Maybe Zeiss has changed their coatings from their initial scopes??
My 10x Zeiss 44 mm objective visibility outlasted my 10x Leupold by almost 7-8 minutes at dusk.The Leupold was similar to a S&B 10x with a 50mm objective. I feel the difference is in the coatings as they all transmit 90+% light when the objectives are "clean"!!
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