Lenses
The 645D uses the 645AF2 bayonet mount, but is also compatible with older 645AF and 645A lenses. For this review I used 150mm f/3.5 and 200mm f/4 lenses, courtesy of MrCad in Croydon (www.mrcad.co.uk), as well as the new D FA 645 55mm f/2.8AL SDM lens that comes as part of the 645D kit. Remember that as the sensor is smaller than the original 645, there will be a crop factor of 1.3x – meaning that lenses will appear longer than they would have done on the old 645 model. The 55mm lens is therefore a 43.5mm (in 35mm terms) or 72mm (in old 645 terms). The 150mm (120mm in 35mm) made a great portrait lens and you can pick one up for around £250.
The aperture ring was fully active, but switched back to the camera when placed in the A setting, and despite being fully manual focus it was easy to find focus thanks to the larger viewfinder and added security from the focus confirmation in the viewfinder. The 200mm f/4 lens is more useful as a mid-range telephoto optic for outdoor shooting due to the longer close-focus, but is still very easy to use with the camera on a tripod or monopod.
The beauty of this lens mount is that not only will many users already have a collection of lenses, but also those who don’t can pick up some great second-hand examples for very little, especially the older manual versions. It’s worth getting in quick, though, because once people start to buy into the 645 system again, prices are likely to rise. There is now a back catalogue of around 30 Pentax 645 lenses in various forms from 35mm to 600mm, including a number of zooms, making it an extensive system for the landscape or studio photographer.
