Sony Ultra Wide 21mm converter review - Photo Jottings

Sony Ultra Wide 21mm converter review

Box and contents

Sony has two converters available for their 28mm F/2 lens, an ultra wide (21mm F/2.8) and a fisheye (16mm F/3.5), each reviewed separately.


The Sony ultra wide converter is one of two for use with the ‘FE’ system, and covers full frame; they will only mount and work on the Sony 28mm F/2 host lens.  These converters are not the same as the two similar ones here for Sony’s aps-c system.

Both converter lenses are quite large, especially the fisheye, but fit nicely on the host lens. The ultra wide uses a four element, four group design. The lens has green and magenta color multi coatings, but shows no special elements in the Sony X-ray view, see below.  Sony lists the converter as having a focal length of 13/16″ on a full frame camera.

An oddity I have to mention; the front cap on the 28mm F/2 lens will secure to the rear cap of the ultra wide lens, how thoughtful is that?

Mounting is supposed to be done when the camera is turned off, however, for this review, I risked destroying the lens by attaching it with the camera turned on, just for kicks, and nothing bad happened. You can also mount the lens upside down, just like a hood and everything still works fine.  Attaching the converter is about the same as putting on a hood: align the orange dots, push and turn clockwise until you hear a click.  Unmount by pushing the black tab up and turning until loose.

When mounted, the EXIF data will show the lens as FE 21mm F/2.8, with ‘Ultra Wide’ or ‘converter’ etc on photo editing software. I see no electrical connections, so I’m assuming the camera knows when it’s attached by identifying the different distortion/vignetting signatures apart from the host lens; and speaking of such, the camera will correct the pretty severe distortion generated by this converter either in camera, or by using the newest versions of photo editing software like lightroom, photoshop and ACDSee etc, which have profiles for these converters as of this review.

Fit and finish. The lens appears to be made up of mostly plastic, including the mount, but it seems to be made well with a nice fit and finish that perfectly matches Sony’s lenses.  Sony claims this lens was designed with ‘dust and slash proofness’ in mind; meaning it is not water proof.  The lens is made in Thailand.

Filter size You can’t mount filters to this lens as the hood is non removable, and there is no gel slot, but you may be able to use a square filter system mounted over the entire front, I wouldn’t bother doing that as it will make the lens ridiculously large and cumbersome, which defeats the purpose of this add-on converter in my opinion.

Focusing. This lens uses the 28mm F/2 host lens for focusing, with accuracy and consistency depending on the camera body.

In the box is the lens, front and rear caps, and a vinyl carrying bag.

  • Mounted on mother lens, Sony FE 28mm F/2
  • Front element
  • Ultra wide and fisheye
  • Sony A7R with ultra wide and fisheye converters
  • Mounted on Sony A7R with mother lens
  • Box and contents
  • Rear element and mount
  • Sony X-ray view


Official lens name and code Sony Ultra wide converter 0.75x   MFR# SEL075UWC  B&H Photo.
Box contents Front cap, rear cap, vinyl strap sack, and user’s manual in multiple languages.
Cost $250 as of 8/16.
Build Quality plastic, but nice fit and finish.
Additional information This converter is made specifically for the Sony FE 28/2 lens.
Optical configuration 4 elements in 4 groups.
Angle of view 92° diagonally, (68˚ when mounted on an APS-C sensor camera).
Aperture none, uses host lens
Coverage for Sony FE 24x36mm sensor. When using APS-C sensor, the focal length (or capture area in 135 format) is equivalent to about 31mm.
Depth of field and focus scales Nothing.
Minimum focus, image plane to subject About 9.7″ (240mm) using manual focus.
Minimum focus, end of lens barrel to subject About 2.4″ (61mm) from front of lens hood, manual focus.
Infinity focus hard stop N/A
Length changes when focusing N/A
Focus ring turn in AF N/A
Filter size no filters
Filter ring rotates N/A
Maximum reproduction ratio 1:15x AF or 1.20x MF.
Minimum F/stop N/A
Sony Teleconverter compatible No.
Length changes when zooming N/A
Dimensions WxL 2.7″ x 2.0″ 69mm x 51mm.
Maximum extended length Lens does not extend.
Weight 9.5oz, (267g) bare.

Optical qualities summary.

Lens flare/ghosting overall, good control, about the same as the host lens.
Light fall-off seems to be about the same at all apertures.
Color fringing good lateral control overall with corrections, moderate with uncorrected RAW. No axial type.
Bokeh harsh at all apertures, but it’s hard to get blur with this focal length unless doing close work.
Color seems about the same as other Sony lenses.
Close-up filter N/A.
Coma a tiny bit at F/2.8, nothing really noticeable.
Regular filters Can not use regular filters.
Filter size N/A
Distortion Quite heavy barrel type, but correctable in-camera or with Lightroom profiles.

Close focus Shot.

The image below is the usual stamp shot from the old site.  The subject is a standard US stamp, 0.87″x 1.0″ or 22mm x 25mm.  It’s very sharp stopped down at F/5.6-11, but pretty small, so no link to a larger version.  There is not much working room; subject to lens hood distance is 2.4″ or 61mm.  The distortion signature is about the same when focused close-up or at longer distances.  As a side note; the ‘1996’ text in the lower left corner of the stamp is a mere 1mm wide in real life!

F/8 close focus

Miscellaneous samples.

The first image shows strong barrel distortion, the second image with in-camera corrections, or using distortion sliders in lightroom etc.  In the third image I see some red ghosts on the right side. Last two (no full size links) distortion samples; uncorrected RAW, and corrected with lightroom Sony FE 28/2 ultra wide converter; but the auto correct doesn’t correct all of it, move distortion slider to 112 for the correction you see here.

  • Sony 21mm F/2.8 Ultra wide converter interior distortion uncorrected, F/11
  • Sony 21mm F/2.8 Ultra wide converter interior distortion corrected, F/11
  • Ghosting and color fringing, F/11
  • Uncorrected RAW
  • Corrected distortion, lightroom slider 112

Click buttons for full size versions.

Resolution samples

Below are some full size samples for you to check out. This scene has a lot of detail scattered around the frame, and shows how much the lens sharpens up as you stop down the aperture. The centers are fairly sharp at F/2.8, but suffer from a bit of veiling haze, just like the host lens. As you stop down, things look better. At F/4 the centers are pretty sharp, but the sides, and especially the corners are a little soft. At F/5.6 the whole image looks sharp, except the extreme corners, which are just a little soft, but do sharpen up nicely at F/8, where the lens seems to be maxed out. There is no need to go to F/11 unless DOF is an issue.  Resolution images here are from RAW capture and are uncorrected except the ‘F/8 corrected’ image.

Please note: mobile devices most likely will not show the full quality of the images.

Click buttons for full size versions.


The purpose of the Sony Ultra wide converter is to turn your Sony FE 28mm into a 21mm lens; which captures a much larger area than 28mm.  It’s also less expensive and smaller than a dedicated 20/21mm lens such as this one from Zeiss, or from Rokinon. But does the converter do a good enough job for the price?

A converter that attaches to a host lens may, or may not be the best solution for your needs, it all depends on what’s important to you.  If your creativity demands really-really wide coverage, with a large aperture for milky-way type shots, or hand held low light shooting, you have a couple of choices such as the lenses mentioned above, but don’t choose this converter, it’s not good enough for that type of work.  However, If you only plan on daylight shooting of landscapes or interiors on occasion, and already have the Sony FE 28mm F/2, then it makes good sense, and I would highly recommend it.  If you don’t have the host lens, and will need to buy both, it may not make sense economically if you won’t be using the host lens by itself.  Plus, when the converter is added to the Sony 28mm F/2, it becomes a long and somewhat heavy package.

The technical image quality is pretty good when stopped down. I used F/11 for the interior distortion shots above because of the small kitchen area and depth of field issues, but landscapes look very good at F/5.6-8.  Issues like flare/ghosting/color fringing and light fall-off are not much of a problem.

The Sony Ultra wide converter actually does a good job, especially at smaller apertures, and would make a good addition to the 28mm host lens for Real Estate photography work if you aren’t interested in the Sony 16-35/4 or 10-18/4.

That’s it for the Sony Ultra wide converter review, please check it out here to help support the site.

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