Sony FE 85mm f/1.8 vs Tamron 20-40mm f/2.8 Di III VXD
The bottom line
These cover different focal lengths — the Sony FE 85mm f/1.8 is 85mm, the Tamron 20-40mm f/2.8 Di III VXD is 20-40mm — so they're not really substitutes. Pick by the field of view you actually need: the Sony FE 85mm f/1.8 for short-telephoto / portrait, the Tamron 20-40mm f/2.8 Di III VXD for standard zoom.
Choose the Sony FE 85mm f/1.8 if…
- ✓You want more light and background blur — f/1.8 is faster than f/2.8, better for low light and subject separation.
- ✓You need more reach — it goes to 85mm vs 40mm for distant subjects, wildlife and sport.
- ✓You prefer a fast, compact single focal length — an 85mm prime over a zoom.
Choose the Tamron 20-40mm f/2.8 Di III VXD if…
- ✓You shoot wide — it starts at 20mm vs 85mm for landscapes, interiors and architecture.
- ✓You want one-lens flexibility — a 20-40mm zoom covers what the fixed 85mm can't reframe.
- ✓You like close-focus work — 0.26x magnification vs 0.13x.
Where they differ
- ›Aperture: the Sony FE 85mm f/1.8 opens to f/1.8 vs the Tamron 20-40mm f/2.8 Di III VXD's f/2.8 — more light and shallower depth-of-field.
- ›Focal range: Sony FE 85mm f/1.8 is 85mm, Tamron 20-40mm f/2.8 Di III VXD is 20-40mm — different framing and reach.
- ›Type: the Tamron 20-40mm f/2.8 Di III VXD is a zoom (flexible framing), the Sony FE 85mm f/1.8 a prime (one focal length, usually brighter and lighter).
- ›Price: the Sony FE 85mm f/1.8 is $599, $100 under the Tamron 20-40mm f/2.8 Di III VXD.
Frequently asked
Is the Sony FE 85mm f/1.8 or the Tamron 20-40mm f/2.8 Di III VXD better?
These cover different focal lengths — the Sony FE 85mm f/1.8 is 85mm, the Tamron 20-40mm f/2.8 Di III VXD is 20-40mm — so they're not really substitutes. Pick by the field of view you actually need: the Sony FE 85mm f/1.8 for short-telephoto / portrait, the Tamron 20-40mm f/2.8 Di III VXD for standard zoom.
Who should choose the Sony FE 85mm f/1.8?
Choose the Sony FE 85mm f/1.8 if you want more light and background blur — f/1.8 is faster than f/2.8, better for low light and subject separation. Choose it if you need more reach — it goes to 85mm vs 40mm for distant subjects, wildlife and sport. Choose it if you prefer a fast, compact single focal length — an 85mm prime over a zoom.
Who should choose the Tamron 20-40mm f/2.8 Di III VXD?
Choose the Tamron 20-40mm f/2.8 Di III VXD if you shoot wide — it starts at 20mm vs 85mm for landscapes, interiors and architecture. Choose it if you want one-lens flexibility — a 20-40mm zoom covers what the fixed 85mm can't reframe. Choose it if you like close-focus work — 0.26x magnification vs 0.13x.
What is the main difference between the Sony FE 85mm f/1.8 and the Tamron 20-40mm f/2.8 Di III VXD?
Aperture: the Sony FE 85mm f/1.8 opens to f/1.8 vs the Tamron 20-40mm f/2.8 Di III VXD's f/2.8 — more light and shallower depth-of-field.
| Product | ||
|---|---|---|
| Optical Design | ||
| Focal Length | 85mm | 20-40mm |
| Lens Type | Prime | Zoom |
| Optical Elements | 9 | 12 |
| Optical Groups | 8 | 11 |
| Aperture & Iris | ||
| Maximum Aperture | f/1.8 | f/2.8 |
| Minimum Aperture | f/22 | f/22 |
| Aperture Blades | 9 | 9 |
| Rounded Aperture | Yes | Yes |
| Coverage & Angle | ||
| Format Coverage | Full-Frame | Full-Frame |
| Lens Mount | Sony E | Sony E |
| Angle of View | 29° – 29° | 95° – 57° |
| 35mm Equivalent | − | − |
| Focus | ||
| Autofocus | Yes | Yes |
| Focus Motor | DDSSM | VXD |
| Focus Limiter | No | No |
| AF/MF Switch | Yes | No |
| Min Focus Distance | 80 cm | 17 cm |
| Max Magnification | 0.13x | 0.26x |
| Stabilization & Video | ||
| Optical Stabilization | No | No |
| Aperture Ring | No | No |
| Declickable Aperture | No | No |
| Parfocal | No | No |
| Internal Zoom | No | No |
| General | ||
| Price (MSRP) | $599 | $699 |
| Filter Size | 67mm | 67mm |
| Diameter | 78mm | 74.4mm |
| Length | 82mm | 86.5mm |
| Weight | 371g (13.1 oz) | 365g (12.9 oz) |
| Weather Sealed | Yes | Yes |
| Tripod Collar | No | No |
