1930's Drem Instoscope. Popular during the 1920's and 30's. Some of the earliest light meters were called extinction meters and didn't require batteries. The center pulls in and out to assist with your eyes focus.When viewing thru the ocular you could see a number of letters (see picture). The least visible letter was explained on the table which was wrapped around the instrument. The table showed the possible shutter-speed/aperture combinations for the least visible letter.
It would be a great addition for many an owner or collector!
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