Sony dt 18-70mm 1:3.5-5.6 review

Design

The Sony 18-70mm stands squarely in line with the current kit lens idiom, being a lightweight design of predominantly plastic construction. However it feels reasonably well-made, with the zoom ring in particular unusually smooth and well-damped. Unfortunately it still suffers from the most common kit lens malaise, with a narrow manual focus ring of disappointingly short travel driving a rotating front element, which in turn precludes the use of a petal-type lens hood. Overall it’s of much the same ilk as the kit lenses from the ‘big two’ (Canon and Nikon), whereas those from Pentax and Olympus are rather more nicely designed with proper manual focus rings and superior lens hoods.

On the camera

The lens is a good match to the entry level cameras such as the Alpha 350, but feels a little lightweight on the bulkier Alpha 700 body. The broad zoom ring falls readily to hand, however the manual focus ring simply doesn’t work very well due to its short travel; this is especially problematic when coupled with the tiny viewfinders of the Alpha 300 and 350 camera bodies, and on these cameras critical manual focusing becomes practically impossible.

Autofocus

Autofocus is driven by a screw-drive system from the camera body, so AF speed, noise and accuracy is fundamentally dependant on the camera used. On our Alpha 700 and 350 test bodies, we found focusing to be generally fast and accurate under most conditions, although with a certain tendency to struggle a bit in low light, especially at the telephoto end with its slow maximum aperture of F5.6.

Lens body elements

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Reasons to Buy Sony DT 18-70mm F3.5-5.6 Lens

Here we’ve included a summary of the advantages and disadvantages of the Sony DT 18-70mm F3.5-5.6 lens in a list form to help you determine whether it offers the features you need.

PROs

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CONs

Lens Mount

Sony DT 18-70mm F3.5-5.6 is compatible with cameras that have a Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A68, Sony A77 II and Sony A58.

Size, Weight and Filter Thread

Size and weight is a very important decision factor when searching for your next lens. Sony DT 18-70mm F3.5-5.6 has a maximum diameter of 66mm and total length of 77mm when not extended. It weighs 235g / 8.3 oz.

Sony DT 18-70mm F3.5-5.6 has a filter thread of 55mm. Below are links to the filters that we recommend you to consider for your Sony DT 18-70mm F3.5-5.6:

Optical Image Stabilization

Sony DT 18-70mm F3.5-5.6 doesn’t have an optical image stabilization system so the only option to stabilize the image taken with this lens is to mount on a camera body with IBIS (sensor based In-body image stabilization).

Alternatively, you can check the Sigma 17-70mm F2.8-4 DC OS HSM C in Sony Alpha mount that have similar focal range but features Optical Image Stabilization.

Lenses Similar to Sony DT 18-70mm F3.5-5.6 With Optical Image Stabilization

Zoom Method

Sony DT 18-70mm F3.5-5.6 features Rotary (extending) zoom method where the length of the lens changes as you zoom in or out. This makes it possible to design the lens with a smaller minimum length ( generally when it is zoomed out) compared to internal zoom lenses. The disadvantages of this design are being harder to seal against dust and moisture, weight balance shifting while zooming and zoom creep in certain lenses.

Maximum Magnification Ratio

Sony DT 18-70mm F3.5-5.6 has a Max Magnification Ratio of 0.25x and has a minimum focusing distance of 0.38m. For a non-macro lens, the 0.25x is considered a high magnification and will come handy for close-up shots.

Below are the 3 Standard Zoom type Sony Alpha mount lens alternatives with highest max magnification ratios:

• Sigma 17-70mm F2.8-4 DC OS HSM: 0.37x — (Compare)
• Sigma 17-70mm F2.8-4 DC OS HSM C: 0.36x — (Compare)
• Sony DT 18-55mm F3.5-5.6 SAM: 0.34x — (Compare)

Aperture

Sony DT 18-70mm F3.5-5.6 is a variable aperture lens with a max aperture of f3.5 and a minimum aperture of f22 at 18mm, and a max aperture of f5.6 and minimum aperture of f39 at 70mm .

