Using the E-M1 converted to full spectrum with the Pinhole Pro objectives is possible. Using a 58 mm NIR filter (Hoya R72) attached to the front of the 11 mm Pinhole Pro S11 worked fine, with no increase in vignetting. Using the StraightEdgeU 52 mm or Baader U-filter 2″ with a step-down ring blocked the corners of the image completely. The original 26 mm Pinhole Pro suffers a lot less from vignetting and can be used with these filters of smaller diameter than the front thread of the lens without problem.
Even if pinholes are simply holes, and consequently do not absorb radiation, their very small apertures mean that exposure times need to be very long in the UVA, even in bright light.
The photographs below were taken yesterday between 16:50 and 17:10.
26 mm Pinhole Pro, f:173 60 s, StraightEdgeU filter.
26 mm Pinhole Pro, f:104 0.6 s, Heliopan RG695 (Schott glass) filter.
26 mm Pinhole Pro, f:104 1 s, Heliopan RG780 (Schott glass) filter.
The photographs were white-balanced in PhotoNinja on the clouds. None of them have been converted to monochrome, but using the long pass filter with longer cut-off wavelength resulted in extremely faint false colour.
All illustrations, text and measurements are of my own authorship, and copyrighted.
(c) 2018 Pedro J. Aphalo