A teleconverter is a small optic that sits between lens and body and multiplies your reach — and it is never free. The 1.4× gives you forty percent more reach at a cost most photographers never notice; the 2× doubles it at a cost most photographers see immediately. The honest advice is nearly always the same: buy the 1.4× first, and reach for the 2× only when the light and the glass can afford it.
What each one costs you
| Converter | Light lost | What it does to the file | When to use it |
|---|---|---|---|
| 1.4× | One stop (f/6.3 becomes f/9) | A slight, usually invisible drop in sharpness; autofocus barely slows | Almost always. Many photographers leave it on and forget it's there. |
| 2× | Two stops (f/6.3 becomes f/13) | Visible softening, lower contrast, noticeably slower and less certain autofocus | Bright light, a top-tier lens, a static or slow subject. Not for birds in flight in shade. |
The light loss is the part people underestimate. Put a 2× on an f/6.3 zoom and you are shooting at an effective f/13 — and many autofocus systems slow down or hunt past f/8, precisely when you need them most. The reach you gained is undone by the focus you lost.
The 1.4× costs what most photographers never notice. The 2× costs what most photographers see immediately.
When the 2× earns its place
It is not useless — it is conditional. On a fast prime (a 500mm or 600mm f/4), in strong light, on a subject that holds still a perched eagle, a basking crocodile, a distant rhino a 2× can deliver a frame you simply could not otherwise reach, and the softness is recoverable. The rule is that a 2× needs three things at once: excellent glass, generous light, and patience. Take any one away and the 1.4× — or no converter at all — will out-shoot it.
The option people forget: crop instead
If your body has the resolution to spare, cropping a clean 45-megapixel file can beat a 2×-softened one. You lose no light, no autofocus speed, and no contrast, and you keep the option open in post rather than committing in the field. On a high-resolution camera, "shoot the 1.4× and crop the rest" often gives a sharper final image than the 2× ever would. Reach is not only a lens decision; it is a file decision.
Which is right for your kit?
The answer turns on your specific lens's maximum aperture, your body's autofocus behaviour past f/8, and its megapixels — the three variables the AI Coach reads. Tell it what you shoot with and the subject you're after, and it says 1.4×, 2×, or crop, for your kit and your light.
Get the call for your exact kit
The AI Coach weighs your lens's aperture, your body's autofocus and resolution, and your subject, then tells you which converter belongs in the bag — and which to leave at home.
Meet the AI Coach