kodak 64T EPY basicallly was the only option) but 'regular' daylight film instead
    - nor multiple second exposures, in the calculation of which the reprocity had to be taken into account,
    - just one, or in case much DoF was demanded maybe several flashes using a high (= closed down) aperture number.

    I however was a poor photography student, and for my own, outside school photography/portraiture all I could afford were a couple of Metz patatohead flashes bounced in umbrellas, (reasonable GN, but no modelling lights) and a few cheapo halogen tungsten lights I picked up during seasonal sales

    But what I found out soon, was that yes, while a flash allowed taking images with low ISO film and closed down aperture, resulting in very sharp images (with a 35mm, and even more with a medium format camera), apart from that 'sharpness' element, it really didn't add much more to an image.

    Sure 'sharp' is imperative for shooting eg products and other subjects where rendering as much detail as possible is necessary.
    But for subject where atmosphere and/or mood are more important (early morning haze filled landscapes, weddings, location portraits and even studio shots) it really gets in the way of what is tried to convene, and rather gets a liability then a contribution

    From a practical point of view, when taking pictures with continuous light, that can be done with the subject being less consious of it (despite the articficial surroundings that come with shooting in a studio or bright light blazing) then when using flash, where each image taken is announced with the flash(es) going off, thus alerting the model of 'yes, antother one taken' to even startling a less camera comfortable subject

    With the modern high ISO capable camera's I personally find less need for shooting at ultra low ISO with (studio) flash, although when shooting events a couple of speedlights can be an absolute lifesafer
    While the improving quality/power output of LED lights make them more and more an affordable and mature alternative for flash and conventional continuous lighst as eg my Bowens Gemini studio flashes and Hedler C12 halogen units

    I'm not that much of an expert that I would/could describe the quality of contiuous light as 'subtle glow or smoothness', but IMO and experience, the softness that usually comes with continuous light for me is closer, and consequently more pleasing, then the 'sharpness above all' that comes with using flash.
    But admittedly I'm also an avid used of older (Nikon pre Ai, AI and AF D) glass rather then sharp and contrasty from corner to corned' glass like eg Zeiss and Sigma Art glass

    I have a problem uploading these images, hence just the links

    Studio image taken with multiple studio flash units
    Nathalie A: Corine's Agency Amsterdam/Ricardo Gay Models Milano/Euromodel Amsterdam/Mozart Models Vienna 092 bew.jpg by Paul K

    Studio image with 1 haogen light (bounced in umbrella) with several (styrofoam panel) reflection screens
    Eva / Elite Amsterdam.JPG by Paul K
    Last edited: Sep 13, 2017
  6. As long as the modelling lights aren't blindingly bright the eye pupils are more dilated with flash. It gives a subtle intimacy to portraits.
    jan_steinman likes this.
  7. Several differences besides my burned fingers when careless. There are 2 places where you can touch that don't get hot, but adjusting the barn doors or inserting or removing wire scrims is tempting with bare fingers when working quickly, gloves nearby or not. First, if on location, bring a flash light for when you kick the breakers and first thing upon arrival find the breaker box so you can find it in the dark and to check what you have circuit wise. I have never had to do that with strobes. Also bring enough power cords to try to get some lights on different circuits. Second, flooded, a fresnel will give you razor sharp shadows, not close only good enough for horseshoes, razor sharp. One major advantage is the subject doesn't get a flash every time you hit the shutter button. It allows taking shots without blasting the subject or even without the subject knowing. They can be made soft shooting through a diffuser scrim or attaching a light to one end of an arm and a 4x4 bounce card on the other end. That set up can be rolled and raised if soft light is desired but with minimal loss of power that passing through diffusion does. I rarely do that, I have strobes/soft boxes for that. But a couple of 650's through a 6x6 give plenty of soft light especially with modern higher iso camera. Great if don't want to disturb a baby or animal with popping flash. I also like the precise control I have of hot lights. I have barn doors or top hats(snoots) on all of them. I think the subtle difference your expert is referring to is the light is passing through a fresnel lens that produces a wonderful effect on the way the light falls on the subject throughout the range of the spot to flood adjustment. Finally, for me, it is the connection to those that came before me who used these lights, including my father in the 30's. He was really into coloring which I hate before going off to wwII . He probably would have loved photoshop, but I recently saw a b&w self portrait he had done. Stunning. I plan on replicating it with me using medium format film and framing the 2 prints side by side. As for pupil control, with Einsteins and their cyber commander, I can adjust the modeling light power from my stool and check the results on the monitor to get exactly the pupil size I want.
  8. "It has a subtle nuance to it, a subtle glow or smoothness because the quality of light is different at the source".

