Sunset portrait lighting with small flashes

[AstroImager]

Just thought I'd share a new blog post I've written on how I do lighting for sunset outdoor portraits:

http://makingitasapro.blogspot.com/

Thanks for looking,
Paul

[Skipper]

Great tutorial Paul. Thanks for sharing. The pix r gorgeous.

-I am curious why u use two flashes shooting into umbrella. One isn't enough? Obviously not but this was a surprise.

-r u saying you r controlling background exposure with shutter speed?

This was very informative.

[mrchile]

It was very informative. The only nit I have was that the printing on your blog was hard on the eyes. The bright yellow print against the dark background was tough to look at after a short while.

[AstroImager]

Thanks for the feedback.
I'll change the typeface to white -- probably should have done that long ago

As for the two flashes: it gives me more options. Often one small flash even on high power bounced into an umbrella doesn't provide enough light to "overpower" daylight ambient, even near sunset. Using two does, amply -- and I can turn the power levels of the flashes down if it's too much.

And yes, the shutter speed alone "controls" the ambient exposure. As long as you're shooting at or below your camera's flash sync speed, changing the shutter speed won't affect the flash exposure at all -- the same amount of light from the flashes will be recorded no matter what your shutter speed is because all of the flash's light occurs while the shutter is open. The only things that will affect the flash lighting is the lens aperture, the distance of the flash from the subject, or the flash power setting. So if you set up the flash distance and power to give you a proper exposure at, say, f/5.6, and set your lens to that, changing the shutter speed won't affect the lighting from the flash. But a faster shutter speed will record less ambient light, while a slower one will record more ambient light. So you can control the ambient entirely by varying the shutter speed up or down.

Paul

[Skipper]

Thank you Paul. That's a helpful explanation. For some reason I have had a hard time grasping this 'shutter speed controls the background exposure' concept. It seems like it should be simple but it's not sinking in for me. I think I'm stuck on the notion that aperture and SS are ying and yang mathematically. Drop one down, jack up the other to get the same exposure, etc.... So why would one affect one part of the photo (background) while the other (aperture) does not. Maybe the principle only comes into play when flash light is involved.

[AstroImager]

Skipper,
It does only apply when flash is involved.
Look at it this way: even at full power, a small flash's "pop" puts out all the light it's going to put out in about 1/1000th of a second. It doesn't matter if your shutter is open for 1/200th of a second or 200 seconds -- in either case it will "see" all of the light from the flash while it's open, and "see" the exact same amount of light from the flash no matter how long or short the shutter speed is (with, as I said before, the caveat that the fastest speed is your camera's flash sync speed). One short pop of the flash delivers all the light it's going to give in about 1/1000th of a second, and leaving the shutter open longer won't see any more light from the flash. Make sense?
But for the ambient light, which instead of happening in one short burst like the flash is constantly "trickling" in, a longer shutter speed will let more of it in. Ambient doesn't all come from one 1/1000th. sec pop, it accumulates over time.
So when you're shooting outdoors with flash, the shutter speed *will* affect the ambient/background light, but it won't affect the light from the flash (within sync speed) -- that means you can change the shutter speed to affect ONLY the ambient/background light, controlling it separately from the flash's short pop.

Changing the aperture *will* change how much of that flash's light your sensor sees, though -- and it will also change the ambient light. Because it lets less light (no matter how quickly or slowly that light comes in) through your lens. If you change the aperture setting (say, close it down one stop), you lower both the flash and ambient light by one stop. But since you can control just the ambient with the shutter speed, if you close down one stop (affecting both flash and ambient), then use a shutter speed twice as long (affecting only ambient), there's no "net" change to the ambient, and all you've done is adjust the flash exposure (you lost one stop of ambient by closing down the aperture, then got it back by halving the shutter speed).
Make sense?

