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View Full Version : LENS/CONVERTER QUESTION...

Steve Parr
7th of March 2005 (Mon), 20:28
If I have a f/3.5 lens, and put a 2X converter on it, does it effectively make the lens an f/7?

Not looking to actually do it anytime soon; just wondering...

Steve
Belmondo
7th of March 2005 (Mon), 20:33
Teleconverters will cause a loss of light through the lens. The Canon 2X TC will cause the lens to lose 2 full f/stops. That will effectively halve the aperture of the lens in question, so in the example you give, the answer would be yes.
Steve Parr
7th of March 2005 (Mon), 20:38
As suspected.

Thanks!

Steve
Andy_T
8th of March 2005 (Tue), 06:27
Even if there is no loss of light, the f/stop is the relation of focal length and opening.

So if you double the focal length, but the opening stays the same, you lose an f-stop.

Best regards,
Andy