Canon 50mm f1.4 plus Tamron 1.4X converter vs. 85mm f1.8

[bmpress]

Bob, Can you comment on the merits of using the Canon 50mm f1.4 with the Tamron teleconverter vs. the Canon 85mm f1.8 which you recently reviewed.
I already own the first two and wonder if I would gain anything by acquiring the 85mm.
Thanks

[Bob Atkins]

I've not used the 50/1.4 + 1.4x Tamron TC so I can't really comment directly. You'd get a 70mm f2 lens rather than the 85mm f1.8, so it would be slighly shorter and slightly slower.

Though I have no hard data to back this up, I'd bet the Canon 85/1.8 would be sharper, and probably significantly sharper at the edge, especially at wider apertures. I'd also expect AF to work much better with the 85/1.8 than the 1.4x + TC combination. I do know that the 85/1.8 + Tamron 1.4x gives decent image quality, but it won't AF properly for me either on a 40D or 5D. I think the focus on that lens is so fast that it overshoots with the TC added. You're in a better position to comment on AF than I am since you own the 50/1.4 and TC.

So if you do a lot of shooting at around 80mm, the 85/1.8 might be a wise choice. If you just occasionally shoot in that range and don't often need fast AF and high edge quality with the lens wide open, what you have may be "good enough". Only you can judge that.

[John Hanlon]

I just tried my 50 f/1.4 with a Kenko Teleplus Pro 300 1.4X mounted on a 5D, indoors. The AF hunts back and forth for a couple of seconds before locking on. Useable, but no substitute for my 85 f/1.8 which focusses instantaneously even in low light. Also I don't think the extra 20mm in focal length is very significant, you can achieve the same result with a 50mm by simply moving in a little closer. Given that a decent third party 1.4X costs around $200, I think you would get better value and performance with the 80 f/1.8 for $370.

[bmpress]

I suspected as much from the combo. Thanks for both responses.