I have an EyeFi card. I bought mine with the idea that I could use it a bit like "tethered" shooting (images show up on my remote device within a couple of seconds of taking the image.) But without the wire.
It turns out the implementation is very slow.
The radio would normally deplete the battery much faster than would normally happen. To help battery life, the device keeps the radio "off" until it has work to do. The card has local storage and keeps track of which images have been completely tranmistted and which have not.
But it wont transmit WHILE you use the camera. You have to stop shooting (you can't use any controls on the camera. Don't use any buttons or dials at all or you'll force the radio to switch off again.
You shoot, then wait several seconds (it seems to be about 5 seconds) and if you have allowed the camera to remain idle for that time it will switch on the radio and start transmitting images.
JPEG images take many seconds to transmit per image. RAW images take... what seems like an ETERNITY for each image.
I've not specificaly timed it, but it was painful enough that it disturbs the flow of shooting. I would have been happy if I could have just kept shooting while it silently transmitted in the background and I could go review the images in a minute or so. But it can't multi-task. That means you cannot do anything but wait while it transmits or your images will never show up.
The idea of WiFi sounds great... but in practice it's painful enough that few people use it.
The WiFi modules for Canon's pro bodies are completely different and don't have these issues.
Tim Campbell
5D III, 5D IV, 60Da
