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Samyang 20mm F1.8 ED AS UMC KAF Mount Review

Samyang 20mm F1.8 ED AS UMC

Main Features

  • 20mm Focal Range
  • F1.8 Max Aperture
  • Filter Thread: 77mm
  • Max Format: 35mm FF
  • Pentax KAF Mount
  • Weight: 497g / 1.09 lb
  • Dimensions(øxL): 83mm x 88mm
  • Min Focus Distance: 0.2m
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Samyang 20mm F1.8 Overview


Samyang 20mm F1.8 is a Fixed aperture Manual Focus (MF) Ultra-Wideangle Prime lens with 35mm FF max sensor coverage, and it is designed to be used with KAF Mount cameras.

What type of photography is the Samyang 20mm F1.8 lens good for?

The type of photography that you are planning to use the Samyang 20mm F1.8 is an important decision factor. Here we have evaluated its suitability to various photography scenarios:

Photography Type Suitability
Bird/WildlifePoor
SportsPoor
PortraitFair
TravelAverage
StreetExcellent
WeddingFair
Walk AroundAverage
VloggingVery Good
LandscapeGood
Macro

Lenses in Pentax KAF Mount with Same Focal and Aperture Range
Model Coverage Weight Focusing Street Price
Sigma 20mm F1.8 EX DG Aspherical RF Lens Sigma 20mm F1.8 EX DG Aspherical RF
Compare
35mm FF 520gr AF Amazon B&H Photo

Reasons to Buy Samyang 20mm F1.8 ED AS UMC Lens

Here we've included a summary of the advantages and disadvantages of the Samyang 20mm F1.8 ED AS UMC lens in a list form to help you determine whether it offers the features you need.

PROs
Aperture Ring
Distance Scale
Hood supplied
Full-time Manual Focusing
Fast Aperture
Covers Full-Frame Sensor
Minimum focus distance of 0.2m / 7.9 inch
Report a correction

Buy Samyang 20mm F1.8 from Amazon or B&H PHOTO


CONs
No Weather Sealing
No Autofocus


Lens Mount

Samyang 20mm F1.8 is compatible with cameras that have a Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III.

Samyang 20mm F1.8 is also available in Canon EF , Canon EF-M, Fujifilm X, Micro Four Thirds, Nikon F (FX), Samsung NX, Sony Alpha and Sony E mounts.


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Size, Weight and Filter Thread

Size and weight is a very important decision factor when searching for your next lens. Samyang 20mm F1.8 has a maximum diameter of 83mm and total length of 88mm. It weighs 497g / 17.5 oz.

Samyang 20mm F1.8 has a filter thread of 77mm. Below are links to the filters that we recommend you to consider for your Samyang 20mm F1.8:

  • 77mm Variable ND Lens Filters
  • 77mm Circular Polarizer Lens Filters
  • 77mm Clear Protection Lens Filters




Focal Range

Samyang 20mm F1.8 has a fixed focal length of 20mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 30mm.


Below are the 3 Ultra-Wideangle Prime type Pentax KAF mount lens alternatives with highest max magnification ratios:

  • Sigma 15mm F2.8 EX DG Fisheye: 0.26x - (Compare)
  • Carl Zeiss Distagon T3,5/18: 0.083x - (Compare)
  • Irix 11mm F4: 0.07x - (Compare)

Aperture

Samyang 20mm F1.8 has a max aperture of F1.8 and a minimum aperture of F22.

Optical Formula

Samyang 20mm F1.8's optical formula consists of 13 elements in 12 groups . Following special elements are used in this design:

  • Two aspherical
  • 3 ED elements
  • Ultra Multi Coating

Lens Hood

Samyang 20mm F1.8 comes with a removable lens hood which is handy to reduce lens flare and glare in your photos.

Popular Comparisons of Samyang 20mm F1.8

Here are the eight most popular comparisons of the Samyang 20mm F1.8 amongst Camera Decision readers.

