If the image (of the building or whatever) is only x millimeters in width at the top of the film frame due to convergence, it's only x millimeters it contains only the information that can be transferred to x millimeters of film width. Expanding by any method post image capture, including oversampling, will increase observed grain and lower apparent lens resolution when the software correction is applied. The shift lens makes best use of the small 35mm real estate so that this problem doesn't exist. If the image is to be corrected, information is *always* lost directly in the photographic process when (with regard to vertical correction) the film plane is at any other angle but vertical. Similar loss exists for horizontal corrections.
It's a matter of the amount of film area you devote to the original image. There is no free lunch. For most real purposes not involving high enlargement, Photoshop is adequate and costs about the same as a used Pentax shift lens. Regards, Bob... From: "Cameron Hood" <[EMAIL PROTECTED]> > > Bob wrote: > > First, this is not a flame. It's simply an observation of the losses > > > > involved in using Photoshop, Paint Shop Pro or other software tool to > > > > accomplish the functions provided by a shift lens. It should be > > obvious that > > > > after the fact "correction" of distortion necessarily involves > > introduction > > > > of errors and/or losses. > > > > > > Photoshop is indeed a great image manipulation tool. Nevertheless, to > > > > achieve the same perspective control, pixels (information) must be lost > > > > and/or pixels must be synthesized (information summarized from > > surrounding > > > > pixels) to produce the effect. Shift lenses do not have this > > limitation. The > > > > perspective control provided by shift lenses does not involve loss of > > > > information, nor does it require information be synthesized. > > > > You can overcome this by over-scanning (increase dpi) so you have lots > available to make the correction. I have done many interior and > architectural shoots and it has not been a problem for me. The only > thing you can't do in photoshop is to use the T/S to increase the depth > of field while keeping the shutter speed up (low f stop).
