I'd take a different approach. This photos are likely not for blowing up but simply watching the progress. Basically saying don't worry about the ISO. Go manual shutter 1/125 maybe 1/250 to catch the little movement of the workers(assuming you want them in focus) set aperture 5.6 maybe 8 and set AUTO ISO. Let the camera pick the ISO and you simply take the shots and not have to play with dials. An ISO of 1000 or even 2000 is not terrible. Sometimes I think people go a bit nuts over minimal ISP when modern sensors handle it very well.
I'd take a different approach. This photos are lik... (show quote)
Only addition I would make is if you don't have a 14 - 50mm 2.8 or something close sometimes avalable light, does wonders for presentation.