Kohler illumination question...

Given that the final step is to hide it behind frosted glass, why is it
necessary to get a focussed image of the lamp filament when setting up
for Kohler illumination?

I tried to answer this myself by taking images at different powers with
the filament defocussed to varying degrees. I couldn't detect any
difference in final image quality for any of the settings (as long as
the filament remains nicely centered of course).

After unsuccessfully Googling for the answer, I've another (maybe
related) question. Is critical illumination considered an old and
inferior technique, or a modern and superior one?

Thanks
Beats

.

Relevant Pages

  • Re: Kohler illumination question...
    ... If the geometry of the coiled filament were the problem, ... me think that in order to create a truly Koehler illumination, ... Why the situation might improve with a frosted glass, ... >I believe the problem originates with the design of the source lamp ...
    (sci.techniques.microscopy)
  • Re: Why does laptop PSU have an earth wire?
    ... Absolute nonsense. ... No lamp filament has ever shorted out a circuit. ... electrical engineering course and think you know everything already. ...
    (uk.comp.misc)
  • Re: Why does laptop PSU have an earth wire?
    ... Absolute nonsense. ... No lamp filament has ever shorted out a circuit. ... the filament is dodgy it blows and it burns out way below any fuse level ...
    (uk.comp.misc)