Teleconverters and autofocus: What every wildlife photographer should know

Canon 60d autofocus teleconverter
Teleconverters and Autofocus

I received the following question via email and thought I should write a post here on ImprovePhotography.com to answer the question for the world.  Here's the question: “I'm looking at buying a teleconverter for my Canon 100-400mm L f/4-5.6 IS lens but I am having difficulty determining if the1.4x or 2.0x teleconverter will still allow for autofocus with this lens. I use a Canon 60d camera.”

Background Information

First of all, a little background.  DSLR cameras utilize two methods to focus: one is phase detection and the other is contrast detection.  Despite what photographers always argue in the blogosphere, BOTH autofocus methods require contrast in order to focus.  This is why it is difficult to focus on a large white sheet of paper.  Since there is no contrast, it is difficult to find focus.

The second piece of background information you'll need to understand teleconverters is that, no matter what aperture you set on your camera, the DSLR will use the largest aperture available to find focus.  It works like this: You set the aperture to f/8, but the lens stays at f/2.8 (or whatever the largest available aperture is) to focus.  Once you press the shutter button to take the picture, the lens quickly snaps the aperture to f/8 and then clicks the shutter.  This method allows the lens to gather as much light as possible for autofocus before closing down to take the shot.

What IS a teleconverter?

With that background, let's take a look at teleconverters and their unintended effects.   A teleconverter looks like a short piece of a lens that goes between the DSLR and the lens.  Its purpose is to magnify the focal length of the lens by 1.4, 1.7, or 2 times–depending on which teleconverter you buy.  Beginning photographers on a budget love teleconverters because it provides a long lens at a low price.  If only it were that simple…

The Drawbacks to Teleconverters

Teleconverters destroy image quality.  Without exception, teleconverters always make lenses less sharp. While more expensive wildlife/sports lenses can do a decent job of controlling a teleconverter, it still means losing some image quality.  If you have  cheaper wildlife/sports lenses (under $2,000), then a teleconverter will bludgeon your image quality to a bloody pulp.  Seriously, it's nasty.  Don't do it.

I'm not at all saying that photographers on a budget are left out in the cold, but I don't want photographers on a budget to waste their money on gear that won't give them good bang for their buck.

If you purchase a teleconverter made by a manufacturer other than the manufacturer of your lens, some data will not be transmitted to the camera. For example, if I use a Kenko teleconverter on a Nikon 400mm f/2.8 lens, some of the data that my lens usually passes to the camera to aid in focusing will not be sent.  Remember this when you go on Amazon and see that a 1.4x Tamron teleconverter costs about $130, while a Nikon teleconverter costs about $600.  Make sure to buy a teleconverter that is of the same brand as your lens.

Unfortunately, teleconverters reduce the aperture size.  A 1.4x teleconverter makes a lens lose 1 stop of light.  A 1.7x teleconverter makes a lens lose 1.5 stops of light.  A 2x teleconverter makes a lens lose two stops of light.  What does this mean?  It means that even the shortest teleconverter, a 1.4x, will transform an f/5.6 lens into an f/8!!!

So can I still autofocus with a teleconverter?

In the question that prompted this article to be written (a Canon 100-400 f/4-5.6 and a 1.4x teleconverter), the answer is no.  Autofocus will not work, or at least will not work well.  This combination will produce a 560mm f/8 lens.  Most cameras require somewhere between f/5.6 and f/6.2 in order to focus.  It depends on the camera, but f/8 probably won't allow for autofocus.

With this combination, manual focus is your best bet.  For untrained photographers, manually focusing a 560mm lens on a crop frame camera would be nearly impossible.  If you're wondering why it's tougher to manually focus a long lens, then check out this previous post.

There is a work-around to this problem by taping over three of the contacts on the teleconverter so the DSLR doesn't know you're using a teleconverter.  This situation will allow autofocus to work, but it will work erratically and improperly.

The bottom line

Don't buy a teleconverter to try and make your tele-zoom a supertelephoto lens.  The results will be disastrous.  Teleconverters should only be used with high-end fast-aperture wildlife/sports lenses.  Using teleconverters in other situations is a recipe for muddy image quality.

27 thoughts on “Teleconverters and autofocus: What every wildlife photographer should know”

    1. This article is antiquated. It’s speaking to the reader in a language of the past. Today, 2016, many camera’s auto focus down to f/8. For instance there is a newish Nikon 200-500 f/5.6 lens available that can be used on any Nikon camera DX or FX. Let’s use the D7200 D500 and the D5 as examples. Two DX and one FX cameras. All will minimum focus to f/8 and the results that users are getting using the 1.4 III teleconverter with this lens are sterling. These users sing the praises of the high quality pictures they are making using this lens with the teleconverter on any of the three cameras. Time marches on, and technology with it. If you are shooting Nikon 1.4 teleconverter with one of the current batch of cameras, (2016) pick up the 1.4 teleconverter without fear of soft images and shoot away! You’ll love the results.

