Aspherical Lens

[Rob.Marsh]

Hi all,

Apologies if this is another stupid question, all I seem to post is questions at the moment. I do use my camera too I promise!!

Anyways.....

I am looking around at potential lenses, and every now and again the term "aspherical lens" pops up.

Can someone explain this to me please, as in what it means to in photography terms and what it'll do to imageds shot with it?

Ta!

Rob

 

[68lbs]

I've been dying to post this link ever since I saw it somewhere else...

But this might help

 

[Rob.Marsh]

Thanks for not helping there!

I had googled it before, but still not fullying understanding thought that TPF members might be able to shed some light on it for me.

Ah well, I'll learn not to ask stupid questions oneday perhaps.

 

[68lbs]

Thanks for not helping there!

Looks fairly self explanatory to me from the wiki link that comes up top. It's a rugby ball shaped lens (much like my eyeballs). Can be used to help combat things like chromatic aberation.

How's that for more helpful

All this is just what i've gleaned from a 30 second squint at that wiki though.

 

[overthere]

An aspheric lens or asphere is a lens whose surfaces have a profile that is neither a portion of a sphere nor of a circular cylinder. In photography, a lens assembly that includes an aspheric element is often called an aspherical lens.


The asphere's more complex surface profile can eliminate spherical aberration and reduce other optical aberrations compared to a simple lens. A single aspheric lens can often replace a much more complex multi-lens system. The resulting device is smaller and lighter, and possibly cheaper than the multi-lens design. Aspheric elements are used in the design of multi-element wide-angle and fast normal lenses to reduce aberrations.




quoted from wikipedia




also


i had to look it up myself-




Aberration is something that deviates from the normal way but has several specifically defined meanings:

• Optical aberration, an imperfection in image formation by an optical system
  • Spherical aberration, which occurs when light rays strike a lens or mirror near its edge
  • Chromatic aberration, caused by differences in refractive index for different wavelengths of light
  • Defocus aberration, which occurs when a system is out of focus