Extender for Ef 70-300mm lens

KWL58 — Sat, 24 Aug 2013 16:18:34 GMT

Does anyone know if Canon makes an extender for my EF 70-3-- f/4.5-5.6 DO IS USM lens? I would like the auto focus to be maintained. My camera is a T5i I would love to get a little more range out of my lens. Thanks Kate

Re: Extender for Ef 70-300mm lens

TCampbell — Mon, 26 Aug 2013 15:17:28 GMT

No.

The issue is the focal ratio at 300mm. Whenever you consider an extender (such as a 1.4x or 2x) you not only have to multiple the focal length of the lens by the extender factor... you also have to muliply the focal ratio as well.

E.g. a 300mm f/5.6 with a 1.4x extender would become 300 X 1.4 = 420mm but the focal ratio becomes 5.6 X 1.4 = f/8.

The problem with this is that almost no camera can focus at f/8... it's too constrained for the AF sensors to work properly. A few cameras can handle it (even though it's not ideal) such as the 5D III and 1D X -- but those are high-end bodies. A T5i wont do it.

Usually a 1.4x extender can be used with a lens if the lens' focal ratio is f/4 or below. A 2x extender needs a lens focal ratio of f/2.8 or below. BTW... even if a lens qualifies the extender still might not work. Canon lists the lenses compatible with their 1.4x and 2x extenders and you'd ultimately need to make sure your lens is on the list.

The Canon EF 100-400mm f/4.5-5.6L IS USM is going to approximately provide the range that you'd get from a 70-300mm with a 1.4x extender, but that's few hundred more than your current 70-300mm DO lens.

And then there's the new EF 200-400mm f/4L IS USM Extender 1.4x which has a built-in extender. Every owner/user waxes poetic and praises the virtues of this lens.... everything except for the price tag (NOT an inexpensive lens.)

Re: Extender for Ef 70-300mm lens

KWL58 — Mon, 26 Aug 2013 15:51:14 GMT

Thank you. Your explaination really helps. Guess its time to start saving for the 100-400mm lens not the one with the extender...thats soo far out of my budget. lol thanks again, Kate

topic Re: Extender for Ef 70-300mm lens in EF & RF Lenses

Extender for Ef 70-300mm lens

Re: Extender for Ef 70-300mm lens

Re: Extender for Ef 70-300mm lens