Event photography outdoors at night (sort of)

Our toddler celebrated his birthday at the Rainforest Cafe. It was daytime and indoors but may as well have been outdoors at night for photography purposes. If you haven't been there, it looks like a scene from Raiders of the Lost Ark: rock-like walls, tropical plants and vines, rainforest creatures climbing all over walls and ceilings, shafts of light here and there like sun streaming through the thick canopy of a rainforest, complete with thunder and lightning.

From a family photography point of view, there are many opportunities in this setting - dramatic and colorful lighting, interesting backgrounds everywhere you turn. The challenges were equally diverse: high contrast inconsistent and often dim ambient light, not many surfaces to bounce from.

My objectives were: highlight the ambience of the place (given that the location was an important element of this party), emphasize the fun we had at the party, and as much as possible to make people look good.

In this kind of setting I would never trust my camera in the 'auto' mode. Otherwise, people will have the deer-in-the-headlights look and the background would probably look black.

This is how I chose my controls / settings:

1. Because it was too dark for an ambient-only exposure, I used flash. I took the flash off-camera to control the direction and make the subjects look more three-dimensional. I also gelled the flash with 1/4 CTO because: the light from a flash is usually a bit bluish, people look better in warmer light, and it matches the warm-looking ambient light better. After thinking a while, I chose to use the direct flash instead of a handheld umbrella because it would be too tight to move around with the handheld umbrella. Because light conditions were inconsistent and were changing rapidly, I set the flash on TTL (as opposed to manual).

2. To preserve the ambience, the exposure had to be sufficient to show the ambient light. However, if the exposure is set exactly for the ambient light, and the subject has just as much ambient light as the background, then there might be flash blur like this (sometimes ok for action shots, but usually not ok for static shots). I thus underexposed ambient light by -0.7 stops through exposure compensation. The underexposed background also creates subject-background separation.

3. I chose matrix metering because the light conditions, though inconsistent, were evenly distributed. "Consistently inconsistent." I didn't think there was anything present that would fool the matrix metering.

4. I wanted to use the fastest shutter speed possible (reminder - I'm using TTL) to further minimize flash blur. I thus chose the widest aperture on my lens (Tamron 28-75 2.8) by using aperture priority, and choosing 2.8. I also set the ISO to the highest decent-looking ISO for my camera, which was 800 ISO. Note: noise shows up much more easily in shadows (of which there were plenty at the location). If there's enough light, even 1600 ISO looks acceptable.

5. In aperture priority mode, the slowest shutter speed that the camera will choose is determined by the flash shutter speed setting (I don't know the Canon equivalent, but IIRC there is one for Canon as well). By default for Nikon, it's 1/60, which was too fast for the ambient to register at f/2.8 and 800 ISO, so I decreased it to 1/15, based on test shots.

6. I took test shots for the flash as well. The flash was too strong for my taste, so I adjusted TTL by -0.7 stops. I also used the wide angle adapter for a couple of reasons - first, I knew I would take some pictures of groups of people, and they would be more evenly lit when the flash beam is wider. Second, the decrease in flash power from using the wide angle was not a problem (because ambient was dim). In fact, the issue is the opposite -- at f/2.8 and 800 ISO and flash directly aimed at subjects, I was close to requiring less than the minimum flash power, risking flash overexposure. Using the wide angle adapter effectively 'decreases' the flash power, making flash overexposure less likely.

7. Because it was dark and I didn't want people to blink from the preflashes, I used the SG-3IR.

Based on these settings, these are the results I got.

Although I was using slow shutter speeds (1/30 or slower), most shots came out reasonably sharp because the subjects were being lit only by flash (I underexposed ambient by -0.7 stops). In effect, I was taking shots at the shutter speed of the flash duration (around 1/10,000). In a few shots, the ambient light was bright enough that there was flash blur (like this). I didn't notice the flash blur when I was looking at the LCD. If I had, I would have reduced exposure comp further for those shots. As for the background, the slow shutter speed wasn't a problem because it was disguised by the shallow DOF of the wide aperture anyway.

I think the results are ok. A bit underexposed. If I had to do it over again, I may have gone with -0.3 stops for the TTL instead. To reduce contrast, perhaps I should have used the pop-up flash as fill (though I would risk more blinking shots). In that regard, I'm wondering how much better a ring flash would work as fill (a la Strobist David Hobby). I also would have liked to take some shots with the handheld umbrella for variety, or clamped it somewhere (which I've never tried before).

Basic Postprocessing for Newbies

Note: this post is a follow up to this post on planning and this post on execution.

I know very little about postprocessing but it's made a big difference for my pictures. If you haven't tried it, you're missing out. Basic pp is easy and doesn't take much time.

From Maty 23+ Months (Las Vegas, with Brayden)

We took the shot above for our kid's birthday invitation. Straight out of the camera, it looked like this:

The unedited shot looks unremarkable to me. But I spent literally one or two minutes on pp and got to the final result above. A good return on investment in my view. :)

PHOTO EDITING SOFTWARE

I don't have a professional photo editing program like Photoshop or Paint Shop Pro. I've tried fiddling with them in stores and got overwhelmed by their complexity. And Photoshop is way too expensive for my needs at the moment. Instead I use:

• picasa (free)
• www.picnik.com (basic is free, premium is $25/yr), and/or
• Adobe Photoshop Elements 6 (came free with a wacom digital tablet).

