Here and elsewhere I've heard reference to lenses being 'digital lenses' - translation, the light exiting the rear of the lens is designed to hit the sensor plane collimated or straight on. Now I know a bit about lenses, but this kinda smelt funny to me and I never encountered any plausible explanation until I came across the links below. Which makes me wonder if the 'digital lenses' photographers are buying are indeed telecentric and producing collimated light at the back end, or whether they're just a scam by the camera companies selling ordinary lenses and obfuscating things with a fine sounding term. For a start it seems that telecentric lenses are considerably bigger than normal lenses, with a lot more glass - and I mean BIGGER (the cited example below would suggest that the aperture needs to be significantly larger than the object or image height!) Secondly, this disadvantages of telecentric lenses - has anyone using a 'digital lens' noticed that Aunty Mary looks the same height whether she's 5 feet away of 100? Apparently a telecentric lens would have her the same height.. Apparently it's relatively easy to check if digital lenses do as they claim, and that's the bit I've been looking for! - all you need to do is look through them .. if the apparent aperture looks to be a REALLY long way away then you may be peering through a telecentric lens (or a wide angle and confusing distant with small ;) Not having any 'digital' lenses I can't check, but I'd be keen to hear any ones observations more on the matter: "What is Telecentricity? Telecentricity is a special property of certain multi-element lens designs in which the chief rays for all points across the object or image are collimated. For example, telecentricity occurs when the chief rays are parallel to the optical axis, in object and/or image space. Another way of describing telecentricity is to state that the entrance pupil and/or exit pupil of the system is located at infinity" "In a system with object space telecentricity, movement of the object toward or away from the lens will not result in the image getting bigger or smaller, " so there is no magnification based on distance from the lens / subject (!) http://en.wikipedia.org/wiki/Telecentric_lens http://www.edmundoptics.com/technical-support/imaging/what-is-telecentricity/ karl
