The type of photography that you are planning to use is an important decision factor. Here we have evaluated the SG-image 25mm F1.8 and the Sigma 18-50mm F2.8 DC DN C RF 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. Sigma 18-50mm F2.8 DC DN C RF is the longer of the two lenses at 75mm. The SG-image 25mm F1.8 with a length of 32mm, is 43mm shorter. Besides being longer, the Sigma 18-50mm F2.8 DC DN C RF also has a larger diameter of 69mm compared to the SG-image 25mm F1.8's 67mm 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. SG-image 25mm F1.8 weighs 145g, which means it is 155g (51%) lighter than the Sigma 18-50mm F2.8 DC DN C RF which has a weight of 300g.
Filter Threads
The SG-image 25mm F1.8 has a filter size of 52mm whereas the Sigma 18-50mm F2.8 DC DN C RF has a 55mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 52mm filters that we recommend you to consider for the SG-image 25mm F1.8:
And these are the 55mm filters that we recommend for the Sigma 18-50mm F2.8 DC DN C RF:
Lens Mounts
The SG-image 25mm F1.8 has the Sony E lens mount whereas the Sigma 18-50mm F2.8 DC DN C RF has the Canon RF lens mount. Some of the latest released cameras that are compatible with these mounts are Sony ZV-E10 II, Sony A6700 and Sony FX30 for the Sony E Mount and Canon R50 V, Canon R100 and Canon R50 for the Canon RF Mount.
SG-image 25mm F1.8 is also available in the Nikon Z and Fujifilm X mounts.
Focal Range
SG-image 25mm F1.8 is a prime lens with fixed focal lenght of 25mm which has an effective (full-frame 35mm equivalent) focal range of
37.5mm when used on a APS-C / DX format camera.
On the other hand, the Sigma 18-50mm F2.8 DC DN C RF has a focal range of 18-50mm and 2.8X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 28.8-80mm when used on a APS-C / DX format camera.