Keep in mind the practical limits, though: you can't use a shutter speed faster than your sync speed (which is the fastest speed at which your camera's shutter curtain is FULLY open, rather than being a moving slit), and you can't practically go lower than about 1/15th of a second for shutter speed if you're shooting people (they'll move, and there will be enough ambient light to show their movement as a "ghost" from the frozen flash burst). But you do have one more exposure control: ISO. Move it up or down to get the shutter speeds/apertures in the range you want.

So typically, I want to shoot at about f/4 to f/8, with a shutter speed of about 1/100th sec. (that gives me room to adjust the shutter speed up or down to control the ambient light). Set up your camera, put it in manual, set your chosen aperture and shutter speed, and adjust the ISO so you get good ambient exposure at your chosen aperture and shutter speed. Then add the flashes, adjust power levels and distance so you get good flash exposure at your chosen aperture (remember, the shutter speed doesn't matter). Then shoot away.
Make sense?
Paul

[Skipper]

Thank you so much Paul for this great information! This is really great.

While a longer shutter speed won't affect the light coming from the flash, wouldn't a longer SS still put more light on the subject's face simply because it puts more light everywhere the longer it stays open?

If your shutter were open for 200 secs. (granted an extreme example) wouldn't the face be wayyyyyy overexposed even if the flash and aperture were set for the correct exposure? Is SS simply irrelevant here except for background and any other areas not hit by the flash? (Ignoring for the moment the movement issue created by long SS.)

Why does't the aperture affect the ambient light? Wouldn't a higher/narrower ap let is less light and vice versa? And thus have affect on background? Or does it and therefore you adjust the SS to respond?

Thanks again!

One short pop of the flash delivers all the light it's going to give in about 1/1000th of a second, and leaving the shutter open longer won't see any more light from the flash. Make sense?

But for the ambient light, which instead of happening in one short burst like the flash is constantly "trickling" in, a longer shutter speed will let more of it in. Ambient doesn't all come from one 1/1000th. sec pop, it accumulates over time.
So when you're shooting outdoors with flash, the shutter speed *will* affect the ambient/background light, but it won't affect the light from the flash (within sync speed) -- that means you can change the shutter speed to affect ONLY the ambient/background light, controlling it separately from the flash's short pop.

Paul

[AstroImager]

Yes, a longer shutter speed will let more of the "ambient fill" on the face in (as will a wider aperture).
But that was the point of putting the subject in the shade, where there's much less ambient light, and having the background be lit by the sun. In the first shot in the article (girl by the tree), the ambient "fill" on her face is about 4 stops lower than the sunlit background. So the vast majority of light on the girl is coming from the flashes, and very little from ambient light. Making a one or two stop change in the shutter speed changes how the sunlit background looks a LOT, but doesn't make much of a change in the ambient fill on the girl at all. Going to a much faster shutter speed (still within flash sync range) would significantly darken the background *and* reduce the ambient fill to the point of the shadows being harsh; while going to a much slower shutter speed would indeed make the ambient fill on her significantly brighter, which looks un-natural.
So yes, it's a balancing act -- but one you have several stops within which to play.
For that shot, "straight" metering of the scene was about:
-- ambient light on girl: 1/15th @ f/4 at ISO 100
-- sunlit background: 1/125th @ f/4 at ISO 100

Adjusting flash power and distance to give a good exposure on the girl at ISO 100 and f/4, I kept the sunlit background pretty light by shooting at 1/100th sec., and that same shutter speed let in enough of the ambient fill on her face to keep shadows from going black and harsh. If I'd shot at 1/30th sec instead, the background would be much lighter, but the ambient fill would still be 1 stop underexposed and so still wouldn't be nearly as bright as the flash-lit parts of her. If I'd shot at 1/200th sec (my max flash sync speed), the sunlit background would be nearly a stop underexposed (and so much darker), and the ambient fill would be almost non-existent (now about 5 stops underexposed), making the non flash-lit parts of her face much darker.

