Talk:Perspective control lens

message: It would be good if someone could relate which (if any) digital SLR systems have compatibility with shift lenses, given how few there are. Or if none, simply state that fact. 82.10.108.49 (talk) 21:53, 26 February 2008 (UTC)
replies: text: Probably hard to summarize - generally the viewfinder overhangs the mount, so mechanical collisions prevent use of the full tilt/shift ranges - not a simple yes/no. Too specific for an encyclopedia - see lens reviews ? --195.137.93.171 (talk) 00:46, 4 April 2011 (UTC)

text: I agree that it would be mighty complex (see the manual for the PC-E Nikkor 24 mm f/3.5; that manual, of course, mentions only bodies that were available at the time of its publication). And it’s not so much an issue of digital as it is one of bodies with built-in flashes; some film SLRs with built-in flashes don’t allow the full range of movements. For example, the Canon EOS 5/A2/A2E allowed full shift, but at full shift, the shift direction could not be rotated without the lens hitting the pentaprism/flash housing. In most cases, the tilt function isn’t restricted. JeffConrad (talk) 08:18, 4 April 2011 (UTC)
thread_title:  Digital Photography 

message: Perhaps I’m being too fussy, but the description of the new Nikkor lenses was reading more like a Nikon brochure than an encyclopedia article. The buzzwords like “electromagnetic diaphragm” and “CMOS” apply equally to Canon, but they’re irrelevant to this article (as probably is “FX-format”, as well), serving only to clutter things up. I also question the statement that only the full-frame formats use the full capabilities of the lenses. It’s true that smaller formats (such as Canon’s 1.6 factor and Nikon’s 1.5 factor) don’t use the full image circles, but they afford some advantages as well (e.g., the shift is a greater fraction of the format size). Arguably, the greatest difference is the narrower ange of view, which sometimes is a problem and other times is an advantage. NPOV would seem to require comparable treatment of Canon and Nikon (and any other) lenses, and throwing in all the buzzwords forces the reader to wade through all sorts of material that has little real bearing on the substance of the article. JeffConrad (talk) 04:46, 4 July 2008 (UTC)
thread_title: Available lenses

message: Can editor 199.227.143.21 provide a source for the availability of K-mount Zenitar tilt/shift lenses? I see MC Arsat versions of these lenses, on both the Arsenal site and the Hartblei site, but can find nothing on the Zenitar site. Whatever the source, the other available mounts should also be mentioned. JeffConrad (talk) 07:44, 1 August 2008 (UTC)
thread_title:  Zenitar lenses 

message: There are serious compatibility issues,  beyond those stated or implied in the article, with Nikon PC-E lenses and various Nikon camera bodies. Automatic aperture control is only available with the D300, D3, and D700 bodies; some other bodies support the electronic preset aperture control via the lens pushbutton, but apparently some do not. Ken Rockwell describes these problems in considerable detail; I've had only brief contact with a 24 mm PC-E lens, so I can't confirm his findings. On some camera bodies with built-in flash, the lenses cannot be rotated if maximum rise is employed; on others, it may not even be possible to set maximum rise without hitting the bottom of the prism housing.
Canon TS-E lenses provide automatic aperture control with any EF-mount bodies, but clearance of the prism housing is an issue on some DSLRs with built-in flashes.
To my knowledge, neither Canon nor Nikon have bothered to identify these incompatibilities. I'm not sure the responsibility falls to this article, but adding at least a general caveat might be a good idea. I'm lukewarm on including a link to Rockwell's article, because I've found his writings to be uneven in quality and even accuracy. Currently, though, I'm not sure what else is available, so perhaps a footnote mentioning an external link would point the reader to the article without the implication of endorsement. I know of no similar article that examines clearances on Canon DSLRs. JeffConrad (talk) 21:29, 31 August 2008 (UTC)
replies: text: The article to which Jeff refers:  Ken Rockwell article Motorrad-67 (talk) 21:35, 31 August 2008 (UTC)
thread_title:  Compatibility of Canon TS-E and Nikon PC-E lenses 

message: Most of this section really doesn't belong in this article; I originally added it only because there wasn't another good source to explain what an automatic diaphragm was. If there is no objection, I'll move most of this section to the Aperture article, leaving only material that specifically relates to tilt/shift lenses. JeffConrad (talk) 00:14, 12 December 2008 (UTC)
thread_title:  Aperture control 

