For lots of years during the film era, I shot with manual cameras, usually the Nikon FM2.
With no automation, I learned a lot of subtle tricks through trial and error, including one that has since been aided by the addition of a feature called slow-sync flash. I can still remember coming back from a nighttime car crash on Fort Sill Boulevard in Lawton, Oklahoma, where I was interning at the newspaper when I was 18. I got my film souped, but struggled to get a decent print, since I had blasted away with direct flash.
Photographer Jeff Dixon (who is still there by the way) told me that if I shot at a shutter speed of a quarter or a half a second instead of the 1/250th maximum sync speed, my backgrounds would have a lot more depth. While true, what he didn’t explain was that those same backgrounds would also probably be blurry compared to the part of the photo that was illuminated by the flash. And so the struggle began: testing, trying, failing, tweaking. In the end, I settled on about a 15th of a second, usually with an 800-speed film. On the night the feed mill burned here in Ada in 2000, those were my settings, and it all looked pretty good.
With growing sophistication in film cameras being carried over to digital, a blessed feature is now present in most of our cameras: slow sync. Basically, the camera mixes the output of your flash with the existing light, just like I did in my head for all those many years. It has the same benefits and the same pitfalls, but works even better now. For one thing, you can crank your ISO to 3200 if need be, making the chance of a blurry, ghostly background less. I use it sparingly, but it is irreplaceable when I need it.