Your 200 sec. example is correct, but who can get subjects to be perfectly still for 200 seconds?
Paul

Thank you so much Paul for this great information! This is really great.

While a longer shutter speed won't affect the light coming from the flash, wouldn't a longer SS still put more light on the subject's face simply because it puts more light everywhere the longer it stays open?

If your shutter were open for 200 secs. (granted an extreme example) wouldn't the face be wayyyyyy overexposed even if the flash and aperture were set for the correct exposure? Is SS simply irrelevant here except for background and any other areas not hit by the flash? (Ignoring for the moment the movement issue created by long SS.)

Why does't the aperture affect the ambient light? Wouldn't a higher/narrower ap let is less light and vice versa? And thus have affect on background? Or does it and therefore you adjust the SS to respond?

Thanks again!

[Russ]

Simplistically, what Paul is saying is that he is creating a shooting environment (subject in the shade) where his flash units are the MAIN light source, ie stronger than the sunlight. Because the sun's light is infinitely more powerful BUT also infinitely further away, there is negligible difference in the amount of light between near and far elements IF they have equal exposure to the sun (ie both unshaded or both shaded). However, the light from the flash "falls off" in strength very rapidly such that near elements get much more of it than further elements (Inverse Square Law). Paul is letting the sun expose most of the scene BUT slightly overpowering the sun's lighting on his near subject to emphasize that subject. By exposing for the background (sunlit) area, the flash will ensure that the subject is properly lit by adding enough light to an otherwise slightly underexposed element (subject) because its in the shade, bringing the lighting on the subject up to that on the background....but controlling HOW it appears to strike his subject.

To practice this, shoot from inside your house on a brightly lit day with an outdoor scene in the background (ie thru a window). Expose for outdoors, staying well below the sync speed. Preflash on the interior. Take the shot. You should have an interior fill flashed with an exterior properly exposed. Now change the aperture by at least 3 or 4 stops and likewise compensate with shutter speed to maintain a properly exposed outdoors. Preflash the interior (to meter the flash). Take the shot. Again you should have a mostly identical histogram (assuming that you preflashed off the same area and that you were within the capabilities of the flash unit). The only differences in the 2 shots will be the DOF due to the respective apertures for each shot.

A 2nd practice is to shoot a dark hallway using manual. Set the aperture. Set a shutter speed several stops less than needed for ambient lighting conditions. Using your flash, shoot the scene. Change only the shutter speed (staying at or below the sync speed). Reshoot the scene. See any difference? NO! Because the sole or dominant lighting was provided in far less than the time allowed. The amount of light provided by the flash was the same, thus the images appear the same and seemingly independent of shutter speeds below sync speed.

[Skipper]

Thank you again Paul. This is very helpful. I love that you explain this in practical terms. Scott Kelby is like that. and Bryan Peterson. And it's also helpful to refer back to your photo to be able to better see what you are talking about. I think one problem with a lot of books (not Kelby or Peterson) is that they assume you already know more than you do. Also, a lot of books try to cover so much in one book that each topic gets only cursory coverage. Another problem is that often you see these great photos with some explanation of how they were made but no settings! Drives me crazy. I love it when they give you the settings. I am going to print out this thread.

I tried to keep some of this in mind the other day when I was shooting people in a dark room. It was a no win situation I think. It was editorial style shot -- two people were showing off the room to a VIP visitor. It was on the fly and no time to set up the shot and could not turn up the lights. Tried to expose background but that would have meant really slow shutter speed. (I was already at 1000 ISO). Because people were talking and moving I could not go below 1/60 shutter speed. And couldn't have too shallow DOF. So I bounced flash off the white ceiling to try not to blast their faces and hoped for the best on the background. It was dark but lightened up in Photoshop. Not great but not a disaster.

Thank you Russ for adding to Paul's tutorial and shaping the explanation is a slightly different way. It helps to put it all together. Thanks for those two good practice ideas. I want I will try them.

I appreciate your posts and responses.