robbins.photo
Senior Member
I've always been pretty happy with the 7100 even at higher ISO's:
ISO 4500:
797 by Todd Robbins, on Flickr
ISO 6400:
955 by Todd Robbins, on Flickr
ISO 4500:

ISO 6400:

I find iso2000 OK most of the time on my D7100, I have my auto iso set at 3200 max, some shots at 3200 are too noisy for my liking , but I do get some keepers.
This shot is at iso2000...minimal noise reduction in PP.
At the higher ISO's try increasing your EC to +1.0 or even a bit higher, then reduce the exposure in post prior to applying noise reduction. I've found it works rather well for higher ISO shooting.
I understand what you are saying but would it not be better to reduce the iso by a stop rather than upping the EC to +1.0 and presumably having to slow the shutter speed down. I'm usually at high iso because I can't decrease the shutter speed or open the aperture up any further.
I don't like to go above iso 1600 with my D7100 but good results are possible beyond that. I think because I'm mostly shooting birds, having to crop makes any noise look worse and I don't want to lose too much feather detail.
I'll try and do some birds in flight tomorrow with high ISO and post the results.
I am pleasantly surprised at how good the IQ is at high ISO on the D7100 - I was originally very sceptical.