      1. Hi Rob, I have a D5 with a new model Nikon 500 mm f45. With the 1.4iii teleconverter, autofocus is erratic. Sometimes autofocus is quick and accurate, sometimes difficult, and a few times, the focus indicator dot showed even when the image was blurred. Appreciate your thoughts. thanx for replying to email.

      2. Janice Vincett

        Thank you for your comment. I have a Nikon D810 with the old Nikkor AF S 70-200mm G ED VRii and have just sent for the 1.4 iii teleconverter from Nikon and was beginning to wonder if I’d made a mistake…..hopefully it will be fine.

  1. I have to disagree too. To tell you the truth, I am so sick of “pro photogs” essentially putting down amateurs because they are trying to find a way to make due with budget equipment and are told they are wasting their time unless they spend thousands on overprices equipment. Screw that. Buy what you can afford and have fun with it. To all of the elitists, stick with the photo.net jerkwads and their “holier than thou” attitudes.

    1. I am not a pro but this guy is talking sense. I bought a 1.4 teleconverter for my 100-400mm IS lens and got no useful results whatsoever so I took it back. Had I read this review before I could have saved my money for something useful!

      1. Same happened to me, so the 100-400mm IS USM II Lens is STILL not enough zoom for me. Wished I’d done more reserach ?

  2. I’d suggest you are a little too gloomy in your conclusions. For Canon users, both the 300 mm and 70-200 mm f/4 lenses will retain autofocus with the 1.4 teleconverter making the 70-200 plus the 1.4 converter a way to get great flexibility with top notch glass. I have also found that for stationary subjects, the 400 mm f/5.6 with the 1.4 teleconverted can autofocus beautifully in Live View via contrast detection mode. This is pretty slow to focus, so isn’t practical for moving targets. Nice intereste range of topics you post!

  3. Pentax K3 with Pentax 18 – 270mm by itself and with added Pentax 1.4x teleconverter…how do I upload images showing that WITH the teleconverter is sharper than withOUT??? I’m baffled…

  4. G’s guy take it easy on each other. I am one of those guys that can’t afford thousands for a camera body and a lens. But I do not hold that against someone who can. I just have to work a little harder to get in position to take a great shot. I use a Nikon camera with a Nikon 18x300mm1:3.5-5.6G ED VR2 with a 77mm optics. This thing will focus at 18″ and show you things on a bug that you never knew they had until you put it on screen. I try never to take a shot beyond 50 yrds. even though I can. I chose this lens because I needed one that would do whatever I needed without changing lens, and having to carry multiple lenses. I take pictures of Bighorn Sheep large whitetail and mule deer at 20 and 30 yds. It takes a lot of patience and hard work to put yourself in these positions. But it can be done. The pics are so detailed it will scare you. But the point is we all love the art. If you are one of these that want to try a teleconverter and not sure what it will do or not do for you, rent one for a few days and find out for yourself. Lets all keep shooting and enjoy ourselves. Ron

  5. I need a telephoto lens for wildlife! I would love the Nikon 400mm, it’s almost $8000. Not in the budget . I have researched and was considering the Sigma Sports model 150-600mm, 5.6 this will cost between $2600-2900 plus tax Canadian. I need a lens to supplement before the 150mm. .. Maybe a 24-120mm?? What would you suggest. I was told if I put a teleconverter Nikon 1.4 this will give me more reach and it will be very sharp? It would be al last a 1260mm?
    I also like it it
    S sealed , made of metal and built like a tank. The weight is a little issue. I am small but tough Have! lol, I will also be attachi g this to a Nikon D 7200. Since this is not a full frame, it’s a 1.5 crop I should get that extra reach! Can someone help! I have expeditions soon. The bears are waking up and birds are migrating through soon! Time is of the essence.
    Please help!
    I am buying the d7200 as well.

    You can see a few shots on my website! My site is under co structuring at the mo ent. I am working at this f/t and need sharp images.
    I also have the d5100
    I bought the new Coolpix p900 due to all the hype! Of course I do t get the results! Sensor ,buffer…it’s a point and shoot. Can’t compare the two.
    Bonnie-Lou Ferris

  6. Hi Bonnie Lou,
    I have a Sigma 150-600 sports and a D7200 camera and 1.4 TC and have an interest in BIF.

    Honestly given the choice again I would not have bought the Sigma lens as its focusing capabilities at the long end with the TC are very poor and also in lower light conditions(cloudy days) at or near the long end yields grainy pictures(the 7200 trends to very high ISO).

    Obviously things improve without the TC but when I contrast my sigma performance with my Nikon 300 2.8 with 1.4 and 2.0 TC’s the results are much better, the extra reach of the sigma with a cropped sensor camera such as the D7200 which has little additional value to me for moving subjects especially.

