MTC Photography Posted March 7, 2004 Share Posted March 7, 2004 <pre> Minoxar and Minoctar probably has the same optical formulation(ie, glass types, power and bending of elements, airspace thicknessetc ). The main difference probably MC-Minoxar is multicoated,(henceMC), Color-Minoctar is not multcoated. There are other subtle differences; Marking: (GT-E, MDC) MC-Minoxar 2.8/35 Germany Color-Minoctar 2.8/35 ; no Germany Depth of field ring: GT-E MC-Minoxar: full circle red color ring with white lettering and white index mark and two left and right white dots as DOF bracket. ML Color-Minoctar: black ring white lettering with red index bracket Aperture control ring: MDC MC-Minoxar: click stop GT-E MC-Minoxar: no click stop, Index mark on aperture ring aperture number 2.8..16 on camera body ML Color Minoctar: no click stop index mark on body aperture number 2.8 to 16 on aperture ring Focusing ring: MDC MC-Minoxar: focus from 90 cm to infinity GT-E MC-Minoxar : focus from 70 cm to infinity ML Color-Minoctar: focus from 90 cm to infinity Exposure meter window on lens GT-E MC-Minoxar ; 180 degree semicircle arc ML Color Minoctar 120 degree arc Screws on focusing ring GT-E MC-Minoxar one screw hole at far left of 0.7m mark, second screw hole between 1.2m and 1.5m ML Color-Minoctar one screw at left of 3ft mark ( about 0.8m position), second screw between 10 and 20 feet (3ft to 6 ft) </pre> Link to comment Share on other sites More sharing options...
subminiature Posted March 7, 2004 Share Posted March 7, 2004 It is very odd that the designers of the MDC would include a lens, Minoxar, that has been in production on the GT-E for some years yet restrict it's use to the same range as the lens on the ML and GT, the Minoctar. The GT-E foucs down to 70cm as do the GT-X, GT-S and GT-E II. The MDC has a minimium focus of 90cm, the same as the ML and GT. Although the name has changed on the lens the MDC still has not taken the full advantage that it apparently offers over the ML. Link to comment Share on other sites More sharing options...
MTC Photography Posted March 7, 2004 Author Share Posted March 7, 2004 <pre> The same Minoxar lens was allow to close focus on GT-E to 70cm, oneMDC close focus only to 90 cm. <p>I believe the designer of MDC wanted to control the lens abberations to tighter specification than on GT-E<p> I use a model four element three group Tessar lenswith Schott glasses, SK16, LLF6 and O_S_TIL27 to see the effect of change of first airspace to Seidel abberations.The front element of this model Tessar is made of SK16(index 1.62041 ) radius 16.392mm, thickness 3.035616mm. The focal length of this element alone is about 25mm, ie, twice as strong as the whole lens.(That is why changing first airspace is an effective means ofchanging focus length of lens to focus. The first airspace is made variable for front element focusing,all the other parameters are left unchanged, ie only the first airspace is allow to change. when air space is 2.779178mm, the focal length of the lens is 50.792358 mm focus at about about 1 M the lens has 9% spherical abberation ( SA3 =-0.090105 ) and less then 2% distortion (DIST3 =-0.014181 ) Whan front element extends out to increase airspace to 3.679178mm, the focal length =49.530873 mm, lens focus at 0.67M spherical abberation double to 19% (SA3 =-0.188079) distortion increases to 23% (dist3= 0.231360) Other Seidel abberations such as chromatic abberation, astigmatism,and field curvature etc are notas sensitive to change of first airspace thickness. In terms of sensitivety of first airspace variation in Tessar,apparently distortion is most sensitive, followedby spherical abberation. Hence limit the close focus distance of MC-Minoxar lens on MDC to 1Mis good idea, in order to keep overall performance standard high. Note: I am not saying that Minoxar close focus to 70cm has 23% distortionbecause my model Tessar is not Minoxar, which I have no lens formulation data. </pre> Link to comment Share on other sites More sharing options...
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