> I have just purchased a PS-Speck kit from Mole Probes. I wondered if any > of you have successfully calculated the PSF of your systems using this kit. > If so I would be grateful to hear your comments, tips etc. I have used such beads (a prototype of PS-Speck) to measure the shift between different colours. This works very well (accuracy of measurement is about 10-20 nm). After such shift measurement a correction can easily be performed. Read about this in the January issue of J. Microscopy. It shows pictures of 3-colour PSF's. Erik Manders CRC Nuclear Structure and Function Group Sir William Dunn School of Pathology Oxford University South Parks Road, Oxford OX1 3RE, UK Tel: (+44/0) 1865 275529 (/275500) Fax: (+44/0) 1865 275501 E-Mail: [log in to unmask]