    This is the sort of unexplained and unsubstantiated statement that always makes my hackles rise.

    This smacks of an "emperor's new clothes" aesthetic snobbery - an attitude of "I have a superior sensitivity to such things that a mere mortal like you can never hope to achieve or understand."

    Ask the guy to put up or shut up. Ask him (invariably a male ego trait) to explain exactly and objectively where this "subtle nuance, subtle glow or smoothness" can be seen, with illustrated examples.

    It's true that most studio strobe light starts with a near-circular source, and that hot lights generally have a more compact filament, but this shouldn't be overly visible after being bounced around a polished or satin reflector, and especially not after diffusion. So I'm highly skeptical of such weasely claims.

    And where does that leave LED or CFL continuous sources?
  9. Joe, I don't think the difference comes from the bulb or internal reflector, I think it comes from the light passing through a fresnel lens. Like using a diffusion panel that becomes the source rather than the light behind it, I expect the lens is the "source" in the same manner. It is hard yet because of the precision of alignment of the light rays by the lens, it is extremely smooth. Different than a bare bulb or 7 inch reflector. I'm not an engineer, but I expect that precise alignment exists from spot to flood. A grid in a 7 inch reflector on strobe tries to coral the rays but within each grid opening they are not all precisely aligned. That's my guess.
    Since my photo is an homage to Karsh who used fresnels as did Hurrell, will re shoot it using 3 hot lights. Will be interesting seeing how the high front main will change the look if shot in spot through flood since the strobe shot is through a sock under grid on a beauty dish. You guys always take me outside the box. Any fresnel lens experts or engineers there that can clarify?
  10. Of course I can see how that would work with a Fresnel spot Bob. It's hard (sic) to get parallel focus from a circular flash tube, and much easier with a small filament.

    However, the OP implied a much broader difference between continuous and strobe sources than only via a Fresnel condenser.
  11. No, but I like them. :)

    I often shoot with two ginormous soft boxes and a Fresnel for specular highlights. That provides an effect that is difficult to achieve with hot lights.
  12. Actually continuous lights with those same modifiers will provide the very same look. I did cine before turning to studio product work and and when the physics are the same (i.e., same size light source, same color temp, same size and type modifier) the look will be indistinguishable. But since it's almost impossible to get all the physical parameters the same there will almost always be a visible difference.
  13. I can tell you one difference that will pass through modifiers: hot lights in old-fashioned dome-shaped reflectors have a hot spot. Directly on the subject, they will be brightest in the center, and then fade out from there. They do the same with umbrellas and some soft boxes (at the modifier, not the subject)--making the light brightest in the center, giving a smaller bright source as projected by the hot spot on the modifier surface, surrounded by a dimmer and diffuse source from the edges of the modifier. This makes the small bright core of the light harsher, and the overall size of the modifier somewhat less important as a softener., while still providing softening fill. This WILL look different, depending.

    I haven't found the same applies with strobes in reflectors--the ones I have used seem calculated to at least attempt even light over their fields--and I imagine boxy quartz lights (Lowepro) would not have such hot spots. Likewise, bare bulbs, no reflector, in softboxes (does anyone do this?) would be more like strobe, where a hot light in a reflector behind a scrim would not.

