Lens review

Sigma A 24 mm f/1.4 DG HSM

8 March 2015
Arkadiusz Olech

3. Build quality

We start this chapter not in a typical way - with a list of full frame A series f/1.4 lenses in the following chart. One glance at the optical construction makes it clear how difficult it is to design a 1.4/24 class device. In the case of 35 mm and 50 mm 13 elements were enough; here Sigma had to use as many as 15 elements in their instrument.

Now let’s compare the new Sigma to its slower predecessor and direct rivals - another chart will make it easier. It is obvious the 1.4/24 class lenses constitute a quite homogeneous group with similar physical dimensions, weight, the same filter thread and the minimum focusing distance. When it comes to the last parameters the old Sigma sticks out a bit – that’s why it had “Macro” in its name. The new Sigma is different when it comes to the number of optical elements for a change.

In the photo below the new Sigma is positioned next to the 1.4/35 model, It is clear their dimensions don't differ a lot.

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Sigma A 24 mm f/1.4 DG HSM - Build quality

The tested lens starts with a metal mount surrounding the contacts and a rear element, 32 mm in diameter. That element is mobile, being situated on the same level as the mount with the focus set at infinity; it hides inside the lens less than1 cm when you pass to the minimum focus. The element is surrounded by a tube which is excellently darkened, matted and ribbed. There are no slits between its rim and the edge of the element. The front element for a change is immobile which means that during the focusing the focal length changes along the optical system.

Sigma A 24 mm f/1.4 DG HSM - Build quality

The proper casing of the lens starts with a smooth, black, shiny and metal ring on which there is a white dot making the alignment with a camera easier. Further on there is the inscription with the name and the parameters of the lens and above it – a distance scale behind a window, expressed in feet and meters. Below you see a depth of field scale but with markings only at f/8.0 and f/16. On the left side of the scale you see an „A” letter meaning the new lens belongs to the “Art” group, an inscription “MADE IN JAPAN” and a focusing mechanism mode switch (AF/MF).

Sigma A 24 mm f/1.4 DG HSM - Build quality

The next part is a huge manual focus ring, as wide as 31 mm. Most of it is covered by comfortable, rubber ribs. The ring moves smoothly and is well-damped; it’s a pity that running through the whole scale takes a turn through just 90 degrees. More precise settings would need something close to 120-150 degrees.

Sigma A 24 mm f/1.4 DG HSM - Build quality

Immediately after the manual focus ring you find a hood mount, surrounding a non-rotating filter thread, 77 mm in diameter; the thread for a turn goes round a convex front element, 55 mm in diameter.

The optical construction diagram is really impressive – just look at the picture below.

Sigma A 24 mm f/1.4 DG HSM - Build quality

You deal here with as many as 15 elements positioned in 11 groups. Once again the number of special elements impresses. Overall you can find as many as three FLD elements, made of low-dispersion glass with the properties similar to those of the expensive fluorite, four classic low-dispersion SLD glass elements and two aspherical ones. Add to that an aperture with nine blades which can be closed down maximally to f/16.

The buyers get both caps, a hard case and a petal-type hood in the box.

Sigma A 24 mm f/1.4 DG HSM - Build quality