10 stop ND filter new flare

[CouncilmanDoug]

I just noticed this new flare that just appeared when I use my 10 stop bw filter, I've had the filter for a while and have never had any problems, the problems appeared when I started using full frame but that has to be a coincidence because these problems would have shown up on dx, any possible solutions? The flare thing shows up a lot more in different photo's but I can't trace it to anything, heres a raw straight out of camera. If any of you have any idea how to stop this let me know please

 

[480sparky]

Cover your viewfinder.... it's light coming in from there and making it's way on to the sensor.

 

[CouncilmanDoug]

that makes so much sense!

 

[table1349]

Your camera may have come with a little eyepiece cover just for such situations.
This is what Canon provides: