Sony 50mm f/1.8 DT SAM SAL-50F18
Lab Test Results
June 29, 2009
by Andrew Alexander
Sony announced its new 50mm ƒ/1.8 prime lens in May 2009, designed specifically for APS-C sensors. When mounted on such a camera, the lens will provide an equivalent field of view of 75mm.
The lens takes 49mm filters and does not ship with a lens hood (nor does one appear to be available for this lens). It will be available for approximately $150.
For its price point, the new Sony 50mm ƒ/1.8 does fairly well wide open, but for maximum sharpness one must stop down to ƒ/5.6.
Wide open at ƒ/1.8, images produced are slightly uneven, softer in the center than on the edges. In this case the center shows between 2-3 blur units, with the corners at 2 blur units. There's not much change at ƒ/2, but stopping down to ƒ/2.8 does improve results dramatically, with 2 blur units in the corners and just over 1 blur unit in the center. Stopping down further shows further improvement, and by ƒ/5.6 and ƒ/8 the lens is basically as sharp as our tests can detect.
Diffraction limiting appears to set in at ƒ/11, but there isn't a visually noticeable impact on image sharpness. Even at ƒ/16 sharpness is still excellent, with just over 1.5 blur units across the frame, and at ƒ/22, we note 2 blur units across the frame.
Overall, excellent results from this lens when stopped down to ƒ/2.8, but just a bit soft when used wide open.
The new 50mm is very nicely optimized to prevent the appearance of chromatic aberration. Looking at the sample images we note only the slightest trace of magenta fringing in the corners when used wide open at ƒ/1.8.
Corner shading is only an issue with the lens when used wide open at ƒ/1.8 or ƒ/2. In these cases, the corners of an image are around 3/4 of a stop darker than the center. Stopped down to ƒ/2.8, corner shading drops to below 1/4 of a stop, or negligible.
There is some statistically relevant distortion, but it shouldn't be very noticeable in images taken with the lens. Specifically, the corners show +0.25% barrel distortion, and there is +0.1% barrel distortion generally through the image. If it's important that your straight lines stay straight, it's easily fixable in image post-processing software.
While the new 50mm ƒ/1.8 is listed as a SAM (Smooth Autofocus Motor) lens, its focus speed and noise suggests to us that the lens doesn't employ a premium version of this system. The lens isn't particularly fast to focus, taking around 1.5 seconds to go from infinity to close-focus and back on an A700. Further, there is a noticeable whirring noise made while focusing.
You can't manually override autofocus results by just turning the focus ring while in autofocus mode; you must switch to manual focus mode in the camera, or disable autofocus on the lens.
The lens isn't overly useful for macro work, with a magnification ratio of just 0.2x and a minimum close-focusing distance of 34cm (just over a foot).
Build Quality and Handling
The lens is very much aimed at the consumer market, with an all-plastic construction; even the lens mount is plastic. However this does have the side benefit of keeping the weight down, meaning that with a weight of just 170 grams (6 ounces) there really isn't a reason to pop the lens into a spare corner of your gear bag. The lens also uses seven rounded diaphragm blades to make up the aperture, meaning out-of-focus elements should be pleasantly rendered.
The construction of the lens is quite basic, with just one switch to deactivate autofocus on the lens, and a distance scale that is etched into the focus ring. There is no depth-of-field scale or infrared index.
Sony has used a different style of focusing ring for this lens, with very little in the way of texture adorning it. In fact it is perfectly smooth, 3/8 inch wide, but as it is made of rubber there is some natural grip to it which makes it fairly easy to turn. There are about 45 degrees of turning action to take the ring through its focusing range, and there are hard stops at either end. There is a little extra room past infinity.
The lack of a lens hood isn't terribly problematic for this lens, as the front element is actually quite recessed within the structure of the lens body to begin with; in fact the inner structure is ribbed, so you could say that it's built with the lens hood permanently affixed. The lens takes 49mm filters, and the front element does not rotate during focus operations.
Sony 50mm ƒ/1.4 SAL-50F14 ~$370
While we haven't yet tested this lens, it's a safe bet that if you're an A900 user, this is your 50mm lens, as the new 50mm ƒ/1.8 will vignette on that body. Build quality is slightly higher with a metal lens mount and a windowed distance scale, but it's also twice the price.
Sony 50mm ƒ/2.8 Macro SAL-50M28 ~$480
Sony also produces a 50mm macro lens, while not as fast as the ƒ/1.8. We haven't yet tested this lens.
