BAK4 vs BK7 Prism Glass What Changes in the Image
BAK4 prisms give a circular exit pupil with even edge brightness. BK7 prisms show a truncated exit pupil and dimmer edges. Available on select models, prism grade is customisable.
Questions About This Topic
What is the practical difference between BAK4 and BK7 prisms?
BAK4 prisms produce a circular exit pupil with even brightness across the field. BK7 prisms result in a slightly truncated exit pupil with dimmer edges, especially in low light.
Which models use BAK4 and which use BK7?
BAK4 is standard on waterproof 42 mm roof models. BK7 is used on the kids WD45 and SRB03 models. The WP48 porro range and SPM01 spotting scope are available in either BAK4 or BK7.
Can we change the prism grade on any model?
Yes. Prism specification is customisable on request. Buyers can choose between BAK4 and BK7 for models that support both.
Should we use BAK4 or BK7 for a higher price point product?
Use BAK4 for higher retail price points where image quality is a key selling feature. It provides a brighter, more uniform image, especially at the edges.
Is BK7 suitable for a lower price point model?
Yes. BK7 is cost-effective and suitable for lower price point models where edge brightness is less critical and budget is a priority.
Does the prism grade affect the optical coating?
No. The prism grade and coating are independent specifications. Coating (FMC broad band green, all blue, or part green) can be specified separately from the prism type.
Put This Into a Quotation
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