Teleconverters are one of those accessories that sound like an easy fix. Extra reach without buying a longer lens seems like a win, but the reality is more complicated. Sometimes they give you more detail, and other times, you’d be better off cropping the image you already have.
Coming to you from Photography Online, this careful video compares 1.4x and 2x teleconverters in real shooting conditions. The test shows that a 1.4x teleconverter can add detail, but only if the lens is already sharp enough and the camera’s sensor isn’t maxing out what the lens can deliver. You also lose a stop of light, which means slower shutter speeds or higher ISO. The 2x option usually brings bigger compromises. Instead of more clarity, it often magnifies flaws and softens the photo. That’s why the results vary so much depending on your gear combination.
You see how different brands and setups change the outcome. On high-resolution cameras, cropping the original photo often gives a cleaner result than using a teleconverter, because the sensor already captures more detail than the lens can resolve. On lower-resolution cameras, the opposite can be true, where a teleconverter adds clarity the sensor wasn’t pulling in on its own. This difference makes it clear why teleconverters can feel like a great tool in one situation and a waste of money in another.
The takeaway is that 1.4x teleconverters can make sense if your lens is very sharp and your camera doesn’t have an extremely dense sensor. A 2x is far riskier and more likely to leave you with softer images than you’d get by cropping. That makes testing your own setup essential before deciding whether it’s worth the cost. The video lays this out in a way that helps you judge your own balance of sharpness, resolution, and light loss without getting lost in marketing promises. Check out the video above for the full rundown.
4 Comments
I find a 'Teleconverter' very useful for very specific use cases. Namely for 'Astrophotography' when I'm shooting the Moon, The Sun, or the Solar Eclipse, all using a tripod. I used it one time to shoot a boat that was very far away, and I had so much time to change lenses, again on a tripod. But generally in a wild-life scenario, time is not on your side, and you wouldn't pack your big lens to go out into the field with the teleconverter on. Which would make it so much heavier. So I've yet to use one for that use-case. I can see certain situations where you may start with it on, if you knew your distance was going to be automatically far far away from the action. Let's say your in a Cruise Boat and your trying to scan the Alaskan Mountains for bears or something you can't see very well with your eyes. It might even be setup on a tripod. What you really don't want to end up doing is shooting at shorter distances with your teleconverter on.. What I mean is. My lens is 150-600m, so then a 1.4 gets me out to 840. So if I'm shooting with my teleconverter on, its not worth shooting under 600m, else the pics will be softer/darker than it would be if I just had the lens without the tele on.
One of the biggest things I rarely see people talk about in regards to lenses in reviews is how well it outresolves sensors but it is often so critical when considering TC use. For example, you have to pixel peep like crazy to see the difference between Nikon’s 180-600 6.3 and their 600 6.3, but throw on a TC and the prime pulls way ahead.
Just throwing it out there, Another issue for soft images may be that the teleconverter Is throwing the auto focus off - Possibly even putting it in a range where the lens can't achieve focus without a dioptic corrective filter.
I'm not sure about telescopic, But i've had this issue with a wide angle converter on the kit lens for a Pentax K5 - Everything out of focus even at infinity - although it did get better towards that range. To get it to work, I had to put a macro filter in between the lens and the adapter.
I would guess according to the laws of optics / depending on how Close it mounds to the lens / I would have the opposite issue using a teleconverter - The central focus being shifted past infinity, making it difficult to focus on anything up close - and i'm not talking macro work. Although I guess you could compensate if you use this on a telephoto lens that has a macro mode - To bring the focus closer if need be.
In the olden days, many DSLRs would not AF at F/10 or whatever f-stop you may be pushed out to because of adding a TC. Now in the days of more modern Mirrorless cameras, they are no longer limited. That being said, as already stated in my comment above, I didn't have a lot of TC use-cases that involved using Auto-Focus anyway, because in Astrophotography, you are using MF by ritual. I can't imagine AF being used for 'Macro' either. I did try once in my life to use a TC for 'Macro', because I seen others trying that, and I do dabble in macro, but I didn't enjoy using my heavy lens for that use case.