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-   -   Uncoated UV/Polarizing filters...good or bad? (https://www.dvinfo.net/forum/open-dv-discussion/81595-uncoated-uv-polarizing-filters-good-bad.html)

John Huling December 12th, 2006 10:47 AM

Uncoated UV/Polarizing filters...good or bad?
 
I just ordered some filters. UV and Circular polarizer. The back of the box says they are non-coated. Wouldn't these allow more lens flare than coated?
Any opinions? The price is $70 for Polarizer vs. B + H is around $200.

Harm Millaard December 12th, 2006 11:47 AM

You get what you pay for. Uncoated is much more susceptible to vignetting and other imaging errors. Whether that is worth the price difference, only you can decide.

John Huling December 12th, 2006 01:50 PM

How does uncoated vignette?

David Tamés December 12th, 2006 02:02 PM

Lens and filter coatings reduce reflections which results in improved light transmission and overall better image contrast. You will see the most dramtic difference between coated and uncoated filters in a situation where light sources areshining directly into the lens. In most cases the differences are subtle, but real. I don't understand, however, how it makes a difference as far as vignetting goes.

John Huling December 12th, 2006 02:09 PM

Me either David?

I understand fully light transmission or at least so I thought.Vignetting would imply less light around the edges of the image. I will do coated anyway.
Thanks

Steve House December 12th, 2006 03:10 PM

Quote:

Originally Posted by John Huling
Me either David?

I understand fully light transmission or at least so I thought.Vignetting would imply less light around the edges of the image. I will do coated anyway.
Thanks

AFAIK, uncoated in video behaves the same as uncoated in still. I'd actually expect flare to be a bit worse in a video lens because of the sheer number of elements in it and the smaller apertures used in general. Vignetting can be a problem but not due to the coating - a lot of video lenses have the lens barrel cut off right at the edge of the image circle anything that adds length to it such as a filter ring can intrude into the frame. Also note that because in many zooms the front element rotates while focussing and zooming, the distinction between a linear polarizer versus a circular polarizer becomes important if you're using it to cut specular reflections and glare.

John Huling December 12th, 2006 04:20 PM

Hi Steve
What's your take then on coated vs uncoated filters?

Duane Burleson December 12th, 2006 11:14 PM

Both linear and circular polarizers must be turned within their mount to achieve the best effect. This is one reason why I prefer a internal focus lens because it does not turn the front screw in filter when focusing, or use a matte box and place the polarizing filter in the matte box.

A good description of the difference between linear and circular polarizers is available about 5 pages down at http://www.rit.edu/~andpph/pf-faq/faq-26.html

Oh, and go with the coated filters.

Duane

John Huling December 13th, 2006 06:40 AM

I am going with the statement that uncoated vs coated makes no difference when it comes to the vignetting question. Having been involved in prophoto for nearly 40 years and not video, I just thought maybe there was something I did not know that might be different in the video world, how, I did not know.
None the less I already decided to go with coated for "clarity" and better transmission of light approaching the lens at various angles.
Coating has nothing to do with vignetting. Although the filter itself might cause vignetting from protruding out.
The store just mistakingly sent uncoated "tradtional" filters instead of coated.

Thanks anyway:)

Steve House December 13th, 2006 10:49 AM

Optics is optics, whether video or still <grin> and the same principles apply to lenses filters etc. Another reason to be aware of the distinction between circular and linear polarizers, BTW, for the benefit of those reading our conversation, is that the sensor blocks in digital cameras in general, both video and still, also polarize the light falling on them and so tend to interact in unpredictable ways with linear polarizers. The filter orientation that cuts glare best or makes the clouds pop out in a blue sky, for example, could end up being cross-polarized with the sensor block itself resulting in the light being completely blocked, something you'd see on a preview monitor but not though an optical viewfinder.

Paul Cypert December 14th, 2006 04:42 AM

Just adding because it wasn't outright stated that the wider the angle of view the more one "might" need a thinner circ polarizer to avoid vignetting, but this has nothing to do with coated or uncoated, but just on the field of view being so wide as to see to the edges of the adapting lens. This is typically not too bad a problem with film as most cameras stock lenses aren't all that wide...actually kind of normal even though called wide. Most are available in thin varieties these days with no loss of quality so might as well pick it up just in case you're going to throw it on your 10-22 or 17-40 Canon or something...

Paul


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