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Title: Going for a Tamron SP 500 f/8 Post by: wallybarthman on April 16, 2011, 12:53:20 PM Bob - based on your article on mirror lenses I picked up a Tamron SP 500mm f/8 lens off of KEH for 189 (Excellent Condition) and a Adaptall to Canon EOS with AF Confirm. My question is this - will I be able to use my 1.4 and 2 converters (locked in place) with this lens since I got the AF confirm model? According to what I've read it will report EXIF data (50mm, 1.4 aperture which will be wrong) so I am thinking it should work fine.
Title: Re: Going for a Tamron SP 500 f/8 Post by: Bob Atkins on April 17, 2011, 01:35:21 PM Probably not. The 500/8 itself doesn't give very good AF indication even on it's own when used with a focus confirmation adapter. At f8 it's really too slow since Canon's AF system on all but a few of the pro level 1D series cameras requires at least f5.6. With a 1.4x it's f11 and with a 2x it's f16 so the focus confirmation adapter is highly unlikely to produce a confirumation signal.
Title: Re: Going for a Tamron SP 500 f/8 Post by: wallybarthman on April 18, 2011, 05:41:34 AM I should have been more clear - I figured the AF confirmation wouldn't work. What I meant was when I've used FD adapters I've found that the converters don't work if the lens is completely in place. What I meant to ask is whether with this lens and the AF confirm adapter if I'd be able to use it with a teleconverter since (and I'm assuming here) that the AF confirm adapter will trip the microswitch.
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