Archived posting to the Leica Users Group, 2000/11/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 04:18 PM 16/11/2000 -0500, you wrote: >Anyone else have any thoughts on whether a UV filter cuts out a measurable amount of light? I haven't tested it. Tina has. I don't use a Noctilux at the present time. In theory, the light loss might be about 2-3% of the incident light at each surface. Very low light levels may be necessary to determine if a difference in the meter reading is noticeable. Suppose on an uncoated filter you loose 10% of the incident light (which is much more than you would expect) how would you determine that your light level has dropped by 1/10th of a stop? I suspect that even a sensitive hand-held meter would have trouble registering this difference in very low light. The UV has a fairly sharp cut-off below 400 nm, so you wouldn't expect to have lower readings either because some of the violet light is being filtered. I've never heard of having to apply extra exposure because of a filter factor of a UV filter. Vignetting? The lens has some vignetting when used wide open. The filter should not increase the amount of vignetting with this focal length. Can anyone else corroborate Tina's observations?