Some photographers cannot be bothered to learn about the good and bad sides of TTL and AUTO modes and go all old school on us and select the 100% manual approach to lighting and yet still nail exposure after exposure consistently. With manual, this is where the photographer disables all sets the flash to one unchanging setting,and therefore turns off all automatic range changing functionality and nearly all communication that is built into the camera and flash.
To do this. set both the camera and the flash to full manual modes. Next, choose an ISO, shutter speed and aperture of your choice based on what your needs are. Old school film photographers will be set to a shutter speed of 1/60th, ISO 200 or 400 and apertures between F/5.6 to F/8. In these scenarios, we are missing one more ingredient to the mix to get good exposures and that is a meter. This meter can be either the histogram of your camera or a flash meter (I own a Sekonic 358L as an example). So, we've set the camera to full manual settings of (for example), ISO 400. shutter speeds of 1/60th and an aperture of F/5.6... and then dial in our flash to 1/4 power, these settings will not vary no matter what we do... as long as we keep the same distance between our flash and subject! The end result is consistency, something that TTL modes lack.
The way that I like to work is preset the camera and flash settings, stand the subject about where I want them to be consistently and take a flash meter reading and then compensate with the flash power (either up or down) until the meter reads what I want it to read. If no flash meter is used, I use the histogram of the camera (we will leave how to read histograms for another article). Now, what if you just went from a 2 person shot to a 3-4 person shot?
This is where a good lens makes all the difference. A lens with a consistent aperture no matter what zoom you adjust to, is mandatory. If you have one of those lower end zoom lenses that is F/3.5 at the wide end and F/5.6 when zoomed in, your exposures will definitely change, not something that you want. As long as your distance is the same, the exposure is the same. So, what is a good trick to know when your distance is good? Well, one old trick is to set up the camera to 9 feet, test the settings and then set the focus to manual. Now, your camera will not be in focus until you are the proper distance from the subject and both exposure and focus are perfect. Modern dSLR cameras have a small dot or indicator in the viewer to let you know you are 100% in focus, and therefore, have a 100% perfect exposure as well.
Another little cheat to know your exact distance is to get yourself something like a lazer distance meter (Stanley makes something called a FAT MAX that is accurate to within a 1/8th of an inch) and you could just point it at your subject and immediately know if you are the right distance or not and make that small adjustment. Now be careful, do not point it anywhere near the head, these toys can damage the eyes very easily. Also avoid them in public, they could be mistaken for a rifle laser scope and you could be spending your next week in jail thanks to someone's misunderstanding.
The good points about manual modes are:
- Consistency. once you nail down that exposure it stays the same with each and every shot.
- It's simple.
- Works the same indoors or outdoors.
The bad points are:
- If you are not used to it, it is slow to setup and change exposure settings.
- Has to be verified with a flash meter or camera histogram
- bounced flash has to be re-checked a LOT and small changes can make big differences in the exposures.
Auto or automatic mode is something thats a little in between TTL and manual. Most of the time, this is when the photographer sets the camera to a totally manual setting (like for example ISO 200, shutter speed of 1/60th and an aperture of F/5.6 as an example), and the flash does all the work based on your metering mode, to try and set the best power setting to get a proper exposure. This is a really good system to have, unfortunately, many Canon systems do not have this mode. Nikon flashes, on the other hand, have not only an "A" mode for auto flash power adjustment, but an "AA" or Auto Aperture mode built-in as well. For our purposes, make sure you use the "A" mode, not the "AA" mode. To set your flash to the proper mode, please reference your flash's manual on how to choose the right setting.
Now, like any of the above options, there are limitations that should be considered. You will find out fast that there is a limited range where "A" mode works really well in, and and really poorly in, when the optimal distances are exceeded. Since it is the flash that that decides power output (and we know that battery powered speedlights, though awesome, do have a limited range), as you increase distances, power goes up and up until it gets to and past a certain distance, a flash will then consistently be pushed to full power.
Thats not good for a couple of reasons:
- batteries drain a LOT faster at full power.
- recycle times are much longer,
- if you are not careful and not give your flash a time to cool down in between pops, you can damage it severely.
One can increase this distance by increasing ISO, but don't raise it so high that all your shots are grainy. Also be aware that the higher the ISO setting is on any camera, there is a drop in dynamic range and detail.
So, how does one find that sweet-spot range that your flash loves to work in? By testing and experience, of course. A great test is to just lay down a couple strips of tape at 1 foot distances from your subject. Start at 5 feet and plop down strips to about 15 feet and take a picture once every foot and look at the results. You will find out quickly what distances your setup is optimal in and learn not to exceed these distances with a little practice. A more accurate way is to use a flash meter and you will find out fast at what point your flash can no longer put out enough light to give you proper exposures at the aperture you have set on your camera.
Now, let me clarify a little. I mentioned that we need to be in manual mode on the camera, and choose settings like ISO 200, shutter speeds of 1/60th and an aperture of F/5.6 as our chocies (in my example, your situation and settings can be totally different, of course). We have to make sure that the flash is in "A" mode, but more than that, we should have the matching ISO and aperture settings defined in our flash settings. That way the flash knows what we want it to read and it adjusts the power to accomodate our needs.
Once you've used the flash meter and recorded the results, you will likely see that up close the system overexposes a bit, then hits the sweet spot then starts to slowly drop off more and more as distances increase. For my D200 and SB-800, when I did my tests, I was within a tenth of a stop of perfect exposures at all distances between 6 to 10 feet. Any closer, it was a little too bright and any further than 10 feet, I started to move further and further away from that perfect exposure setting, reaching being off by a 1/2 stop at the 13 foot mark and almost 1.5 stops off by 15 feet. Of course, if I somehow memorize these stats, I will know that when I am close, I can use exposure compensation (ON THE FLASH NOT THE CAMERA!), and lower it when I am close, and raise it when I am far. How you choose to memorize things is up to you, but the best setup I once saw was a piece of masking tape on the head of the flash with this info written down on it, so every time the photographer raise the camera to his face, this info was right there.
Please understand that if you change things up by using a bounce card, by changing the settings or angles or any of these items that affect light quality and strength, you will have to do this test again, so that you know the ranges and sweet spots and where to lower and raise power to get those perfect exposures.
Auto Exposure good points:
- Is very consistent.
- Is very accurate in it's sweet spot range.
- Is very easy to test and set up.
The bad points are:
- The exposure system of the flash is not as accurate as the camera, so bright whites or blacks can affect the exposure.
- Back or front lit subjects will affect our exposure even more.
- Unfortunately, not all flashes have this Auto mode.
- In this case, setup does ideally require a flash meter.
- Requires frequent testing... a new room/location means a new test, just to be sure.
Next: Time to pull that flash OFF the camera!