Extension tube calculation

Home · Register · Search · Software · Hosting · Software · Join Upload & Sell

FM Forum Rules
Canon SLRs, primes, and zooms lenses reviews

FM Forums \| Canon-mount SLRs \| Join Upload & Sell
end

Tom Kelley
Offline
• •
Upload & Sell: Off

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
Offline
• • • •
Upload & Sell: Off

p.1 #2 · Extension tube calculation

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

Nov 26, 2012 at 06:25 PM

Wobble
Offline
• • •
Upload & Sell: Off

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
Offline
• •
Upload & Sell: Off

p.1 #4 · Extension tube calculation

Thanks everyone.

Nov 26, 2012 at 07:00 PM

end
FM Forums \| Canon-mount SLRs \| Join Upload & Sell end