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Archive 2012 · Extension tube calculation
  
 
Tom Kelley
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p.1 #1 · Extension tube calculation


How do i calculate the ratio on an extension tube? I have an 18-55 IS Canon and a 55-250 IS. I'm interested in the Kenko set from B&H with three different tubes.


Nov 26, 2012 at 06:00 PM
15Bit
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p.1 #2 · Extension tube calculation


https://www.google.no/search?q=macro+tube+calculator


Nov 26, 2012 at 06:25 PM
Wobble
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p.1 #3 · Extension tube calculation


"An extension tube increases lens magnification by an amount equal to the extension distance divided by the lens focal length. For example, adding a 25 mm extension tube to a 50 mm lens will give a magnification gain of 0.5X. Therefore, if the lens's original magnification was 0.15X, then the new magnification will be 0.15X+0.5X=0.65X. The closest focusing distance will also decrease to ~210 mm."

Use the link below to get to a calculator for your lens' original magnification.

Quoted from Cambridge in Colour



Nov 26, 2012 at 06:26 PM
Tom Kelley
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p.1 #4 · Extension tube calculation


Thanks everyone.


Nov 26, 2012 at 07:00 PM





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