USED 70-200 VRI with NEW 2xTCIII

Started Apr 1, 2013 | Discussions thread
slimandy
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Re: USED 70-200 VRI with NEW 2xTCIII
In reply to aquarian light, Apr 4, 2013

aquarian light wrote:

slimandy wrote:

aquarian light wrote:

slimandy wrote:

aquarian light wrote:

If I won the lottery tomorrow I'd buy the sexy sigma 120-300 2.8 and put a kenko 1.4x on it. mmmmm 630mm f4. only in my dreams.

You won't have a 630mm f4, you'll have a 420mm f4. You can use it in DX mode to get the equivalent of a 630mm f5.6.

I wouldn't get Kenko for a Sigma lens though. Get Sigma. And only the 1.4x.

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www.andrewsandersphotography.co.uk

you most certainly would. dropping into dx mode dosn't lose you another stop of light.

It doesn't get you a longer lens either. Just a crop.

1.4x converters lose one stop.

300x1.4=420 *1.5-630 only losing one stop off the f2.8. a 2.8 lens is a 2.8 lens on both fx and dx. I'd have a 252-630 constant f/4 zoom.

Nope. You still have a 168~420mm f4 which is the equivalent of 252~630 f5.6 when used on DX.

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www.andrewsandersphotography.co.uk

*facepalm*

Your error is a common one as can be seen in this thread, but there are enough people chipping in with explanations as to why the equivalent applies to the aperture as well as the focal length (if you are actually interested).....

http://www.dpreview.com/forums/post/51203390

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www.andrewsandersphotography.co.uk

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