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What you need as glass (Part IX - Special lenses)

July 20th, 2011

This is part IX of a series of what glass you will need. Each part will discuss a certain lens type and its applications.

There are three kinds of special lenses:

  • Fisheye
  • Effect lenses
  • Perspective Control (PC)

They are special, for special application, so you will need them rarely unless you already specialized in a special field.

Fisheye

Fisheyes are non-rectilinear lenses, this means that straight lines, unless they cross the center of the frame, will be bend. It can be imitated by adding an extreme barrel distortion to an image and conversely you can correct to some extend in post-processing a fisheye image to appear “normal”.

Fisheye lenses where originally made for scientific purposes, but current lenses are aimed at artistic and underwater photography (visibility in most waters is rather limited)

Optically all fisheyes such, but all are good enough. I think the three most interesting are the Tokina 10-17 which lets you control the effect (Canon has some similar EF lens), the Samyang 8mm (DX!) which is stereographic and the 8mm Peleng which is fully circular on FX for the full effect.

Lack of AF with these exotic lenses is not a problem, the DOF is ridiculously large. To shoot fisheye try to put the dominating line through the center of the frame to achieve a “correct” image - or do just the opposite. It is difficult to get a good photo with them, this will prevent it to be overused.

Effect Lenses

Lens, Baby! Lensbabies became popular recently. It is Lomography with the price of of Nikonography. It is for sure fun to experiment with oddly shaped apertures, but for me it is like spending your tuition money in Disneyland instead of studied literature when becoming a writer.

Same Lensbabies have a tilt capabilty, but it is just for even odder effects, unlike what you can do with perspective control (PC) lenses.

Consider buying such stuff as entertainment fee - getting a copy of CS5 might be a saner option - although thoses lenses are crap (optically), they are all but cheap.

Some fun stuff is the plastic Holga lens in F-mount. This is really cheap, but useless. A 60mm lens on FX/DX is not the same as on 120 film.

Perspective Control (PC)

When shooting a church you get these falling lines, you can avoid that when you point the camera perfectly horizontal, but then you will cut off the towers while half of the frame is filled with the pavement in front of it. PC lenses allow you to displace the lens upwards (rise) to get the towers in and use the frame more efficiently. So if architecture interest you, this is something to get. Of course a tripod is a big help and I prefer to do only a partial correction by pointing the camera  to the lower third/fourth and rise the lens to fill the frame. This gives a more lively photo. To my knowledge there are no current “shift-only” lenses, but there are vintage PC-Nikkors and Schneider makes some high end lenses (with high end prices). Cheaper solution: Postprocessing. This looses resolution, but even good PC lenses loose at extreme displacement. Overall you might be better off with that than using an Kiev mount lens on an adapter.

An interesting application of shift lenses is parallax-free stitching. You need a tripod mount on the lens for that, like the Schneider/Hartblei lenses have. It is like panorama stitching, but you don’t turn the lens,  so you avoid stereoscopic errors.

The modern PC lenses also can tilt, this does not imply any distortion, but tilts as well the focal plane. There are three uses for that:

  • Creating an infinite DOF, by “laying the focal plane on the floor” so that you have an image sharp from the bottom to the horizon
  • Miniature effect by tilting up and shooting from a high point of view (the wider the lens the better the effect)
  • Adjust focal plane to subject in close up photography

The last point is important in product photography, but as well in shots like this:
DSC_4626.jpg
At close distances it would be impossible even at small apertures to have the whole column in focus. Combine this with a fall and you could shot a un-distorted shot of a matchbox entirely in focus. For this to work the fall has to be in the same direction, the PC Nikkors need to be adjusted by service personnel, Hartbleis Superrotators are much more flexible here.

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