Quick TC question

ESiggins

If I use a good quality, AF teleconverter with a fast-focusing lens, will it effect AF speed? Does it make a diference if the lens has an internal focusing motor? Any experience with specific combos would help. Thanks,

Fred.

ziggy53

ESiggins wrote:

If I use a good quality, AF teleconverter with a fast-focusing lens, will it effect AF speed? Does it make a diference if the lens has an internal focusing motor? Any experience with specific combos would help. Thanks,

Fred.

The quick answer is that yes, it will negatively impact focus speed.

A 2x converter will reduce the light throughput by 2 stops, while also reducing contrast and resolution. That combination of factors has a dramatic effect in low-light with low contrast and "soft edged" subjects. Some consumer lenses loose autofocus capabilities with a 2x teleconverter on the lower level camera bodies with less AF sensitivity.

On the other hand, I can verify that a Canon 70-200mm, f2.8L, on a Canon 1D MKII, using a Tamron 1.4x "F" teleconverter is hardly affected at all, even in low-light. (A Canon 1.4x teleconverter would probably be better still, but for what I use a TC for, the Tamron is fine.)

ziggy53

ESiggins

Thanks again, Ziggy. I kinda figured that good glass + a good TC would function better, but I just wanted to know if it's an absolute rule like the light loss. Anyone else have combos they can describe??