The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Venus 25mm F2.8 2.5-5X Ultra Macro and the Sigma 30mm F1.4 EX DC HSM 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. Venus 25mm F2.8 2.5-5X Ultra Macro is the longer of the two lenses at 65mm. The Sigma 30mm F1.4 EX DC HSM with a length of 59mm, is 6mm shorter. Besides being longer, the Venus 25mm F2.8 2.5-5X Ultra Macro also has a larger diameter of 82mm compared to the Sigma 30mm F1.4 EX DC HSM's 77mm 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. Venus 25mm F2.8 2.5-5X Ultra Macro weighs 400g, which means it is 30g (6%) lighter than the Sigma 30mm F1.4 EX DC HSM which has a weight of 430g.
Lens Mounts
The Venus 25mm F2.8 2.5-5X Ultra Macro has the Pentax KAF2 lens mount whereas the Sigma 30mm F1.4 EX DC HSM has the Pentax KAF lens mount. Some of the latest released cameras that are compatible with these mounts are Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III for the Pentax KAF2 Mount and Pentax K-3 III Monochrome, Pentax KF and Pentax K-3 III for the Pentax KAF Mount.
Venus 25mm F2.8 2.5-5X Ultra Macro is also available in Canon EF , Nikon F (DX) and Sony E mounts.
Sigma 30mm F1.4 EX DC HSM is also available in Canon EF-S , Nikon F (DX), Four Thirds, Sony Alpha and Sigma SA mounts.
Focal Range
Venus 25mm F2.8 2.5-5X Ultra Macro is a prime lens with fixed focal lenght of 25mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
37.5mm.
On the other hand, the Sigma 30mm F1.4 EX DC HSM is a prime lens with fixed focal lenght of 30mm which has an effective (full-frame 35mm equivalent) focal range of 45mm when used on a APS-C / DX format camera.