Sigma 50mm ƒ/1.4 EX DG HSM ~$500
The Sigma 50mm is a fair bit more expensive than any of the Sony options, but is a fair bit sharper than the Sony ƒ/1.8 when used wide open at a comparable aperture (eg., ƒ/2). Stopping down further, this is always a bit of corner softness with the Sigma, while the Sony becomes tack-sharp. CA is also much better handled by the Sony, though the Sigma distorts less.
Konica Minolta 50mm ƒ/1.4 AF ~$300
You won't be able to find this lens new, but you might find a good used copy, which would work just fine on your Sony body.
While the lens is just slightly soft at ƒ/1.8, it's no more soft than its contemporaries from other manufacturers, and when stopped down to ƒ/2.8 it provides sharp images indeed. Chromatic aberration is very well-handled, though when used wide open there is a bit of corner shading to contend with. Distortion is also very slightly noticeable. But, for the money you really can't go wrong; the only way it could be any better would be if it were full-frame compatible. If you're contemplating a move to a Sony full-frame body, this lens won't make the transition. But for everyone else looking for a nifty fifty, it's a no-brainer decision.
The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.
As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.
Sony 50mm f/1.8 DT SAM SAL-50F18
Sony 50mm f/1.8 DT SAM SAL-50F18 User Reviews
8 out of 10 points and not recommended by Filwood1 (2 reviews)Light, modern coatings, inexpensive, reasonably fast.Plastic construction, APS-C only.
The Sony 50mm f1.8 DT is a pretty good lens working effectively as a 75mm on APS-C cameras. If you have such a camera and have no ambition to move to full frame then it will serve you well.reviewed August 24th, 2018 (purchased for $40)
However, for less money you could buy a full frame Minolta 50mm f1.7 on the secondhand market that is faster (marginally), better built (much, much better), only marginally worse for flare (older coatings), and has the fabled Minolta colour.
I also have a full frame Minolta 50mm f2.8 Macro that gives tack sharp images and 1:1 macro for around the price of a new Sony 50mm f1.8 DT - if you don't need the extra stop of light and can cope with the extra weight it's a far, far better lens.
If the Minoltas weren't so easy to come by I'd rate this lens a point higher and recommend it to the budget conscious buyer - it's not a bad lens it just isn't as good as a cheaper alternative.
8 out of 10 points and recommended by translucent mirror (4 reviews)Cheap, light, nice bokehfor this price, none
The lens would effectively give you a 75mm focal length on a APS-C camera. It gives beautiful colors and sharpness and the bokeh is good too. At f/1.8 it is a relatively fast lens and pretty good for low light photography. All in all it is good value for money and the plastic does not bother me at all as that makes the lens lighter.reviewed June 10th, 2012 (purchased for $200)
To see some sample pics check out http://translucentmirror.com/2012/06/walking-around-with-my-50mm-well-75mm-lens/
9 out of 10 points and recommended by Beachrider (22 reviews)Very light. Good on LA-EA1 on NEX 5n, very sharp @ f/2.8, very inexpensive, adapts quickly to temperature changesPlastic sides and lens mount
The last of my plastic-fantastic lens purchases. SAM is quieter than in-camera focusing, but noisier than SSM/HSM/USM. Although purchased for LA-EA1 AF compatibility, has also been very-sweet on LA-EA2 with video. Lens performance @ f/2 and f/1.8 is like 'olde 50 f/1.7'. Use at f/2.8 and above is terrific.reviewed February 20th, 2012 (purchased for $125)
I don't-get where anyone complains about noise on this lens, though. It was not-noticeable during video on NEX5n
When I bought it, it was on-sale. It was an easy bargain.
9 out of 10 points and recommended by Nas79 (3 reviews)Small, Light, Bright and CheapCheap, Noisy
I now rarely use this lens because I recently purchased a SAL1650 that is much sharper than this lens. I did use it for some time though and for an inexpensive lens it had pretty good image quality. It was quite capable of taking good portrait shots indoors. I have recently bought Macro extension tubes and an adapter to mount this lens backwards to use it as a macro lens and it works great.reviewed January 2nd, 2012 (purchased for $150)
My biggest issue with this lens is the amount of noise it produces when focusing and how slow it is to do so.
For a $150.00 lens I think it's an easy addition to a camera bag that needs an Ok performing portrait lens.
9 out of 10 points and recommended by armyhidi (2 reviews)light,natural color,bayonet plastic(not a big deal takig in consideration lens weight)
good lens, sharp at F 2.8 . rare I used it at F 4.5 were seems to be very sharp(at least in my PC and accrding my eyes).no flare .u dont need a hood as front element its very inside of lens body.sam motor not so silent as proclamed.AF hunting is normal to moderate fast.reviewed October 16th, 2010 (purchased for $150)