The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Tamron 100-400mm F4.5-6.3 Di VC USD and the Pentax DA 300mm F4.0 ED 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. Tamron 100-400mm F4.5-6.3 Di VC USD is the longer of the two lenses at 199mm. The Pentax DA 300mm F4.0 ED with a length of 184mm, is 15mm shorter. Besides being longer, the Tamron 100-400mm F4.5-6.3 Di VC USD also has a larger diameter of 86mm compared to the Pentax DA 300mm F4.0 ED's 83mm 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 DA 300mm F4.0 ED weighs 1070g, 5% (65g) lighter than the Tamron 100-400mm F4.5-6.3 Di VC USD's weight of 1135g.
Filter Threads
The Tamron 100-400mm F4.5-6.3 Di VC USD has a filter size of 67mm whereas the Pentax DA 300mm F4.0 ED has a 77mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 67mm filters that we recommend you to consider for the Tamron 100-400mm F4.5-6.3 Di VC USD:
And these are the 77mm filters that we recommend for the Pentax DA 300mm F4.0 ED:
Lens Mounts
The Tamron 100-400mm F4.5-6.3 Di VC USD has the Nikon F (FX) lens mount whereas the Pentax DA 300mm F4.0 ED has the Pentax KAF2 lens mount. Some of the latest released cameras that are compatible with these mounts are Nikon D6, Nikon D780 and Nikon D3500 for the Nikon F (FX) Mount and , and for the Pentax KAF2 Mount.
Tamron 100-400mm F4.5-6.3 Di VC USD is also available in the Canon EF mount.
Focal Range
Tamron 100-400mm F4.5-6.3 Di VC USD has a focal range of 100-400mm and
4.0X zoom ratio . When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
150 - 600mm.
On the other hand, the Pentax DA 300mm F4.0 ED is a prime lens with fixed focal lenght of 300mm which has an effective (full-frame 35mm equivalent) focal range of 450mm when used on a APS-C / DX format camera.
