I have 2 X-T1's, one of which ,when shut down with the HP mode activated, will have it's eye sensor glow for approx. 20+ minutes and is clearly seen from a distance across a dimly lit room. The other x-t1's eye sensor LED can only been seen in very low light . early/late production sequence does not appear to be a factor as the one that glows more prominently has the higher serial number and later manufactures date. I have not been able to judge any difference in battery life between the two.