The AndreaU Mk II - 358BP46

The AndreaU MK II UV bandpass filter from UVROptics was developed in 2016 to follow the success of the popular AndreaU filter. Some adjustments have been made since then. The transmission peak has been moved recently, to 358nm from 363nm, allowing more transmission in the range of the diminishing UV-intensity in natural sunlight. Additionally, the slight "toe" in the 402nm range has been eliminated with a minimum optical density (OD) of >OD3.7 from 398nm to 1100nm. (See the diabatic graph for out-of-band blocking.) This higher OD provides stronger near-Infrared blocking thus making ultraviolet photography possible even in conditions such as rainy days, when the amount of UV is low, the percentage of NIR wavelengths may be high, and a long exposure time is necessary. As the AndreaU MK II is an ionic filter, it can be used with wide-angle lenses without the bandshift issues of dichroic filters such as the Baader Venus filter or our own UVROptics Dichroic 379BP43.
Dichroic filters shift their cut-off wavelength according to the  angle of incidence of the incoming light.  This makes the dichroic filter difficult to use with wide-angle lenses. The AndreaU Mk II, on the other hand, is an absorptive filter, providing an accurate, reliable image without the dichroic bandshift.
The graph above is representative of the performance of the filter as measured with a Beckman-Coulter DU 520 spectrophotometer.

The AndreaU MK II has, over the years, proven to be popular worldwide among scientific, technical, and art photographers. The new AndreaU Mk II with its exceptional out-of-band blocking, high-speed, low cost, and durability will enable even more photographers to enjoy the world of UV reflectance photography.

AndreaU MK II is provided in a custom 52mm threaded ring with 3D-Printed stack caps, front and rear.
............ $249.00 USD plus shipping.

Please allow three weeks for delivery.

For more facts about UV bandpass filters go to Filter FAQS.