Canon SX50HS v Nikon P510 v Sony DSC-HX200v

Subject: Canon SX50HS v Nikon P510 v Sony DSC-HX200v
From: "Ákos Lumnitzer" <>
Date: Fri, 5 Apr 2013 12:55:04 +1100
Hi Bob

While I cannot comment on compact cameras as I never use one for bird
photography, I would like to clarify one small point with regards to the
AF system of Canon cameras. (do seriously consider a DSLR with a good
prime lens though, compact cameras just don't rate for serious bird
photography in my opinion)

All Canon DSLRs will autofocus with all available and selectable AF points
at a maximum aperture of f/5.6. Therefore, if you put a 300mm f/4L IS USM
lens (which I personally own too) and add a 1.4x converter (meaning a loss
of one stop of light) you get a 420mm lens (300 x 1.4 = 420) with an
aperture of f/5.6. This means that any Canon DSLR will autofocus with all
AF points, including the 7D. There are millions (likely) using the 7D
around the world with a myriad of lenses and if it were only to have the
one available AF point (the center one) then the sales would diminish very

Although if you were to put a 2x converter on a 300mm f/4L IS ISM lens it
would be a 600mm f/8 lens due to the extra glass (being the 2x converter)
causing a loss of two stops of light. Then you would only get manual

However, Canon's 1D series use only the center AF point when a lens with a
maximum aperture of f/8 is attached (from this month I believe the 5D
MkIII will also have the AF at f/8 feature enabled).

For example my 500mm f/4L IS USM lens coupled with a Canon EF 2x converter
(making it a 500 x 2 = 1,000mm lens). Because the 2x converter costs a
loss of two stops of light it means that my lens becomes f/8 not f/4. It
sounds complicated, but it is quite simple once this basic concept of
measuring light in stops is grasped.

Best wishes with your bird photography.

Akos Lumnitzer


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