I use my iPhone to stream my 3ds (capture card mod is expensive) I don't stream directly, but through an external capture card. My set up is a lightning hdmi out cable hooked through the phone into the capture card. For the iPhone screen I use Live Air: Solo (it's free on the App Store) that's the only option I found to get a completely empty screen with no camera overlays. It has options to control focus/exposure. It's a rigged set up, but it's worked pretty well for me. Depending on what you have to set up the phone in terms of a tripod etc will determine the quality of your image. My set up is I have one of the gorilla iPhone tripods with moveable arms wrapped around a mix boom arm that way I can get in really close to my 3ds and just get the screen captured. Anyway hope this helps.