The type of photography that you are planning to use is an important decision factor. Here we have evaluated the PENTAX 55-300mm F4.5-6.3 ED WR and the Pentax 18-270mm F3.5-6.3 ED SDM for their suitability to various photography scenarios:
Size and Weight Comparison
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 18-270mm F3.5-6.3 ED SDM weighs 453g, 3% (18g) lighter than the PENTAX 55-300mm F4.5-6.3 ED WR's weight of 471g.
Filter Threads
The PENTAX 55-300mm F4.5-6.3 ED WR 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 F4.5-6.3 ED WR:
And these are the 62mm filters that we recommend for the Pentax 18-270mm F3.5-6.3 ED SDM:
Lens Mounts
The PENTAX 55-300mm F4.5-6.3 ED WR has the Pentax KAF3 lens mount whereas the Pentax 18-270mm F3.5-6.3 ED SDM has the Pentax KAF lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF3 Mount and Pentax K-3 III Mono, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Focal Range
PENTAX 55-300mm F4.5-6.3 ED WR 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.
