lens question.

[jnsuffolk]

70-200mm f4 l lens. Would it work well with a 2x converter. I will be shooting on sunny days with it wildlife

[Padre]

You will lose two stops of light, but I'm not quite sure about the quality difference. I suppose quality will suffer a bit. It depends on what your intended purpose is with the images. I use a 1.4 on mine and it performs beautifully. Here's an example from a recent trip to Colorado. I printed a 13 x 10 of it and it is great office art!

[brian.austin]

As Padre noted, you'll turn your 70-200/f4 into a 140-400/f8 lens. If it's bright & sunny, sure, the lost stops won't be that big of a deal...unless you want to adjust your depth of field at all.

I find the quality of the Canon 2X TC to be a bit soft, however. Optically, the 1.4X TC is considered a better choice. You can always crop and enlarge in post if it's not too far away.

[Imagesgranted]

i would only want to use the 1.4 x convertor would only loose one stop of light that way and as far as i can see less i.q loss.

[richardpcrowe]

The 1.4x will cost you a stop but, will keep autofocus capability and will also provide very good IQ. I have no hesitation using my 1.4x Canon TC on my 70-200mm f/4L IS lens.

The 2X will cost you two stops and transform the lens into one with a maximum f/8 aperture. The Canon 2x TC will severely hamper auto focus on 1.6x cameras (you need to tape off pins in order to autofocus at all) and will degrade the autofocus when using a non-Canon TC and/or when using a full frame camera. The IQ will also be degraded.

Whether you opt for using the 2X TC in order to increase your focal length to 400mm depends solely upon your critical desires for autofocus and image quality.

IMO, the 2X TC transforms a superlative lens into a mediocre glass.

I have used a borrowed Kenko 2X TC at one time and I get far-far better IQ and auto-focus quality from a 400mm f/5.6 Tokina ATX, for which I paid less than $125 (including shipping) on eBay.

If 400mm is your absolute need, haunt eBay and the used equipment sections of various forums (such as this one) and wait for a Tokina 400mm f/5.6 ATX SD. You should find one for $150 or less. Don't get the previously issued 400mm (non-ATX) SD lens because the IQ from that lens is not all that great.