There are more than 4 basic lens designs, and they are mixed and matched depending on the lens design. If you really want to know about lens design, read these articles:
http://www.lensrentals.com/blog/2011/08/lens-geneology-part-1 http://www.lensrentals.com/blog/2011/09/lens-genealogy-part-2 http://www.lensrentals.com/blog/2011/01/cooking-with-glass https://www.lensrentals.com/blog/2010/11/the-schott-heard-around-the-world http://www.lensrentals.com/blog/2011/02/who-invented-the-telephoto-lens https://www.lensrentals.com/blog/2010/10/from-petzvals-sum-to-abbes-number On Tue, Oct 23, 2012 at 10:06 PM, Larry Colen <l...@red4est.com> wrote: > > On Oct 23, 2012, at 2:15 PM, Brian Walters wrote: > >> Interesting article that uses a K-5 and a Sigma 50-500 mm HSM lens. The >> article doesn't say what focal length was used in the tests but presumably >> it was the long end. >> >> http://www.digitalversus.com/digital-camera/image-stabilisers-optical-mechanical-a1608.html > > Interesting. I assume that they tried it at 500mm, how about at 50mm? > > I remember seeing something recently about how there are only about four > different basic types of lenses, and that the lens formula that works for > zoom lenses is only good to about f/2.8. I suspect that it takes one of > those lens formula in order to do optical stabilization. > > I also remember reading about how having a moving element in the optical path > decreases the sharpness of the photo. I note that he doesn't perform MTF > calculations on the images, so he's not actually quantifying levels of > sharpness with the different methods. > >> > > -- > Larry Colen l...@red4est.com sent from i4est > > > > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- David Parsons Photography http://www.davidparsonsphoto.com Aloha Photographer Photoblog http://alohaphotog.blogspot.com/ -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
