Thanks Mat. I've had them for a few years, with the idea of building a giant bino. I have the monster prisms needed for the erecting systems/interpupilary adjustment as well. I'm hoping that the focal lengths are close enough to permit the project. These are the Surplus Shed 127mm dia x 700mm focal length objectives in thermoplastic cells. The US Mil standard for magnification differences between the two halves of a binocular is 2%, above which the stereo effect is lost. The eye can accommodate for differences below 2%. That would mean that with 25mm eyepieces, for example, yielding 28X with a nominal 700mm focal length, the other objective could be mismatched about +/- 12mm before we exceed the Mil standard. So it's not as bleak as I first thought. But something like 5mm mismatch or less would be almost ideal. The closer the match, the higher I can push the magnification and stay within the Mil spec. On Mon, Feb 18, 2013 at 8:50 AM, Hutchings, Mat <mat.hutchings@siemens.com>wrote:
Yes, absoulutely let's measure their focal lengths.