on 20/12/02 9:14 pm, Dick.Roadnight wrote: > Is he saying than making a rectangle image of a rectangular subject is > distortion?
Hello Dick He here. The answer to your question is yes! and no!. The thread has been concerned with perspective correction, and is based on the assumption that we are all using rectilinear lenses, i.e., not fisheye lenses. The first post you selected from was:- >In view cameras there is a streaching of an object as it gets nearer the edge >of the frame. This can be seen if you look at a circular object near the edge >of a wide angle shot. It becomes an elipse. This effect of wide-angle lenses is not in question, and is not confined to view cameras, but using the movements of a view camera exaggerates the effect. The second post you selected from was a reply to Shangara:- >> See above...you're not cropping any more but distorting your image to look >> the way you want it to. You get the impression that you're un-distorting but >> in fact you're doing the exact opposite. > >Yes in the exactly same way that using movements on a view camera distorts an >image, to make it look the way I want it to! This was concerning reproducing the effect of camera movements in photoshop. Perhaps putting 'distorts' in inverted commas would have been advisable. This then comes back to your question "Is he saying than making a rectangle image of a rectangular subject is distortion?" The simple answer is no, but if you then ask a supplementary question. Is the removal of the perspective effect of converging parallels distortion? It can be argued yes. Lets still think of a rectangular object, say a building which is 17m high. This has a face covered in rectangular windows all the same size. You set up a camera 10m from the front of the building, and using camera movements you get a square corrected image on the camera screen. The nearest window is 10m away. The furthest away window is 20m away, using Pythagorus. But on the screen they are the same size. Is that distortion? The effective enlargement of a distant object is distortion. Even though it is the result of the choice of camera, and optics. Is it wrong? No! Ian -- Ian Goodrick, Tel/Fax +44 (0) 1474 333066 Ian Goodrick Photography, Mobile 07860 362322 Gravesend, Kent, UK =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
