Here now a test using that previously mentioned Petri Kuribayashi f3.5/35mm lens when used with the standard UV transmission filter, the Baader-U as well as my shorter wave Jupiter-U filter, compared to the Noflexar f3.5/35mm lens, but now also in comparison to a quartz fluorite lens, here the CERCO f4.1/94mm.
[click on image to see a larger one]
The CERCO 94mm delivers a peak transmission of about 55% at 350nm when used with the Baader-U filter and about 48% at 338nm when using the Jupiter-U filter. That compared to the Kuri 35mm which has a peak transmission of about 58% at 362nm, wheras the Noflexar 35mm shows one of about 45% at 365nm when teh Baader-U filter is used. And when using the Jupiter-U filter, the Kuri 35mm has a peak transmission of about 43% at 350nm, wheras the Noflexar 35mm shows one of about 30% at 358nm.
So using the very same filters, the CERCO 94mm reaches much deeper into UV, which could have been expected, based on its flat UV transmission. However it is a much more expensive lens and quite hard to find, so the Kuri 35mm certainly is a welcome new find for the aspiring UV shooter, also considering that it virtually has no focus shift between UV and visible light.
Stay tuned, more will follow on that fascinating subject...
More info on this very interesting field may be found on my site http://www.pbase.com/kds315/uv_photos