Here is another look at "what lights do". This time uses a camera hot shoe mounted flash (frontal lighting), in various configurations. I think sometimes people do not realize at first what they should be looking for in such comparisons. Judge the softness of the light by the shadows, under the shell here, and in the detail on the shell. Harsh hard light (dark shadows with sharp edges) can show detail better, where soft light (dim, vague shadows with fuzzy edges) sort of smooths and covers up surface blemishes (for example, the ridges on the shell - compare the hard and soft light). There are reasons to use either method. FWIW, these pictures were with a Nikon D300 at four feet, a 60mm f/2.8 micro lens, and a SB-800 hot shoe flash.
Bounce is also somewhat less affected by the inverse square law - the longer path up and down is more able to "fill" a small room with even light everywhere, instead of being dark behind our subjects. When there is a suitable ceiling, bounce is the best thing you can do for a hot shoe speedlight, but it does need a slight frontal fill (small bounce card). Bounce also requires a lot of flash power. Start at ISO 400 and f/4, which is mostly failsafe in most situations (a small flash likely needs more ISO). With lower ceilings, you can experiment with f/5.6 and/or maybe ISO 200, but watch the Ready LED for insufficient power warning, and for excessive recycle time.
But this forward spill adds the same rear shadows as direct flash (under bear's ears and arms for example), however they are a little less dark here because the bounce light fills them, and the direct spill fills the bounce shadows too. Question: Which does it more? Rhetoric, but a question you should be able to answer about your own pictures. In this case, the flat frontal fill shadows are the darker shadows, so the direct spill is the major light here, not the bounce. We would prefer the opposite, the forward spill should be fill, not the main light. Excessive direct forward spill in this case. Clear to see if we just look.
We like to pretend the dome's spill light hits all the room's walls and comes back to subject from all directions, but consider that the inverse square law says this is usually not very likely. The dome above is four feet from the bear, and five feet from a wall on camera right of the shell, and there is no evidence of any shadow on the left there. The light is just lost. But there is the obvious frontal fill though, which is why we use it.
It is good to know that this forward spill is what domes do, however the bounce ought to be the major effect and main light (my opinion). But the forward spill fill with bounce is what the domes add, and any imagined diffusion is the least of it (the dome is just too tiny). The domes should be judged by how well they do this (and not by how warm their higher power requirement changes flash color - which was balanced later here). IMO, these are some of the things our comparisons should be looking for.
Above: Bounce flash with SB-800 pull-out white bounce card - its forward spill adds the same catch lights and fill as the dome. Less amount, but you can use larger bounce cards, if you have to. My opinion is that the small bounce card is usually better than the dome, and better than a large card, because less is more (and the card does not reduce the overhead bounce power like the dome does). The camera was too close for bounce here, stand back a bit and zoom in if necessary, a little more angle, to have less extreme vertical light. We always want to keep the camera at least six feet from human faces anyway (for the proper perspective, to prevent enlarging noses, etc). For bounce, stay 8 or 10 feet back, to make the angle less steep. Zoom in when necessary, but don't stand too close. For the greater distances, perhaps aim the light near the halfway point on the ceiling, but watch your forward spill, you are aiming it too. I am routinely at about the angle shown in the red picture here.
In this bounce card picture, on our left side of bear, we see the direct shadow of the outright arm, and we can also detect the arms bounce shadow down on floor by leg. Direct is a darker shadow, we are only four feet away, but both are still present, and we did not totally blow away all effect of the bounce. On the previous diffusion dome picture before, this same lower shadow from the bounce is imaginary - we only have a direct frontly lighted picture there. Was that the intended lighting? If we are going to use bounce, we ought to see some trace of it (and we do some, in closer gaps, but we have to hunt for it).
But all situations are NOT equal. This is from very close distance, and the direct spill will fall off to become weaker at greater distances (inverse square law), but the bounce light will hold up a little better at distance (in a small room). The point is ... look. And think. This is how we know what the lights are doing. Don't simply just add a huge forward direct spill and think you've done something. Direct flash will do that easier.
The size of the bounce card, and its degree of forward spill, is distance dependent. If you use a Large bounce card, probably all you get in small rooms is flat frontal fill, which may overwhelm and cover up all the soft bounce light which you spent flash power to try to get. You can see all of this if you think to look. The trick is each situation is a little different (different subjects), but there are many common situations too (distances). This SB-800 white card effective area above the flash is small, only 2x1.5 inches, and it does a LOT in small rooms. More is often not better, often less is more. But sometimes more is needed. We can watch what happens, and we can know to use different size bounce cards for different situations, see this bottom picture, for example. But I normally use the pull out card routinely, except at larger distances. Just watch, and if you don't see soft shadows from the ceiling bounce, you used way too much frontal fill (the bounce is no longer your Main light then). For example, the shadows around the bear's legs are very natural, expected, no problem. The shadows on the rear wall are less natural, less expected, more problem.
The Theory: Both the umbrella and the diffusion dome are "diffusers", scattering the straight flow of light. The dome is only 2 inches wide (tiny, near zero, only 2.4 degrees wide as seen from four feet), so the only direction it can scatter light is outward, so that much of it simply misses the subject all together. The umbrella size is 40 inches (actual) and it is curved to catch and scatter the outer light inwards. It is placed close to the subject, making it be "large" in the face of the subject, 45 degrees large as seen by the subject at four feet. So light is coming from either side of the subject, from their left and from their right, and from top and bottom too. All these multiple paths of light from every which direction fill the shadows from all the other paths, so what we have is self-filling light, which is a very soft light. Large is what makes soft. And close is one factor of what makes large.
This picture of a bear is not important, but looking a minute to understand what the flash is doing is a good skill to polish. It is really not rocket science. It is merely about the size and direction of the light. The trick is to look at what you can see. Yogi Berra said "You can observe a lot just by watching".
These are the same pictures as above, in same order, from RAW, but now all with constant Flash White Balance, and are not individually corrected for color as was done above. The different methods do cause the speedlight flash to operate with differing power levels... close direct flash is minimum power and blue, and ISO 200 f/7 bounce on a ten foot ceiling is maximum power and red (studio flash are often the opposite, a design that becomes red at low power). The various methods and modifiers cause the power difference, but do not cause the color variations directly. The flash power level causes the color. The red pictures simply used more flash power than the blue pictures. Regardless of the modifier, the color will continue to vary with flash power, for example with subject distance and ISO and aperture and ceiling height. The point is, weigh this into your evaluation of these various gadgets. That is, don't confuse color with lighting. Don't attribute the color to the device, because the color will still vary with power level, with the same device.
Note that Auto White Balance does a lot for a hot shoe mounted flash, because the Nikon or Canon system will get relatively accurate color temperature information from the hot shoe mounted flash, and can use that information with Auto White Balance (but not if you specify Flash White Balance, which is a constant).
2. Continuous vs. Instantaneous light - vs. Shutter Speed
3. Soft light (and diffusion domes?)
4. Flash pictures are double exposures
5. Extras (Rear Curtain Sync, White Balance with Color Gels)
Copyright © 2009 by Wayne Fulton - All rights are reserved.
