Seals

Plan achromatic lens achieve both depth resolution and width of viewing field. A good plan achromat will be sealed.

While simple achromats resolve resolution and spectrum dispersal, the width of the curved viewing field is only a working 70% or less. 

The simple achromat may not be sealed.

If the 40x (or 100x) is not sealed or poorly sealed by the manufacturer, oil may accumulate between the lens due to capillary action.

We do not charge to seal objectives.