No this isnt about the issue circulating right now about some A7's leaking light around the lens mount on certain torture tests. Im not sure if mine has that and not really concerned since I dont shoot those type of exposures. Although Sonyalpharumors is reporting that Sony has acknowledged that problem and is researching it.
No, this light leak is much more insidious. And it can effect anyone who shoots with adapted lenses. And not just on the A7. What I find is that I have a light leak in my C/Y adapter.
The only reason I saw it was that I had forgot to turn my camera off after a recent shoot testing my new Tokina 17/3.5. I put the lens cap back on and got in the car. That was when I noticed light trails on the back of my A7 on an otherwise dark screen. I thought surely this was just from the lens cap so covered it with my hand. No change. Hmmmm I thought...
I moved my hand all over the lens adapter combo and then noticed the light leak went away when I covered the small lens release pin on the adapter. I confirmed it a couple of times in the car and again when I got home.
Moral of the story? Check your adapters. Irregardless of the issue Sony is having right now your own adapter may be adding to the issue. We all know that most of these adapters are made pretty cheaply in China and there can be all sorts of tolerance issues. But dont just assume if you get a good seal on both the camera side and lens side that the adapter is a good one.
Just wanted to share this.