I give you an example . 1000 iso on DX give you a quantity of noise 1000 iso on FX give you a quantity of noise which is roughtly twice cleaner than the DX bobyso we can say that if we shoot at 450 iso on DX we get the same image amount of noise as if we shoot at 1000 iso in FXPS i just speak in image quality result . if i have a FX and i shot at 300 mmF 4 at 2200 iso , I will have the same image in term of noise deaph of field angle of view if I shoot with a DX at 200 mmto match the angle of viewF 2 , 8 to match depth of fields and iso 1000 too match amoung of noise . to simplify this relation , we can reduice to the fstop only . pratice there is a bird setting for FX are 300 mm f 4 iso 2200 11000 same image with a DX 200 F 2 , 8 iso 1000 11000 unity for camera are really bad , cause they always relied on sensor sizeISO , aperture , focal depend of the crop factor to get the noise quantity , angle of view and depth of fieldsand we often see sellers convert the focal to match the angle of view but they never convert aperture cause it ' s not very appealing to say that your 1 , 8 smarphone is in fact something like a F 10 equivalent we can simply say that when you pass a lens from FX to DX , you loose a FSTOP but win 1 , 5 reachso in the case of going DX to FX , you will win a fSTOP and loose 1 , 5 time the reachhere is a videoDtDotqLx 6 nA