Adjusting FEC vs adjusting Flash power manually

I trigger my of camera flash via 7D pop up flash. Most of the time I need to do FEC+1 to get the correct exposure for the model.
If I use Cactus V5 and adjust the power manually at the back of the flash, will I get the same result? Assuming same shutter speed and Aperture

You will get more consistent results since you'll be setting the flash power manually. FEC is used for off camera flash with ETTL, so your flash is determining how much power to use and then compensating over or under based on your FEC setting. So if a moth flies in between your model and the flash it might give you an incorrect exposure, whereas setting the flash manually will give you the same exposure every time, all things being consistent (camera settings, model distance from flash, etc, etc)

FEC is like EC is for ambient exposure...it tells the flash meter that the subject is brighter/darker than the meter usually expects, so it needs to give more/less output than it would without FEC. Metering is Automatic and makes life less complex for the photographer, although some of the control is given up in the process.

Manual flash power gives total control to the photographer, but with that control comes the burden of always keeping track of how far your subject is, and as subject distance (from flash) changes, it is necessry to adjust aperture selection on the camera. Moving from 8' to 11' from subject, you have to open up +1EV on the aperture, for example. Zoom heads make that even more difficult because not only does the Guide Number change with power (1/1. 1/2. 1/4, etc.) but it also changes with FL coverage (50mm has GN130 at 1/1, GN65 at 1/4; 105mm has GN190 for FF coverage at 1/1, GN95 at 1/4)

Thanks for the responses. I only use my flash off camera with a softbox so its always zoom to 24mm.
I use Av mode when shooting outdoor and TV mode when shooting indoor to kill the ambient lights at 1/250, all in ETTL. Is there other steps I need to do other than changing the power if I switch to manual?

ching wrote in post #12345343
Thanks for the responses. I only use my flash off camera with a softbox so its always zoom to 24mm.
I use Av mode when shooting outdoor and TV mode when shooting indoor to kill the ambient lights at 1/250, all in ETTL. Is there other steps I need to do other than changing the power if I switch to manual?

A speedlight in a softbox is essentially fixed coverage angle, manual power setting.

So you need to simply alter exposure based upon distance from softbox to subject, and if that is not changing during the shoot, you need do nothing more than initial exposure setting...until you alter power level, or until you alter distance