E.L.. Shapiro wrote:
Think of it this way- When you meter is set for electronic flash readings it automatically assumes that the FLASH is the principle and only light source and except for synchronization limitations, the shutter speed, as far as the meter is concerned, is the flash duration- whatever it might be. It "thinks" the camera shutter speed is irrelevant. The only time the actual camera shutter speed impacts the exposure is if you drag the shutter (use a slow enough shutter speed) to admit some or all of the ambient light.
So, if you want to select an aperture for selective focus (minimal depth of field) or to incorporate more depth of field in any particular shot when the flash is you among light source is to either adjust the flash output up or down to accommodate your requirements or adjust the IOS setting.
For this reason, when I recommend flash equipment for studio use, especially portraiture, I usually opt for units that have a very vast and adjustable power range. If you should want to provide selective focus, bokeh, etc., it is just as important to be able to power down your flash system to enable wider apertures as it is to boost the power when more depth of field is needed. The same goes for being able to establish a wide variety of lighting ratios in multiple flash setups or daylight to flash fill ratios when working with flash out of doors.
I use several meters, most of which are older models. Perhaps some of the newer issues can calculate both daylight and flash simultaneously or somehow correlate the separate readings and therefore enable an aperture priority function? I just take separate readings and do my own calculations.
My main point is that when the flash is the principle, dominant, or sole light source the sensor only "sees" the flash at its duration and reads accordingly and only supplies an aperture setting for the power output (quantity of light), at the distance between the flash unit and the subject (or the metering sensor in an incident light reading) as per the ISO setting. Your variation controls are distance, power output settings, attenuating the light with diffusion material, using neutral density filters on the camera, or the lights or employing bounce techniques or utilizing light modifiers. The camera shutter speed kicks into the equation when you eliminate or admit ambient light.
In certain thyristor and TTL controlled flash systems, the flash duration can be anything for 1/300sec to 1/10,000 sec or less but the meter doesn't care, it is just interesting in light quality.
The exception to the rules is in some High-Speed (HSS) Flash systems that are designed to synchronize flash with focal-plane shutter beyond their usual maximum synch speed, the actual camera shutter speed will influence exposure. In this case, the flash tube glows much like a continuous light source.
Think of it this way- When you meter is set for el... (
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Yes I have experience the shutter appearing in the image when I set the shutter speed too fast.
I am thinking I may need to employ filters to get the effect I want when I cannot adjust down in low light circumstances like when I am shooting with a black background for example.
My flash duration on the D1 AIR 500 is 1/1000 sec at lowest setting and faster at the highest. The other two strobes are Profoto Compact 600's (I bought all in like new condition and for a song ) and they are not as fast, 1/850 sec. I understand now that I am limited to just adjusting the light source, ISO and too a lesser degree the shutter speed to control DOF. My camera trigger is not a problem, it's capable of wire like speeds at 1/2500 sec.
Studio photography is a lot of fun but certainly a steep learning curve and very expensive as a hobby.