October 6, 2022

Filters - UV and other

It is a popular topic to argue about whether or not to put a UV filter on a lens. These days the "UV" filtering is of no importance, it is just a question of whether or not to put a protective piece of glass over the end of your lens.

I once knew a fellow who scoffed at the idea and asked "why should I spend $1000 for a first class lens and then screw it up with a $20 filter on the end of it?". If you have deep pockets, you are welcome to take the same view.

Other people think it is reckless and absurd to have an expensive lens and not protect the front element with a UV filter.

This is a famous and long standing controversy in the photography world.

What UV filter

It is your camera, your lens, your money, your life, and you can do as you please. You are also quite free to disagree with me.

I am satisfied that UV filters do no produce perceptible image degredation. The one exception is flare when shooting into the sun. I have made the decision to keep filters on all of my more expensive lenses.

Some lens designs (such as the Canon 17-40 f/4 L) require a filter for full weather protection.

I am currently shopping for a 77mm filter to protect my 24-70 f/2.8 lens.

The cheap option is an uncoated filter. The current bargain option is an Amazon Basics filter for $9. I am holding one right now, and it seems to be a quality item in every way. It is made of glass, with an aluminum ring.

Tiffen offers an uncoated filter for $15. It is plastic, not glass. This is worth thinking about (plastic would not shatter like glass). For $37 you can get their coated "HT" filter which is glass.

A coated filter is much less likely to produce lens flare. I found the recommendation to buy filters made by "Urth" (previously Gobe). Urth filters are designs in Australia, typically made with glass from Germany or Japan, and are assembled in China. These are nice coated filters and the ring is either brass or an alloy they call magaluminum.

10 stop ND filters

Get one of these and you can photograph silky water like all the pros do these days.

The tips are -- select the lowest ISO (100), stop down, use a tripod, shoot in manual.

Shutter speed should be at least 1/2 second, perhaps 4 seconds.

You can get 10 stop (ND1000) filters, 6 stop (ND64), even variable 1-8.6 stop ND filters. The variable filter is likely to vignette on a lens wider than 24mm. I am also reading about soft images and an "X" pattern with wide lenses.

So, 6 stop or 10 stop (or both?). A 6 stop filter passes 1.56 percent of the light. A 10 stop filter (ND1000, really ND1024) passes 0.10 percent of the light.

I ended up ordering a 6 stop filter to get started. I was guided by comments in this article (from 2019):

Urth (was Gobe) filters

First things first. Gobe became Urth and what you want to do these days is to order the Urth Plus+ grade. This gives you their best product, which has Schott glass with a 30 layer coating.

Back in the days of Gobe, you chose between Peak 1, 2, and 3. 3 was their best "pro" stuff (but most filters were unavailable in this grade). The filters I did buy were 2Peak grade, which have a 16 layer coating and unknown glass.

Why are Gobe branded filters still available? Who knows. Maybe the company has a huge stock of the older filter in boxes printed with the Gobe branding.
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Tom's Photography Info / tom@mmto.org