Oberwerk 20x80 lt or 15x 70

Thanks to the group I am excited about a Oberwerk Bino. My objective is to teach myself to recognize smaller and smaller fields of view in order to better utilize my f/11 SC. Of course, taking a peak at Andromeda etc is a bonus. My concern is that I live in Stamford, CT and because of the light pollution in the area I am afraid that with the 20x80 LT I might lose contrast and should buy the 15x70 although I think I want the power. I currently have an Orion 9x63 with a 5 degree field of view. Any thoughts? Thanks

Lawrence,

15X70 binos have 4.67mm exit pupil; 20X80s 4 mm. I wouldn't worry about lost of contrast with the 20X80 LWs. Higher power and smaller exit pupil will darken the background and IMPROVE contrast. I have 7X50, 12X60, 20X80 and 25X100 binos. The 20X80LW is my most used astro bino because it's light weight and wide 70 deg APFOV. Higher power and larger objectives of the 20X80 brings out stars nearly invisible in my 12X60s. My skies in central NJ are no better than mag 4.5.

Most people recommend that 15X70 binos should be tripod mounted anyway. You might as well go for the 20X80 LWs since they weigh just 9 oz more than the 15X70s.

Erik D