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05-17-2012, 04:56 PM   #1
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Lens hood questions

Is there any advantage/disadvantage with lens hoods that are of the "flower petal" design or the older "tube" type?
Thanks for any advice,
Dewman

05-17-2012, 08:06 PM   #2
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Standard hoods work great(I currently use 3), but certain lenses need the flower petal design to avoid vignetting. At 18mm, my Sigma lens can see the hood if I turn it out of the locks.
05-18-2012, 02:40 AM   #3
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Cut-Away?

Hi Dewman,
Manacho is right, the wide-angle zooms + primes need a little more "space" on the sides of the hood to avoid cutoff or vignetting. If you notice, most of the petal-types are uneven lengths, the longer "petals" go on the top + bottom, the shorter ones on the sides. Many of the OEM hoods are the click-on bayonet type, not screw-on. That's so they will only fit on in this orientation.
My understanding is the long cutaways between the petals is so you can rotate a polarizer with the hood in place. In practice this is pretty difficult to do. Pentax also has some hoods with a little removeable section, sort of a hatch, to get at the polarizer without removing the hood. Easy to lose that little piece when it's off the hood!
Once you get longer than the normal focal length of 35mm-50mm I believe the regular tube hoods work just as well. I use screw-on tube-types on all my telephoto primes and zooms from 50mm and up.
Ron
05-18-2012, 10:55 AM   #4
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Sensors are not round - or square. They are longer than they are wide. That's the basic reason that petal shaped filters make sense. The rest is just details based on that fact.

05-18-2012, 11:03 AM   #5
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QuoteOriginally posted by Dewman Quote
Is there any advantage/disadvantage with lens hoods that are of the "flower petal" design or the older "tube" type?
Thanks for any advice,
Dewman
A properly designed flower petal hood offers the maximum protection, because the petals if shaped for the lens exactly, would be just outside the field of view of the lens, therefore not impacting at all the performance but providing from any angle the best protection against flare and loss of contrast. in practice however, with the exception of wide angle lenses where the field of view is quite wide, a cylindrical hood is good enough for most situations.

Note that flower petal hoods MUST be attached to the lens body, not to the front element, for the cases where the front element rotates. either during focusing or zooming.

also note for zooms, the petal cut out is for the widest focal length,
05-18-2012, 11:24 AM   #6
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And a side note: Sometimes we reverse lenses for close work, not necessarily macro (1:2 / 0.5x or greater magnification) but just to get close. And sometimes even reversed lenses need hoods. A reversed prime with a working distance around 4.5cm / <2in doesn't leave much room for a hood.

But a reversed ZOOM (with an aperture ring) may have a much greater working distance, and may even focus to infinity when reversed. My 35-80 and 28-90 etc zooms can reach infinity at around 75mm; I haven't experimented with longer zooms. Hmm, let's fix that... [/me slips on a Samyang 70-210] Ah, this reaches infinity focus at around 100mm (reversed). Killer bokeh too!

So, how to hood a reversed lens? Taping a piece of paper around the front-facing lens base is rather inelegant. But salvation is at hand! The trick: use macro tube sections as lens hoods. That's another reason to keep extra macro tube sets around, in M42, PK, maybe Nikon if you're reversing any AI zooms.
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