Spring Lake, MI. Sponsored Topics. Spring Lake is a village in Ottawa County in the U.S. state of Michigan. The population was 2,514 at the 2000 census. The village is located within Spring Lake Township. After Captain Benjamin Hopkins purchased land here in 1837 and built a mill, the place became known as Hopkins Mill.
All binoculars will have two numbers to designate them, such as 10x50. This means a binocular with 10 times magnification and 50mm objective lenses (the big ones!). Common sizes are 8x42, 10x50, 20x60, 15x70, etc. Optical glass is generally BAK4 or BAK7 standard, BAK4 is denser and gives superior vision.
If you have a single PD number, which would be one number between 50 and 75, subtract three. For example, letâs say your distance vision PD is 63. Lower this by three, to 60, for single-vision reading glasses. However, you may have a dual PD, which is the measurement from the center of each pupil to the center of the bridge of your nose. In this case, you would have two numbers, each somewhere between the mid-20s to the mid-30s.