Hello!
For many years I have tried to take pictures in low light with my D7100 with no success. Noise and movement unsharpness is only what I get, even if I chose a high ISO, such as 5000 or more. Is it impossible to freeze pictures on moving people or cars in low light without flash with this model? I want to take sport with good results.
Isn't this a simple matter of having overly optimistic expectations?
Momentarily disregarding the high ISO capacities of the D7100 (I have one myself and have at occasions used it at ISO 6400) just look at the shutter speeds needed to 'freeze' moving people (I do so regularly shooting catwalk) or fast moving objects (in the past for a while specialized in shooting surf photography)
While when shooting a moderately fast moving/striding model during a catwalk show I may be able to get away going as low as 1/200th, even under good light, for capturing a fast moving car (or surfer in the enclosed picture) I need to go at least as fast as 1/1000
Those minimum speeds remain valid no matter whether there is enough/plenty of light or whether you're shooting in the near dark
I admittedly have never ventured seriously into 'night' photography
But from the rare occasions I did some experimenting with astro photography (actually it was at the occasion of a 'supermoon') I found that even at ISO6400 using a shutterspeed of 1/200th, let alone 1/1000 even with a f1.4 lens (the fastest lens I got, the OP unfortunately fails to mention how fast the lens is he uses) is impossible but for the well exposed parts of the image like the (in my case) moon or eg streetlights
If I would also want to get properly exposed shadow, going (much) slower (in particular when not using a fast ens, or stopping the lens down a few stops) is inevitable, as illustrated by the exif details in the images in other reactions posted
As far as the 'noise' is concerned, in my experience even the most recent DX cameras in that respect do not perform as well as their full frame counterparts
While I find the noise at ISO 6400 with my D3 and D800 more then acceptable (with my DF I can go even higher up to ISO 12800), on my D7100 I if possible prefer not to go over ISO3200, although under reasonable lighting I can get away with ISO 6400 (on condition I don't extremely under expose and don't crop too much)
While I don't own a D7200 or D500, I have at occasion downloaded high ISO NEF's of those camera's to play around with (I was very much interested in getting a D500 for shooting catwalk because of the much improved AF and DX factor, making my 2.8/70-200 a virtual 105-300mm)
While they do perform much better then my D7100, I think that at over IS0 3200 my 'workhorse' FX D3 and D800 (let alone DF) still give a superior IQ despite their age
In short, sorry IMO a D7100 (and again, I have one and am quite satisfied with it within its limitations) doesn't cut it for low light condition photography of (fast) moving subjects like cars or sports