Hood Clip for Sigma 400mm/5.6 lens

thingiverse

The old Sigma 400mm lens has an integral hood which can be slid forward to reduce flare. Unfortunately, it is only held in place by Art. Well, that and the velvet-like inner coating on the hood rubbing against the wider part of the lens. As these lenses are now very old, this means you can't tilt the lens upwards without the hood sliding back to its rest position. This plastic clip slides around the wide part of the barrel and grips it lightly. You can release the grip by squeezing the tabs. It grips tightly enough that if you slide it up behind the extended hood, it won't fall back even if you hold the lens vertically. The FreeCAD spreadsheet allows you to adjust the tightness of the grip. Be aware that a small change to the inner radius makes quite a difference.