Reading the recent thread on Sony's answer (actually non-answer) to flash compatibility questions, and some posts there noting that some, but not all people have experienced flash exposure issues (but without stating how they use their flash), and knowing my own experiences, I thought it might be interesting to do a little survey.
Basically, here are the questions:
Have you experienced flash exposure inconsistencies with a 7D/5D and an external flash?
If so, what are the general conditions (e.g., distance to subject, maximum aperture of lens(es) used, focal length of lens(es), indoor or outdoor, camera mode - e.g., P, A, S or M, other that you think relevant)?
Was your camera/flash re-calibrated by KM?
If you are experiencing inconsistencies, is it with straight ahead direct flash or with some kind of light modification (including bounce flash or attachments to the flash head such as diffusers, bouncers, etc.)?
What is the tonality of your subjects where you experience the problem (e.g., light, middle or dark toned)?
I ask these questions because in my experience they generally relate to the situations that can give rise to problems that most people are experiencing.
My own experiences, with a recalibrated camera/flash, are that the primary exposure inconsistencies occur in two situations (the operating mode of the camera - P, A, S or M - does not matter):
(1) With dark toned subjects (like a groom and groomsmen at a wedding all wearing black suits), which usually can be corrected by dialing in minus flash exposure compensation. This is basically like normal exposure, where the camera sees a dark toned subject and adds more light to make it a neutral middle tone. Thus, to retain the dark tonality, some amount of underexposure compensation is needed.
(2) With light modifiers and/or bounce flash, when the pre-flash is weakened to the point the camera can't read it and therefore puts out a full power burst resulting in overexposure. Dialing in minus flash exposure compensation cannot correct this because the camera is unable to use the pre-flash for a correct flash meter reading. One solution is to stop the lens down further until you get a "correct" flash exposure with the full power burst. But this is trial and error. One partial solution I have found that maintains flash metering is to put the flash head zoom in the manual mode and at a longer focal length (e.g., 50-85mm). This will effectively strengthen the pre-flash increasing the chance that the camera will be able to "read it," while using the flash bounced or with the light modifier provides full flash coverage of your scene even shooting with wide angle lenses (the 1.5x crop factor also probably helps in this regard). A second partial solution is to use a lens with a faster maximum aperture (if you have one). The wider maximum aperture allows more light into the camera including, presumably, the pre-flash. At a recent wedding, while having some problems with a bounced 5600HS flash and 24-85/3.5-4.5 lens, I obtained better results when I switched to my 28-75/2.8 lens (I was using the 24-85 for the great focal length range). These partial solutions will not always work, but will increase the success rate.
--
Mark Van Bergh
Basically, here are the questions:
Have you experienced flash exposure inconsistencies with a 7D/5D and an external flash?
If so, what are the general conditions (e.g., distance to subject, maximum aperture of lens(es) used, focal length of lens(es), indoor or outdoor, camera mode - e.g., P, A, S or M, other that you think relevant)?
Was your camera/flash re-calibrated by KM?
If you are experiencing inconsistencies, is it with straight ahead direct flash or with some kind of light modification (including bounce flash or attachments to the flash head such as diffusers, bouncers, etc.)?
What is the tonality of your subjects where you experience the problem (e.g., light, middle or dark toned)?
I ask these questions because in my experience they generally relate to the situations that can give rise to problems that most people are experiencing.
My own experiences, with a recalibrated camera/flash, are that the primary exposure inconsistencies occur in two situations (the operating mode of the camera - P, A, S or M - does not matter):
(1) With dark toned subjects (like a groom and groomsmen at a wedding all wearing black suits), which usually can be corrected by dialing in minus flash exposure compensation. This is basically like normal exposure, where the camera sees a dark toned subject and adds more light to make it a neutral middle tone. Thus, to retain the dark tonality, some amount of underexposure compensation is needed.
(2) With light modifiers and/or bounce flash, when the pre-flash is weakened to the point the camera can't read it and therefore puts out a full power burst resulting in overexposure. Dialing in minus flash exposure compensation cannot correct this because the camera is unable to use the pre-flash for a correct flash meter reading. One solution is to stop the lens down further until you get a "correct" flash exposure with the full power burst. But this is trial and error. One partial solution I have found that maintains flash metering is to put the flash head zoom in the manual mode and at a longer focal length (e.g., 50-85mm). This will effectively strengthen the pre-flash increasing the chance that the camera will be able to "read it," while using the flash bounced or with the light modifier provides full flash coverage of your scene even shooting with wide angle lenses (the 1.5x crop factor also probably helps in this regard). A second partial solution is to use a lens with a faster maximum aperture (if you have one). The wider maximum aperture allows more light into the camera including, presumably, the pre-flash. At a recent wedding, while having some problems with a bounced 5600HS flash and 24-85/3.5-4.5 lens, I obtained better results when I switched to my 28-75/2.8 lens (I was using the 24-85 for the great focal length range). These partial solutions will not always work, but will increase the success rate.
--
Mark Van Bergh
