Saturday, March 23, 2019

Further 645 Experiments

Over the past few weeks I've been 'perfecting' my 645 workflow, using my RhinoCam and a Sekor 35mm lens. The lens is a second hand one and exhibits a little 'softness' in one corner/edge, however, it's manageable, as this isn't my prime system. Afterall, If I want sharpness over the entire image I'll use my 5D3 with my 24mm TSE lens.

To help with the infield workflow, I wrote a new script which I'm calling the Cycler, whose job is to help manage the EOSM's rather limited button UI, as I need to change camera states a few times.

The script should work on any EOS camera running Magic Lantern. To use the script simply press the [PLAY] button twice, eg [PLAY]+{<1000ms}+[PLAY] = cycle to next programmed ML state. In the script as downloaded the states that are cycled through ETTR, Auto-Bracket, Zoom, Dual-ISO.

Pressing [PLAY] and waiting will result in the top ML bar moving through various options, eg BOOK, <<>> and PLAY. BOOK will set a dark frame exposure, <<>> will change cycler direction and PLAY will result in the [PLAY] button acting as normal.

Taking an image with BOOK set results in the shutter being reset to the exposure before the bookmark image was taken.

As for the RhinoCam, this allows a 645 digital image to be taken with the Canon EOSM, ie 8 sensor brackets, creating a 645 image that is about 12500x9900.

In addition to the sensor bracketing, I also focus bracket in the same image. The approach is to set the lens to F/16 and focus at about 3.5m for the top four brackets; then take the bottom four brackets at a distance of 1.2m. Using these distances results in an infinity blur of about 22 microns, compared to a 'normal' CoC-based blur of about 45microns on a 645.

In this test image I also used Dual-ISO, once again accessed vi the Cycler. BTW this image is scaled by 50% in pixel space.

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