Methods of Testing Equipment- 2 

by William Lulow

The best way to achieve consistency of results in your images is to make sure that all your equipment is functioning optimally. I usually perform regular tests to keep everything working as it should. One such test is one I perform with my portable flash units.

I use my portable lights quite a bit these days. I use a Canon 430EX on my camera and two Sunpak 120J units as extras. First, I start with the unit on my camera. I make sure that the batteries are fully charged, then I set my shutter speed to 1/125 (since I have determined that I can hand hold my camera, with the flash on it, successfully at that speed) with a diffusion dome on the top and aim the flash one click down from vertical.  I usually use the flash in this position with the flash powered to ½ power, because I bounce the flash off the ceiling and I like the results. I make a series of exposures going through the various f/stops. (Main ones: f/2.8, f/4, f/5.6, f/8, f/11 and f/16). These are the ones that provide a 1stop difference between each one. I look at the images to get a rough idea if each looks approximately one stop different from the other. Without getting into the science of histograms, you should be able to discern the difference in exposures and they should be getting darker by a stop as you stop the lens down to f/16.  Settings on DSLR’s these days can probably provide smaller increments between f/stops, but to the untrained eye, it’s really hard to tell the difference between f/8 and f/9.  This kind of test should let you know if your flash is putting out consistent light. I run through the same test with all the units I use. When I am satisfied that each unit is putting out consistent light, I’m ready to do some test shots that try to simulate conditions under which I normally shoot. I make a series of exposures of things or people in a room with a white ceiling and basic white walls. I use the same f/stop, same shutter speed (1/125 second) and same power setting on the flash. All the images should have a consistent exposure. If one image looks darker or lighter, then it is most likely do to the flash unit itself. If you make some exposures in a room with a higher ceiling, the image should look a bit darker. You then know that you need to increase the flash’s power setting or f/stop to allow for the greater distance the light has to travel.

 

There are many caveats to using flash (especially one attached to the camera) but the most important rule to keep in mind is that exposure is created by the distance from the light to the subject, its intensity and of course, the lens aperture. Since speedlights are usually set to give a consistent speed of approximately 1/400th of a second, shutter speed doesn’t really play a part in determining exposure unless you want to increase the effect of ambient light. (Much more about this in a subsequent article).  The greater distance the light has to travel, the more exposure you need to compensate.

 

So, by now, you have a pretty good idea of how your speedlights are performing and whether they are adequate for the subjects you normally shoot. You can always increase the power of the unit if you need more light. You can most always DECREASE the flash-to-subject distance if you need more light and you can DECREASE the shutter speed if you want more ambient light to influence the exposure.

 

I realize that these “tests” are not exact, but they should let you know if your units are functioning properly and whether or not you need to change exposures for most of your shooting situations.

Methods of Testing Equipment

by William Lulow

The best way to achieve consistency of results in your images is to make sure that all your equipment is functioning optimally. I usually perform regular tests to keep everything working as it should. One such test is one I perform with my portable flash units.

 

I use my portable lights quite a bit these days. I use a Canon 430EX on my camera and two Sunpak 120J units as extras. First, I start with the unit on my camera. I make sure that the batteries are fully charged, then I set my shutter speed to 1/125 (since I have determined that I can hand hold my camera, with the flash on it, successfully at that speed) with a diffusion dome on the top and aim the flash one click down from vertical.  I usually use the flash in this position with the flash powered to ½ power, because I bounce the flash off the ceiling and I like the results. I make a series of exposures going through the various f/stops. (Main ones: f/2.8, f/4, f/5.6, f/8, f/11 and f/16). These are the ones that provide a 1stop difference between each one. I look at the images to get a rough idea if each looks approximately one stop different from the other. Without getting into the science of histograms, you should be able to discern the difference in exposures and they should be getting darker by a stop as you stop the lens down to f/16.  Settings on DSLR’s these days can probably provide smaller increments between f/stops, but to the untrained eye, it’s really hard to tell the difference between f/8 and f/9.  This kind of test should let you know if your flash is putting out consistent light. I run through the same test with all the units I use. When I am satisfied that each unit is putting out consistent light, I’m ready to do some test shots that try to simulate conditions under which I normally shoot. I make a series of exposures of things or people in a room with a white ceiling and basic white walls. I use the same f/stop, same shutter speed (1/125 second) and same power setting on the flash. All the images should have a consistent exposure. If one image looks darker or lighter, then it is most likely do to the flash unit itself. If you make some exposures in a room with a higher ceiling, the image should look a bit darker. You then know that you need to increase the flash’s power setting or f/stop to allow for the greater distance the light has to travel.

 

There are many caveats to using flash (especially one attached to the camera) but the most important rule to keep in mind is that exposure is created by the distance from the light to the subject, its intensity and of course, the lens aperture. Since speedlights are usually set to give a consistent speed of approximately 1/400th of a second, shutter speed doesn’t really play a part in determining exposure unless you want to increase the effect of ambient light. (Much more about this in a subsequent article).  The greater distance the light has to travel, the more exposure you need to compensate.

 

So, by now, you have a pretty good idea of how your speedlights are performing and whether they are adequate for the subjects you normally shoot. You can always increase the power of the unit if you need more light. You can most always DECREASE the flash-to-subject distance if you need more light and you can DECREASE the shutter speed if you want more ambient light to influence the exposure.

 

I realize that these “tests” are not exact, but they should let you know if your units are functioning properly and whether or not you need to change exposures for most of your shooting situations.