MFT Lens Turbo II Flare

Started Jul 13, 2017 | Discussions thread
obsolescence Contributing Member • Posts: 722
Re: MFT Lens Turbo II Flare

E Dinkla wrote:

Hoods with a rectangle mask reduce the unneeded light even more, a square mask already has a 37% smaller opening compared to a round mask. The percentage increases when the sensor sizes ratio gets to 2:3 or beyond. It is however not easy to calculate the right shape of the mask as the extension from the lens front element, lens design, focal length and aperture opening play a role then. I converted an old Canon SLR (opal light source in the film plane, mirror + shutter for ever open) to get some idea about the needed size but even then it becomes a trial and error system to get the best mask size. After making the mask the FF digital camera is set at infinity on a copy table, widest stop an image is made of the white evenly lit table. Then the vignetting is examined compared to an image without the hood. Mask size changed accordingly. I tolerate some extra vignetting in the corners but not on the edges.

Before I printed 3D lens hoods, I made some designs of masks that fit into lens filter rings and had them laser cut out of polycarbonate. Using small stamped magnetic vinyl discs glued into the masks I could attach even smaller masks for APS sensor size on the masks for FF. While the Sony FFs allow making APS size images too I will not use that much so the concept is there but may not be used on the 3D hoods.

Faint image of the projected illuminated film gate, that image normally is copied with a digital camera on the copy table in a dark room. Grid is in mm. Considering a widest aperture projection through a transparent mm grid to the ceiling now for a better representation of what is needed.

On the left the converted SLR for mask estimation, must be one of my ugliest creations ever.

Met vriendelijke groet, Ernst
750+ inkjet paper white spectral plots: OBA content etc.

Fabulous idea! Makes perfect sense. You could design a set for popular lenses and market this accessory. Do a Kickstarter campaign.

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