    Hope this helps, if you can afford it I would recommend sticking with a quality prime lens with matched TC’s even if the reach is slightly below that you can achieve with the Sigma as in reality the performance at the longer end, in my view, is of limited value if sharp/clear(non grainy pictures)are your thing.

  7. I have been photographing pelagic birds – far out at sea – with a Nikon D7200, Nikon 300 PF (fresnel) lens and a 1.4x extender (the ancient version I). The results are razor-sharp, high in micro-contrast, with nothing to complain about. The autofocus is fast, and while pelagic birds are difficult to grab focus-wise, I get a reasonable number of sharp, sharp hits. Love this combination.

  8. Dr.RavindraKharade

    Thanks I am passionate about bird photography and having Canon 100-400 lenses and Canon 5D and 7D bodies Planning to buy 1.4x teleconvertor for it.Now cancelled after reading your view Thanks

  9. I use a teleconvertor Nikon 1.4TCEiii along with a 200-500 nikon lens in my Nikon D750 camera. The results are stunning with some jaw dropping photographs of Birds with superb clarity. There is a little problem in extreme low light conditions or during the sun set but quiet understandable. Automatic focus functions works normal although a little slow in focusing flying birds. I suggest go in for a teleconvertor with the New generation cameras and FX lenses but restrict it to 1.4 or 1.7 max.

  10. Thanks for your input ???
    I bought the 1.4 TC Nikkor 200-500 mm HMM its ok! The reach is not what I expected! I find it’s soft at the top end, need to pull back quit a bit!
    I’m now enjoying Aerial Photography as well. I have worked very hard and I’m now a SFOC Licensed Commercial Aviation Pilot, Transport Canada Approved! With Commercial Liability Insurance. It is a ton of red tape and studying, paper work! You also have to have a VHF RADIO Licence that all Commercial Pilots have to communicate with ATC. I can film up to 4 k resolution and my images I capture are sharp with my GImbal Head on my Quadcopter. This technology is amazing! Just had to share with you! Please check out my website: BonnieLouFerris.Com
    this technology is absolutely amazing!! When I have time I will upload more shots to my website!
    Cheers Bonnie-Lou
    Appreciate your time to respond to my question!! ?

  11. This post was old and so WRONG. Tamron 150-600 with a 2.0 teleconverter is amazing. Of course both of these are brand new and with new technology.

  12. Hi friends, I have Canon 550D body and Canon-55-250 lens. do u advice to put teleconverter to this for the utility in wildlife??
    I am beginner….

  13. I have a Nikon DX body and my 300mm F/4D ED lens is my go-to for hiking and backpacking. That being said, how will using the TC-14e III FX affect my results? I know it will reduce me to a F/5.6. But, I also that the 300mm FX lens is cropped to a 450mm shot on my DX Body. Will the FX teleconverter ruin sharpness on this lens with the DX body? Since it is an FX TC, will it stay a true 1.4x or will it also be cropped to perceive a higher magnification? I haven’t seen anyone using an FX TC with and FX lens on a DX body in forums and am worried there may be a reason why. Thank you for any insight.

  14. I would recommend finding a good 300mm prime lens to use for wildlife. Then use a TC on top of that if you feel you need more length. Also, invest in a tripod (some come with a detachable monopod too!). The tripod (or monopod) will provide better stability producing a sharper image. Cameras can even pickup the press of a shutter release button. Also, I’m no pro, just have been doing a lot of reading and practicing. You can see some of my shots on Instagram @jacowitz_photo if you would like to see if there’s worth to my comment. 🙂 Thanks for reading and happy snapping!

  15. I had Canon setup: 5D Mark III, 100-400 USM II and 1.4 III extender.
    Autofocus did not work at first try. After upgrading 5D to latest firmware 1.3.4 (April 2017) the autofocus worked fine.

  16. Clean the contacts before giving up on converter-I was about to send a used 1.4 Canon converter back but cleaned the contacts with an eraser and viola it worked-on a 70 200 L 4.0 lens on a t2i rebel-much less weight and sharp photos. Not bad! May send my tamron 150 600 to sell-tired of the weight-get about 450x which is sharp.

  17. I sold my Nikon D3s and bought a little used Nikon D4. I set the camera up as I normally would and took it on a trip to Kraków in Poland (and on to Aushwitz) After viewing the images on the back of the camera I thought all was well and good. After viewing the raw files I realised that the camera was actually back focussing. It was a major over site on my part, so I went into the calibration menu and was amazed at what I found. The previous owner had almost identical lens collection to mine and calibrated each accordingly. These calibrations were MASSIVELY different to mine. I re-calibrated all my lenses and all soft/ out of focus areas were eradicated. Although I calibrated my 70-200, when I then matched it with my 2x converter, I found that it was much softer than normal and front focussing. I had to create a separate profile for the two separate optics. Maybe some of you posters might like to try a recal with lens and converter just to see if it’s mismatched in any way. I am usually pretty good when it comes to focus, but this one stumped me for a while til I realised my own

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