Optimal Photometry for CMDs - Aims and Achievements

The Aim

• Obviously the most accurate and precise photometry and astrometry possible, with realistic errors. This is why we use optimal photometry.
• We do not throw away any object, but use data flagging.
• But do flag any even slightly dubious object.
• Rigorous procedures for assessing completeness.
• Rigorous checking of final results to show our errors and completeness are actually correct.
• Software which is quick and easy to use.
• Sensible archiving of code so questions about old reductions of data can be addressed.