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08-18-2015, 03:14 PM   #31
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QuoteOriginally posted by audiobomber Quote
Rectangular lens elements would show the same image as round, assuming the square element could be manufactured with similar distortion
They can't, Anamorphic lenses are profoundly weird - their flare characteristic is from a visual perspective, inherently more distracting than spherical lenses due to the geometry of the lenses. The matte boxes used for cinematography purposes are always an extendable rectangular bellows.This extension is important for managing stray light, as ruining several hundred feet of film is a bigger catastrophe than a single 35mm frame. Standard aspect ratio for these matte boxes is 16:9 - though cinematographers use front mounted masks for exotic formats like 5:4, 4:3, 2:35.1(CinemaScope) and 2:39.1


Last edited by Digitalis; 08-18-2015 at 03:56 PM.
08-18-2015, 03:34 PM   #32
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QuoteOriginally posted by Ontarian50 Quote
While rectangular or petal shaped hoods are better at shading, there's a whole pile of lenses out there that just can't use them.
Any lens with a rotating front has to use a round hood - otherwise the corners of the rectangle or petal would be misaligned most of the time (aside from looking silly).
Actually a bayonet hood that clips to the outer lens body might be fitted to a lens where the front element turns. In that case it would be possible but strange.

I get your point though. There are many lenses with filter thread mounted hood that have rotating front elements. Round is the way there.
08-18-2015, 03:54 PM - 1 Like   #33
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Any hood that can't keep OFF-axis light off the front lens surface is of little or no use.

Any hood that does prevent unwanted light from striking the lens front surface is useful to some degree or another -- usually it's beneficial.

The only useful hood for a zoom lens is only useful at the widest FL regardless of the design if it doesn't vignette. Vignetting is OK if it's necessary for zoom use.

Any lens shade, from any source, works as well as the best, most expensive hood regardless of the design. My HAT works as well as the best hood!!

Use one -- makes NO difference where the shade comes from.



IMO, of course; but from half a century of practical experience.
08-18-2015, 10:41 PM   #34
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QuoteOriginally posted by Digitalis Quote
They can't, Anamorphic lenses are profoundly weird - their flare characteristic is from a visual perspective, inherently more distracting than spherical lenses due to the geometry of the lenses. The matte boxes used for cinematography purposes are always an extendable rectangular bellows.This extension is important for managing stray light, as ruining several hundred feet of film is a bigger catastrophe than a single 35mm frame. Standard aspect ratio for these matte boxes is 16:9 - though cinematographers use front mounted masks for exotic formats like 5:4, 4:3, 2:35.1(CinemaScope) and 2:39.1
Cinema lenses, though, have virtually no issue with vignetting near the edges. It's one of the massive differences between still and cinema lenses. The ideal matte box shape for a cheeks lens might not be the same as the ideal shape of a hood with vignetting issues.

08-18-2015, 11:16 PM - 1 Like   #35
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QuoteOriginally posted by audiobomber Quote
Why don't you explain it to me?
You didn't seem to have read the link other have provided, otherwise you have a clue why the petal hood is designed like it is.
08-19-2015, 03:01 AM   #36
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QuoteOriginally posted by fuent104 Quote
Cinema lenses, though, have virtually no issue with vignetting near the edges
But many of them have issues with Chromatic aberration, LoCa,distortion, and Vignetting - sometimes the principal photographer makes artistic use of it and deliberately provokes it.
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