[Filter Test] AndreaU UV-Pass

May 3, 2015

EDITOR'S NOTE: 2021 December 10.

This AndreaU UV-pass filter was an earlier version which is no longer sold.

I like the AndreaU - and not just because it shares my name! This UV-pass filter is robust against IR under typical UV exposures in strong sunlight. And and it can be used artistically for interesting false colours by setting an in-camera white balance or by making converter/editor tweaks.

Under good strong sunlight, I found no particular benefit to stacking the AndreaU with an IR-blocker like the S8612. FWIW, the UV index was at 8-9 while I was shooting according to my weather app. With any of our UV-pass filters is always useful to keep an IR-blocker handy for longer exposures or exposures under certain artificial UV illumination that might also be outputting some visible or IR light too. I did find minor false colour changes with using the S8612 over the AndreaU.

In the technical stacked filter tests, I needed long exposures to push any leaked light through the stacks. I decided, somewhat arbitrarily, to show you the set of 10 second exposures and one 5 second frame. Light may leak through sooner - or later - than that depending on the strength of the illumination in the scene. I don't know whether there is a solid way to pin that down. But the point should be made that it is not particularly easy to leak a lot of visible or IR light through the AndreaU.

Equipment: UV-Nikkor 105/4.5 + D600-broadband + Sunlight

Reference Fotos

Dandelion for its classical UV-absorbing bullseye and false yellows.

CC Passport for its false blues.

Visible dandelion and BaaderU dandelion for comparisons.

Baader UVIR-Cut Visible

BaaderU UV-Pass

Profiled false colour and white balance.

AndreaU UV-Pass

Profiled false colour and white balance.

There is a bit of green tint in the bullseye.

AndreaU UV-Pass

Raw composite made in Raw Digger.

AndreaU UV-Pass

An in-camera white balance which gives some pretty magenta/violet false colours.

AndreaU UV-Pass

The CC Passport in profiled false colour and white balance.

Stack: AndreaU UV-Pass + S8612 IR-Cut

To test whether AndreaU benefits from additional IR-blocking.

Profiled false colour and white balance.

There are only minor false colour changes - less green than in the preceding set.

Stack: AndreaU UV-Pass + S8612 IR-Cut

Raw composite made in Raw Digger.

Stack: AndreaU UV-Pass + S8612 IR-Cut

An in-camera white balance.

Stack: AndreaU + S8612 IR-Cut

The CC Passport in profiled false colour and white balance.

Technical Tests

Even though the AndreaU does not particularly benefit from the addition of an IR-blocker during normal exposures in strong sunlight, it is important to test for the types of leakage which can be "pushed" through the filter. I stacked the AndreaU with some other filters and made fotos of my Labsphere reflective standards set. Only the fotos of the 99% white standard are shown here. The exposures were 10 seconds long with the exception of the visible test which was 5 seconds long. We know the AndreaU passes a very small amount of visible violet and violet-blue wavelengths so a shorter exposure length is not unexpected for that test. With certain white balance settings some violet/blue can be brought out in UV shots for a very pretty effect.

These fotos are all raw composities made in Raw Digger unless otherwise noted. Following each foto is a histogram made from sampling as large an area as possible inside the Labsphere circle. These reading are not absolute, of course. They are only valid for the light in which I was working while shooting. But they do serve to indicate in which channels visible or IR light leakage might be recorded. A range from -4 EV to +2 EV was chosen with a bin of 1/96 EV in size except for the very last IR test which only started to record at -6 EV.

AndreaU UV-Pass

Raw composite.

Histogram.

Stack: AndreaU + S8612 IR-Cut

To test whether AndreaU benefits from additional IR-blocking.

Almost the same as the preceding set.

Raw composite.