Hi  @AnnieB 

Thank you for the feedback, for test purpose, you can put the C100 and C110 in the same place, and have similar light environment around the cameras. 

So far there isn't a contrast setting in the app, but you can try to adjust the angle of the camera to allow more light coming in the camera/ on the objects or add extra light in the night.If still the same, this can be due to the hardware factors with the camera,  you could consider purchasing another Tapo C100. Hope this helps.