PP programs can help you with

• Exposure
• Color
• Composition.

For the shot above I benefited from all three uses.

BACKGROUND INFO - WHITE BALANCE

White balance (wb) is the color cast of the light in the picture. Extreme examples: Incandescent lamps cast yellow light. Sodium parking lot lights cast greenish light. Fixing white balance means making the color cast neutral or changing it actively.

Check this out to learn more about white balance:

http://www.cambridgeincolour.com/tutorials/white-balance.htm

Most of the time, your camera's automatic white balance does an ok job of neutralizing wb. But in this regard, DSLRs don't seem to do as well vs. point and shoot cameras. There are many ways to make sure that wb is correct when you take the shot but I'll write about that next time. This entry is only about pp.

BACKGROUND INFO - HISTOGRAMS

Skip ahead if you know this or don't want to bother with details.

A histogram of a picture shows progressively from left to right how many pixels are dark (left) and bright (right). There are separate histograms for white, red, green and blue channels.

It's a guide for exposure. If the pixels are in the leftmost or rightmost column, then the picture does not show any detail in those pixels except to show them as pure black (leftmost) or pure white, red, green, or blue (rightmost).

More info here

http://www.cambridgeincolour.com/tutorials/histograms1.htm

ACTUAL EXAMPLE OF BASIC POSTPROCESSING

I used Photoshop Elements for the result above, but I've recreated the changes using the free version of picnik.com to allow anyone to practice with them. Even the free version of picnik is just as capable as PSE for basic adjustments, and the premium version of picnik holds its own for moderate PP.

Steps for PP in picnik:

1. Go to picnik.com, and upload the picture from your computer or from an online album. Move your mouse over the picture and click on the down arrow on the bottom right and select edit.

2. correct the white balance.

- click on colors

- if there's a white or gray part of your picture, you can click on neutral picker and select that part.

- adjust color temperature. Generally people look better in slightly warm-looking light. Flash is also slightly bluish so you generally have to warm up the image a bit if you used flash (as I did here). Here I set temperature to 19, which is less warm than the result above.

- adjust saturation. I prefer saturated colors. Here I increased to 4.

- click ok

3. correct the exposure.

- click exposure

- click on advanced

- adjust the highlights and observe the histogram. Here I moved it to 28. The histogram shows that the sky gets blown out but that's ok. There's no detail there anyway.

- click local contrast and adjust. I really like this effect because it makes the subject look more three-dimensional. I tend to move it as high as I can without the image looking strange, then I back off a bit. Here I adjusted to 16%.

- click ok.

4. crop if necessary.

- click on crop

- click on "no constraints" and change it to the ratio you want. Here I picked golden ratio.

- adjust the crop. To follow the rule of thirds, keep the points of interest near the intersections of the lines.

- click ok.

5. save your work.

- click "save & share"

- if saving to an album, choose whether to replace the old file or save as a new one. Here I saved as a new file.

- click on save

That's it. You're done.

DID YOU GET VALUE FROM THIS?
Does this article help you with your photography? If so, please leave a comment and recommend this blog to your friends. To get updated headlines from this blog, subscribe to the feed on your pc/mac and your smartphone. Thanks!

TTL Flash FAQ for digital cameras

Updated: May 8, 2010
Number of times updated: 9 (mainly to #14 - mixing ambient and flash)

This FAQ guide is a super-simplified intro to flash. It assumes no knowledge about flash but requires that you already have some understanding of exposure.

1. Why use a flash?

Properly used, a flash is another way to control the image and improve the lighting of your image.

2. What do you mean by proper way? Don't you just turn it on?

No. Proper use of flash requires understanding how flash metering and controls work in relation to your exposure metering and controls. Just as with exposure for existing light, if the power of the flash is incorrectly set, then your image will be over- or underexposed. In addition, flash can serve a variety of functions (as the main or key light, fill, background, hair, rim light, etc.) and the ideal flash exposure differs depending on the function of the flash.

3. Isn't your flash exposure simply determined by your exposure settings?

Ambient exposure and flash exposure are two different concepts. (Ambient exposure is the amount of light recorded on the image if you had not used the flash. Flash exposure is the amount of flash recorded in the image.)
Your exposure settings for the ambient light (aperture, shutter speed, ISO) may or may not affect your flash exposure.  In manual mode, ambient exposure controls do affect your flash exposure.  In TTL mode (see #4 below), ambient exposure controls generally don't affect flash exposure.  In either case, learning to control your flash exposure is a separate skill.

