Telephoto lenses underexpose?

[MDesigner]

...or am I on drugs?

My 55-250mm, when zoomed in at 250mm, seems to underexpose my shots a bit. Bumping the camera up to +1.5EV or so seems to look good. Is this a trait of telephotos when they're at their full focal length, or am I doing something wrong?

 

[Alex_B]

since your lightmeter measures the light through the lens, there should not be such an effect. strange