Lens Hoods (Quick Q)

One of these... Shades the lens from harsh light.

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While we're at it, something I've always wondered: why are some the butterfly shape vs. the regular cylindrical shape? I've thought it over and I can't think of any reason why, but I'm probably missing something stunningly obvious.
 
Ah, I get it—it's because the aspect ratio of sensors/film is wider than it is tall, making the angle of view greater in the horizontal than the vertical. Makes sense.
 
robmiller said:
Ah, I get it—it's because the aspect ratio of sensors/film is wider than it is tall, making the angle of view greater in the horizontal than the vertical. Makes sense.

Ahh, correct, learn something new everyday :)
 
alexisonfire said:
Yeah, petals are used for short focal lengths so that you can't see the edge of the hood in the corners of the photo i think.

the 70-200 2.8 is a short focal length?

Its a more efficient design of hood as the design accounts for the rectangular shape of the sensor. It gives a greater protection against flare than a circular hood.
 
xolotl said:
the 70-200 2.8 is a short focal length?

Its a more efficient design of hood as the design accounts for the rectangular shape of the sensor. It gives a greater protection against flare than a circular hood.

Correct. :)
 
Also on lenses where the front element rotates when focusing, a petal type would be a pain in the backside so a round hood would be the better hood...
 
FranchiseJuan said:
Actually one of the reasons for a petal style lens hood is so you can reach in and turn a circular polariser.

Just a coinsidence tbh. If you look throught the viewfinder with the lens on its widest focal length, and trace the edge of the hood, it will appear to form a rectangle the same size as the field of vision.

Tonks said:
Also on lenses where the front element rotates when focusing, a petal type would be a pain in the backside so a round hood would be the better hood...

Cheaper lenses do this, the more expensive, better ones tend not too. meaning that the petal ones are infact the better design.
 
woodsy2k said:
Nearly all lenses dont rotate when zooming I thought? It's the focusing that tonks was talking about? or are we barking up different trees :o

Thats what i meant, my bad.

My 28-105 don't rotate when focusing, but my kit lens does.
 
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