4. How is flash exposure controlled?

It depends on your flash mode (manual, auto, or TTL). Let's get something straight: flash output (the amount of light from the flash) and flash exposure (the amount of flash that is recorded in the picture) are two related but different concepts. Mostly, what we care about is flash exposure. There are several ways a flash exposure is determined. Generally, they are:

a. Manual - user controls flash exposure by specifying the flash output (usually on the flash itself). With manual flash, there is no built-in metering (unlike switching the camera to manual exposure mode, which at least gives you a light meter). With manual flash exposure, you either use the guide number (the flash power rating), a handheld incident light meter, or trial and error to determine the correct flash exposure. Using manual flash is outside the scope of this FAQ. FYI manual flash power is sometimes expressed as an f/stop which is an indication of the aperture required for a correct exposure (according to a light meter). So, setting the flash at f/8.0 means putting out twice as much power as setting it for f/5.6. Sometimes expressed as a fraction, e.g., 1/2 power, 1/4 power, etc. Usually in full stops. The latter is less informative because different flashes have different light outputs for the same amount of power.

b. Auto - You don't control flash output per se. Instead the flash (not the camera) uses its own sensor to control flash exposure. You initially specify on the flash the aperture and the ISO you're using. When you press the shutter, the flash fires and detects its reflection through a sensor on the flash. (On more advanced flashes made for your particular camera, the camera automatically communicates the aperture and ISO to the flash.)  When the flash sensor detects that there's "enough light" based on the aperture, the ISO, and the reflection,  it cuts off the power.

c. TTL ("through the lens") - You also don't control flash output per se. Instead you use the camera to control flash exposure. When you press the shutter, the camera tells the flash to fire a test flash. The camera (not the flash) detects the reflection from the test flash coming in though the lens. Based on the amount of reflected light, aperture, and ISO, the camera tells the flash how much power to put out. All this happens in a split second before the shutter even opens. When your shutter opens, the flash power has already been set by the TTL system.

5. In 4b and 4c, you didn't mention shutter speed as affecting the amount of flash. Why?

The flash only lasts 1/1000 to 1/20,000 of a second, so changing the shutter speed generally doesn't affect the amount of flash. 

Note 1: shutter speed becomes relevant if the shutter speed is so high that the shutter starts to close before the flash is fired. That maximum speed before this issue occurs varies from camera-to-camera and is called the "sync speed." Some cameras have X-sync exposure mode. That is a shortcut way of choosing shutter priority exposure at the sync speed.

Note 2: although shutter speed doesn't affect the amount of flash, it is relevant for controlling the ratio of existing light to flash. See #14 below.

Note 3: Modern flashes have a way of increasing the sync speed at the expense of power/distance through high speed sync.

6. I'm using a filter (e.g. a neutral density filter). Will that affect the flash metering results?

With Auto, yes because there's no way for the flash to know whether you're using a filter or other accessory. With TTL, no (because the test light comes in through the lens).
6b. I'm using a large diffuser that's blocking part of my external flash.  Will that affect the flash metering?
If you have a diffuser or accessory attached to your external flash, and it's large enough to block the sensor of your external flash, Auto won't work correctly.  However, TTL will generally function without problems because the flash metering is done through the camera's lens, not a sensor on the external flash.  However, TTL may screw up if your accessory directs some of the flash into the lens (instead of bouncing off from the subject).
6c. My flash is off-camera (i.e., removed from the camera) and positioned closer  to or farther  from the subject than is the camera.  Will that affect the flash metering?
If you are using TTL, then the flash metering should not be affected by any difference between the flash-to-subject and camera-to-subject distance.
If you are using Auto, then the flash metering will likely not be accurate.  If the flash is closer to the subject than the camera (e.g., the flash is 3 feet away from the subject while the camera is 10 feet away from subject), then the flash exposure will likely be underexposed and vice-versa.

7. Do my ambient exposure controls (aperture, shutter, ISO) affect the TTL flash exposure? What about exposure compensation?

With TTL, generally no.  Within a wide range of ambient exposure settings, the flash exposure should be the same regardless of ambient exposure controls. For example, if you're using f/5.6 @ 100 ISO a TTL flash will put out more flash power than if you had used f/2.8 @ 400 ISO, so that the flash exposure in both cases is about the same. Exposure can start affecting the flash exposure if the exposure settings force the flash to exceed its maximum or minimum power. If you're at f/64 and ISO 100 and 30 feet away from your subject, your flash is not going to put out enough power for the 'correct' amount of flash exposure. If you're at ISO 1600, f/1.4, and 5 feet from your subject, you will have way too much flash exposure. In addition, although ambient exposure settings in many cases don't affect flash exposure itself, you have to balance ambient and flash properly for the photo to look nice. See balancing ambient and flash in #14 below.
Using exposure compensation may or may not affect your flash exposure.  With Canon, the flash exposure ignores the exposure compensation and is unaffected.  With Nikon, exposure compensation will affect flash exposure.  For example -1 stop EC will reduce the ambient exposure by 1 stop and the flash exposure by 1 stop as well.  There are advantages to both approaches.

7b. How do I know if I will exceed the minimum or maximum power from the flash?  What can I do about it?

One way to tell is through the distance range displayed on the backs of some flashes.  Some flashes will show you the minimum and maximum range in TTL mode for any given exposure setting.  Note however that those ranges work only if you are using the flash directly.  If you are bouncing the flash, the distance range won't be reliable.  Knowing that there is a maximum and minimum power, what can you do about it?  If you want the highest maximum range, set the shutter at your camera's maximum sync speed or less, use a wider aperture, and/or use a higher ISO.  Note: using a wider aperture and higher ISO will of course affect your ambient exposure.
If you want to decrease the shortest minimum range, you can either decrease your aperture, decrease your ISO, or if your camera has high speed sync enabled, choose a shutter speed above the sync speed (which will rapidly decrease the effective power of your flash).

