Digital Camera Watch by Impress published an interview to the Nikon designers of PC-E Nikkor 19mm f/4E ED:
http://dc.watch.impress.co.jp/docs/news/interview/1070229.htmlAs always, the texts are all in Japanese. Here is a summary of points of interest:
--The PC Nikkor 19mm f/4E ED (PC19) was developed in response to the requests from photographers who wanted a T/S lens wider than the existing 24mm.
--The lens of the initial design was about 1.5x bigger than the final product in order to achieve the required optical performance, which halt the developing process.
--They decided on the focal length of 19mm instead of 17mm of Canon’s counterpart, because they had found out that most of the architecture photographers had been using 65mm or 75mm lenses on 4x5” or 47mm one on 6x9 formats, which corresponds to around 20mm on FX format. And they decided that 19mm is the best focal lenses that can balance between the size and the optical performance.
--According to their research, more than 90% of the architecture photographers are using FX format DSLRs.
--The advantage of shooting with PC lenses over the perspective correction in the post process is that the former can retain the proportion of the architecture, while the latter may alter it. Also, the former can control the final composition on-site without affecting the resolution, which is inevitable in the latter method.
--They are “aware” that the renewal of PC24 by employing the same revolving system as that of PC19 is desired.
--The Nikon camera bodies released before PC19 will compensate for the light fall-off when the in-camera aberration control is activated, which doesn’t work correctly when the lens is tilted/shifted. Nikon recommends the function to be deactivated when using PC19.
--PC19 is named “PC” instead of “PC-E”. They say that the term “PC-E” is transitional, and that they had to add “D” (like PC-E 24mm F/3.5D ED) because they have aperture rings, and, they had to add “E” because their apertures are electrically controlled.
--The angle-of-view of PC19 is roughly the equivalent of that of a 12-13mm lens on FX format. The exact coverage is not officially disclosed. They omitted the lens hood to avoid the vignetting when the lens is revolved. They also discarded the idea of separate hood, because a hood for a 12-13mm equivalent lens would be too big and not so effective.
--The published MTF chart only represents the performance within the normal FX format. The MTF curve within the actual coverage can be approximated by extrapolating the lines.
--The distortion is kept close to zero within the image circle when the shift is not excessive, but the image can show some barrel distortion in the extreme peripherals. If the distortion would be more perfectly controlled, the lens would be, as mentioned above, much larger.
--Some people combine teleconverters with the PC lenses of other makes. PC19 cannot be mounted onto the teleconverters in the first place, and Nikon doesn’t recommend that method even you can mount it onto the teleconverter (by removing the tab, I guess?).
--PC19 is made to focus past the infinity and the closest index of the distance scale, because you would need to do that according to the amount of tilt.
--The lead screw is employed for the shift mechanism to avoid the creep.
--They don’t discard the idea of a AF PC lens.
Good News for Erik and Pedro:
--The area right behind the focus ring is designed to be stronger with the possible tripod collar in mind.
Hope this would be of any help.
