Pentax HD DA70mm F2.4 Limited is a compact, sharp lens which works well for portraiture.
Pentax HD DA70mm F2.4 Limited (499.95 USD direct): This compact, small telephoto lens is compatible with APS-C Pentax SLRs. The lens has a similar field of view to a full-frame camera's 105mm lens, and produces sharp images. This lens is part of Pentax's Limited series and boasts an all-metal construction as well as being compact. It does not have the same weather sealing as entry-level Pentax cameras.
The aperture of the Pentax SMC FA77mm F1.8 Limited (899.95) is a bit smaller than the Pentax SMC FA77mm F1.8 Limited. This full-frame lens is built to the same standards and compact, but is more costly.
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It measures 1 by 2.5 inches (HD), and weights just 4.6 ounces ($496.95 on Amazon). The 70mm F2.4 is the same size as the SMC DA70mm F2.4 Limited but has an upgraded HD lens coating. It also features rounded aperture blades. The lens cap is a push-on, screw-in, and telescoping steel hood. To add or remove the 49mm filter you will need to pull off the hood. This can prove difficult if your filter settings are constantly changing. The lens can be purchased in black or silver, with an accent ring of red.
All metal barrel with narrow, knurled, manual focus ring. You can turn the focus ring at any moment, even if autofocus is enabled. The distance the lens was set is indicated by a focus scale. It can be measured in meters and feet. The scale runs from minimum focal distance of 2.3 feet to infinite, with stops on either side. Although the working distance works well for portraiture it doesn't make the 70mm a macro lens. The lens magnifies objects to a maximum of 1:8.3.
The 70mm Limited lens isn't weather-sealed, unlike most Pentax D-SLRs and lenses such as the HD DA 20-40mmF2.8-4 ED Limited DC WR ($745.91 on Amazon).
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Imatest was used to test the sharpness of the lens, as well as the distortion characteristics when it was paired with the Adorama 24-megapixel K-3 ($1,085.95). An image is considered sharp when it has 1,800 lines per inch of picture height. This was calculated using a center-weighted method. With just a bit of softness around the edges, the 70mm captures 2,003 lines at F/2.4. The aperture can be resized to f/4 to get 2,319 lines. It is crisp and clean from all edges. At f/5.6, the lens records 2,396 lines.
The 70mm lens shows only about half of the distortion, so it is not an issue. Field conditions are irrelevant. The illumination is fairly uniform from one edge to the other. At f/2.4, the corners appear slightly darker than the middle, at about 1.3EV, and at f/2.8 it is barely noticeable at f/4.
Although the 70mm lens is not designed to be used with full-frame cameras like the K-1 ($1,599.00 on Amazon), its image circle can cover larger format image sensors, although it has weak quality around the edges. The edges and vignette are moderate at f/2.4. However, if your subject is framed towards the center of the frame they will be obscured by depth-of-field.
At f/4 the vignette disappears, but blurry edges remain until you drop to f/16. The 70mm is a good lens, although it's not ideal for the K-1. However, if you are upgrading from an APSC camera, and do not have the funds to purchase the 77mm FA Limited right away, then the 70mm should suffice. This image was taken with the K-1 and the 70mm at f/2.4.
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Pentax HD DA70mm F2.4 Limited is a stunning lens. The Pentax HD DA 70mm F2.4 Limited is compact and well-built. It also has a sharp aperture. The edges are a bit soft at f/2.4 but this is not an issue if the lens' purpose is to be used for portraiture in shallow depth of field. By the time the aperture reaches f/4, the lens becomes razor-sharp from end to end. It's not limited to the FA 77mm. That is all you have to say. This lens is a legend in Pentax's world.
It is built according to the same standards that the DA 70mm and can capture more light, as well as a deeper field of view. Although it is more costly, the DA 70mm offers full-frame compatibility and a unique look. It's not a cheap option, but the DA 70mm is a great choice if you like its small size and can live with an f/2.4 optical.