[Ztrejfer]

I'm investigating which UV-filters to buy for my FA 31mm Ltd, DA 18-135mm & DA* 60-250MM lenses. Of course I've come across the test Lenstip UV filters test - but this was issued in May 2009, and I was wondering what development there has been since then on UV filters? Which one would you buy today?

The test announced the Hoya 72 mm HMC UV-0 as best buy on both quality and price - any better than that one today?

[Paul the Sunman]

Interesting question. An even more interesting question is whether there is any point at all (apart from protecting the front element) of using a UV filter on a digital camera. I suspect the answer is "no".

[Ztrejfer]

Interesting question. An even more interesting question is whether there is any point at all (apart from protecting the front element) of using a UV filter on a digital camera. I suspect the answer is "no".

With all due respect - you may be wrong, Sir.

Why? Because in the same article we are informed of the following fact:

For waves shorter than 285 nm the glass transmits less than 10% of the light and for 200 nm or lesser range it is as little as 3.2%. But for the UV weve range close to the visible light limit the glass transmits as much as 90% of UV radiation. Should we worry about that? We know, from everyday life, that the image in the picture is in most cases the same as the image we see. It is caused by absorption and strong radiation dispersion by the earth’s atmosphere. Many kilometers above the earth the ozone absorbs some of the UV radiation. The closer to the earth’s surface, the more the UV radiation is absorbed. At the same time the light disperses while meeting atoms and the atmosphere, all the time building molecules along the way. The shorter the radiation waves, the stronger the dispersion. This effect is called the Rayleigh dispersion effect. The consequence of this effect is that blue light is 10 times more dispersed in the atmosphere than red light. This is why the cloudless sky has a beautiful blue color. However the 300 nm long UV radiation wave is dispersed 30 times stronger than red light. We cannot notice this effect but the film or CCD/CMOS detector can.

And further:

In summary, UV radiation is strongly absorbed by the atmosphere and the higher we are (on a plane or in the mountains) the more radiation we encounter. At the same time, the radiation is strongly dispersed, so when taking a picture of the Morskie Oko high mountain lake or Giewont Peak we get the impression that the image is slightly more blurred than we see with our naked eye. These are situations in which the use of UV filters would improve the picture quality.

So - if any Gentlemen or Lady in this forum has a tip for some other UV-filter than the mentioned Hoya 72 mm HMC UV-0 (which is very good, I suppose) I'd be very glad to hear of this.

Thank you kindly.

[Driline]

I use a UV B+W 007 Neutral MRC filter that works great. It's the F-Pro series of filters from B+W. This filter stays on my FA 31 if I'm not using my Marumi color polarizer filter which I purchased from Adorama.

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Last edited by Driline; 09-20-2014 at 10:05 AM.

[RGlasel]

when taking a picture of the Morskie Oko high mountain lake or Giewont Peak we get the impression that the image is slightly more blurred than we see with our naked eye

Giewont Peak is 1895 meters above sea level, but I've never been there. This summer I took this picture of Sylvan Lake in South Dakota which is at 1873 meters above sea level (at the surface of the water), without a UV filter.


If anything, this is sharper than how the scene appeared to me, but I wear glasses and after hiking they were dusty. In theory, the dispersion of UV light should have an impact, but in practice, it doesn't appear to. I've used UV filters in the past, some high quality, some low quality, and the low quality filters definitely seem to degrade the image, especially after long time use resulting in scratches and smudges. I take better care of my lenses now that I don't put UV filters on them, so perhaps it's unfair to say that they don't offer any benefits, but reducing the blurriness of images taken at high elevations doesn't seem to be a benefit of using UV filters.

[Driline]

This summer I took this picture of Sylvan Lake in South Dakota which is at 1873 meters above sea level (at the surface of the water), without a UV filter.

I bet it would have even looked better with a color polarizer. It does look like a very nice sharp image though.

[Paul the Sunman]

The issue turns on the frequency response of modern consumer-type CMOS sensors in the UV. It is certainly far less than in film, and ranges from very low to completely negligible for different sensors. So, depending on your sensor, placing another layer of glass in front of your lens may do no good. I have not seen the frequency response curves of the sensors used in recent Pentax DSLRs. Hence my question. Has anyone seen the UV response figures for the K5 or K3 sensors? I would be interested to know.

It should also be noted that optical glass in lenses effectively filters out UV below about 310 nm, so only UVA should be an issue.

[reeftool]

I'm avoiding the argument about the value of a UV filter other than to say there are conditions where a protective filter is necessary. If you want one, buy one. That said, the Hoya is just as good now as it was in 2009. Is there a better one? Maybe. I have some B&W filters that are very good and cost just as much or more. Buy a good one. Keep in mind that plain window glass blocks most UV light so technically fills the requirement of a UV filter. Filters from top tier manufacturers are quality optical glass and won't degrade image quality and be less likely to cause flare.

[m42man]

Yes, do buy a top quality brand - and also make sure the one you get is multicoated. Plus, there are a lot of counterfeits out there (filters are easy to fake, and are a financially attractive item for fraudsters), so make sure you buy from a very reputable dealer.

[Ztrejfer]

Well - I have to give in here. The UV-filter may not be exactly what I'm looking for, since my main goal is to get clouds to stand out which would else get lost on the photo.

I've thus cast my eyes on the Hoya 58mm Circular Polarizer HD Hardened Glass 8-layer Multi-Coated Filter (in all its glory) - but there seems to be an issue with fitting it on my FA 31mm Pentax lens....

Because is it really possible to fit this filter on that lens? When I look at the lens, my logic goes "No way!" because of the built-on lens hood - but there may be an option that I'm not a rare of.

Does anyone have any experience with placing CPL-filters on the FA 31mm?

[noelpolar]

Well - I have to give in here. The UV-filter may not be exactly what I'm looking for, since my main goal is to get clouds to stand out which would else get lost on the photo.

I've thus cast my eyes on the Hoya 58mm Circular Polarizer HD Hardened Glass 8-layer Multi-Coated Filter (in all its glory) - but there seems to be an issue with fitting it on my FA 31mm Pentax lens....

Because is it really possible to fit this filter on that lens? When I look at the lens, my logic goes "No way!" because of the built-on lens hood - but there may be an option that I'm not a rare of.

Does anyone have any experience with placing CPL-filters on the FA 31mm?

See post no 4....Driline is happy with his.....and I use one on my 43.....

[stevebrot]

So - if any Gentlemen or Lady in this forum has a tip for some other UV-filter than the mentioned Hoya 72 mm HMC UV-0 (which is very good, I suppose) I'd be very glad to hear of this.

Thank you for the lengthy explanation except that the sensors have relatively poor response to UV light. Unlike photographic film, they are biased to the red end of the spectrum. As a result, your classic UV filter (all of which are plain optical glass, nothing more) are basically just another reflective surface in the optical path and useful mostly as protection.


Steve