Originally posted by ElJamoquio I don't need the (lack of) DOF of a 560 f/4. I do want the autofocus performance of an F4 though, and I would like to be able to AF with a T/C. I don't really agree with your f8.9... sure Pentax will A/F there but really it's a slow and inaccurate process.
it is F6.9 not 8.9 pentax wont reliably AF at F8.9, i know, Ive tried by using a 1.7x AF TC on an F5.6 lens, it just wont lock ever. but at F6.9 (by using my 1.7x AF TC on a K300/4) it is fast and reliable even in relatively low light.
Quote: The brighter screen is a welcome bonus but not required.
agreed on both counts
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I hope they use an intermediate/rear filter like most other lenses this size do. I'm not sure what 500/f4.5 you're talking about but the sigma 300 f/2.8 and the sigma 500 f/4.5 use rear filters..
Tamron offer both options, rear and front on their 300/2.8
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I think it's been announced that's it's a 5.6, but I could be mis-remembering.
F5.6 would lead to a front attachment thread size (if they offered) of about 112mm. which is why I think they will remain somewhere in this range..