secrets- how to improve the performance of any lens. (The Lens Hood)

Here's the secret. The enemy of Optics, especially in photography is a simple thing. Flare.

A crappy plastic lens has a lot of flare, and can focus an image on the lens or sensor but has a lot of dispersion- flare- and gives you the effect of looking through dirty glasses. A good lens, with good glass and coatings, minimizes that. Expensive lenses are built using designs that are decades-old, and the cool new stuff a modern lens brings to the table- rare-element coatings, extra-low dispersion, etc etc, is simply stuff that controls flare.

Flare comes from light coming from the subject, but also, from stray light hitting the glass surfaces of the lens. Any light at all that hits the glass on the lens will create flare. Period. If you can see the lens, light is hitting it, and flare is happening. All the engineering that goes into your lens is there to fight that flare. You can have the best, most expensive lens made for your camera, but if there is light striking the glass, you're losing much of the value of that lens.

Back in the days of Leica and Nikon 35mm cameras, I often heard it said that Nikon lenses had amazing color, but Leica lenses had contrast. That is, they had more tonal range, truer and richer rendering from light to dark, making them so ideal for B/W photography. Guess what they had? You got it, better control of flare...

Want to know the secret of lens performance? Eliminate what flare you can. How do you do that? Use a lens hood.

Wow. No. Really. That's it.

Think I'm pixel-peeping and splitting hairs? Look at these examples.



I shot a few images with my Canon G9, with and without a basic lens hood. Here's what they look like in Camera RAW. At first glance, they look pretty much the same, but on the first set, let's look at the lower corner. There's a distinct circle of flare from the inner barrel of the lens.

Without hood:



With hood:



On the second group, there's more a more general, and common, effect of flare, an overall cast, lightening the image, but most obviously adding lightness to the shadows. Here's the first image without the hood, and the second below it, with the hood.

Without hood:



With hood:



Now, look at the histogram, you can even see it here. The shot without the hood has shadows with higher values, and a more compressed tonal range. The shot with the hood has deeper, more defined shadows.

Without hood:



With hood:



For around $20, you can take a decent lens and make it look good. You can take a great lens and get every drop out of it that the designer intended.

Use your lens hood!