8. TTL sounds like a reasonable way to set flash exposure. What could go wrong?

A number of things can cause TTL to set the wrong exposure:

• If the reflectiveness of your subject is not average, then you can get over- or under-exposure. For example, if your subject is wearing black velvet, then your camera will try to put out as much flash as it can to try to bring the velvet to gray, and the subject will be overexposed. If your subject is wearing a reflective vest, then the camera will cut off the power very early because of the efficient reflection of the vest, and the subject will be underexposed. Those are extreme cases, but there are more common situations that are analogous, such as having a shiny object near the middle of the image.
• In some flash systems (e.g. Nikon), the camera measures the preflash reflection toward the middle of the image. If your subject is off-center, the TTL system doesn't know that and will try to set the flash exposure for whatever's in the middle of the image, usually resulting in overexposure of the subject if the object in the middle is further away.  One solution for this kind of situation is to frame the subject in the middle, lock the flash exposure (in Nikon cameras, with the FV Lock), recompose, and take the shot.
• If there is a reflective object in the foreground, it can cause overexposure of that object and underexposure of your subject.  Sample:

One solution for this kind of situation is to zoom in to the subject until the problematic foreground image is out of the frame, then use FV Lock.

• In addition, as discussed above, the correct amount of flash differs depending on the purpose of the flash (as key/main, fill, hair, rim, or background, etc.).

9. If the flash is overexposed or underexposed, what can I do to adjust flash exposure?

With TTL, you use flash exposure compensation ("FEC"). If there's not enough flash, you increase FEC, and vice-versa. With TTL, changing your aperture, shutter or ISO won't change your flash exposure (unless your exposure settings are such that they exceed the minimum or maximum power for the flash).

10. OK I understand how to set the flash exposure. Am I good to go?

In addition to the amount of power from the flash, the basic variables include quality (hard vs. soft), color, shape, ratio to existing light, and direction. More advanced techniques (not covered in this FAQ) include: adding more than 1 flash, and adjusting those variables for each flash, using a stroboscopic (repeating flash), and more.

11. Why and how do I change the quality of the light from the flash (hard vs. soft)?

Hard light (with hard, well-defined, high contrast shadows) is more dramatic but potentially unflattering if not used correctly. Softer light is generally more flattering for people and makes it easier to achieve an acceptable image. To soften light, increase the apparent size of the light source. To increase the apparent size of your flash, you can bring it closer or use bounce techniques or use a flash modifier such as a softbox, umbrella, or any number of flash modifiers out there.  The larger the apparent size of the light source compared to the subject, the softer the light will be.

• Using bounce techniques:  instead of directing your flash at the subject, you direct it at a large surface such as a wall or ceiling, and use the reflection to light your subject.  Note: this will eat up much of your flash's power because of the extra distance the light has to travel and because the surface is likely not a perfect reflector.  Thus, you usually have to select a higher ISO like 800 or more.
• Using umbrellas: to attach a flash to an umbrella, you’ll need an umbrella holder (aka umbrella swivel). An umbrella holder is equipped with: 1) a hole to insert a photographic umbrella, 2) a shoe for the flash, and 3) a way to insert a 5/8 stud, which is the standard size for lightstands. Some brackets use a tripod 1/4-20 mount instead.
• Using softboxes: there are a variety of softboxes out there – some made for studio lights and others made for hotshoe flashes. To use the ones made for studio lights, you'll probably need some sort of adapter.  The ones for hotshoe flashes use different ways of attaching the softbox such as velcro.
• Using flash modifiers: there are a myriad of flash modifiers that are supposed to soften the light from the flash. If you’re concerned about softening your flash, just ask yourself whether the flash modifier is making the light from the flash larger or not. If it’s not, it doesn’t soften the light. For example, some people think the sto-fen omni-bounce diffuser softens the flash. Actually it doesn’t because it doesn’t change the size of the light. It does help bounce the light around indoors, so the softening effect of the sto-fen diffuser is from the bounced light, not the diffusion. Outdoors, where there’s nothing to bounce from, there won’t be a softening effect.

12. Why and how do I change the color of the light from the flash?

Three reasons: to correct existing light conditions, to change the emotion of the image, or to use color as an element of your composition. If existing light is not neutral and you want to make it neutral, you need to change the color of the flash to match the existing light so that when you correct for white balance, both flash and existing light will have the same color. Second, you can use colored flash to change the emotion of the image (e.g., red is hot, blue is cool, green is sickly etc.).  Third, you can use colored flash to actively control the color of the subject, shadow, and/or background for composition purposes.

Three ways: 1. through gels; 2. through your white balance; 3. add or subtract colored lights.

• Gels: Gels are colored sheets of plastic (like colored transparencies), velcroed or taped or somehow attached to the flash, like this.
  
• White balance: You can gel the flash for a particular color, use white balance to ‘correct’ that color, and the existing light will become the complimentary color. For example, if you gel your flash orange (with a CTO gel) and adjust your WB for incandescent light, the flash will look neutral while the existing light will look blue.
• Mixing colored lights: Another way to change color is to add or subtract lights. For example, if you have a red light and a green light, the areas where they are both shining on will look yellow.  More on adding and subtracting colored here: Color addition: http://www.physicsclassroom.com/class/light/U12L2d.cfm and Color substraction: http://www.physicsclassroom.com/class/light/U12l2e.cfm

13. Why and how do I change the shape of the light from the flash?

Why: changing the shape of the light changes the shape of shadows and highlights from the flash. Shadows can add three-dimensionality to an image and can add drama or become an element of composition.

