> > From: "Rob Studdert" <[EMAIL PROTECTED]> > Date: 2005/04/27 Wed PM 02:33:18 GMT > To: [email protected] > Subject: Re: A Macro Lens Question > > On 27 Apr 2005 at 7:16, Shel Belinkoff wrote: > > > Isn't a macro lens designed for flat field work? If so, wouldn't a regular > > lens > > used with an extender, a bellows, or helicoil focusing device, be a better > > choice for 3D objects, such as close-ups of flowers or small objects? Or > > maybe > > close-ups of not so small objects? > > Yes, most dedicated macro lenses are flat field corrected. If the primary > point > of interest is in the centre of the frame you might get away with a non-macro > lens pretty easily but the point is that the generally distorted plane of > focus > on the subject side of most non-macro lenses can become a problem at macro > distances. It certainly would be no better for 3D objects, a flat field lens > will generally record any object in close focus with less optical distortion.
In addition, I suspect the curve of the plane of focus in the non-FF lens will be the "wrong way". In other words, if focussed correctly in the centre, the curve of plane of focus will move back towards the lens towards the edges of the frame. In most macro pictures, one would want the plane of focus to move away from the lens as it moves towards the sides. I think... mike ----------------------------------------- Email sent from www.ntlworld.com virus-checked using McAfee(R) Software visit www.ntlworld.com/security for more information
