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.
Pinholes need to be very small to provide a useful image. Consequently the corresponding f-values are small, in most cases f:100 or smaller. This results in either very long exposures, or requires the use of very high ISO values. As we will see in the example images this is less of a problem than what could be expected because as the resolution of the pinhole is low, the images tolerate very strong noise reduction processing without losing there character or mood.
I have been testing some objectives for their UV transmission using LEDs as sources of radiation. I developed a protocol for such tests. Although used in this example to measure the spectral sensitivity of a camera sensor, the protocol can be easily adapted for the measurements of biological action spectra.