so 12.6mm exit pupil for the 44mm VS 20.8mm exit pupil for the 50mm on lowest power setting. Middle aged eyes can use about 5mm of light at best. The 50mm offering about 14% more light gathering on 10x than the 44mm might be a more real world advantage. New 50mm has 50% more windage and elevation adjustment available, which is a big improvement over the 3.5-18x44