A long focus lens typically has back focus same approx. length as focal length, i.e. the lens is same distance from focal plane as focal length.
A telephoto len typically has much shorter back focus such that the lens is physically shorter and the lens is much closer to the focal plane than the focal length. RE: Large Format The other main difference is telephoto lenses have typically have less coverage and lower image quality for a given format than a long focus lens of same F.L. OR another way of looking at it is a long focus lens that gives same coverage angle as a tele at same focal length will nearly always give superior image quality for a given format. JCO -----Original Message----- From: Graywolf [mailto:[EMAIL PROTECTED] Sent: Wednesday, June 08, 2005 12:53 PM To: [email protected] Subject: Re: Long Focus v Telephoto A long focus lens is one that is longer than the usual normal focal length for the format, but still of standard design. A 50mm for a 35mm camera would be a long focus lens on an *istD A telephoto is a lens that is physically shorter than it focal length. That is accomplished by building in what is basically a teleconverter (or a barlow lens). I will add two more definitions: A wide-Angle is a lens that is shorter than the usual normal focal length for the format. A retro-focus lens is a WA that is physically longer than its focal length (a reversed telephoto) graywolf http://www.graywolfphoto.com "Idiot Proof" <==> "Expert Proof" ----------------------------------- Shel Belinkoff wrote: > Could someone be kind enough to remind me what the diff is between a > long focus and a telephoto lens. Thanks! > > > Shel > > > -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.323 / Virus Database: 267.6.6 - Release Date: 6/8/2005
