Telephoto 1.4 or 2.0 extender

edited June 2015 Posted in » Canon T5 / 1200D Forum
I'm a two year beginner in taking band photos at our local high school with my T5 and would like some extra focal length for my 300mm and 400mm Sigma lens. Do you recommend the telephoto 1.4 or 2.0 extenders? Would the added weight be bad for the existing mounted lens?


  • edited February 2016
    I doubt the weight will be a problem if the lens is not, but I would suggest that unless you really need the extra length you stick with 1.4. It's likely to be sharper, and a 1.4 extender changes effective aperture by only one stop,.while the 2.0 changes it by two stops. In other words, if you have an f/5.6 lens, a 1.4 extender will make it f/8, and a 2.0 will make it f/11. Most modern cameras will autofocus still at f/8, but slower than that will make AF difficult, as well as causing a pretty dim viewfinder.

    Back in film days, the general rule was that, despite image softening, a tele extender was almost always better than a crop. Nowadays with sharp lenses and sharp sensors, you may find that at some point you're better off cropping than extending. I don't know the quality of your lenses and sensor here, but in my quick and dirty testing, I found that a good matched 1.4 extender on my needle-sharp 400mm f/5.6 lens, used on the 24 megapixel Nikon D3200, was about a wash with the 400mm cropped to the equivalent of 560mm. But for greater crops, the extender starts to gain if it's a good one.

    In another test, a decent but unspectacular 2.0 extender that I used to find useful on my 80-200mm zoom in film, and which gave me a pretty decent 400mm on that rig, was not as good as simply cropping on a sharp digital sensor.
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