Nikon 1.7x tc EV loss

[htid]

I know that the Nikon 1.7 loses 1.5 stops, but what would that be on an f4 lens? One stop is obviously f5.6 so would 1.5 stops be about 6.7 or something? I'm just guessing, my maths isn't very good so I can't work it out!

Thanks

 

[ianbarber]

6.3 at a guess

 

[HoppyUK]

f/4 x 1.7 = 6.8

 

[Martyn...]

The camera will show it as f6.7