Is it possible to have light meter solve for ISO? Sekonic L-358

I am trying to take shallow depth-of-field studio portraits with flash, with required settings 1/200 and f/2.8 for example. Both of these settings have to stay this way, so I am wondering if theres a way I can have my light meter tell me what the ISO should be or even what the flash power should be?

Im sure this is a complicated question, thanks for help.

Set your ISO at 100 and shutter at 1/200 on the light meter, and adjust the lights until you get F 2.8. I would imagine that the power on the flashes will be very minimal.

The quick and easy way to do this without a hand held meter is to use the histogram on your camera. First, set your lights. Set their power to 1/4 (or 1/8 or 1/16...it really doesn't matter). Then have your subject hold up a white card, facing the camera. Set your ISO to 100 and shoot a test shot. If the white card doesn't blow out and is quite underexposed you have two choices; you can up the power of your lights or increase your ISO (assuming that you don't want to change your aperture).

Once you've increased either or both, keep shooting a test shot until the white card just starts to blow out. Congratulations. You now have a setting that will give you excellent results.

Try some iPhone apps. I have one called simply 'light meter'. I just ran through your scenario in about 5 seconds. I brought up the Time value (1/200) as a constant and then spun the ISO wheel till your desired F/stop of 2.8 came up. Voila. Shutter, F/stop and ISO.

moodlover wrote in post #17427956
I am trying to take shallow depth-of-field studio portraits with flash, with required settings 1/200 and f/2.8 for example. Both of these settings have to stay this way, so I am wondering if theres a way I can have my light meter tell me what the ISO should be or even what the flash power should be?

Im sure this is a complicated question, thanks for help.

It appears to me that you don't understand electronic flash exposure control.

If flash lighting is significantly overpowering ambient (constant source) lighting, the shutter speed is essentially not a factor in controlling the exposure. That's because the time of the flash burst is MUCH shorter than any shutter speed at or slower than the "max sync speed". Thus, the three variables in flash-only lighting exposure calculations include the power of the flash unit, aperture, and ISO.

Since you have a light meter, based on Skip's review, here is one approach.
It's kind of like Jim Coleman's suggestion but using the light meter rather than the camera LCD.

Set up lights, Place white card or model in shooting position.

Set lights to middle of their power range. i.e. if they go down to 1/32 power which is 5 EV put them down 3EV or 1/8 power.

Set ISO on meter to at least 3 EV above minimum on camera, and take a reading. Let's say reading on meter is F8.

You want F2.8 which is 3EV more open. You now have choices; reduce power on Lights 3EV, or reduce ISO setting on camera 3EV (the one I'd choose.)

moodlover wrote in post #17427956
I am trying to take shallow depth-of-field studio portraits with flash, with required settings 1/200 and f/2.8 for example. Both of these settings have to stay this way, so I am wondering if theres a way I can have my light meter tell me what the ISO should be or even what the flash power should be? .

Are we to assume you are using ETTL flash, or are we to assume you are using non-ETTL studio lighting units?