> On 25 May 2018 at 23:12 Matthew Hunt <[email protected]> wrote: > > > It's not for astrophotography, but it is interesting! > > A telecentric lens almost sounds like magic: The size of an object imaged > with the lens doesn't vary with distance from the lens. So if you image a > certain object, and its image is 10mm tall on the sensor, and you move the > object further away from the lens, the image stays 10mm tall instead of > getting smaller. Another way of putting it is that the lens' projection is > orthographic, the "view from infinity" perspective. This property makes it > useful for measuring the sizes of objects, such as for quality control on > an assembly line.
IIRC, there was a function on the Z1-p, when using Powerzoom lenses, that allowed the user to maintain subject size in the image as it moved around. > > Since the field of view is more like a cylinder projecting from the lens to > infinity, instead of a cone (like normal lenses), the field of view is > basically set by the diameter of the lens. That's why this lens has a > rather large looking diameter and is described as "large field". > On Fri, May 25, 2018 at 2:26 PM <[email protected]> wrote: > > > At least that's what the language makes me think it is. > > https://columbus.craigslist.org/pho/d/invaritar-large-field/6596751903.html -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
