Baader UBVRI Photometric Filterset 50x50mm (5 Filters) - 2459444

Baader All filters planoptically polished

• Baader UBVRI - Filterset, 1pc each of U, B, V, R, I Filter
• Photometric Johnson/Bessel filter system
• partial dielectric design with BBAR minimized reflections
• Planeoptically polished, 4mm glass thickness
• non-ageing sealed coating edges

Our 4 mm thick UBVRI filters are a self-construction that strictly adheres to the classic Johnson/Bessel transmission specification. Unlike the original construction however, they are made up of dielectric layers as well as absorption filters. This allows for a smaller filter thickness of 4 mm, the original stack of pure coloured glass would have a thickness of 5 or 6 mm and would be too thick and too heavy for many filter wheels.

In addition, the susceptibility to reflections of the internal transitions and also potential cementing errors would be significantly higher with an original stack, a clear advantage of our modern production method.

However, we still use a combination of short pass and long pass filters in our design for perfect off-band blocking - this would not otherwise be possible with pure dielectric layers over such a large transmission range.