The type of photography that you are planning to use is an important decision factor. Here we have evaluated the Sony 500mm F8 Reflex and the Sigma 18-250mm F3.5-6.3 DC OS 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. Sony 500mm F8 Reflex is the longer of the two lenses at 118mm. The Sigma 18-250mm F3.5-6.3 DC OS HSM with a length of 101mm, is 17mm shorter. Besides being longer, the Sony 500mm F8 Reflex also has a larger diameter of 89mm compared to the Sigma 18-250mm F3.5-6.3 DC OS HSM's 79mm 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. Sigma 18-250mm F3.5-6.3 DC OS HSM weighs 628g, 5% (37g) lighter than the Sony 500mm F8 Reflex's weight of 665g.
Filter Threads
The Sony 500mm F8 Reflex has a filter size of 55mm whereas the Sigma 18-250mm F3.5-6.3 DC OS HSM has a 72mm diameter. Larger filters are generally more expensive than the smaller ones given all the other features are equal.
Below are links to the 55mm filters that we recommend you to consider for the Sony 500mm F8 Reflex:
And these are the 72mm filters that we recommend for the Sigma 18-250mm F3.5-6.3 DC OS HSM:
Lens Mounts
Both the Sony 500mm F8 Reflex and the Sigma 18-250mm F3.5-6.3 DC OS HSM has the same Sony Alpha lens mount. Some of the latest released cameras that are compatible with the Sony Alpha lenses are Sony A99 II, Sony A68 and Sony A77 II.
Sigma 18-250mm F3.5-6.3 DC OS HSM is also available in Canon EF , Nikon F (DX), Pentax KAF3, Sony Alpha, Sigma SA, Canon EF, Nikon F (DX), Pentax KAF3 and Sigma SA mounts.
Focal Range
Sony 500mm F8 Reflex is a prime lens with fixed focal lenght of 500mm. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides a 35mm (FF) equivalent of
750mm.
On the other hand, the Sigma 18-250mm F3.5-6.3 DC OS HSM has a focal range of 18-250mm and 13.9X zoom ratio which has an effective (full-frame 35mm equivalent) focal range of 27-375mm when used on a APS-C / DX format camera.
