film thickness vs focus : LUSENET : Minox Photography : One Thread

because of the tiny focal lengths involved, could different film thicknesses actually make a difference in focus? I know I should quit worrying about such insignificant details and just go take pictures, but this technical stuff is interesting.

-- tony pierson (, May 02, 1999


Tony, If you are worried about film thickness in a Minox camera, the trouble is not from focal length but from mechanical ware caused by thick film (over 6 or even 5.5 mils). In all cameras, when film is introduced to the pressure plate and pressed into position, it is the emulsion which faces the lens. The emulsion thickness on all films can only be measured on an atomic scale (fairly large, maybe 30 atoms thick, but that's just a guess would appreciate comment) The area that actually is chemically changed by the light cannot be more than a few atoms thick, whatever the thickness of the film behind it is utterly inconsequential as no image is formed there and it thus, not part of the focal plane. The only exception to this rule are cameras such as the tessina which place the emulsion side away from the lens, but NO Minox is designed in this fashion. Also the depth of field is extraordinarily large in Minox subminis, any measurement difference of one or two ml would be small (though not that small, on the order of a foot) Good Luck! George Maltezos

-- George Maltezos (, May 02, 1999.

Avoid using thick film in Minox, particular in Minox III/IIIs/B where the film plane is curved .

Thick film is hard to conform to the curved film plane, and the image will not be as as sharp.

Thick film is hazardous to Minox camera and Minox slitter, avoid them like plague.

As the discussion on "Mid roll change film" pointed out, the coiled up film in Minox cassette is like a tensioned main spring in a watch. The thicker the film, the thicker the spring, the harder is is to wind the film,; you may exert too much too much stress on the film advance mechanism.

-- martin tai (, May 03, 1999.

May I correct your affirmation, George? Even Tessina shows the emulsion side towards the lens (better, towards the mirror), it could not be the other way since the film is not transparent enough before developing and fixing. Tessina films are reversed during printing, showing the emulsion towards the condenser instead of to the objective.

-- Wolfgang Fischer (, May 12, 1999.

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