I've always been a firm believer in that natural light and available light is better and all I need, but slowly, very very slowly, I'm starting to realise the need for a flash does indeed exist.
There are always workarounds and ways to do things differently, but if you are shooting as a profession and for different types of clients, you most probably do not have the luxury to command that there is beautiful natural light available at set time in the set place. Especially if it's winter time and one lives above 60° Northern latitude...
For moody portraits and conveying emotions, for sure natural light, when it's available, is superior if you have the luxury to shoot how ever you want with it. Of course even though I haven't really used flash more than a few times, I have used hot lights and your average ceiling or table lamps just like one would use flash, but with less control. In theory I should be able to work how to make dramatic portraits with flash too, but somehow I'm quite scared of it. I know one of my favourite photographers ever, Peter Lindbergh, used flash (and continuous video lights) to make amazing images, so the unnatural lights can not be the devil.
Something I really struggle with is making portraits that are not moody, especially when there really is not much natural light to work with. If I want to make a living, for real, with photography in a small city, I need to be able to produce decent, bright and evenly lit portraits. Are they sexy? No. Are they exciting to shoot/look at? No. Do people need them? Yes. Do they pay money for those? Yes.
I think technically these would be what one calls corporate portraits. Nothing exciting, but they serve a purpose and need to be done very efficiently.
This week I loaned a flash and a small softbox from school for one afternoon so I could try to make some portraits with using the flash as an addition to natural light. Our school studio doesn't have windows so I could do this there. I first tried what I could get with using just natural light, without opening up the aperture all the way, and without going over ISO 250, and obviously keeping the shutter speed at a level that doesn't cause blur when the subject moves a bit. I could definitely work with this light, for my own use, but for something like a beauty salon with everything on their website looking bright and calm, would not go over well.
I kept the same settings and added the softbox pretty much above my camera, right next to the window so the light would come from the same direction, just filling in the shadow side more, and also spilling onto the background that was too dark. I think I did fairly well with this, if we don't look at the messy background, I couldn't be bothered to move my plants. I did cheat a bit by using the TTL mode on the flash, and since it did calculate the amount of power needed pretty well on its own, I didn't feel like I needed to go full manual.
I can definitely see the benefits of a flash when you have very limited light, it also keeps everything even if you shoot multiple people in a row, and you also don't have to use much time with retouching. But then again, you have to lug around a shit ton of gear, set it all up accordingly and if you move around, you have to set everything up again.
I'm always eager to learn and get better at my chosen craft, and I really want to be able to make good pictures with using a flash too, natural light I can handle, we real good pals. Just keep learning just keep learning.