As you can see from the spectral response curve the IDAS UIBAR filter didn't cut off light till the wavelength got below 375nm. This was just what I wanted. I ordered one from Hutech on 3 Jun. It was OOS but that was OK I was prepared to wait. The 'UIBAR' filter was shipped on 13 Jun. It was now mid winter and I had to wait a few days to get suitable conditions. Eventually the sun and some time off coincided and I tested out the filter....nothing...no signal at all on the camera, no matter what shutter time I set. Major disapointment. I mulled this over and a few days later sent an e-mail to Ted at Hutech explaining the situation. I received a reply the next day :

"I'm so sorry, it looks like type III was sent to you.We will arrange type IV for you ASAP."

Type III, type IV ???? none of this differentiation was on the website or price list. Oh well all is not lost then. I'll send back my type III and await type IV. These notations aren't marked on the filters by the way, they're marked only 'IDAS UIBAR'

The Type IV was shipped on 10 Jul and I received it on 19 Jul