Top Alternatives of Samyang 20mm F1.8 Lens
Model Coverage Weight Focusing Street Price
HD Pentax DA 21mm F3.2 AL Limited Lens HD Pentax DA 21mm F3.2 AL Limited
Compare
APS-C / DX 134 g / 0.29 lb AF Amazon B&H Photo
Rokinon 24mm f1.4 Aspherical Lens Rokinon 24mm f1.4 Aspherical
Compare
35mm FF 580 g / 1.28 lb MF Amazon B&H Photo
Pentax smc DA 21mm F3.2 AL Limited Lens Pentax smc DA 21mm F3.2 AL Limited
Compare
APS-C / DX 140 g / 0.31 lb AF Amazon B&H Photo
Sigma 24mm F1.8 EX DG Aspherical Macro Lens Sigma 24mm F1.8 EX DG Aspherical Macro
Compare
35mm FF 485 g / 1.07 lb AF Amazon B&H Photo
Sigma 20mm F1.8 EX DG Aspherical RF Lens Sigma 20mm F1.8 EX DG Aspherical RF
Compare
35mm FF 520 g / 1.14 lb AF Amazon B&H Photo
Voigtlander 20mm F3.5 Color Skopar SL II Lens Voigtlander 20mm F3.5 Color Skopar SL II
Compare
35mm FF 205 g / 0.45 lb MF Amazon B&H Photo
Sigma 28mm F1.8 EX DG Aspherical Macro Lens Sigma 28mm F1.8 EX DG Aspherical Macro
Compare
35mm FF 500 g / 1.10 lb AF Amazon B&H Photo
Carl Zeiss Distagon T 2,821 Lens Carl Zeiss Distagon T 2,821
Compare
35mm FF 600 g / 1.32 lb MF Amazon B&H Photo


**This post contains affiliate links, and I will be compensated if you make a purchase after clicking through my links. As an Amazon Associate, I earn from qualifying purchases.

