Been wanting a flexible lens hood for a while as, when scrambling or climbing with the camera out, the lens sometimes hits rocks or trees, which the Sony hood's hard plastic doesn't cushion much against.
Some soft options exist but are either not compatible with a 20mm wide angle, don't fit snuggly, can't be easily reverse mounted, or are too large to fit with the camera in tight sling cases.
Even found a couple of 3D printed hoods for Sony lenses with a 72mm filter diameter: Bumper for SONY Lenses (72mm type) by gumo_design and Lenshood for Sony 20-70/4 SEL2070G by Markus
But they both have notable shortcomings and neither is designed for flexible filament:
So I designed a basic hood that can be printed in TPU, and that is reversible, compatible with circular polarizers, vignetting free and small enough to fit in most tightly shaped cases.
It consists in 2 parts that tightly snap together: a rigid PLA lock ring that securely locks onto the lens, and a flexible hood that can take physical abuse. Works well, much better protection and cushioning than Sony's hard plastic.
Also, I've never been able to reverse a Sony hood on a lens without fidgeting for a while. Because their hoods have 2 independent sets of twist-and-snap mechanisms that are 90° out of phase, and the user is first supposed to visually align 2 dots. Thwarts my feeble brain every time. Instead, I incorporated only 1 twist-snap set, and added a bump under the hood for haptic feedback on orientation. So now the same insert-then-twist motion works for both the extended and the reversed position. Has become an automatic no-look gesture. Love it.
Finally, the design is compatible with a circular polarizer, leaving the polarizer's serrated rim accessible and away enough from the wall to still allow rotating it with a finger. Even when using very thin CPs like the Hoya 72mm NXT Plus Low Profile Circular Polarizer Filter
Note that the rim shape is just a basic circle, not a wavy profile that optimizes shading versus vignetting all around the sensor. Working on that, and on the geometric principles behind an optimal 4-petal hood. In a later post.
2 parametric models are included: 1 flexible version for TPU, and 1 rigid version for PLA / PETG.
The length in the CAD model is parametric and can be changed. The current length is the longest possible before vignetting appears in the corners with the 20-70 lens on a full frame sensor.
This is designed for the Sony 20-70mm F4 SEL2070G lens. It should mount as well on other Sony lenses with a 72mm filter diameter, though shading won't be optimal until the length parameter is updated accordingly.
Am planning to design one too for the 24-105mm F4 SEL24105G lens that has a 77mm filter diameter. Compatibility list for Sony hoods (incomplete, no 24-105): havecamerawilltravel.com/sony-lens-hood-compatibility-chart/
The Fusion360 CAD model (messy), STEP and 3MF files are on Github and MakerWorld
Feel free to copy, remix, whatever (non-commercially)
Happy flare-free shots to all !
______________________________________________
Printing
Settings
- 0.4mm nozzle, 0.1mm Layer Height
- 8 Walls, 4 Top, 4 Bottom
- Concentric Pattern top & bottom
- Infill: don't care, 8 walls makes everything solid
- 75mm/s Speed Outer & Inner Walls (prevents drooping waves on outer wall)
First, decide whether to print a flexible hood (TPU 95A, grey part below) or a rigid one (PLA / PETG, blue parts). They each use a different lock ring design, so pick either the flex hood parts pair (right side) or the rigid one (left side).
In any case, the lock ring must always be printed in PLA / PETG for rigidity and snapping power.
The 75mm/s speed for both outer and inner walls is key to avoid drool and waviness on the outer perimeter for the chamfered bottom section. No idea why this happens as this area only overhangs by 30°. Should be a breeze for modern printers:
Rant warning...
Also noticed that issue previously on other parts with round convex shapes over gentle overhangs. Benchmark tests don't show that. No idea why 3D printer manufacturers (and shills 'reviewers') don't investigate such specific issues.
Suppliers seem to push slicer tech only to sell new HW features (multicolor, mixing materials, etc) instead of fixing longstanding slicer bugs and shortcomings (cases of wrong bridge / wall / overhang classification, outer wall bulge due to flat inner surface, bad overhanging inner double walls, cavities split as objects, no internal-ribbing concept, baffling orbiting, no texturing, etc).
Poor billion dollar companies, probably can't afford it. They're pouring too much dough into AI in order to steal "help with" people's creativity. Must be easier to wait and just pirate "leverage" solutions from open source, I guess. Our hearts bleed for them.
Assembly
TPU version
1. remove brim on both parts
2. insert the ring near the bump
3. complete the insertion and push hard all around the ring's rim until it fully clicks into place
Done.
One can also spray some matte black paint inside the hood to cut down further on stray reflections (I have since reprinted in black TPU / PLA. Used colors in this guide to make part features stand out).
Reversed and extended positions:
PLA version
Same steps as in the TPU version, but first add superglue along the rim inside the hood and in each of the grooves that the tabs on the lock ring latch into.
The lock ring will deform while the tabs get pushed down (#3 in pic), until the tabs take their place in their respective grooves. At which point it should spring back into a round shape, indicating that each tab is successfully engaged and locked (#4).
Practicing first on a sacrificial print is advised.
CAD
The front_length parameter sets the length of the hood in front of the locking tabs.
13mm is the shortest distance possible before vignetting shows up in the corners on a full frame camera (Sony A7 series) in the worst optical condition: 20mm, F22, min focus distance
Obviously, if using the lens only with a smaller sensor than full frame, the max length before vignetting will vary. For instance, when used on the Sony A6 APS-C series, the 20-70 lens becomes ~30-105 equivalent. In that case an even longer hood can be used.
Talking of which, also had fun printing a longer hood, for more shading when zooming in. L'impression 3D c'est vraiment le pied !
Comments
Post a Comment