Pentax gears up for its full-frame DSLR launch with a new zoom lens

Pentax-D FA 24-70mmF2.8ED SDM WR

Just a few days after our story about the new Pentax full frame DSLR teaser page, Pentax has announced a new standard zoom lens for this camera.

The HD PENTAX-D FA 24-70mmF2.8ED SDM WR offers a 2.9x zoom range covering standard everyday wideangle to short telephoto focal lengths and matches similar premium-quality optics for full-frame Canon and Nikon cameras.

The constant f/2.8 maximum aperture is what marks this out as a pro lens – and this is effectively what you're paying for. Consumer lenses, to keep down the cost and weight, use variable aperture zooms, so that a typical cheap kit lens might have a maximum aperture of f/3.5 at its shortest zoom setting but can only offer f/5.6 at its maximum zoom.

Constant aperture advantages

A constant aperture zoom like this new Pentax model offers three advantages over a consumer lens – faster shutter speeds at maximum zoom, better 'bokeh', or shallow depth of field effects for blurred backgrounds, and the ability to shoot in low light without having to bump up the ISO as high.


The 24-70mm f/2.8 has a Quick-Shift Focus system that lets you instantly switch to manual focus after the camera has focused with the AF system.

Pentax 24-70mm f/2.8

The new lens uses Pentax's own multi-layer HD Coating to cut flare and ghosting and increase contrast.

Interestingly, Pentax makes no mention of an image stabilization system in this or any other of its full-frame lenses. Is this a hint that the new full-frame DSLR will have Pentax's SR Shake Reduction system built in, just like its smaller APS-C models?

'SDM' in the product name indicates that the new Pentax 24-70mm f/2.8 uses Pentax's Supersonic Direct-drive Motor, which is designed to deliver quiet, high-speed autofocus. It should be a lot more refined than the 18-55mm kit lens supplied with the company's APS-C DSLRs, befitting the new camera's professional status.

'WR' stands for weather resistance – this is a lens designed for tough outdoor use.

This is not the only full-frame lens in the Pentax range. Pentax also has 50mm and 100mm full-frame macro lenses updated from its days as a film camera maker, and in February 2015 announced new full-frame 70-200mm f/2.8 and 150-450mm f/4.5-5.6 telephoto zooms.

Price and availability

The price does reflect the 24-70mm f/2.8's professional aspirations – it will cost £1,149.99 (about US$1,750, AU$2,500) when it goes on sale in late October 2015. This is, however, on the same level as comparable full-frame pro lenses from Nikon and Canon.

If you want this lens but can't wait for the new full-frame camera, you can use it on a regular APS-C format Pentax DSLR in the meantime. The smaller sensor means the effective focal length becomes a slightly longer 37-107mm, but you still get the benefit of that constant f/2.8 maximum aperture.

Pentax is some way from the full frame lens range it will need to compete with Canon and Nikon's full frame cameras, but it's made a good start. All it needs now is a super-wideangle 14-24mm f/2.8 lens to go with the 24-70m f/2.8 and 70-200mm f/2.8 to complete the 'holy trinity' of everyday full frame professional lenses.

Rod Lawton is Head of Testing for Future Publishing’s photography magazines, including Digital Camera, N-Photo, PhotoPlus, Professional Photography, Photography Week and Practical Photoshop.