    As a friend of mine used to say, different can never be exactly the same. :)
    Last edited: Dec 17, 2017
  14. As you later point out, that's a huge "if!"

    Yes, in theory, anything can be put into practice. But in practice, not all theory can. :)

    Use each for their strengths, or to avoid the weaknesses of the other.

    For cine, of course you need continuous light! And you can pay an arm and a leg to get "a certain look" that might be trivial to do for still photography with flash!

    The salient feature of most still photography is that it isn't expected to move much. I believe the original poster wanted to photograph quilts. To me, that screams "flash!"

    It seems the sole advantage of continuous light for photographing quilts is "what you see is what you get," which might have been worth a lot of time and money in the film days, but you can assess your flash exposure with one button push on most modern digicams.

    On the other hand, you can dump a lot more photons for a lot cheaper price with flash than with continuous. The OP was complaining about not having enough light. It seems to me that the OP can add light more cheaply with flash than with continuous lighting.

    Ain't a thing in this world that doesn't have both advantages and disadvantages. The trick is in balancing those so they work for you, not against you.
  15. [this question is only about the visual look or appearance, not about power, convenience, features, temperature, etc]

    Asking to respond only on appearance and leaving out all the other reasons is like asking what car would I buy based only on color. As you stated light is light and as others stated to achieve the same quality of light comparison between flash and hot lights they need to be of same temperature, size and same use of modifier. That leave a big hole in the reason you would choose one over the other. The real world question is what is the differences between hot lights and flash when it comes to the logistics of capturing an image. It will require you to consider more than just the aesthetic look.
    Wilmarco Imaging likes this.
  16. As an advertising art director I had the good fortune to work with many different photographers and cinematographers. The element you cannot divorce from the discussion is skill and experience. Most masters of lighting can do almost anything with the right tools. I worked with one still shooter that always used continuous lighting and employed the subtractive method of controlling the light. He had all sorts of flags and scrims of all sizes. Very hard (not impossible) to do that technique with strobes. This goes to the "Logistics" of capturing an image Michael mentioned. Aesthetic differences? I doubt it all things being equal. Which is easier to say, than do.
    Wilmarco Imaging likes this.

  17. Agree with you that light is light.

    I haven’t done a test as you have outlined.

    Flash looks like flash because the photographer didn’t light the subject properly, unless the creative goal was to achieve the “flash” look. Flash looks like flash for many reasons, one is the lighting ratio of key to fill to background. All key and no fill or background is part of the “flash” look. Also the light’s temperature, size, distance from subject and modification. This topic is very broad and deep, better covered by targeted books and websites. I like Sekonic’s website.

    The idea of “looks like flash” comes from generations of family vacation snapshots with improperly lighted subjects. I have made a few of those... ;)

    As already commented, cinema lighting is done by a crew of career professionals, often with the best equipment possible at their disposal. The results are commensurate with the skill and effort.
  18. Light is light but when it is modified, with a diffuser, a lens, a gel, it looks different. Having a light source and some modifiers is like having the ingredients for a dish, how you use them can vary from a McDonalds burger to Beef Wellington.
  19. Yes. But do models act differently under hot vs strobe? Will they produce different facial expressions? (even with identical ingredients, can you produce La Bernadine's quick seared Fillet Mignon on a 17,000 BTU home range?)
  20. I can tell you that in a 110 degree garage in central CA with 3 hot lights and a fog machine going, it will produce an hour of cloning out sweat beads. But I just had to align chins then chins to bg slash, then chest and collar then hand and slash they eye slightly above power point, then fine tune angle of main and barn doors, then fire fog machine and get the billowing fog just right-now that the humidity was near 100% then take a shot. Hey, it's more fun when it is darn near impossible. Making it look easy is the real trick. With my prior bbq, if I preheated with all burners full blast, my phone would ring...Nuclear regulatory commission checking on a possible nuclear explosion. Can't be too rich, too skinny or have too many btu's. My subjects act as I direct them, they just don't know it. It's like a wife, always let them think it's their idea. Just kiddin?

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