Greyscale tones and focus are good. Photographs of photographers taking pictures generally do not fare well at DPC but they have been top performers in some challenges.
Like a well told story everything in the image should tie together to a singular theme or related themes and not contain elements that do not support it. In your image the viewer that notices the rings will wonder what purpose they serve in the composition. The reversed name Nikon at the top will be a distraction for most viewers.
Some viewers may feel you are flaunting the challenge topic with this image and will vote it lower. The composition is OK but nothing really unique or special.
On the technical side there does not appear to be a true black point for this image. It is rarely a good idea to include overexposed areas in any image but I understand why you did here. It is still a technical flaw though.
I can hear the Canon's! Yes! YES! Darkness is owning a Nikon! JK! But if you feel you can no longer go on with it let me know and I'll make a good home for it!
I like this idea, but unfortunatley it does not translate to darkness for me. Yes the flash illuminates darkness, but there just isn't enough of a connection for me. I don't know how much you played with changing the darkness, but a darker image with more contrast might have added a nice touch.