How: Diffusers, snoots, grids, gobos, cookies, and other similar devices. Homemade or store-bought.

• Diffusers spread out the light from the flash.  Some flashes have built-in diffusers.  There are also a number of flash modifiers out there that act as diffusers. See #11.
• Snoots are like tubes that you attach to the flash to make the light beam narrower. Longer snoots = narrower beams.
• Grids have a similar function to snoots but they composed of many smaller tubes (e.g., in a honeycomb or grid pattern). Generally, the resulting light is even narrower than snoots. Longer and smaller-tubed grids have tighter beams. Louvers are similar to grids but they channel light in one axis but not the other.
• Gobos or flags: something placed to partially block the light beam from the flash. For example, gobos are used to reduce lens flare.
• Cucoloris or "cookie": a surface with a pattern of holes to let the light beam shine through with a particular pattern (e.g., to simulate shadows of foliage).
• Found objects: many objects around us, whether opaque, translucent or transparent, can be placed in between the flash and the subject to shape the shadow and or highlights from the flash.  For example, a common technique is to shine the flash through a glass of water to project an ethereal highlight on the background.

14. Why and how do I change the ratio of ambient light to flash?

Why: allowing enough ambient light to appear in the image preserves the atmosphere of the scene you’re shooting.  Conversely, having no ambient light (as in a background that is turned black) can direct the attention to the subject or simplify the composition.

How: With TTL, you adjust the ratio of ambient light to flash by:
1) adjusting the ambient light exposure: To adjust ambient light exposure, just change the exposure controls (aperture, shutter, ISO). As discussed above in #7, changing those controls generally doesn’t change the flash exposure in TTL mode but doing so will change the amount of ambient light exposure on the image.
2) adjusting the flash exposure:  You can also change the ratio by adjusting the flash exposure (which for TTL is done by adjusting FEC).
3) controlling the amount of flash that reaches the background (lighting depth of field*): other than through controlling the direction of the flash (toward or away from the background) or using flags, this can be done by controlling the distance between the flash, subject, and background. If the flash to subject distance is much shorter than the subject to background distance, then the flash exposure of the subject will be much greater than the flash exposure of the background due to the inverse square law.  Example of this technique here.
(*Note: usually depth of field means the part of the image that is in focus.  In lighting terms, however, depth of field means the part of the image that is illuminated. See this Strobist lesson)

15. Why and how do I change the direction of the light from the flash?

Why: changing the direction also changes the shadows. See #14. Changing the direction also allows selectively highlighting parts of the image.

How: You need an external flash. With your pop-up flash alone, you basically can't change direction unless you use reflectors or mirrors.

Changing light direction with an external flash depends on how the external flash is connected to the camera: the camera’s hot shoe (“on-camera flash”), with a cord, or use a wireless connection.

a. On-camera flash: to change direction, you need an external flash with bounce and/or swivel (ideally both).

b. TTL cord: look for a TTL cord specifically made for your camera brand. One end attaches to your camera’s hotshoe. The other end attaches to your flash’s hotshoe. Then you put the external flash on a lightstand, flashbracket, or hold it with your hand.

c. Wireless TTL connections:

i. optical – each major camera maker has its own way of implementing wireless TTL via optical preflashes (like morse code), although some flash systems allow more sophisticated control than others. Generally, you’ll need a commander, and a flash that is capable of acting as a receiver for such systems.

ii. Radio – wireless TTL via radio is relatively new. To date, wireless TTL via radio are featured in products available from quantum (freexwire system), pocketwizard (control TL), radiopopper (PX system).

16. How do I choose an external flash? Can I get just any flash for my camera?

You’ll maximize the features of the flash if you pick one that’s specifically designed by your camera maker (or a third party version of such a flash). For example, if you have a Canon DSLR, search for “Canon flash.”  To be really sure, confirm that the flash is compatible with your specific camera model.  For example, the SB-900 is not fully compatible with Nikon film bodies or Nikon cameras not compatible with Nikon's CLS (Creative Lighting System).

The features you’ll probably want are:

a. power – flash power is rated by guide number. The higher the better, especially if you intend to bounce the light.

b. wireless mode – to allow wireless TTL assuming you have a compatible commander.

c. bounce and swivel – bounce means the flash head can be tilted upward to bounce the beam from the ceiling to the subject (to soften the light). Swivel means the flash head can be rotated (to bounce the beam from walls). Note the maximum swivel angles.

d. high speed sync – allows you to exceed the sync speed at the expense of flash power.

e. optical slave mode – this is different from optical wireless TTL. With this feature, some flashes can be triggered when they sense the camera’s popup flash (or other flashes) being fired (usually, it's limited to manual mode). Useful when you don’t have other wireless connections available but the disadvantage is that there's no TTL and your flash can be triggered by other cameras or flashes or pre-flashes from a  TTL type pop-up flash.

f. zoom head – some flashes have beams that can be zoomed. This is useful for controlling the shape of the beam. Zooming the flash makes the beam narrower and maximizes the flash’s power and vice-versa.

If you want to choose some non-dedicated flash, then at a minimum:

a. Assuming you’re connecting the flash to the camera, you have to check the voltage of the flash. Older flashes have very high voltages that can fry your digital camera.

b. Next you should make sure the flash’s hotshoe can fit on your camera. Sony/Minolta use a different sized hotshoe from other brands. Other than Sony/Minolta, I’m not aware of any other uniquely-sized hotshoes.

c. Check whether the flash is advertised as being compatible with your camera brand.

