> > From: Chris Stoddart <[EMAIL PROTECTED]> > Date: 2005/08/25 Thu PM 12:15:18 GMT > To: [email protected] > Subject: Re: Re: Wideangle enablement :) > > > On Thu, 25 Aug 2005, mike wilson wrote: > > > They don't need to have a curve on them to act as a lens. If a light > > ray is hitting them at an angle, it will be deflected by refraction. > > http://www.ps.missouri.edu/rickspage/refract/refraction.html > > Would make all the difference between a sharp and soft image. > > Mike, > > Yesssss, I do happen know a smidge about refraction(*). But tell me about > those filters everyone puts in front of their lenses... or do they not > have the same effect? :-) Is it only at the rear of the lens you reckon > it makes a difference? > > But that brings out the scientist in me. It would be an interesting to > place a small, flat disk of optical glass at the rear of (say) the Pentax > 24mm f/2.8 - you're saying it should have some effect at higher incidence > angles (i.e. the edges of the frame)? > > (*) there's a touch of irony in there. > > Chris
I do remember what you do for a living. That's why I was suprised. There is a definite (visible in the viewfinder) difference with the 16mm Zenitar, although those filters _may_ be slightly curved. Any piece of glass in a lens set will make a difference. The question is, will the difference be noticeable? Maybe somewhere between 16 and 20mm and between flat and very slightly curved the answer changes from yes to no. Same for inserting the piece at the front or the back of the lens set - it seems obvious to me that angles of incidence will have an effect. Those angles are greater in WA lenses at the back of the lens group. Empiricism seems to be the only saviour here. Time to get 'em out! 8-) mike ----------------------------------------- Email sent from www.ntlworld.com Virus-checked using McAfee(R) Software Visit www.ntlworld.com/security for more information
