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Full review of the Sony NEX 50mm F/1.8 OSS lens. 

2012/sn5018box.jpg
Box and contents

 
 
The Sony NEX-C3 was used for this review.  For a better understanding of terms and methods used in this review, go here.
 
The usual center, mid-section and corner crops are located at the very bottom of the page.
 
  
Introduction.
 

The Sony NEX 50mm F/1.8 OSS lens was introduced in 2011, and become widely available in the spring of 2012.  This relatively small lens, (about the size of the NEX 18-55mm kit lens) is build solidly, has a smooth manual focus action and a silent auto-focus motor which is great for keeping focusing noise out of movies.  The focal length and view of 50mm is considered 'normal', but due to the APS-C sensor of the NEX system, it's being marketed as a telephoto and portrait lens, and has the same coverage as 75mm in full frame terms, or 135 film format.  This lens has 'optical SteadyShot' and Sony claims a 4 stop advantage when using it.  Based on my use, it's more like 2 stops.

 

The Sony 50mm F/1.8 OSS lens has nine elements in eight groups.   Apparently Sony uses no special glass elements, like 'ED' or 'asperical' etc; it's just a plain ol' lens.  Says made in China.

 

Fit and finish are very good.  The lens appears to be clad in high quality plastic and metal, (Sony says 'aluminum alloy") and has a metal mount, but it's very light-weight.  Filter size is 49mm, just like most NEX lenses to date. 

  
Focusing.  This lens auto-focuses quickly, accurately, and without a peep.  It's much smoother and quieter than the SAM or slot-screw drive devices Sony uses on it's Alpha system.  The front filter ring doesn't turn when focusing, so your polarizers and grads will work great.  The focusing ring is easy to turn, and is damped about right.
 
The aperture blades form a nice circle from about F/1.8 to F/6.3, but at smaller apertures, the opening is oblong.  That's no big deal, I'm just pointing it out.  
 
When the hood is mounted, you can still remove or install the front lens cap because it's a pinch type design.
 
In the box is the lens, front and rear caps, plastic solid hood, and owner's manual.  
 

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Requisite product shots.

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Side shot
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Back side
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Sony X-ray view and MTF chart

 
 
General information and specifications.

Lens

Box contents

Front cap, rear cap, hood (ALC-SH116), and user's manual.

Cost

Approximately $300 

Build quality

Very good.

Additional information

Made for Sony NEX cameras, won't work on A-mount cameras.

Specifications below

 

Optical configuration

9 elements in 8 groups

Angle of view

32˚  Equivalent to about 75mm in full frame (135 format) terms.

Aperture

7 blades, curved

Full frame and APS-C

Sony NEX only.

Depth of field and focus scales?

Nothing.

Minimum focus, image plane to subject

About 15.1"  (384mm)

Minimum focus, end of lens barrel to subject

About 11.75"  (299mm) 

Hard stop at infinity focus?

No.

Length changes when focusing?

No.

Focus ring turns in AF?

No

Filter size

49mm.

Filter ring rotates?

No

Distance encoder?

Yes
 

Max magnification

1:6.25 or 0.16x 

Min. F/stop

F/22  

Sony teleconverter compatible?

No

Length changes when zooming?

N/A

Dimensions WxL  (my measurements)

2.45" x 2.45"   62mm x 62mm.  

Maximum  extended length (my measurements)

2.45"  (62mm)                                                    

Weight bare (my scale)

7.1oz  (202g) bare

 
 
Optical qualities summary.
 
Lens flare/ghosting.  Average to good control of ghosting, see examples below.
 
Light fall-off.  Nothing to worry about.  See samples below.

Color fringing (CA).  You'll notice an abundance of axial color fringing at wide apertures, but closing the aperture to about F/4 eliminates this.  Lateral color fringing along the sides is well controlled.
 
Bokeh.  Very smooth.  See examples below.
 
Color.   Seems about the same as other Sony lenses.
 
Close-up filter.  Used +4; offers a much closer and sharper image, with soft sides.   
 
Coma.  A very small amount at F/1.8, basically gone at F/2.5.
 
Regular filters cause no additional light fall-off.  
 
Filter size.  49mm.  Other Sony lenses that use 49mm filters; CZ NEX 24/1.8, NEX 16mm F/2.8, NEX 18-55 F/3.5-5.6, 30mm F/2.8 macro, 50mm F/1.8 SAM and 28mm F/2.8.
 
Distortion.  Almost zero!
 
Distortion example directly below.
 

