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Taped Contacts - 1.4 X

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Author Topic: Taped Contacts - 1.4 X  (Read 367 times)
brianb
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« on: June 19, 2009, 11:44:02 pm »

Ummm, it doesn't make the lens a stop faster, it just means the camera believes the lens to be a stop faster.

Similar things happen when you stack tele-extenders - if I use both 1.4x & 2x extenders on a f/2.8 lens the camera believes the lens to be working at f/5.6 rather than at f/8, the autofocus "functions" but is slow & inaccurate. Switching to manual focus is a big improvement - for me - but then I'm not chasing objects which vary their distance significantly. But the biggest problem with stacking extenders is that the 1.4x has to go next to the camera, put them the other way round and the mount on the 2x hits the glass in the 1.4x and will mark it.

I know of one "pro" who regularly uses two 2x extenders and apparently gets acceptable AF performance, but he's using 1 series bodies which have significantly better AF sensors than the cheaper versions.

You need to be really careful with taping over contacts; if you get the tape too thick the contacts in the body can be displaced so that they don't make proper contact when you would like them to, you will them probably get "error 99" or "error 1" and the camera will lock up when you try to fire the shutter.
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