UV filters from Leica

Are there any disadvantages of using UV filters attached to a lens?

An UV filter does not influence exposure, but it represents an additional glass to air surface. This can worsen lens flare in some critical situations, such as night scenes with street lights.

What is the advantage of using an UV filter on Leica lenses?

The expensive lenses will be protected from front tube and front element damage, and keep their (collector's) value better if they don't show any cleaning marks.

Are there any alternative ways to protect the front end of the lens?

Many photographers find it sufficient to use the lens hood and cap as protection.

Are the coatings on Leica filters as good as those on B+W MRC filters?

Judging from the reflections on the surface of the filters, the high-end B+W offerings appear to have a more sophisticated coating.

Are the mounting rings of Leica filters made of brass or aluminum?

Leica's filter rings seem to be made of aluminum, and hence are lighter but possibly less solid than brass mounts (as used on B+W's MRC filters).

For which lenses with reversible hoods do Leica filters provide a superior fit?

There are a number of Leica lenses with removable sun shades where the lens hood fits so tightly that the outside diameter of the filter is critical and non-Leica filters, such as those from B+W, do not fit. Examples include the Elmarit-M 21/2.8 ASPH, Elmarit-M 24/2.8 ASPH, Elmarit-M 28mm/2.8, Noctilux 50mm/1.0, and Summilux 75mm/1.4.

Which filters can be used with the Summilux-M 21mm f/1.4 ASPH?

This wideangle lens is designed to accept Series VIII filters in the lens hood. Alternatively, screw-in filters can be used with Leica's optional adapter ring 14481. This adapter will natively take E82 filters, but can also be used without vignetting with E77 filters in connection with step-down rings.

What does UVa mean compared with UV?

UVa refers to the long-wave, "black light" part of the ultraviolet spectrum with a wave-length of 400-315nm.

What are UVa/IR filters?

UVa/IR filters were offered by Leica (and other filter brands) for use with the M8 to address issues of a magenta cast in some images due to the sensitivity of the sensor to infrared light.

Why do some filters carry the name "Leitz" and others "Leica"?

The filter designations reflect the change of branding over time.

Are Leica's order numbers unique to a particular type and version of a filter?

In general, Leica order numbers are specific to individual products. However, there are exceptions (mistakes?), such as order number 13374, which has been used for the silver version of the E55-UVa filter and also for the Leitz E55-Polarizing filter.