Specular reflection in GI scene again.

[K-UDA]

Hello list.
I rendered the Samples/Rendering/Global Illumination file in Version 6.1 and 
Version 7 demo.
I got a blurred specular reflection image.
Which parameter should I change?
I hope for advice.
Best regards,
K-UDA
<<attachment: V6_GI_SPECULAR_REFLECTION.jpg>>