Help/info needed please

[squitty]

Hi,

If I put a Teleconverter on a Sigma 70-300mm APO DG would it work or would I lose the auto focus? Its on a Canon 400d.

Neil

 

[Garnock]

It all depends on the max aperture of the lens.
eg With a 1.4xTC you will lose one stop of light, meaning a max aperture of f5.6 will become f8 in which case your 400D will lose AF.

There are ways around this but that's another story.

 

[squitty]

Oh tell me more, I like a good story

Thank you for the reply.

 

[Garnock]

Oh tell me more, I like a good story

Thank you for the reply.

The old tape trick.
Cover the 3 pins on the TC and you're sorted.
http://www.allensphotoblog.com/blog1/2006/12/the_old_tape_trick.html

 

[squitty]

Thank you for the link will give it a go.

Neil

 

[pxl8]

It also depends on if the TC is reporting itself or not. Some don't so AF keeps working albeit slowly.

 

[squitty]

I was just going to ask will this work on all converters?

Neil

 

[andrewc]

depending on the tc it may not fit the lens