Do we still need a TC?

Started Nov 11, 2013 | Discussions thread
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Alastair Norcross
Veteran MemberPosts: 5,119Gear list
Re: Do we still need a TC?
In reply to MightyMike, Nov 11, 2013

MightyMike wrote:

awaldram wrote:

MightyMike wrote:

Alastair Norcross wrote:

awaldram wrote:

Anastigmat wrote:

If your lens is f/5.6, a 2x teleconverter requires manual focusing, Unless you focus correctly, you won't get a sharp image.

Only if you own a Canon, a Pentax will Auto focus an f5.6 + 2x converter with ease.

Really? A Pentax will perform phase-detect auto focus with a lens whose widest aperture is F11? I didn't know that. How fast is it?

Actually things have changed... It used to be (K10D to K-5) F8 with ease, F9 with little issue and F10 was pushing your luck, F10.7 only in the most extreme cases. When the K-5IIs came out F9 started to become a lot more difficult to focus... I don't think the K-3 has been fully tested for this yet.

K3 , 50-500 f6.7 + 2x converter

F 13.4 = no issue

Nothings changed as far as I can see maybe you need better quality converter ?

Sorry about subject matter but it's dark out and hand holding 1000mm Auto focusing indoors take some light.

Confirmed... i tried focus trap at F11 with one and 2 1.4x TC's on mirror lenses and it does focus trap! Sorry i don't have a 2x TC or a lens that is slow that would accept both 1.4x TC's as the one is the Sigma with protruding element. I bet Ron could do a heck of a lot more testing

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Mike from Canada
"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."
'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'

So, just to be absolutely clear, these are using phase-detect AF, not live view AF? So everything I read about the PD AF system needing lenses with a maximum aperture of F5.6 or faster in reviews of the K5 and K5II was wrong? Or is this with a non-reporting TC? What is the AF speed like?

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