strange camera output effect when looking at emissive objects

[anonymous_user_707bbe64]

I am working to get an image of an emissive plane(unlit) using a orthographic camera. But I found that left and right sides of output image will become darker due to some unknown effects. It looks like a dark corner effect(but up and bottom sides are normal). Then I tried to render a white emissive plane, I deleted all the light sources and got a picture below:

Although the material is unlit, it still seems to be affected by some light. I am so confused.

Thanks in advanced!

[Piroman]

Just go to the post process settings and disable vignette effect, its the culprit causing darkening of your screen edges.

[anonymous_user_707bbe64]

Thank you! By the way, the solution is not disable the vignette because the default value of camera is 0.4. We must enable this effect and set it to 0 in order to cancel this.