Sony Distagon T* 24mm F2 SSM: 2. Design and Operation: Digital Photography Review

Design

Like Sony's other Carl Zeiss-branded lenses, the 24mm F2 is a beautifully-constructed object that exudes quality, with its utilitarian lines, solid metal body and super-smooth focus ring. The side of the barrel plays host to a large AF/MF switch, plus Sony's familiar Focus Hold button, which can also be customized for such functions as depth of field preview and 'Intelligent Preview' depending on the camera body used. The lens focuses by moving the rear group internally, so its length (and therefore balance on the camera) never changes.

Compared to Planar T* 85mm F1.4 and Vario-Sonnar T* 16-35mm F2.8 SSM lenses

This comparison gives an idea of the 24mm F2's size in comparison to two of Sony's other Carl Zeiss lenses - the 85mm F1.4 on the left, and the 16-35mm F2.8 SSM on the right. Lenses from almost all manufacturers seem to have been growing in size recently, and the 24mm doesn't buck this trend; it's very similar in size to the 85mm, being just a fraction longer but slightly narrower in diameter. However it still offers a rather more compact alternative to the wide zoom.

Compared to Canon EF 24mm F1.4L II USM

To get a second perspective on the Distagon's dimensions, here it is alongside one of its main competitors, the Canon EF 24mm F1.4L II USM (which is a little larger than Nikon's AF-S Nikkor 24mm F1.4G ED). The Sony is a bit more compact than the Canon, although perhaps not as much as you might hope given the latter's whole stop light gathering advantage. Of course it's worth remembering that the Sony will benefit from the Super SteadyShot stabilization built-in to Alpha SLR bodies, which in principle makes it hand-holdable in extremely low light (just as long as you don't have to worry about motion blur from subject movement).

On the camera

	The size of the Distagon 24mm F2 makes it a perfect match for the chunky full-frame Alpha bodies (here it is on the Alpha 850). The controls are all well-placed and easy to operate.
	The lens isn't completely out of place on smaller bodies, but it can start to feel a little front-heavy on budget models such as the A230 here. (Of course this isn't really a combination we'd expect to see out in the wild very often.)
	The 24mm F2 can also be used on the mirrorless NEX bodies via the LA-EA1 adapter, but it's limited to manual focus only. One word we'd struggle to use here, though, is 'proportionate'.

Autofocus

The 24mm F2 employs a ring-type ultrasonic SuperSonic Wave Motor for autofocus, and as expected it's fast, near silent and extremely decisive. The Direct Manual Focus feature means its also possible to manually tweak the focus position at any time, even when the camera and lens are both set to autofocus.

Lens body elements

	The lens uses Sony's Alpha mount, which is identical to Minolta's A-type. The gold contacts are used for communication with the camera, and the black metal lever controls the aperture. Notably, there's no seal around the mount against dust and water ingress.
	The filter thread is 72mm (shared with the 85mm F1.4), and does not rotate on focusing, which facilitates the use of filters such as polarizers and neutral density gradients.
	The 45mm deep, petal-type ALC-SH110 hood is supplied as standard and bayonets firmly onto the front of the lens. It's made from thick black plastic, with a felt lining to minimize reflection of stray light into the lens, and reverses neatly for storage.
	The finely ridged grip on the focus ring is 18mm wide. It rotates about 130 degrees from infinity to the closest focus mark of 0.19m, with a silky-smooth action. The rear-focusing mechanism means that the lens's length doesn't change. The focus ring travels slightly past the infinity mark, apparently to allow for the effects of ambient temperature variations.
	This large window shows the focus distance in both feet and meters. The depth of field scale is calibrated for use on full frame cameras; if you want to use it on APS-C bodies you'll need to close the aperture down by about a stop and third beyond that marked.
	The side of the barrel plays host to Sony's slightly unconventional, but very easy to operate circular focus mode switch, which surrounds the customizable focus hold button.