GENorkus Loc: Washington Twp, Michigan

I'm one that always uses a clear filter or another, on my lenses. Please don't start a "filter or not" war. This is a technical question only.

Having one filter needing replacement, I purchased another brand, (Hoya Pro1), to replace my aged other filter, (Cokin). When I started exchanging the two filters, both clear, I noticed the Hoya had a light blueish tint and the Cokin had a green tint as I made a final cleaning.

The green tint is an indication of a coated filter of some kind and I suppose the blue is also. Does anyone know what the difference in color tint is and/or does?

Thanks in advance.

ClarkG Loc: Southern Indiana USA

It’s because the mfg’s use a different chemical for their coating. No big deal.

bleirer

Here's a good article, but doesn't really tell why the color is different. https://www.lensrentals.com/blog/2017/06/the-comprehensive-ranking-of-the-major-uv-filters-on-the-market/

SonyA580 Loc: FL in the winter & MN in the summer

That's why I don't use "Clear" filters.

E.L.. Shapiro Loc: Ottawa, Ontario Canada

Over the years I have used hundreds of lenses and filters. Some of the coatings appeared decidedly blue, others greenish and yet others seemed brown. I don't recall any shifts, differences, or issues in colour balance or rendition due to the appearance of the coating.

If you have any concerns, shoot a few frames with and without the filter and carefully scrutinize the colour response.

With good quality, there should be no appreciable differences in colour, contrast, sharpness or flare at moderate degrees of enlargement.

GENorkus Loc: Washington Twp, Michigan

Having tead the filter test mentioned above last year, I don't really have any concerns. From the overall ratings I figured, why worry about 1/2 of 1 precent.

My question was mearly out of curiosity.

DirtFarmer Loc: Escaped from the NYC area, back to MA

I suspect the color is a surface effect and doesn't significantly affect the white balance of the image produced.
Filter coatings are generally very thin layers stacked in such a way as to reduce reflections from surfaces. The color is probably an interference effect.

User ID

For your curiosity ....

You hafta realize the effect is dichroic.
Walk into any "glass tower" building
that looks golden from the outside and
you will see a slightly blue filtered view
of the outside world [from the inside].

As to your two filters:
What looks blue is reflecting blue.
What looks green is reflecting green.
What reflects blue transmits yellow.
What looks green transmits red.

So the "blue" is a haze/UV filter and
the "green" is a skylight 1B.

.

GENorkus Loc: Washington Twp, Michigan

Interesting, something I never thought about.

Alaskangiant

Get what most Pro use Breakthrough filters

Doc Barry Loc: Huntsville, Alabama USA

Correct.

carl hervol Loc: jacksonville florida

its the coating. I never use filters .

Doc Barry Loc: Huntsville, Alabama USA

There are a few reasons you might want to consider using a UV filter Carl. First, it can protect your very valuable lens front surface. Second, image degradation is not noticeable; indeed, many lenses are designed to anticipate a filter will be used (flat plate and nominal thickness). Third, very blue light (< 360-380 nm) is blocked. This is important because general photographic lenses are not chromatically corrected for the very blue light which can result in loss of MTF/resolution and cause chromatic problems in the image.

Also, a UV filter is not a UV filter because it is marked UV filter. Some manufacturers' filters are useful for just the first point above because they don't really block until much shorter wavelengths. Good quality filters do all three of the points. Hoya UV filters starts rolling off about 420 nm with about 50% transmittance at about 380 nm (a bit too soon in my opinion). Its transmittance in the visible is about 92%. A better filter IMHO is the B+W UV filter that starts its roll off about 390 nm and has a transmittance in the visible of about 96% (has a HEAR coating). Its 50% transmittance point is about 360 nm. Both of these filters are very flat which is most desirable.

Cheap UV filter are good for keeping out dirt. Quality UV filters improve the performance and quality of your photographic endeavors I suggest. I note that filters provided in "bundles" with cameras and lenses are just good to block dust and dirt.

bleirer

I've read, probably here, that sensors are not sensitive to uv.

Doc Barry Loc: Huntsville, Alabama USA

It depends upon the camera. Some detector packages have filters that sharply cutoff about 420 nm. Others cutoff at shorter wavelengths. For example, the Nikon D700 peak blue response is at about 460 nm and is about 25% as responsive at 400 nm. There is no general rule what the spectral response is for the RGB curves nor the cutoff in the UV or NIR. Just look up your camera to get an idea of its spectral response.