Metering ambient and flash advice needed

StepheKoontz said:

"I have a leaf shutter lens so no sync problems. The meter I have is a Sekonic Flashmate L-308S and will be using HP5 rated at ISO 200."

And again, what you are doing will work, but it's a really hard way of doing it when there is a much more simple way. It's especially hard if you have multiple manual flash heads setup, have already balanced them between each other and just want a bit more ambient. It's like trying to drive a stick shift car using your left foot for the brake and the clutch. If we are talking using a digital camera using something like nikon's iTTL system, that's a whole different discussion, but we aren't.

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This shot was taken in full afternoon sun with Tri-x rates at 250, Mamiya RB 67 ProSD The back wall was two stops under ambient, so I had that as an advantage starting out. The concrete was full sun, so I knew that I had to have enough flash power to over power the sun putting me at a shutter speed of 1/250 or 1/400 to make the numbers work. I know that for my go to lens, a 90 mm that my far focus at 6 feet is around 8 feet helping me to lose focus at the wall. My flash, a Nikon sb 800 and a Nikon sb 910 through my magbox just barely gives me enough flash to overpower the sun so that I can use flash for the contrast on the subject. Being that the wall was in shade due to the sun being overhead I didn’t need to worry about ambient in the background.

That was shot Ilford Panf 50 rated at 50. Same camera and flash setup, in full afternoon sun on the models. I wanted the light values to fall off down the wall to the right and I wanted the texture of the wall to be in focus. At f16 and 10 feet from subject I know I’ve got enough depth of field and enough room to control ambient at f16 down the wall by controlling flash power and higher shutter speeds to out power sun and have ambient controlled by down the wall at a f16 or more.

My point is with modern strobes and modifiers you can factor aperture in ambient, you can factor shutter speed in ambient to get the image you want. You’re not limited to one or the other.

My partner with the lighting setup we used.
No flash, natural light late afternoon with Tri-x rated at 250.

Chan Tran said:

Most modern flash meters do combine both ambient and flash reading in one reading. Some even display the percentage of flash to ambient light contribution.

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Some apparently did not understand what I stated earlier. Let me try again...There ARE essentially two scenes captured in one photo,

1. when the indoor shot 'main portrait scene' has a different lighting and resultant exposure than
2. the outdoor portion (as seen thru the window) of the shot, which could be lit by sunlight/cloudy sky and therefore has its own exposure combination which renders that 'other scene'

If I put my meter into reflective mode and aim its lens thru the window to the outside scenery, it might record ISO 100 1/100 f/16 (sun) or f/5.6 (cloudy)
If I then put my meter into incident mode, stand at subject position and aim its hemisphere at camera position, depending upon the ISO and selected shutter speed, it will record either

• flash only, when shutter speed is too high/ISO is too low
• flash illumination with window illumination contribution (not the scene observed at camera position, but the second window which lets outside light into the studio), when shutter speed is slow enough/ISO speed is fast enough; in both cases, the meter makes ONE reading that factors in the two sources of light accordingly

The problem with this particular scenario and finding a solution to the given scenario is assuming that there is a perfect solution. Unless the room dimensions, color or reflectivity of the walls, ambient brightness through the window, and film speed are ideal, there is not a solution, there are compromises and sacrifices to make based on the given conditions.

This is a one light setup using a directional modifier, the soft box which reduces light spill as opposed to an umbrella. It would be great if the soft box had a grid. Position the soft box 45 degrees above and 45 degrees off axis from the subject. Meter ambient outside the window, decide if you want the window scene in focus or out, decide on an aperture accordingly. If things outside are f16 at 1/250, then meter the subject and adjust flash output accordingly to achieve f16 at 1/250. Also meter behind the subject at the wall just so you know how much light falloff you have. It’s just nice to know what to expect in the final image. Personally I would want to create separation of the subject from the background. If the background is not intended to be in focus but at equal light value I’d adjust aperture. If the background is to be in focus, which I doubt you’ll be able to achieve given your subject to camera distance unless you are in a very large room with a long focal length lens (105mm to 210mm in 35 mm format) I’d either increase background exposure one stop or decrease background exposure one stop in order to separate the subject from the background. Given other variables including camera format I may do that using aperture or shutter speed. Ask the subject to point there nose at the light, lean forward slightly, push there head up from the shoulders, breath out through the mouth to relax the lips and fire the shutter. Given ideal conditions.

wiltw said:

Some apparently did not understand what I stated earlier. Let me try again...There ARE essentially two scenes captured in one photo,

1. when the indoor shot 'main portrait scene' has a different lighting and resultant exposure than
2. the outdoor portion (as seen thru the window) of the shot, which could be lit by sunlight/cloudy sky and therefore has its own exposure combination which renders that 'other scene'

If I put my meter into reflective mode and aim its lens thru the window to the outside scenery, it might record ISO 100 1/100 f/16 (sun) or f/5.6 (cloudy)
If I then put my meter into incident mode, stand at subject position and aim its hemisphere at camera position, depending upon the ISO and selected shutter speed, it will record either

• flash only, when shutter speed is too high/ISO is too low
• flash illumination with window illumination contribution (not the scene observed at camera position, but the second window which lets outside light into the studio), when shutter speed is slow enough/ISO speed is fast enough; in both cases, the meter makes ONE reading that factors in the two sources of light accordingly

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I only answer John statement saying that flash meter can't measure both ambient and flash at the same time and that is why there is the shutter speed setting on these meters. But of course in the OP case it's 2 different scenes and the light from one scene doesn't contribute to the others like in the case of fill flash. So my initial answer to the OP is what I stand by.