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Compare Samyang 20mm F1.8 ED AS UMC vs Pentax-FA 31mm F1.8

Construction

Aperture Blades
7 blades
9 blades
Colors
Black, silver
Form Factor
Ultra Wide-Angle Prime Lens
Wide-Angle Prime Lens
Image Size
Full-Frame
Full-Frame
Lens Barrel
Physical aperture ring, Distance scale
Physical aperture ring, Distance scale, DoF scale
Lens Mount
Canon EF-mount, Canon EF-M-mount, Fujifilm X-mount, Micro Four Thirds-mount, Nikon F-mount, Pentax K-mount, Samsung NX-mount, Sony A-mount, Sony E-mount
Pentax K-mount
Material
Aluminum
Motor
Screw drive from camera
Optical Formula | Elements
13 elements
9 elements
Optical Formula | Groups
12 groups
7 groups
Optical Formula | Special Glass
Two aspherical + 3 ED elements, Ultra Multi Coating groups
HD + Super Protect coatings groups

Dimensions

Filter Diameter
77 mm / 3.03 in
58 mm / 2.28 in
Size | Diameter
83 mm / 3.27 in
65 mm / 2.56 in
Size | Length
88 mm / 3.46 in
69 mm / 2.72 in
Weight
497 g / 17.56 oz
341 g / 12.05 oz

Function

Angle Of View
94.5° Diagonal | 84.0° Horizontal | 61.9° Vertical
69.9° Diagonal | 60.3° Horizontal | 42.3° Vertical
Aperture
f/1.8 ~ f/22
f/1.8 ~ f/22
Autofocus
No
Yes
Focal Length
20 mm
31 mm
Focus Type
Internal
Internal
Image Stabilization
No
No
Weather Resistance
No
No

Performance

Max Magnification
0.16x
Min Focus Distance
200 mm / 7.87 in
300 mm / 11.81 in

Production

Accessory
Lens hood included
Lens hood included
Debut
2016-08-08
2021-02-24

Reviews

Neofiliac score
59%
50%
Pros
  • Rather affordable
  • Comes with physical aperture ring
  • Beautifully built
Cons
  • Lacks weather sealing
  • Not the highest grade of build
  • Only f/1.8 for the price
  • Lacks weather sealing
  • Unusual focal length

Price

Offers (incl. referral links)
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