[Brightcolours]

There are websites that show sketches of the lens construction for all Canon lenses, and all Tamron Adaptall lenses.  Since that is what most of my lenses are I have fallen into the habit of looking at the layout sketch of so many elements in so many groups.  I can't say this is criticle information for me, but it is fun.  I have not come across diagrams for the Tamron AF 90mm f/2.8 di Macro, ect.  The earlier one with the micro motor. 

 

Tamrom AF SP 90mm f2.8 Di Macro



(Sorry for the small size... the double element group sits in the middle.)

 

Here is a more clear diagram:



Nice lens, btw.

Or the Sigma 70-300 so-called APO with the 1:2 macro,

Sigma f4-5.6 APO DG Macro



The blue elements are SLD (special low dispersion glass) elements.

 

and its little brother the Sigma AF 28-80mm f/3.5-5.6 Aspherical with 1:2 macro at 80mm.

Sigma 28-80mm f3.5-5.6 II Aspherical Macro



The pink one is the aspherical element.

Is there someone who knows the layouts of the above three lenses?  Much thanks!

My pleasure.

- Arthur

You might also find this thread interesting.

http://forum.mflenses.com/list-of-lens-d...22934.html