Petal vs. round lens hoods

Discussion in 'Canon EOS' started by nail33, Jun 24, 2007.

  1. I've tried searching here for an answer to this question but to no avail. It's a
    newbie question, so please excuse me if it's stupid. What's the advantage of a
    petal style hood vs. a round hood? I have noticed that petal style hoods (4
    blades) are positioned vertical and horizontal to the camera body. I assume this
    is so you can take a picture vertically or horizontally with one of the petals
    always being directly overhead so as to block out the light source from above
    (to prevent glare or CA?). But what if the light source is 45 degrees to the
    subject where the petal style hood is at its minimum protrusion. Wouldn't a
    round hood work better at all light source angles provided both style hoods have
    the same depth? I'll thank you in advance for your responses. I've posted other
    questions here before and you have all been very helpful. Thanks.
     
  2. Start with a petal hood designed so that at all points around it's circumference the outer edge is projecting as far as possible. To revise it to be circular all of the petals would have to be trimmed off, back to the low points.

    Any time you have a square or rectangular picture the petals are more efficient. only with a round picture (say with a fisheye lens) would there be no advantage to the petals.
     
  3. a general rule is that round hoods are for lens where the front rotates during focusing, i.e EF-S 18-55, and petals are for lens such as EF-S 10-22 where the front does not rotate.
    Petals give the most coverage that they possibly can without showing in the photograph, and round hoods do as well, but as they are designed to rotate with the front of the lens, there are, and cannot be a specific 'corner' to the hood as it will sometimes show up at the edges of the photograph, depending on what position the front of the lens is in.

    with regards to what is better, it depends what lens you want to use it on. For maximum benefit, always buy the dedicated hood for your lens.


    Jim
     
  4. The thing I don't like about the petal hoods is that they are made out of plastic. I worry that one day I might step on one by mistake. The circular hoods, the rubber collapsible types are very convenient for travel, but not as good as the petal hoods from what I understand.
     
  5. Petal shape stops mattering once you get to a reasonably long focal length. The ES-71 hood for the 50/1.4 is round, but it is a bayonet hood that could have been made petal-shaped.
     
  6. Here's an excellent article about hoods that answers your questions and gives a lot more information too:

    http://www.vanwalree.com/optics/lenshood.html
     
  7. Hmm ... some interesting and "creative" responses here ... very imaginitive.

    My understanding is that petal hoods are required for wide lenses, to prevent vignetting in the corners. "Round" hoods (no corners cut out) are for longer lenses, where the field of view is small enough that vignetting is not a concern.
     
  8. Lessee: I've got Canon lens hoods for a 50mm f1.4: it's round, and a 70-200 f2.8 L IS: it's petal design.
     
  9. Mendel, yes my 70-200 also, a number ET-86. My 100-400 has a round hood number ET-83C
     
  10. `Hmm ... some interesting and "creative" responses here ... very imaginitive`

    I gotta agree with you there Jon, lens design and vignetting is the way I`ve known it and mainly for wide angle or the widest end of shorter FL zooms. I do use a Sigma 15 30 which has a permanant fixed petal hood, this lens improves significantly by putting on the aux round hood when used on a x1.6 crop body eg 20d/30d as the FOV is different, flare is reduced and contrast improves, so I`ve found that some lenses can use both without vignetting because of the crop factor.
     
  11. My understanding is that petal hoods are required for wide lenses, to prevent vignetting in the corners.
    Well, it's perfectly possible to make a circular hood that will avoid vignetting on a wide-angle lens. But the thing would be huge. If you take a circular hood and squash it so that its shape more closely matches the 3:2 aspect ratio of the frame, that would be a good start. Now make it more compact by trimming off the corners, which are the largest parts, and what you're left with is pretty much a petal-shaped hood. You see, there is indeed a method to the hood designers' madness: it's a good combination of effective flare control and compact size.
    The thing I don't like about the petal hoods is that they are made out of plastic. I worry that one day I might step on one by mistake. The circular hoods, the rubber collapsible types
    If you step on the plastic hood while it's attached to the lens, the hood will absorb much of the force of your step. It will likely break, but all of the energy that goes into breaking it is kept from breaking the lens. If you step on a rubber collapsible hood, it will collapse immediately, and virtually all of the force from your foot will be applied to the lens. I don't know about you, but if I were to step on a lens with a hood attached, I'd much rather break the hood than the lens.
     
  12. Yeah, come to think of it the super's are all (built-in) circular hoods.
     
  13. I guess the message I take from this post is not to step on lenses.
     
  14. Thank you all so much for all your answers and input. I realized from the first response that I should have thought a little bit more before I posed this question. It never dawned on me that you would of course have to have a petal shape on the outside of the lens when going from a round image (lens) projected onto a rectangular surface (sensor). That's what happens when I ask a question before I really think it out. Some things are so obvious that you can't see them until someone else points them out. You guys are the best and this site is a great place for information. Thanks again.
     
  15. Well, often one person has to stick their neck out and ask the question. And a lot of times those answering are just thinking it through as they answer. In other words, we all learn.
     

Share This Page