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Dyptorden

28 Ian 2015 18:14


Clarificare vis-a-vis de terminologie

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Salut,
In diferite surse gasesc doi termeni si nu imi e clar daca au legatura.

- BK7 care face referire la un tip de sticla (Borosilicate glass)
http://en.wikipedia.org/wiki/Borosilicate_glass

- BAK7 care face referire la un tip de prisma (Barium Crown Prisms)
http://www.eabco.com/Binoc01.htm

Buba e ca prin alte surse , de exemplu : 
http://www.birding-binoculars.net/buying-guide.html
sau
http://www.birdwatching.com/optics/binoculars2_porro_roof.html - si nu sunt singurele site-uri
gasesc exprimari de genul 
"The two more common types are BK7 and BAK4"
sau
"Better Porro prisms binoculars are made from a high density glass, BAK-4. If you hold binoculars away from your eyes and up to the light, you can see the circular exit pupils in the eyepieces. The less expensive BK-7 prisms will have squared-off, non-circular exit pupils"
Sigur nu e greseala deoarece se repeta exprimarile...

Acum intrebarea mea este : exista vreo legatura intre BK7 si BAK7? prismele BAK7 folosesc sticla BK7? desi nu prea cred .. una e Borosilicate si alta e Barium....

Thanks,