Optical Formula

Sony DT 18-70mm F3.5-5.6’s optical formula consists of 11 elements in 9 groups . Following special elements are used in this design:

• 1 aspherical
• 1 ED glass element

Lens Hood

Sony DT 18-70mm F3.5-5.6 comes with a removable petal shaped lens hood which is handy to reduce lens flare and glare in your photos. The model number of the hood is PH-RBA.

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Studio Tests

The Sony kit lens is at best a competent performer, but overall falls a little short of similar lenses from other manufacturers in our tests. Sharpness is disappointing at the extremes of the focal length range, especially towards the edges; there are also issues with chromatic aberration from wideangle through to 35mm.

Macro Focus

Specific image quality issues

As always, our studio tests are backed up by taking hundreds of photographs with the lens across a range of subjects, and examining them in detail. This allows us to confirm our studio observations, and identify any other issues which don’t show up in the tests. Overall this lens is a competent performer, rarely throwing up any nasty surprises, but never hugely impressing either.

Chromatic Aberration

We’re never surprised to see chromatic aberration on a kit lens at wide angle, but this lens unusually continues to show quite strong CA on zooming in to around 35mm. The visual effect of this is also effectively amplified on higher pixel count sensors, making it highly visible in the 100% crop from the Alpha 350 below (although no more likely to impact on an actual print).

Flare

The Sony 18-70mm shows admirable control of flare for a kit lens. With the sun placed in the top corner of the frame, it shows no discernible flare patterns, except for a slight loss of contrast towards the opposite corner. Even in strong side- or back-light, it rarely shows much more than a slight loss in contrast — impressive stuff.

Background blur (‘bokeh’)

One genuinely desirable, but difficult to measure aspect of a lens’s performance is the ability to deliver smoothly blurred out-of-focus regions when trying to isolate a subject from the background, generally when using a long focal length and large aperture. At 70mm F5.6, this lens can give substantially defocused backgrounds, but the blur pattern isn’t particularly smooth (although no better or worse than other similar lenses).

Overall conclusion

The DT 18-70mm is an inexpensive and reasonably capable lens, which will at least give new owners a starting point for their adventures into DSLR photography. The slightly extended telephoto range compared to other manufacturers’ equivalents is welcome for portrait work, and it must be said that in some areas this lens performs very well; it’s unusually resistant to flare, and shows very little light falloff towards the corners of the frame even wide open at 18mm.

Unfortunately the one area where the lens does fall short is that of resolving power, as it struggles to deliver sufficient detail for the latest generation of 10-14 megapixel sensors. The fundamental problem is that, whilst it can give quite sharp results in the centre of the frame, it simply doesn’t deliver sufficient resolution towards the edges and corners. This becomes especially noticeable when using it on the 14.2 MP Alpha 350, which ends up merely amplifying the lens’s imperfections when viewing files on screen at 100%.

So the 18-70mm finds itself in a slightly uncomfortable position, as an aging design with insufficient resolution for the latest cameras. It simply can’t match the optical quality of the other manufacturers’ kit lenses, and has become the limiting factor in overall image quality when paired with Sony’s new DLSRs. This in turn means that buyers who choose the Alpha 350 in the 18-70mm kit will likely be somewhat underwhelmed, and see effectively no increase in quality compared to the 10Mp Alpha 300 under most conditions. Indeed this highlights a fundamental issue with the megapixel race in APS-C DSLRs; there’s not much point in increasing sensor resolutions if the lenses most users will be employing can’t deliver sufficient detail, and Sony really need to update their kit lens to keep up.

In summary, the 18-70mm is perhaps a reasonable starter lens, but if you really want to get the most out of the latest 10Mp+ DSLRs, you’ll certainly need to find an alternative which can deliver the resolution the sensor demands. Personally I’d suggest anyone buying a new Alpha DSLR should look elsewhere for a better performing lens.