Samyang 20mm F1.8 ED AS UMC Alternatives in Pentax KAF Mount
Model Coverage Weight Focusing Street Price
Pentax smc DA 14mm F2.8 ED IF Lens Pentax smc DA 14mm F2.8 ED IF
Compare
APS-C / DX 420 g / 0.92 lb AF Amazon B&H Photo
Pentax smc DA 15mm F4 ED AL Limited Lens Pentax smc DA 15mm F4 ED AL Limited
Compare
APS-C / DX 212 g / 0.47 lb AF Amazon B&H Photo
HD Pentax DA 15mm F4 ED AL Limited Lens HD Pentax DA 15mm F4 ED AL Limited
Compare
APS-C / DX 189 g / 0.42 lb AF Amazon B&H Photo
HD Pentax DA 21mm F3.2 AL Limited Lens HD Pentax DA 21mm F3.2 AL Limited
Compare
APS-C / DX 134 g / 0.29 lb AF Amazon B&H Photo
Pentax smc DA 21mm F3.2 AL Limited Lens Pentax smc DA 21mm F3.2 AL Limited
Compare
APS-C / DX 140 g / 0.31 lb AF Amazon B&H Photo
Samyang 14mm F2.8 IF ED MC Aspherical Lens Samyang 14mm F2.8 IF ED MC Aspherical
Compare
35mm FF 552 g / 1.21 lb MF Amazon B&H Photo
Samyang 16mm f2.0 ED AS UMC CS Lens Samyang 16mm f2.0 ED AS UMC CS
Compare
APS-C / DX 583 g / 1.28 lb MF Amazon B&H Photo
Voigtlander 20mm F3.5 Color Skopar SL II Lens Voigtlander 20mm F3.5 Color Skopar SL II
Compare
35mm FF 205 g / 0.45 lb MF Amazon B&H Photo
Samyang 24mm f1.4 ED AS UMC Lens Samyang 24mm f1.4 ED AS UMC
Compare
35mm FF 580 g / 1.28 lb MF Amazon B&H Photo
Samyang T-S 24mm f3.5 ED AS UMC Lens Samyang T-S 24mm f3.5 ED AS UMC
Compare
35mm FF 680 g / 1.50 lb MF Amazon B&H Photo
Schneider PC-Super-Angulon 28mm f2.8 Lens Schneider PC-Super-Angulon 28mm f2.8
Compare
35mm FF 565 g / 1.24 lb MF Amazon B&H Photo
Sigma 15mm F2.8 EX DG Diagonal Fisheye Lens Sigma 15mm F2.8 EX DG Diagonal Fisheye
Compare
35mm FF 370 g / 0.81 lb AF Amazon B&H Photo
Carl Zeiss Distagon T 2,821 Lens Carl Zeiss Distagon T 2,821
Compare
35mm FF 600 g / 1.32 lb MF Amazon B&H Photo
Carl Zeiss Distagon T 2,825 Lens Carl Zeiss Distagon T 2,825
Compare
35mm FF 480 g / 1.06 lb MF Amazon B&H Photo
Carl Zeiss Distagon T 228 Lens Carl Zeiss Distagon T 228
Compare
35mm FF 520 g / 1.14 lb MF Amazon B&H Photo
Carl Zeiss Distagon T 3,518 Lens Carl Zeiss Distagon T 3,518
Compare
35mm FF 470 g / 1.03 lb MF Amazon B&H Photo
Sigma 20mm F1.8 EX DG Aspherical RF Lens Sigma 20mm F1.8 EX DG Aspherical RF
Compare
35mm FF 520 g / 1.14 lb AF Amazon B&H Photo
Rokinon 14mm f2.8 IF ED MC Lens Rokinon 14mm f2.8 IF ED MC
Compare
35mm FF 552 g / 1.21 lb MF Amazon B&H Photo
Sigma 24mm F1.8 EX DG Aspherical Macro Lens Sigma 24mm F1.8 EX DG Aspherical Macro
Compare
35mm FF 485 g / 1.07 lb AF Amazon B&H Photo
Rokinon 24mm f1.4 Aspherical Lens Rokinon 24mm f1.4 Aspherical
Compare
35mm FF 580 g / 1.28 lb MF Amazon B&H Photo
Sigma 28mm F1.8 EX DG Aspherical Macro Lens Sigma 28mm F1.8 EX DG Aspherical Macro
Compare
35mm FF 500 g / 1.10 lb AF Amazon B&H Photo
Venus Laowa 25mm F2.8 2.5-5X Ultra Macro Lens Venus Laowa 25mm F2.8 2.5-5X Ultra Macro
Compare
35mm FF 400 g / 0.88 lb MF Amazon B&H Photo

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Samyang 20mm F1.8 Detailed Specifications


General
Brand Samyang
Lens Type Prime
Lens Type Wideangle Prime
Lens Mount Pentax KAF
Max Format 35mm FF
Focal Range 20mm
Image Stabilization
Colour Unknown
Zoom Method No Zoom
Power Zoom No Zoom
Zoom Lock No Zoom
Zoom Ratio 1.0X
APERTURE
Max Aperture F1.8
Min Aperture F22
Aperture Ring Yes
Diaphragm Blades 7
Optics
Optical Elements 13
Optical Groups 12
Special Elements Two aspherical + 3 ED elements, Ultra Multi Coating

FOCUSING
Min Focus Distance 0.2m
Max Magnification unknown
Autofocus No
AF Motor Type No AF
Full Time Manual Yes
Focus Method Internal
Distance Scale Yes
PHYSICAL SPECS
Weight 497g
Diameter 83mm
Length 88mm
Weather Sealing No
Filter Thread 77mm
Filter Notes -
Hood Supplied Yes
Tripod Collar No
Report a Correction
Frequently Asked Questions about Samyang 20mm F1.8 ED AS UMC
is the Samyang 20mm F1.8 ED AS UMC a Weather-sealed lens?
What is the Minimum Focusing Distance of Samyang 20mm F1.8 ED AS UMC
is the Samyang 20mm F1.8 ED AS UMC an Autofocus (AF) lens?
What is the Filter Thread Size of Samyang 20mm F1.8 ED AS UMC
Does Samyang 20mm F1.8 ED AS UMC have Image Stabilization?
Does Samyang 20mm F1.8 ED AS UMC have Aperture Ring?


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