Sony has been on a roll with E-mount glass for a long time. Some of my all-time favorites that stick in my head from hands-on time are the FE 135mm F1.8, FE 50-150mm F2, FE 35mm F1.4, FE 28-70mm F2, FE 600mm F4 GM, FE 50mm F1.2 GM and the FE 70-200mm F2.8 GM II. The one that surprised me the most, though, is the FE 300mm f2.8 GM OSS. Sony took the classic 300mm sports prime and made it the smallest, lightest, and one of the sharpest in its class. I rented it twice, loved it both times, and then just bought it. Keeper.
Sony FE 300mm F2.8 GM + 2.0X Teleconverter vs Sony FE 600mm F4 GM without the hoods
Like most 300mm GM owners, I use it mostly for wildlife. 300mm is short for small birds, but add Sony’s FE 2x TC teleconverter and you are effectively at 600mm F5.6. A lot of lenses fall apart with a 2.0x TC. This one takes a small hit and keeps going, which I credit to the optical design.
Does that make the 300mm + 2.0x a true substitute for the FE 600mm F4 GM OSS? Not exactly. The 600mm can also run 1.4x and 2.0x for 840mm F5.6 and 1200mm F8 equivalents. Different tool. But depending on the shot and how you share your photos, the 300mm combo can absolutely get the job done with similar looking results. And since it is smaller and cheaper, it is a very real alternative for a lot of people.
I own both now, so I started a simple real-world resolution check to see how 300mm + 2.0x at 600mm stacks up next to the native 600mm F4. Bring on the chart-mania.
Sony FE 300mm F2.8 GM + 2.0X Teleconverter vs Sony FE 600mm F4 GM without the hoods and CamDec Lens Caps
TIP: Consider our Heavy-Duty Lens caps to turn these lenses in to even smaller packages.
Also read: CamDec Heavy-Duty Lens Cap for Sony FE 300mm F2.8 OSS GM
Test setup
I shot both lenses on a sturdy tripod with a remote release on the A7R V, shot RAW at highest reaolution, and applied no post-processing to the files. Manual focus, manual aperture, manual shutter, manual ISO, Stabilization turned off to keep things consistent. This round compares the 600mm F4 GM at F4 against the 300mm F2.8 GM + 2.0x at F5.6.
Sony A7R V with the FE 300mm F2.8 GM and FE 2.0x TC
Test Results - What I saw
At normal viewing sizes the files are closer than you might expect. When you zoom to 200 percent in Lightroom, the differences pop more clearly. I pulled crops from the center, midfield, and extreme corner and viewed them side by side.
Click on the images for larger version
Center
Sony FE 300mm F2.8 GM + Sony FE 2.0x TC vs SOny FE 600mm F4 GM - Center Crop
Midfield
Sony FE 300mm F2.8 GM + Sony FE 2.0x TC vs SOny FE 600mm F4 GM - Midfield Crop
Corner
Sony FE 300mm F2.8 GM + Sony FE 2.0x TC vs SOny FE 600mm F4 GM - Corner Crop
The 600mm shows more bite and contrast and looks a touch brighter than the 300mm + 2.0x. That is what I expected and probably what 600 GM owners want to hear. On the flip side, 300 GM owners should be pretty happy because the combo holds its ground in practical use.
If you drop resolution to something below 60MP, the visible gap shrinks even more. Downsize for web or small prints and you will work to tell which file is which.
Sony FE 300mm F2.8 GM + 2.0X Teleconverter vs Sony FE 600mm F4 GM with hoods reverseds
Where each lens fits
If you want the absolute best image quality at 600mm in E-mount, the 600mm F4 GM is the pick. You can crop harder with less penalty and you get a small exposure advantage that can keep ISO down. If you want something smaller and easier to carry that still delivers very high performance, the 300mm F2.8 GM with the 2.0x TC makes a strong case.
My plan going forward
I am keeping both. I grab the 300mm when I want to travel light. I grab the 600mm when size and weight are not a problem, when I need maximum reach, or when I want the cleanest file possible.
Summary takeaways
- 600mm F4 GM is sharper, higher contrast, and slightly brighter than 300mm F2.8 GM + 2.0x at 600mm.
- At normal viewing sizes and smaller prints, the differences are small and hard to spot.
- On 60MP bodies the gap is visible at 200 percent. On lower resolution bodies the gap narrows.
- 600mm gives you more comfortable cropping latitude and a small ISO advantage.
- 300mm F2.8 GM + 2.0x is a lighter, cheaper package that still performs at a high level.
- Choose the 600mm when absolute IQ and reach matter most. Choose the 300mm combo when mobility and cost matter more.
- I will use the 300mm for light kits and the 600mm when I need every pixel to count.
CAMDEC Lens Cap for Sony FE 300mm F2.8 OSS GM
$55.00
$45.00
Comparison Table
| FEATURE and SPECS COMPARISON | |  |  |
| Model | Sony FE 300mm f2.8 GM | Sony FE 600mm F4 GM |
| Lens Type | Prime | Prime |
| Lens Mount | Sony E | Sony E |
| Focal Length | 300mm | 600mm |
| Max Format | 35mm FF | 35mm FF |
| Image Stabilization | | |
| Number of Diaphragm Blades | 11 | 11 |
| Optical Elements | 20 | 25 |
| Optical Groups | 16 | 18 |
| Minimum Focus Distance | 2m | 4.5m |
| Max Magnification | 0.16x | 0.14x |
| Weight | 1470g | 3040g |
| Length | 264mm | 449mm |
| Diameter | 124mm | 164mm |
| Filter Thread | 41mm | 41mm |
| Weather Sealing | | |
| Price | Amazon, B&H Photo | Amazon, B&H Photo |
