This filterholder is designed for the Tamron 15-30 2.8 SP and requires a filtersize of 100x105mm. I used a square filter by Rollei that had foam rubber attached to it which needed to be removed. In addition, I needed to cover the sides of the filter with electrical tape to stop light from passing through the marking of the filter. The filterholde is designed to hold the glass in very tightly, additionally securing it with four holders which are screwed using each two M3 screws.
The holder itself needs to be printed with square side facing downwards and with paint on supports in the corners. Additionally you need to print the “Screw on holder” four times and have eight M3 screws ready for assembly. For printing I used a layer height of .15mm and PETG filament, but PLA should also work just make sure there is no light transmission through the filament.
The holder itself slides on the lens in the same way the cover does, it needs to be pushed on all the way to minimise vignetting. Speaking of which, I attached images of the vignetting when shooting at 15mm. The first two are at f2.8 and the last two are at f22. The second and fourth are corrected for distortion.
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