Sigma 20mm f/1.8 EX DG Aspherical RF

Last updated (08 July’10):
- Review by SLRlensreview

The Sigma 20mm f/1.8 EX DG Aspherical RF features 20mm at focal length with maximum aperture of F/1.8. The lens construction has 13 Elements in 11 Groups and has diagonal angle of view at 94.5 degrees. Closest focusing distance at 20 c /7.9 in and has a filter size of 82mm. The Sigma 20mm f/1.8 EX DG Aspherical RF lens weighs 18.3 Ounces and it measures 3.5 inches in diameter and 3 inches long.

Sigma 20mm f/1.8 EX DG Aspherical RF
Overall Rating: ★★★★☆ | Latest Price Info

Expert Reviews

Sigma 20mm f/1.8 EX DG Aspherical RF Reviews

SLRlensreview reviews the Sigma 20mm f/1.8 EX DG Aspherical RF and writes;
“Sigma 20mm f/1.8 EX DG lies somewhere in between an excellent and a completely mediocre lens. It sports an ultra fast (for a wide angle) aperture, but does not deliver good quality at such wide apertures. Nevertheless, quality improves with stopped down aperture and can be considered quite good in the f/5.6-f11 range.”
rating: N/A

Photozone reviews the Sigma 20mm f/1.8 EX DG Aspherical RF and writes;
“At f/1.8 the center resolution is already quite fine but the borders are very poor. However, at f/2.8 the performance is very respectable and it’s increasing further till f/5.6-f/8 where it peaks in excellent center- and very good border quality.”
Rating: ★★★★☆

Cameratown reviews the Sigma 20mm f/1.8 EX DG Aspherical RF and writes;
“Center lens sharpness was excellent at virtually all apertures except f/1.8, where it was still good. Corner sharpness was very soft at f/1.8 but quickly sharpened up at f/2.8 – f/16 and was just a bit soft at f/22. The Auto focus system worked very well, even in dim lighting, though low light focus performance my be more dependent on whether or not your camera or flash uses an AF assist lamp.”
rating: N/A

The-digital-picture reviews the Sigma 20mm f/1.8 EX DG Aspherical RF and writes;
“If you can get past the softness, vignetting and flare, the Sigma 20mm f/1.8 EX DG Lens actually produces decent image quality. Colors and contrast are good. Foreground/background blur quality are nice (9-blade aperture). Some CA (chromatic aberration) is visible at the wider apertures. Full frame body users will see mild barrel distortion. Exposures tend to average at least .25 stops brighter than typical Canon lenses. “
rating: N/A

User Opinions

Sigma 20mm f/1.8 EX DG Aspherical RF User Reviews

Ultra-wide lens with sharpest optics! | Rating: ★★★★★
“Takes very good wide angle shots of buildings, parks and friends and family picnicking in the park. Shots have come very sharp and crisp with edge to edge brightness and sharpness. 20mm wide angle focal length gives you a very large depth of field which is essential for taking shots of wide open outdoors, filling your frame with a large expanse of ground/sky. Fast f1.8 aperture will let you take snaps indoors in natural light and hand-held shots of lighted buildings etc.” – by Denzil Thakur

“I find this lens to be sharper than either of them wide open. The lens provides images which have excellent color saturation and contrast. Of course, at f1.8, depth of field is razor thin, by design, which is great for bokeh or out of focus background, but which also requires care concerning the desired focal point being in focus. Speaking of bokeh, I find it to be very attractive compared to any other lens I have used.” – by Canon

Absolutely fabulous images, | Rating: ★★★★★
“The lens rounds out such shots just slightly and really enhances facial features. The effect is almost like a very mild fisheye. I have used this to create some of the most compelling captures of the human range of facial expressions that I’ve ever taken. “ – by Freeman

Wonderful!! | Rating: ★★★★★
“This is one of my all time favorite lenses. I usually just leave it mounted. It’s fast max aperture and close focusing make it indispensable to me. Check it out–it focuses to within an inch of the front lens element! [edit: re-checked and it's actually about 3" from the front element. For reference the Nikon 20/2.8 focuses about 9" and the 28/1.4 focuses about 11" from the end of the lens.] “ – by Micah

Great fast wide lens! | Rating: ★★★★★
“Love the colors, bokeh and sharpness even almost fully open. Some might not like the bulk but I like being able to firmly grab the lens for a better camera grip. “ – by N. Savoiu

Best Indoor Lens for Your Pentax SLR ! | Rating: ★★★★★
“I typically use prime lenses for shooting indoor shots and this is one of the best, because of the wide angle (30mm equivalent), sharpness, and speed. No other wide lens has the speed of this one (f1.8). I have taken shots in DIM light without flash that have come out great…” – by William B. Newkirk

Fantastic bokeh | Rating: ★★★★★
“I picked this up just over a month ago when I got my D90. It has been on my camera more than my 18-200mm VR. I truly love this lens. The bokeh is amazing. It is a touch soft but that is easily fixed with software. The low light shots always surprise me on how well they look even over my Nikon 50mm 1.8.” – by M. Heinrich

Bulky but very useful for available-light shooting | Rating: ★★★★☆
“The lens works beautifully. It’s a tank and feels well-built. Not as tight as an all-metal lens, but solid nonetheless. If you note, the 20mm doesn’t have a macro mode – the 24mm and 28mm do. Really, it focuses very close without any problems, but at this focal length it’s kind of silly to be thinking ‘macro photography’ anyway. “ – by Chris B.

More user opinions | Write your opinion


Sigma 20mm f/1.8 EX DG Aspherical RF User Manual

- Download Sigma 20mm f/1.8 EX DG Aspherical RF User Manual (PDF – 1.9Mb)

Features & Specifications

Sigma 20mm f/1.8 EX DG Aspherical RF Specifications

The Sigma 20mm f/1.8 D EX DG Aspherical Lens has a clutch-like system for switch between AF and MF modes. The system is very similar to the Sigma 105mm f/2.8 EX macro lens I reviewed previously. You push the manual focus ring forward to disengage the focus ring for auto-focusing. For manual focusing, you pull it toward you to engage the clutch. When the ring is set to AF, you can rotate the focusing ring all you want, you won’t change the focus on the lens. When the lens is auto-focusing, it also doesn’t effect the position of the manual-focusing ring. The manual focus ring is wide so there is no chance that you’ll miss it in operation.

See also: Lens Reviews | Sigma Lenses

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