The focal length representing the distance between a lens and an imaging element at the time of bringing a subject into focus. It is an important point to be considered when determining the angle of view for photo taking. In the case of photographing of wild birds in particular that involves dynamic expressions of subjects in the distance, it is important to use a lens with a long focal length that is capable of enlarging and photographing the subjects. For "HD PENTAX-D FA150- 450mmF4.5-5.6ED DC AW," by mounting it to a K-mount digital SLR camera, you can use a 35mm equivalent focal length of 230 to 690mm. Therefore, it is suitable for taking photos of an airplane and a moving subject in the distance in motor sport or other sports as well as wild birds, or taking a handheld shot using a blurred background.
Four AF buttons are laid out to allow for stable AF operations irrespective of whether the camera is in a vertical or horizontal position. You can assign preferred settings to the AF buttons such as "focus preset mode" where you can record a preset focus position and move a focus point to the focus position, and "AF cancel" mode which allows the focus position to be fixed during the continuous AF.
As well as camera, lens requires duration in harsh environmental conditions while taking outdoor photos. In contrast, this dustproof and drip-proof (all weather) lens is developed with overcoming issues opposite to high performance waterproofing such as air vent structure required depending on extension and light operational feeling. Each part is sealed so that you can freely take photos without being affected by rain, fog or dust.
Typically, multicoatings are formed by using vacuum deposition to apply a thin layer to the lens surface. However, this fabrication process also presents problems because of the difficulty in increasing the density of the coating film and the variation in refraction rates and film thicknesses. PENTAX's solution to these problems was our HD Coating, where high-density film is applied with high precision at the nanometer level. This enables the reliable formation of the designed film thickness for a dramatic reduction of the reflection rate (up to 50% compared to conventional coatings) over the entire visible light range. It is also effective in reducing ghosting and flare. Moreover, the film coating has an extremely high hardness for providing superior durability
The refraction rate of glass varies depending on the light wavelength. For this reason, because natural light consists of light of various wavelengths, this light fails to converge to a single focal point when passing through a lens. When an image is enlarged on a computer screen, you can sometimes see purple blurring around images of red points, for example. This is called chromatic aberration. In typical lenses using optical glass, this is difficult to correct as the focal length becomes longer. To minimize the chromatic aberration, PENTAX uses extra-low dispersion (ED) glass, extraordinary-low dispersion glass, and high-refraction low dispersion glass, all of which have low spectral dispersion of light beams. The appropriate glass types are used for attaining exceptional imaging performance.
