Ron (post 1101)
On this forum Porro's have almost a cult status, but I agree that it is cheaper to make an excellent quality Porro binocular for a lower price than an excellent roof binocular.
Since there is a lot of discussion abut HT glass and light transmissions of different binoculars I want to present some of our measured data on different porro's. I will give only the transmissions at 550 nm, the transmissions at 500 nm are generally 1-4% lower depending on the porro model. I have also listed the year of production (as far as I could find) to give an overview of the historical developments:
Leitz Binodal 6x21 (1908): 51%
Leitz Binot 6x30 (1915): 54,5%
Leitz Binux 8x30 (1927): 54%
Leitz Mardocit 12x60 (1948): 72%
Leitz Camparit 10x40 (1950): 73%
Leica-Kern 8x30 (2000): 68% N.B. Transmission lower due to heat filter
Hartmann Compact 8x30 WW (1985): 70,5%
Hartmann Bernina 7x50 (1975): 77%
Kern Pizar 8x30 (1995?): 83%
Zeiss RLN 68200 (1943-1945): 73% N.B. The outstanding technology for this binocular is most likely identical to that used for U-boat glasses.
Nedinsco Nedelta 7x50 (1955): 75% (this binocular is based on the RLN Zeiss)
Bleeker 6x30 (1955): 79%
Beck Zenith 8x30 (1970): 66%
Beck Luchs 7x50 (1975): 70,5%
Beck Tordalk 22x80 (1985?): 76,5%
Hensoldt Diagon 7x50 (1955): 67%
Swarovski Habicht 6x30 (1949): 45%
Swarovski Habicht 6x30 (1963): 83,5%
Swarovski Habicht SL 10x40 (1985?): 90,3%
Swarovski Doppelteleskop 30x75 (1990): 88%
Nikon Monarch 8,5x56 (2000?): 79,3%
Nikon Tropical 7x50 (?): 87%
Nikon 10x70 (?): 82%
Nikon 7x35 nr 780xxx (?): 86,9%
Nikon 8x30 FOV 8,3 deg, nr 414xxx (?): 77,9%
Nikon 8x30 FOV 8,5 deg. nr. 537xxx (?): 74%
Nikon 8x30 EII nr. 808xxx (?): 74%
Nikon 8x32 SE nr 550xxx (?): 88,3%
Fujnon 10x50 FMTR-SX (2010?): 84,8%
Swarovski Habicht 8x30 WW (2010): 95%
N.B. The Swarovski roofs 8x30 CL and 8x32 SV both have light transmissions of 93% .
I add that I do not believe the transmission value of 95% of the Fujinon 10x50 or 98% for the Nobilem 8x56 until I have measured it myself. Up to now that is not the case.
My conclusion is that hasty remarks with regard to high light transmissions of porros are limited to only a few examples and until now it is only Swarovski that has the highest scores.
Gijs