message: The paragraph on using shift to negate the effects of motion blur in aerial photography is nearly incomprehensible as well as unsourced. Absent a reliable source, as well as a better explanation, I think this material should be removed. JeffConrad (talk) 03:47, 4 September 2009 (UTC)
replies: text: I agree. I've never heard of anyone doing that myself. howcheng  {chat} 04:37, 4 September 2009 (UTC)
replies: text: Shifting the lens to compensate for ground speed is how spy planes (including the U2) take photographs without needing exceedingly ridiculous and physically impossible (1/100000th or faster) shutter speeds.  I'm sure any reference on the U2 would include this information. NetJohn (talk) 22:50, 28 September 2010 (UTC)
replies: text: I must admit this is an area with which I'm unfamiliar, but even if correct, it sounds different from how we use shift here (it sounds more like image stabilization). In any event, it would need a better description and support from a reliable source. JeffConrad (talk) 01:02, 30 September 2010 (UTC)
thread_title:  Use of shift in aerial photography 

message: The linked article Tilt-shift miniature faking doesn't really have anything to do with the use of tilt; it's almost as if that article attempts to describe digitally faking a technique that doesn't really fake miniatures. In the second paragraph under Techniques, that article states
:It is perhaps improper to refer to this technique as "tilt-shifting".
That statement is correct for two reasons:
# There is no such thing as “tilt-shifting”, and use of that phrase as a noun or compound adjective almost invariably reveals a person who doesn't understand camera movements. What's employed in “miniature faking” with a TS lens is tilt.
# The shallow DoF that obtains from using tilt to rotate the plane of focus doesn't look anything like the shallow DoF that obtains from close-up photography.
The emphasis of that article is a bit difficult to discern, but it appears to describe a technique (e.g., Smallgantics that actually does simulate DoF that obtains from close-up photography. JeffConrad (talk) 09:09, 7 September 2009 (UTC)
thread_title:  “Tilt-shift miniature faking” 

message: I've cleaned up the lead section a bit, and updated a couple of comments to reflect the improvements in the image circles of recent lenses, and the availability of longer focal lengths that almost certainly aren't used primarily for architecture.  I removed reference to “other technical photography” because I have no idea what it means; I have no objection to it's being restored if an adequate explanation can be provided.  The first sentence in the second paragraph should probably be supported in any event; I know of many photographers who use 24 mm lenses for landscape work.
I don't especially like the description of shift, but it's by far the most common I found in about a dozen books I examined.  I would prefer something to the effect of
:“Shift allows changing the line of sight without moving the camera back, allowing the position of the subject in the image to be adjusted without changing the subject's shape”.
But I'm not sure everyone would understand what the “line of sight” is, and this explanation isn't common in sources (Merklinger uses the term, but not in relation to translational movements).  Howard Bond speaks of using shifts to point the camera, which I think is actually a pretty good description of what happens, but it strikes me as a bit informal for an encyclopedia.  In any event, it's important not to say that perspective is controlled by shifting the lens, because that's not at all what happens—perspective is controlled by the orientation of the camera back relative to the subject. On a view camera, perspective is directly controlled by tilting or swinging the back; with a PC lens, this movement is emulated by reorienting the camera and using the shifts to adjust framing.
I think it may be worth adding a brief section on the convergence of parallel lines: they result from changes in magnification when parts of a subject are at varying distances from the camera, such as when it's pointed up at a tall building.  Another consequence of the camera back not being parallel to the subject is that the subject is foreshortened.  This important when perspective is corrected in software; two steps are usually needed: one to correct converging lines, and a second to correct the aspect ratio (removing the effects of foreshortening).  There's a good Rodenstock article to support this.
The great remaining task is to address tilt/shift lenses, since they now represent almost all available lenses.  Offhand, I don't see a good way to adequately cover them in this article without some major changes, and possibly making a mess of things.  I'm consequently leaning towards a separate article to avoid some of the problems.  As I've mentioned, there would necessarily be considerable duplication, and one significant question would be how to handle the Nikon PC-E lenses.  They're tilt/shift lenses in everything but branding, but I'm sure some still use them only for the shift functions, especially the 24 mm. But I'm interested in ideas others might have. JeffConrad (talk) 00:26, 28 March 2010 (UTC)
thread_title:  Edits of 28 March 2010 

message: This article is terribly Nikon-centric in both terminology and examples. A tilt-shift-swing lens doesn’t and can never ‘correct’ perspective. Perspective comes, by definition, from a point of view, a position in space. Unless the camera moves, the perspective is the same, regardless of focal length or tilting, shifting, or swinging the lens. You can change the focal plane or crop from a different area of the image circle, but that doesn’t change perspective.
And statements like ‘Short-focus perspective-control (PC) lenses’ really don’t help. A macro lens would be short-focus, a wide angle lens has a short focal length.  — Preceding unsigned comment added by Hugowolf (talk • contribs) 00:43, 7 November 2013 (UTC)
thread_title:  Nikon centricity and other gripes