Archived posting to the Leica Users Group, 1999/09/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> ...I was looking at some other slides taken by the T5 today at short > range and there is very marked vignetting in the images. It's in the optical design. The four element Tessar design is remarkably good for its simplicity but characteristic of Tessars is a certain amount of light falloff and softness at the corners of the image when used at apertures close to wide open. The Yashica T5 camera's program holds the lens wide open until an EV value which allows at least 1/125 second is achieved, then it starts to close down the aperture. Tessars do their best performance typically around f/8-f/11. This happens most likely at about EV 15-16, which is fairly bright illumination. They are also noted for increasing softness and vignetting when focused close up due to the front element movement ... most Tessars are front element focusers, I'm not sure about the T5 design. This means that the T5 can return some beautiful images with very high sharpness across the field when the light is high enough or you are using fast film, but as the light level goes down or the focusing distance comes in they lose that edge. Not to say that the T5 is anything but a superb Point and Shoot, you understand. It is. The Tessar lens in it is one of the best in the class, certainly at the price. Godfrey