Originally posted by sapateiro Thanks guys, but unfortunately I'm still not sure...
@gofour3 - I see what you're saying - the next full stop up is 1.4, but then that's inconsistent when it then jumps a full stop further to f2, then only half stops from there forward?
@jimr - thanks for that, but according to that half-stop scale, there would be 2 unmarked 'clicks' between 1.2 and 2.
@notanumber - good idea with seeing if the manual metering will shed some light, I'll try that myself.
Does anyone know if there's any archive of old manuals/documentation that would confirm this?
Cheers,
Gary.
OK I was able to check my Pentax lens guides and these are what the unmarked clicks are when a lens has a non-standard maximum aperture. Pentax treats the non-standard maximum apertures as the next full stop up and then carries on with the regular half/full stop rotation.
Example a lens with a maximum aperture of f3.5 is treated like the full stop f/4 then the unmarked click is f4.8, then the full stop f5.6.
Lens with a maximum aperture of f/1.2: 1.2, 1.7 (unmarked), 2.0, 2.4 (unmarked), 2.8
Lens with a maximum aperture of f/1.7 or 1.8: 1.7/1.8, 2.4 (unmarked), 2.8, 3.4 (unmarked), 4.0
Lens with a maximum aperture of f/2.5: 2.5, 3.4 (unmarked), 4.0, 4.8 (unmarked), 5.6
Lens with a maximum aperture of f/3.5: 3.5, 4.8 (unmarked), 5.6, 6.7 (unmarked), 8.0
Phil.