2012/sn5018dis.jpg
almost flat

 

Distortion is not a problem with this lens, it's basically flat.

 

 

Bokeh samples.

 

           F/1.8

             F/2.8

2012/sn5018bok18.jpg
2012/sn5018bok28.jpg

           F/4

             F/5.6

2012/sn5018bok40.jpg
2012/sn5018bok56.jpg

 

Bokeh looks smooth at all apertures, although the aperture shape shows up at F/4.  These crops show bokeh at a distance of about 35' (10m) when focused at 6-8' (2.5m). 

 

Light fall-off

 

           F/1.8

              F/2.8

2012/sn5018vig18.jpg
2012/sn5018vig28.jpg

 

There is no problem with light fall-off or 'corner shading' with this lens. 

 

 

Flare and Ghosting

 

Magenta streak, F/5.6

Orange blob, lower left, F/5.6

2012/sn5018gst1.jpg
2012/sn5018gst2.jpg

 
Ghosting control is average to good when super bright lights are in the image.  About the only thing I see is a magenta streak if the sun is around the edge of the frame.  There are a few colored blobs that show up too, noticeable in the second shot.
 

 
 
 
Let's check out the close-focus capabilities of this lens.

The sample shot was taken with the Sony NEX-C3 16.2MP camera, so don't compare it with others that were taken with 12 or 24mp sensor cameras.  The subject is a standard US stamp, 0.87"x 1.0" or 22mm x 25mm.  The shot was taken as close to the subject as focusing allowed; in this case a somewhat long 11.75" (299mm), measured from the front of the lens barrel to the subject.  
 
This lens has a reproduction size of 1:6.25, which is a little small compared to other new lenses in this focal length.  I see a relatively sharp stamp shot, but it seems to lack contrast at close focusing distances.  The shot below was taken at F/5.6, but F/8 was almost as good.  As a side note; the "1996" on the bottom left of the stamp measures a mere 1mm wide.  
 

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As close as you can get, F/5.6.

  
 
 
Conclusion 
 
The Sony NEX 50mm F/1.8 OSS lens is a welcome addition to the NEX family, producing sharp images with good contrast at nearly all apertures, very smooth bokeh, and almost no distortion.  While there isn't really much to dislike about the lens, there are a few qualities I'd like to see improved.  One, the reproduction ratio is a little low, so you can't focus very close.  The other thing I noticed right off is; I see a somewhat high amount of axial color fringing, (occurring all over), but that kind goes away as you stop down, and isn't so noticeable in low light.  I'd consider the color fringing issue to be minor to moderate depending on how picky you are.  Landscape shooters using smaller apertures (F/5.6-8) should not be bothered by this, or people shooting in low-light with limited DOF. 
 
If you're wondering how this lens compares to Sony's AF 50mm F/1.4; be advised the Sony NEX 50mm F/1.8 OSS will out-perform it in almost all areas, check out this indoor, controlled comparison.
 

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Full image showing crop area.

 

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Sample crops from the centers, mid-sections and corners.

 

 

          Center

          Mid-section

             Corner

F/1.8

2012/sn5018ctrf18.jpg
2012/sn5018midf18.jpg
2012/sn5018cornerf18.jpg

F/2.8

2012/sn5018ctrf28.jpg
2012/sn5018midf28.jpg
2012/sn5018cornerf28.jpg

F/4

2012/sn5018ctrf40.jpg
2012/sn5018midf40.jpg
2012/sn5018cornerf40.jpg

F/5.6

2012/sn5018ctrf56.jpg
2012/sn5018midf56.jpg
2012/sn5018cornerf56.jpg

 

First off, I took these test samples in broad daylight, and using F/1.8 as the base exposure, which, at maximum shutter speed (1/4000sec) just barely kept the highlights from blowing out.  So what you see here is probably the harshest test (and not real world) for this lens.  In less bright conditions, the performance looks better.  With that said, the F/1.8 crops show a little soft, but stopping down to F/2.5-2.8 helps eliminate some of the veiling haze.  I see some magenta color fringing throughout the frame at wide apertures, but it goes away as you stop down.  The mid-sections are about as sharp as the centers at all apertures, that's good to see!  The corners sharpen up, and look their best at F/5.6.  Maximum performance seems to be around F/4 in the centers, F/4 in the mid-sections, and F/5.6 in the corners.  Exposure differences are from light fall-off.

 

For more crops and a comparison to the full frame Sony AF 50/1.4, go here.

 

Please check out the Sony NEX 50mm F/1.8 OSS at B&H Photo and help support the site!