17. Where do I go from here?

To try out some of the ideas here, check out the TTL Flash Tutorial.  For another tutorial on TTL techniques, check out http://www.planetneil.com/tangents/flash-photography-techniques/ or the book On-Camera Flash. For technical explanations of how TTL works exactly, read the Nikon CLS Practical Guide and Flash Photography with Canon EOS Cameras. For aesthetics and lighting ideas, I look at parenting magazines, movies, movie posters, high-budget TV shows and ads, and the work of skilled photographers.

Seeing CLS flash metadata with ViewNX

Reviewing the metadata of a picture (e.g. EXIF info on exposure details, focal length, etc.) is one way I improve my skills by learning what settings worked and what didn't. One of the settings that I have been looking for is the flash metadata. And I've found it in View NX. With Picasa, all I had been seeing is whether flash was used or not, and sometimes it was even inaccurate (although I wasn't sure why). With Adobe Photoshop Elements 6, I got a little bit of additional info: whether flash was used and whether the camera detected the reflection of the flash. The latter gave me the idea that perhaps when there was no flash reflection detected (e.g., I used a modifier to soften the flash, and decreased flash exposure compensation), perhaps Picasa would show it as having not used flash. I would still have to guess what flash exposure compensation setting I used, and whether I used the pop-up flash to contribute light or not. After surfing around Nikon's site, I came across ViewNX 1.4, Nikon's NEF and JPEG viewer. For something described as a mere viewer, it's quite powerful. First, it shows extensive metadata, including full CLS wireless lighting info (which groups were active, what mode they were on (TTL, AA, manual), what the individual flash exposure comps were). Second, View NX allows you to do some postprocessing on the pictures. Notable postprocessing features include: - simulating a variety of color reproduction modes, just like the D3, D700 and D300 - applying D-Lighting (none, low, medium, high) - highlight protection to recover highlights, shadow protection to recover shadows. - chromatic aberration correction. I've read a few comments criticizing ViewNX as a resource hog and as an inferior RAW processor, but so far I haven't noticed anything that would convince me not to use it. Bottom line - this is a valuable learning tool. And it's free! http://www.nikonusa.com/Find-Your-Nikon/Product/Imaging-Software/NVNX/ViewNX.html

A Day Without a DSLR - Results

Got the pictures developed from our trip to Knott's Berry Farm. Not as good as I was hoping but better than I expected for a disposable camera and given my inexperience with film. Album link: http://picasaweb.google.com/creadvty/Maty24thMonthKnottSBerryFarm The scenes had wide ranges of contrast, making it a technical challenge to capture the image correctly. Although I had no exposure control, the pictures as printed have reasonably correct exposures, which I think is due to the forgiving latitude of negative film. I'm wondering how much additional detail can be squeezed from the negative, if for example, contrast was reduced. (It seems that the contrast in the pictures is set too high.) I ordered a CD of the pictures hoping to postprocess the images. However, it seems the CD is a scan of the print, not the negative, so there wasn't much I could do to adjust the exposure and contrast, and no additional detail was available. I'm still intrigued by negative film's dynamic range and have added to my to-do list sending one of the negatives to a PMT drum scanning service to see just how much detail I can get from film in scenes of wide contrast. If the results are satisfactory, or maybe even if they're not, I am strongly considering buying a film camera for 'critical' shots (and to do capture wide angle shots). Given the results I got when I had zero control over exposure from a disposable camera with a plastic lens, I've gained some confidence in getting usable shots from a more sophisticated film camera.

"Stealth" flash eliminates blinks: SG-3IR flash panel product review

UPDATE: 9/6/12 - See Aokatec IR panel under alternatives

Wouldn't it be great to dramatically reduce the number of shots where your subject is blinking?

I rely heavily on wireless TTL flash via Nikon's CLS Advanced Wireless Lighting and really like the ability of the D80 (and higher-end cameras in Nikon's line) to use the pop-up flash as a commander. One drawback to Nikon's wireless system is that there are longer preflashes that occur (for the commander to communicate with remote units) and many times, our son ends up blinking in the shot. The preflashes also create visible specular reflections. Great if you want an extra catchlight in the eyes but otherwise potentially problematic.
Nikon has a dedicated infrared commander (SU-800), which I'm assuming emits invisible preflashes, but it's not cheap. Moreover I sometimes use the pop-up to add a little bit of fill (generally -2 stops flash exposure comp), which the SU-800 can't do.

The SG-3IR (that's "ir" as in infrared, not "1r") flash panel looks like a simple and cheap piece of plastic, but it's an effective and affordable solution to the preflash problem. It's not easy to find but I got one from B&H and it works as expected.

From pictures, I thought the panel was just a piece of solid black plastic with small slits to let some light through. But the panel actually has no holes and is made of a material that blocks visible light but is translucent to infrared (which is what the slave units need to see). The panel is also larger than I expected - about 2/3 the size of a credit card.

The panel attaches to the camera's hot shoe. Its plastic base has a spring-loaded pin that secures the panel into the hot shoe. Removing the panel is kind of tricky because of the pin. The way I remove it is by pulling the unit up to lift it very slightly then sliding it off.

