Will yashica 50mm lens fit to Olympus e-pl1?

The Yashica 50mm lens is typically an M42 mount lens, while the Olympus E-PL1 uses the Micro Four Thirds (MFT) mount. To use the Yashica 50mm lens on the E-PL1, you would need an M42 to Micro Four Thirds adapter. Keep in mind that using this setup will result in a crop factor, making the effective focal length approximately 100mm due to the smaller sensor size of the E-PL1.