On 26 May 2018, at 08:29, mike wilson <[email protected]<mailto:[email protected]>> wrote:
On 25 May 2018 at 23:12 Matthew Hunt <[email protected]<mailto:[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. Hitchcock zoom: http://www.slate.com/blogs/browbeat/2014/01/21/dolly_zoom_supercut_video_shows_the_vertigo_effect_in_jaws_goodfellas_raging.html?via=gdpr-consent 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]<mailto:[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.