DOES IT WORK?
The panel is very effective in reducing blinking shots. All that the subject will see from the popup flash is a dim red light from the panel (much dimmer than the AF assist light). There is still a preflash from the slave (when in TTL or AA mode) but: 1. If the slave is off on one side, it's less likely to cause the subject to blink, 2. using fv lock fires the preflash, so that in the actual shot there is no preflash. If even that preflash bothers you, you can switch to Manual mode - no preflashes.

In real life, I've used the panel to take about 200 shots in a variety of ambient light conditions - daylight to dim indoor light. I've had literally a handful of pics with blinking subjects. I speculate that those few blinking shots are due to the subjects anticipating the flash even though they can't really see it.

What if you want to use the popup as fill? The panel has a hinge that lets you flip it up and it will stay up. Nice!

EFFECT ON RANGE
In tests I conducted, maximum range was reduced by about 1/3 to almost half, but probably won't make a big difference for family photographers. The farthest distance I was able to trigger an sb800 in near-ideal conditions (dim parking lot lights at night, in direct line of sight, sensor window facing the camera) with the popup covered by the panel is about 75 feet. With the bare popup flash I was able to trigger the sb800 under those conditions at about 110 feet. In daylight, with the panel covering the popup flash and the camera facing toward the sun, I was able to trigger the SB800 at about 45 feet. With the bare popup flash in those conditions, I was able to trigger the SB800 at about 80 feet.

In real life, in some shots in difficult conditions for optical triggers (bright daylight) the paneled popup didn't trigger the sb800 when it was off to the side. However I was able to trigger the sb800 if I moved the sb800 closer to the camera axis.

I wish to emphasize that IMO the reduced range is a small disadvantage compared to the benefit of virtually eliminating blinks.

WHAT ABOUT NON-NIKON CAMERAS?
I haven't tried it but in theory the panel should also work for other cameras. Issues:
1. Is the shoe mount the standard size shoe mount? (For example, Sony cameras use a different shoe mount.) Note: The panel has a pin but it is spring-loaded so I think it will just not drop down if there's no corresponding hole. Please note the panel might not sit securely.
2. Do the slave flashes sense infrared light? If they only sense visible light, they won't be triggered with the panel.
3. Will the popup flash physically fit behind the panel? The panel sits about 2 inches forward from and 2 inches above the shoe mount.
9/6/12 Update: Canon and Sony shooters can try the Aokatec IR panel (see below under alternatives).

ALTERNATIVES
1. Exposed negative film
Get undeveloped 35mm film, overexpose it, have it developed, cut it to size and cover the flash. I haven't tried this myself. I've read that the film may heat up and emit a burnt odor.

2. SG-2
Nikon also produced a similar flash panel called the SG-2. The difference is that the SG-2 panel is made of white plastic. But I don't know if the white plastic completely blocks visible light.

3.  Aokatec IR panel.
There is now a third party product that is similar to the SG-3IR, produced by a company called Aokatec.  The most significant difference for Canon users is that the Aokatec foot has a recessed area so that it won't push down the TTL pins on a Canon hotshoe.  Aokatec also produces a version of the IR panel for Sony/Minolta cameras with the Sony/Minolta hotshoe.  For a more detailed review of the Aokatec panel go here.

CONCLUSION
Pros: blocks the visible light effectively, greatly reducing the chance of subject blinking. Can be flipped up if you need to let the popup contribute light. Reasonable cost for the quality.
Cons: a little hard to remove. When attached, camera may be hard to store in the bag. Triggering range reduced. Not easy to find.
Rating: 4/5. Strongly recommended for anyone who uses CLS Advanced Wireless Lighting, or uses the popup flash as an optical trigger for infrared-sensitive slaves. Would be 5/5 if the panel were easier to remove (e.g. with the same kind of lock as the sb800) and the camera could be stored in a bag with the panel attached and was completely transparent to IR.

A Day Without a DSLR

We decided on a whim to celebrate our son's actual birthday at Knott's Berry Farm. In our haste I forgot to bring my camera. Not even my pocket digicam. My options were: phone cam and a disposable.



I surfed for specs on disposables. Apparently, shutter speed is around 1/125, aperture is 5.6 or smaller. I was surprised that the disposable we bought (the only one available) had an ISO of 800. Given that it was a bright summer afternoon, I was afraid we would only get blown out pictures (unless the aperture is really small). There's also a flash, which I'm pretty sure has only one power setting to capture the perfect deer-in-the-headlights look.



I know film has a lot of latitude for correction. I also ordered digital copies of the pics so I can do at least some post processing (though I'm not sure to what extent...). We'll see what happens. Hopefully the pics turn out ok. It was my first time ever to go to Knott's and I found it very picturesque especially in the late afternoon light. We had an awesome time (our 2 year old loved the many rides for kids) and we traded our tickets for annual passes.

Shadows; three-dimensional lighting; softer hard light without modifiers

After learning about the advantages of moving the flash off-camera, I'm now learning how to deal with shadows. Conventional photo wisdom is to fill in the shadows with omnidirectional light or on-axis fill. Here is a sample:

In this shot, I used the popup flash to fill in the shadows.

The flash did lift the shadows but there are basically only 2 intensities of light on the subject's face - lit and unlit. I think this looks ok but looks "insufficiently 3d" or kind of flat because there are only 2 main intensities of light - the filled-in shadow and the highlight.

