Having 3 Nightforce NXS scopes I elected not to purchase my Mark6 with illumination. Because I have found that with good glass that has high light transmission and a high exit pupil in low light conditions I can see better using the scope than my naked eye ( I have 20/10 vision) making an illuminated reticle pointless. If it is so dark where I need to illuminate my reticle to see it I probably can no longer identify my target or what surrounds the target. This is not based on theory this is from practical experience from the countless training hours I have done in low light and night firing exercises I have done for my job.