For sharpness testing, we used an Edmund Resolution Power Chart and performed field tests with the lens on a Pentax K-5. A sample of the chart is seen below. Since the DA* 300mm is a telephoto, it was necessary to place the chart 34 feet from the camera. Once the chart filled the viewfinder a series of pictures were taken at various apertures. The use of standard test chart allows the viewer to compare different lenses subjectively. When conducting an image comparison test it is useful to have a lens to compare against. Although this review is only looking at the DA* 300mm we decided that it might be good to compare a popular alternative to the lens. For the image quality we decided to compare the DA 55-300mm zoom at 300mm to the DA* 300mm.
For the field sharpness testing, we selected an Addax antelope with fine details that allow for a detailed examination. Best viewed in Firefox or Chrome.
The results of the lens test chart photos and the outside field test clearly show that the DA* 300mm is considerably better than the 55-300mm zoom at 300mm. While not a fair comparison, the difference between the two lenses highlights the advantage having of a telephoto prime. The DA* was still sharper wide open but improved dramatically when it was stopped down. If only the DA* 300mm was as affordable as the DA 55-300mm, it would be the perfect lens!
As you can see from the test photos, the DA* 300mm also has very smooth bokeh, thanks in part to its 9 aperture blades.
Often people ask how much closer the DA* 300mm makes subjects appear. Below is a scene taken with a 35mm lens (which is considered a normal focal length on APS-C) and the Pentax DA*300mm. Click on either of the images to enlarge.