First, I want to put out there that I really don't like selectively coloured photos. Way too cheesy for me. But this weekend I was doing a weird experiment which went wrong but turned out kind of cool.
I'd like to say here that there was no post-processing done to these photos other than adding sharpness to the RAW and a slight curve adjustment before exporting to JPEG. No saturation or colour adjustments at all.
I was trying to play with altering colour temperatures in camera alongside gelled flash to achieve crazy background colours while keeping portraits looking normal. Well, I over powered it a bit and realised I could blow the colour right out of the photos leaving them black & white! So I took a few documentary style shots like that and created a natural vignettes by zooming the flash.
Not something I would ever use professionally but a fun little accident none-the-less.