But does this already exist ?

I recently picked up a DSR 500 for a bargain price . However , having been used to using newer cameras with flip out LCD screens , it was something of a culture shock to go back to the monochrome viewfinder , good as it is .

After a rummage in the attic , I unearthed a couple of small CRT monitors ( a JVC TM10 and a Sony PVM 6041 ) both of which are useful if shooting from a static position , if a little bit cumbersome .

I know there are plenty of flat panel monitors available these days , but then it occurred to me that most of us now have iPhones , iPads or similar devices , and I wonder if anyone makes a small transmitter which accepts the video output of a camera , and links either by Bluetooth or Wi-FI to enable the image to be displayed on a mobile device ?

I haven't come across such a thing , but it strikes me as simple and obvious , and I'm sure would be quite a popular item .

Camranger does this for canon (& Nikon?) dSLRs. Retail $300. It plugs into the USB terminal on compatible cameras.

Teradek has several transmitters hdmi & HD-SDI that can be used to hop to a receiver, or an iPad or such. Very slick, the least expensive I'm aware of is the VidiU for $700.

I'm sure there are others out there. Not sure if there's an SD composite solution.

Thanks , that's interesting , although these solutions are more costly than just buying a small monitor .

Considering that so many small action cams costing hardly anything have the facility built in , a small transmitter needn't be expensive .

If someone made one which took composite , YC , or HDMI , at a reasonable price , I'm sure it would be popular .

For that matter , if it were possible , even a wired solution allowing , say , an iPad to be used as a field monitor , would be useful .