When Speedliting, it always gets down to flash power – how much power and how it is set. You can dial the power level in manually. Or you can have your camera and Speedlite work together to calculate the power level automatically via E-TTL. Both modes have their strengths. Both modes have their shortcomings. One is not always better than the other. I routinely switch between E-TTL and Manual — depending upon the situation of the shoot.
A lot of photographers don’t understand the difference between E-TTL and Manual mode. Further, a lot of photographers always use one mode and never explore the other — often because someone else told them to do it that way. A photographer who always uses one mode and never the other is like the carpenter who says, “I don’t need a hammer, I have a big wrench.”
[P.S. If you shoot Nikon rather than Canon, all of the following applies to you as well. Just think “i-TTL” every time you read “E-TTL.”]
My Basic Guideline For Deciding Between Manual and E-TTL
When deciding between Manual and E-TTL, I think about the situation in which I’m shooting. In broad strokes, if the distance between the subject and the Speedlite(s) is fixed, then I will work in Manual. If the distance to or position of the subject is dynamic, then I will work in E-TTL.
Why does the distance between the subject and the Speedlites matter? It matters because the Inverse Square Law is always lurking out there somewhere. You already know this simple truth — the closer your light is to the subject, the brighter it appears. If your flash is 3′ from the subject, it appears brighter than if it is 12′ from your subject. Put another way, a Speedlite that is 12′ from the subject needs to fire at a higher power level than one that is 3′ away.
So, if you are shooting in a controlled situation, where the distance between the subject and the flash is fixed, then Manual mode is great. I use Manual for tabletop work (food, still-life, and product). This type of work requires precision and repeatability. Manual gives me the ability to fix the power level so that it does not vary from shot to shot. This is very helpful when you are doing repetitious product photography.
Use Manual: When Learning The Basics Of Flash Photography
I think Manual mode is the best way to learn the basics of flash photography. You make a decision, you take the shot, you see the results. When it does not work the way you expected, you repeat the process and learn a bit more.
When you are starting out with flash photography, the problem with E-TTL is that you have no idea what power level was used for a shot. You can’t read it on the Speedlite’s LCD. You can’t find it later in the shot’s metadata. E-TTL is an automatic flash mode (which I’ll describe in detail in Part 2). If there is too much or too little light, you won’t necessarily know why.
Use Manual: When The Subject Will Pass Through A Preset Zone
Manual is perfect for situations when a moving subject will pass through a preset zone. For instance, at a wedding, you know that the bride and groom will come down the aisle after the ceremony, so you can preset your lights in Manual mode before the ceremony starts. The dramatic contrast of the bride’s white gown and the groom’s dark suit is better handled in Manual than E-TTL.
Any sport with a net can be another situation where you will know that the subject is going to pass through a preset zone. The net in a basketball game provides the opportunity to preset your flash and adjust the power before the game starts. For instance, climb a ladder at home or climb on the roof and shoot junior practicing his slam dunks. (Just be careful when you do…it’s not the fall that breaks gear; it’s the sudden stop at the end.)
Sports that involve jumping are also good situations for Manual flash. Motocross and BMX racing always have track obstacles that will send the rider into the air. Hurdlers at a track meet provide the opportunity to know where a fast-moving subject is likely to pass. Of course, for safety reasons, it is essential that the event organizer and participants have preapproved your flash work.
Use Manual: To Maximize Your Speedlite’s Power
This is an esoteric point — another consideration in deciding between Manual and E-TTL comes up when you need to get either the absolute maximum or minimum power from your Speedlite.
When you need to squeeze every very bit of power from your Speedlite, switch it to Manual mode and set it to 1/1. In E-TTL, the Speedlite uses a bit of its power for the pre-flash. By switching to Manual, you eliminate the pre-flash and send all the juice straight out in one big burst.
Conversely, if you are shooting in Manual at the lowest power setting and still have too much light, switch over to E-TTL. The pre-flash will suck up a bit of power and thereby reduce the intensity of the flash. The change will be small, but it might be just enough.
Use Manual: To Trigger Off-Camera Flash With Optical Slaves
For all the details on how to use optical slaves with Canon Speedlites, click here. The short version is that the E-TTL pre-flash tricks optical slaves into firing pre-maturely. Manual does not have a pre-flash. So it is the way to go with optical slaves.
Coming soon: Deciding Between E-TTL and Manual – Part 2: E-TTL Flash.
Portions of this article excerpted from my to-be-published ‘Speedliter’s Handbook‘, coming December, 2010.
For a calendar of my seminars and workshops on Speedliting, click here.