The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Pentax 55-300mm F4.0-5.8 ED and the Pentax 18-270mm F3.5-6.3 ED SDM 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 55-300mm F4.0-5.8 ED is the longer of the two lenses at 112mm. The Pentax 18-270mm F3.5-6.3 ED SDM with a length of 89mm, is 23mm shorter. On the other hand, the Pentax 18-270mm F3.5-6.3 ED SDM has a larger diameter of 76mm compared to the Pentax 55-300mm F4.0-5.8 ED's 71mm 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. Pentax 55-300mm F4.0-5.8 ED weighs 440g, which means it is 13g (2%) lighter than the Pentax 18-270mm F3.5-6.3 ED SDM which has a weight of 453g.
Below you can find the dimension and weight table of the Telephoto Zoom Lenses in Pentax KAF Mount for size comparison purposes.
Super Telephoto Lenses in Pentax KAF Mount for Size Comparison
Filter Threads
The Pentax 55-300mm F4.0-5.8 ED has a filter size of 58mm whereas the Pentax 18-270mm F3.5-6.3 ED SDM has a 62mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 58mm filters that we recommend you to consider for the Pentax 55-300mm F4.0-5.8 ED:
And these are the 62mm filters that we recommend for the Pentax 18-270mm F3.5-6.3 ED SDM:
Lens Mounts
Both the Pentax 55-300mm F4.0-5.8 ED and the Pentax 18-270mm F3.5-6.3 ED SDM has the same Pentax KAF lens mount. Some of the latest released cameras that are compatible with the Pentax KAF lenses are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III.
Focal Range
Pentax 55-300mm F4.0-5.8 ED has a focal range of 55-300mm and
5.5X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of
82.5-450mm when used on a APS-C / DX format camera.
On the other hand, the Pentax 18-270mm F3.5-6.3 ED SDM has a focal range of 18-270mm and 15.0X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-405mm when used on a APS-C / DX format camera.
