Canon
RF 800mm F5.6 L IS USM
Canon RF Mount
RF 800mm F5.6 L IS USM — 800mm f/5.6 for Canon RF, a popular choice in the canon lineup.
$16,999
Launch priceReleased Feb 2022
Sony
FE 300mm F2.8 GM OSS
Sony E Mount
World's lightest 300mm F2.8 — 1470g with XD Linear AF, OSS, and G Master resolution.
$6,999
Launch priceReleased Jan 2024
FE 300mm F2.8 GM OSS is 1.9 years newer.
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Wins
RF 800mm F5.6 L IS USM
Wins
FE 300mm F2.8 GM OSS
TL;DR — Key differences
- BFE 300mm F2.8 GM OSS has lower Weight (1470 g vs 3140 g)
- BFE 300mm F2.8 GM OSS has lower Max aperture (Wide) (f/2.8 vs f/5.6)
- BFE 300mm F2.8 GM OSS has lower Max aperture (Tele) (f/2.8 vs f/5.6)
- BFE 300mm F2.8 GM OSS has lower Min focus distance (200 cm vs 400 cm)
- BFE 300mm F2.8 GM OSS has lower Length (265 mm vs 432 mm)
Key specs at a glance
Size and weight, to scale
RF 800mm F5.6 L IS USM
⌀140 × 432 mm
3140 g (6.92 lb / 110.76 oz)
Credit card
85.6 × 54 mm
for scale
FE 300mm F2.8 GM OSS
⌀124 × 265 mm
1470 g (3.24 lb / 51.85 oz)
RF 800mm F5.6 L IS USM is 167mm longer and 16mm wider than FE 300mm F2.8 GM OSS.
RF 800mm F5.6 L IS USM is 1670 g heavier than FE 300mm F2.8 GM OSS.
Diameter (⌀) is the maximum barrel width; length is measured from the mount to the front of the lens.
Use-case scoring
Which one for what?
Algorithmic scores from verified specs · 10 = best in class
Why pick one over the other
Reasons to choose the RF 800mm F5.6 L IS USM
- ✓
Special elements
Adds 2 Fluorite, 2 Super UD, 1 UD
Reasons to choose the FE 300mm F2.8 GM OSS
- ✓
Special elements
Adds 3 Super ED, 1 ED
- ✓
Weight
1470 g vs 3140 g — lower is better
- ✓
Max aperture (Wide)
f/2.8 vs f/5.6 — lower is better
- ✓
Max aperture (Tele)
f/2.8 vs f/5.6 — lower is better
- ✓
Min focus distance
200 cm vs 400 cm — lower is better
- ✓
Length
265 mm vs 432 mm — lower is better
- ✓
Diameter
124 mm vs 140 mm — lower is better
- ✓
OIS effectiveness
5 stops vs 4.5 stops — higher is better
Shared specifications
Internal focus
Both support internal focus
Optical stabilization
Both support optical stabilization
Weather sealing
Both support weather sealing
Control ring
Both support control ring
Custom function button
Both support custom function button
Pros & cons at a glance
Editorially curated highlights and trade-offs.
RF 800mm F5.6 L IS USM
Pros
- ✓Prime design typically delivers strong sharpness and lighter weight
- ✓Built-in optical image stabilization
- ✓Weather-sealed construction for outdoor shooting
Cons
- –Premium price point
- –Relatively heavy for extended handheld use
- –Slower maximum aperture limits low-light performance
FE 300mm F2.8 GM OSS
Pros
- ✓Prime design typically delivers strong sharpness and lighter weight
- ✓Built-in optical image stabilization
- ✓Weather-sealed construction for outdoor shooting
Cons
- –Premium price point
- –Relatively heavy for extended handheld use
Decided which one is right for you?
Compare live prices for the RF 800mm F5.6 L IS USM and FE 300mm F2.8 GM OSS at major authorized retailers.
Canon RF 800mm F5.6 L IS USM
Sony FE 300mm F2.8 GM OSS
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Full specifications
✓ = category winner
Specs sourced from manufacturer data. Use-case scores algorithmically derived. Last reviewed June 2026.