Choosing a Lens from Catalog Specifications
Begin with the original product number and the specifications listed for that model. Compare the material, diameter or rectangular size, focal-length field and coating before selecting a model.
Read each focal-length field separately
The catalog distinguishes effective focal length, back focal length and source-listed focal length where those fields are available. Use the field actually listed on the product page. A value marked as requiring confirmation should be reviewed with your quotation.
Check size and thickness
Diameter, rectangular dimensions, center thickness and plate thickness are separate catalog fields. Review the applicable tolerances for your selected model rather than substituting a nominal size from a different series.
Include application requirements
Provide the working wavelength, mounting constraints and required quantity with your request. If a required parameter is absent from the product page, ask for confirmation instead of assuming a value.