The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sigma 18-300 F3.5-6.3 DC OS HSM and the Pentax 560mm F5.6 ED AW for their suitability to various photography scenarios:
Size and Weight Comparison
The size of a lens is a crucial factor to consider when comparing two lenses. Pentax 560mm F5.6 ED AW is the longer of the two lenses at 522mm. The Sigma 18-300 F3.5-6.3 DC OS HSM with a length of 102mm, is 420mm shorter. Besides being longer, the Pentax 560mm F5.6 ED AW also has a larger diameter of 130mm compared to the Sigma 18-300 F3.5-6.3 DC OS HSM's 79mm diameter.
The weight of a lens is equally significant as its external dimensions, particularly if you intend to handhold your camera and lens combination for extended periods. Sigma 18-300 F3.5-6.3 DC OS HSM weighs 585g, which means it is 2455g (80%) lighter than the Pentax 560mm F5.6 ED AW which has a weight of 3040g.
Filter Threads
The Sigma 18-300 F3.5-6.3 DC OS HSM has a filter size of 72mm whereas the Pentax 560mm F5.6 ED AW has a 112mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 72mm filters that we recommend you to consider for the Sigma 18-300 F3.5-6.3 DC OS HSM:
And these are the 112mm filters that we recommend for the Pentax 560mm F5.6 ED AW:
Lens Mounts
Both the Sigma 18-300 F3.5-6.3 DC OS HSM and the Pentax 560mm F5.6 ED AW has the same Pentax KAF3 lens mount. Some of the latest released cameras that are compatible with the Pentax KAF3 lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Sigma 18-300 F3.5-6.3 DC OS HSM is also available in the Canon EF , Nikon F (DX), Sigma SA and Sony Alpha mounts.
Focal Range
Sigma 18-300 F3.5-6.3 DC OS HSM has a focal range of 18-300mm and
16.7X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
27-450mm when used on a APS-C / DX format camera.
On the other hand, the Pentax 560mm F5.6 ED AW is a prime lens with fixed focal lenght of 560mm which has an effective (full-frame 35mm equivalent) focal range of 840mm when used on a APS-C / DX format camera.
