[Ira]

Although Lowell's answer is of course correct and the main reason why aperture blades are black, there is indeed another one which most people are unaware of:

It's an equal opportunity thing.

[khardur]

Let's see, the iris is black to minimize reflections, right? But if the blades aren't too shiny and the glass is well-coated, reflections shouldn't be a problem. So there should be no good reason for not coloring the blades matte red, orange, green, polka-dot, etc. And they needn't be single-colored -- why not a harlequin iris? Or the blades could have patterns designed into their outer surfaces, forming... a toothy mouth... a bloodshot eye... a starfish... a planet... a brand name or logo, maybe even paid advertising... And if the pattern/design doesn't appear properly, that's a signal of lens trouble. Yeah, Perry Mason and the Case of the Tattletale Iris.

Hey someone could make custom aperture blade kits, similar to how people have those odd colored brakes in their tricked-out cars. Sell them in colors to go along with the K-x colors.

[bentax]

Although Lowell's answer is of course correct and the main reason why aperture blades are black, there is indeed another one which most people are unaware of:

It's an equal opportunity thing.

Haha Then where's the white aperture blades? Thats like the "equal opportunitys" of Aboriginals... wheres my Commodore?

[georgweb]

I can offer a small variety of different flavors: grey, grey-sprinkled, oily .-)

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Last edited by georgweb; 08-23-2010 at 02:51 PM.

[pacerr]

Why are aperture blades always black?

The florescent orange or yellow ones make your portrait subjects squint.

H2

[opiet70]

Although Lowell's answer is of course correct and the main reason why aperture blades are black, there is indeed another one which most people are unaware of:

It's an equal opportunity thing.

Ouch...Didn't expect that one from you Ira

As light comes through the lens, it is prone to reflect off surfaces. Those reflections cause ghosting and such, but also degrade the image relayed to the sensor. By putting a material that absorbs instead of reflects the light, that goes away as much as possible.

We don't see that as much in photography lenses as with telescopes, but the same exact situation exists. However, with telescopes, there is much less light, much greater light gathering capabilities, and a small area of missing paint inside the tube of a telescope is very easily seen. I had a Dob a few years ago with a small scratch on the inside that would do some horrible ghosting when looking at a full moon. It was due to this reason.