You know when you're looking to buy a car and all of a sudden you start seeing that same car everywhere you go...not because there are suddenly more of those cars on the road, but because you're paying more attention to those specific cars. Well, for the last year, I’ve been checking out everyone and anyone who has a DSLR camera on them and what goods they have...maybe hoping one of them will hold the key to helping me take more professional and crisp looking photos. I haven't learned anything earth shattering from that yet...darn! What I have noticed is that many of them have different lens lengths, depending on what they're shooting, but they also have these (sometimes elaborate or funky) lens hoods. Because I've been so distracted with camera brands and lens types, I haven't put much thought into the lens hoods until recently.
Do I have to have one?
I have figured out that it's not a requirement to use a lens hood, but there are some very good reasons why photographers do use them. Apparently, more expensive lenses come with a lens hood included...as they should! You will most likely have to purchase one separately if you buy a less expensive lens. (Most lens hoods costs around $30.)
So, what purpose does the hood serve?
Purpose #1: The primary use for a lens hood is to prevent harsh light from hitting the front of the lens at an angle causing reduced contrast and annoying flare in your photos. (If you have no clue what flare means, look at the very bottom of this post for info.) Photos taken with a lens hood can avoid flare and result in a photo with richer colors and deeper saturation. I have many pictures I’ve taken with flare in them, not even knowing that was causing it!
Purpose #2: A secondary reason to use a lens hood is to protect the lens. Lens hoods are pretty strong and stick out from the lens some distance. Accidentals such as fingerprints and scratches to the front of the lens are drastically reduced because the glass is more difficult to reach with a lens hood. I have also found mine to be handy when I’m changing lenses. I can stand one lens up on its hood without a lens cap on while I’m taking the other lens off my camera. Is that a bad habit? I don't know yet. :-)
Also, some impact protection is gained from having this tough plastic hood take the blow if your lens is dropped. Although, ultra-wide angle lenses might not be as protected, as they have very short hoods that offer very little protection. Lens hoods on longer focal length lenses offer more front lens protection, which tends to be useful to avoid rain and dust damage. A clean and dry lens will allow the camera to deliver a better photo, which is what we're all trying to achieve here right? .
Plus, as I'm sure you already know, your lens is a lot more expensive than the cost of a lens hood, so it’s important and definitely worth the money if you’re protecting a lens worth hundreds of dollars. (Case in point, on Halloween, I was chasing after the toddlers in my family - snapping shots of them trick-or-treating, when all of a sudden my lens came right off the front of my camera…don’t know how that happened, but luckily my lens was okay.). Major bummer though, and a few seconds of no breathing!
What Size Hood Do I Need?
A wide, long hood is a better choice than a narrow, short hood. This is partially because of a term called Vignetting, where the outer edge of the photo is blurred and/or darkened, which can pretty much ruin your image. At its worst, vignetting can leave your photo with sharp black corners. However, if a lens hood is just slightly too long, it can cause a gradual corner darkening in a similar fashion as natural and optical vignetting.
How Can I Tell if My Lens Hood is Too Long?
Most companies sell specific lens hoods for each lens width and length. Although, if you have a lens that is regularly used at various apertures, it will require hood adjustment from time to time. One way to test for the right hood length is to take a series of photos - a minimum of four (4) shots. You will want to find an object and/or subject that is evenly lit from far away, as vignetting happens more at long distances tan close-up. (One site suggests: a brick wall on an overcast day.)
Of the four (4) test shots that are fired, two (2) at the lens' full aperture (with and without the hood) and two (2) at the smallest aperture (again with and without the hood). If the pictures taken with the hood in place result in no corner darkening, in comparison with the pictures taken without, you are safe. Black corners however are not a good indication that the hood is right for your specific lens.
What Shape of Hood Should I Purchase?
Obviously, a circular lens hood has the same shape as the lens. However, the round image is not fully used as the camera crops the image to a rectangular section. This is important for lens hood design, and thus the most effective lens hood is not round. Both the tulip hood and the rectangular hood are more effective than the round hood, not only because they are longer, but also because their shape is more similar to the shape of the sensor.
No Hood
Circular Hood
Tulip Hood
Rectangular Hood
Although the tulip hood is very effective, it is larger in size and more difficult to fit in the camera bag. However, the two longer petals can be clipped to yield the chopped tulip hood below, which will likely be easier to fit in your camera bag. I've seen more small business photographers utilizing tulip lens hoods or chopped tulip hoods, than round. I've also noticed that more of the larger lenses (like those operated by sports photographers) use a round lens hood, instead of a tulip or rectangle lens hood.
Chopped Tulip Hood
The 'chopped and capped' hood below is sort of a compromised version of the tulip lens hood. It works great for people who don't need a long lens hood and still works great against flare.
Chopped and Capped Tulip Hood
What have I learned from this?
Its funny that lens hoods are rarely discussed in online forums and tutorials...almost as if everyone already knew this information. I am definitely going to buy a lens hood for my kit lens to avoid the flare I posted in photos below. I can't imagine why a photographer wouldn't always keep one handy while shooting outdoor photography, to avoid unnecessary flare. I'm sure there are occasions where a lens hood is not needed, but its always better to be prepared for the elements and adapt to your lighting environment.
If you're reading all of this and already knew about lens hoods, then you're more advanced than I am. **lol** However, I'm hoping this will serve as good reference for me to reflect on things I've learned and maybe help someone who's newer than I am.
By The Way, What is Flare?
Flare is caused when light hits the lens at the wrong point or angle and reflects off the inside edges of the lens aperture (or diaphragm), essentially it reflects internally on the lens elements an un-determinable amount of times. Flare can be seen in photos in many shapes and colors, but most commonly it’s a bright polygonal form (usually 5-8 sides). If you’ve seen the polygonal, round, or any strange colored patches, ghostly images, halos, or just a light haze over your photo, then you’ve seen flare before. The presence of flare in your lens, and ultimately in your photos, can greatly reduce the contrast and saturation in your photos. Flare causing light sources may include the sun, artificial lighting and even a full moon.
What it Looks Like? Different Types of Flare?
Aperture Ghosting
Aperture ghosting is essentially multiple reflections or patches of flare forming a streak of patches.
Veiling Glare
Veiling Glare is a whitish haze that covers the entire image, or obvious/large parts of it. Veiling Glare also causes the contrast and saturation of the photo to be greatly reduced. However, if the veiling flare was unavoidable and it produced a washed out photo, the adjustment levels in post-production can be corrected to increase the contrast and saturation.
The image below is one I found on a photography website. The left image in the picture below is affected by veiling glare. The photographer noted that the built-in hood was inadequate to block the direct sunlight, so he used his hand as an effective shield in the right image. Its hard to see any glare in the first image, until you see the two images compared.
Presence (left) and absence (right) of veiling glare.
Mirror Ghosting
I have never seen mirror ghosting until looking up this information. This is really strange looking. This mirror ghosting was apparently caused by the filter he used.
Mirror ghosting. Photograph courtesy of Arthur Hood.
I got some of my images and info from: http://www.cambridgeincolour.com/learn-photography-concepts.htm
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