Another approach is cross-lighting. It looks very cool, like a still from a hollywood action movie but is sometimes too unnatural.

A third approach I'm learning about is to let the fill light come from around the same direction as the key, except closer to the camera axis. What this does is to fill only a part of the subject, leaving a portion still in full shadow.

Here's how I think it works (click on the diagram to enlarge).

Disclaimer: I'm not an engineer or physicist. In the diagrams above, assume that the view is a bird's eye view with the camera on the bottom of each diagram. In the top diagram, the red circle is lit by a small light source. The circle is lit basically in two ways: either it's lit (parts exposed to the light) or it's not.

The green circle shows the effect of a large light source. I simplified the large light source by representing it as 3 points. The circle has parts that are exposed to all 3 points, some that are exposed to only 2 points, some that are exposed to only 1 point, and some that are exposed to none of the points. The parts exposed to all 3 points are brighter than those exposed to only 1 point. Thus instead of having almost binary lighting like with a small light source, there is a smooth gradient (don't forget - there are an infinite number of points between the 3 points).

The blue circle is what I'm hypothesizing - that to some degree, it's possible to simulate a larger light source with 2 smaller light sources, where 1 of the light sources is closer to the axis of the camera. Like a larger light source, there are parts lit by 2 lights, parts lit by 1, and parts that are unlit. Unlike a larger light source, however, there is nothing between the two points of light, so the gradient won't be as smooth. I think it would look "more 3d" though, than just using a simple omnidirectional fill.

Real world sample: In the following shot, light from the window acted as the rim light. Instead of using on-axis fill to lift all shadows in the subject's face, or cross-lighting from the angle opposite the window, I positioned the flash from the same side as the window (as far as my arms could reach :) ). This is somewhat like having point A and B from the diagrams above. As a result, there are at least three distinct lighting intensities on the subject's face: rim light from the window, light from the flash which is functioning as the key light, and an unlit shadow area. (There's actually another area from the reflection of the music sheet but that's a separate point.) The effect IMO is to make the subject appear more 3d than binary lighting as used in the previous shot. In addition, even though the flash is hard light (I didn't use an umbrella or diffuser or anything - look at the shadow cast on the music sheet), it doesn't seem very hard on the subject's face (but I'm not yet sure if that's just because of the roundness of our son's face...).

Lighting Strategies

I’ve been trying to organize the variety of lighting techniques that I’m learning about. It seems that they fall into 4 broad strategies:

1. Ambient light only.
2. Overpower ambient, use artificial light.
3. Mitigate ambient light, e.g. fill flash.
4. Enhancing ambient light or simulating ambient light.


Ambient only.
Self-explanatory. A good strategy when the ambient light already has or can be modified to have favorable quality, direction, color, and intensity.

• Pros: lighting looks natural.
• Cons: May be difficult to get favorable quality, direction, color, and intensity.
• General technique: modify the ambient as necessary, meter for the ambient as key.

Overpowering ambient.
Artificial light becomes the key light, and ambient becomes the fill or is minimized. Fine strategy when there’s not enough ambient, or the ambient is unfavorable. Ideal strategy if we want a literally “unreal” look.

• Pros: allows significant control over the lighting.
• Cons: can look unnatural; the lighting might call undue attention to itself.
• General technique: underexpose ambient by 1 or 2 stops (or more), use a high shutter speed (if you want to minimize the ratio of ambient to flash, use sync speed), expose for flash as key.
• Examples: check out the photos from the flickr Strobist group that look surreal.

Mitigating ambient light.
Ambient light sometimes has unfavorable aspects, but instead of overpowering it, we mitigate the ambient’s unfavorable aspects. For example: midday sun causes harsh shadows on faces and contrast is too high. One way to mitigate such light is to fill in the shadows with a reflector or a flash.

• Pros: lighting looks natural.
• Cons: must give up some control of the light.
• General technique: meter for ambient as key, underexpose flash by 1 or 2 stops.
• Examples: check out Neil van Niekerk's excellent tutorial on flash techniques, particularly those where he talks about lifting shadows.

Enhancing ambient light.
Sometimes, the ambient light or the source of the ambient light has a significant role in the photo, but is unusable in its existing state. Artificial light is modified so that the light appears to come from the source of the ambient light. For example, a portrait lit by a single candle. In this approach, instead of just using a softbox to light the subject ‘properly,’ the color, direction, and if practical, the quality of the artificial light are modified to match those of the candle (e.g. a flash with a flame gel, reflected against a not-too-soft reflective umbrella positioned to give light from a similar direction from the candle).

• Pros: lighting looks natural, allows significant control over the lighting.
• Cons: requires more analysis and planning/preparation.
• General technique: analyze the ambient light’s color, direction, and quality. Modify the flash to have similar (not necessarily identical) color, direction and quality. If ambient has sufficient intensity, meter for ambient as key, underexpose flash by 1 or 2 stops. Otherwise, meter for flash, allow as much ambient as practical.
• Examples: check out Bob Krist's Secrets of Lighting on Location (an awesome book - I'll post a review soon).

Combining strategies
These techniques are not necessarily mutually exclusive and there is some overlap. But awareness of these general strategies gives me a starting point for figuring out whether to use artificial light, by how much, and what modifiers I might need.