Thursday, August 28, 2008

Probleme Installation Windowblinds 7

Tubes d'extension macro

The macro-picture, what is the art of photographing very small objects, and they appear larger. Two possible approaches to the problem: get closer to advantage, or grow older.

The first possibility, it is the fashion macro small digital cameras and more generally, some zooms: decreasing the minimum distance of development, we photograph more closely, so the object is bigger on the plate resulting. This is made possible targets baptized macro by manufacturers: the optical panel can benefit advance (you've probably seen: the objective is growing " , especially since we want to develop closer), which allows to develop two or three times closer than with a normal lens - 23cm with the SMC Pentax-M 50mm f: 4 macro, cons 45cm with 50mm f: 1.4 . This at the cost of opening up much less.

A related possibility, which I will: the close-(close-up lenses ), returning to put his glasses lens so he could see closely, it will of course remove them to see by far, more than fifty years who read me see what I mean.

The alternative then: grow more. For this, the method is to remove the entire lens of the receiver (film or sensor). For optical reasons I'll spare you, but who are well scribbling with paper and pencil, it grows much the resulting image; by cons, we lose practically possible to develop: the larger the elongation, the larger the range of focus becomes small, situated a short distance in front of goal.

To do this, devices without lenses, which are inserted between the lens and body: the bellows, which provides for removal (and hence magnifications) variables, extension tubes, which have a longer fixed helical extension tube, intermediate between the two: a tube with adjustable length.

I wanted to explore the possibilities of macro without breaking the piggy bank, so I bought a set of extension tubes low end, to see what happens.

  • Type: set extension tubes macro
  • Manufacturer: unknown ( made in China )
  • Purchase Date: August 22, 2007
  • Composition: Adapter Pentax K front and rear, tubular screw (60 × 0.75 mm) No. 1, 2 and 3;
  • Length: 12 to 60mm following composition;
  • Magnification (for a 50mm setting at point at 45cm): 1:0,22 (adapters only) to 1:1,31 (adapters and tubes 1, 2 and 3).

note in passing that the use of macro is to give the magnification on the sensor (the film, in my case). 1:1 means that a 24mm will be the full height of the frame; over the denominator, the more it grows.

What about this game tube? It allowed me to do what I wanted, to discover the macro cheaply. However, the system is screwed tube adapters + malcomode strong, especially as the threads seize up mediocre easily. In short, The settings K adapters, I do not install it on my boxes without fear that they stay there forever ... For further use, it will move to material of better quality.

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