2024年6月1日土曜日

5 Group 5 Element MD35mm f/2.8 modified into 2G2E








As a matter for deep regret, I bid at 1 yen on a janky Minolta MD Rokkor 35mm/f2.8, telling some inconvenience in optical construction and I got it. A most posterior lens had clack in the center with mistened. Complete void as it was, I tried an experiment, removing all the rear element behind the iris construction and checked the focus point.

7.50mm reduction from Minolta SLR MD mount flange back 43.50mm could focus on the infinity position, the angle of view does not change so much around original 35mm. Pics show f/2.8 open, 4.0, 5.6, 16,  respectively.

Though it was pre-imagined that unexpected aberrations appeared grandly, it was some strange and dreamy scenery through this junky lens and the rate of aberration reduce in accordance with the angle degree of f number ring rotation. In another words, the rate of aberration is easily controlled. 

This kind of specific character is just going against the trend of lens designing! Because all of the engineer in the field try and intend to eliminate them with several meanings, lens element increases in number. This is what computer analied lens construction designing does.

Now, original 5 group and 5 element design of MD 35mm/f2.8 has changed into 2 element only as shown in the fig. One is concave with meniscus convex front and meniscus convex rear, and the other is thick convex with meniscus convex on both side. How poor the residual lens component remained if the rear group is removed!

Remember here the undeniable and unforgettable Scientific Principle, "The less glass material and the less reflective surfaces, the more transparent clarity could be obtained as a matter of fact !".

Consequently, I would like to make use of this unusual character for fantasy-like and Jioramic expression especially in table photos.

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