Compare Pentax-FA 31mm F1.8 vs Pentax-D FA 21mm F2.4ED vs PENTAX-D FA 15-30mm F2.8
Construction
Aperture Blades
9 blades
8 blades, Rounded diaphragm
9 blades
Colors
Black, silver
Black, Silver
Black
Form Factor
Wide-Angle Prime Lens
Ultra Wide-Angle Prime Lens
Ultra Wide-Angle Zoom Lens
Image Size
Full-Frame
Full-Frame
Full-Frame
Lens Barrel
Physical aperture ring, Distance scale, DoF scale
Distance scale, DoF scale
Distance scale
Lens Mount
Pentax K-mount
Pentax K-mount
Pentax K-mount
Material
Aluminum
Aluminum
Motor
Screw drive from camera
Ultrasonic
Optical Formula | Elements
9 elements
11 elements
18 elements
Optical Formula | Groups
7 groups
8 groups
13 groups
Optical Formula | Special Glass
HD + Super Protect coatings groups
4 ED elements, 1 Super ED element groups
Three ED and aspherical elements + HD and SP coatings groups
Dimensions
Filter Diameter
58 mm / 2.28 in
67 mm / 2.64 in
Size | Diameter
65 mm / 2.56 in
74 mm / 2.91 in
99 mm / 3.90 in
Size | Length
69 mm / 2.72 in
89 mm / 3.50 in
144 mm / 5.67 in
Weight
341 g / 12.05 oz
416 g / 14.70 oz
1040 g / 36.75 oz
Function
Angle Of View
69.9° Diagonal | 60.3° Horizontal | 42.3° Vertical
91.7° Diagonal | 81.2° Horizontal | 59.5° Vertical
110.6° Diagonal | 100.4° Horizontal | 77.3° Vertical (wide) ~ 71.6° Diagonal | 61.9° Horizontal | 43.6° Vertical (tele)
Aperture
f/1.8 ~ f/22
f/2.4–22 ~ f/2.4–22
f/2.8 ~ f/22
Autofocus
Yes
Yes
Yes
Focal Length
31 mm
21 mm
15 mm ~ 30 mm
Focus Type
Internal
Internal
Internal
Image Stabilization
No
No
No
Weather Resistance
No
Yes
Yes
Performance
Max Magnification
0.16x
0.26x
0.2x
Min Focus Distance
300 mm / 11.81 in
180 mm / 7.09 in
280 mm / 11.02 in
Production
Accessory
Lens hood included
Lens hood included
Lens hood included
Debut
2021-02-24
2021-10-21
2016-02-17
Reviews
Neofiliac score
50%
76%
31%
Pros
- Comes with physical aperture ring
- Beautifully built
- Weather-sealed
- Great image quality
- 8-bladed aperture for sunstars
- Constant f/2.8 aperture
- Great optical performance
- Weather-sealed
- Beautifully constructed
Cons
- Only f/1.8 for the price
- Lacks weather sealing
- Unusual focal length
- Rather long
- On the heavy side
- Lacks front filter thread
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