Why Don't UV / Protection Filters Cut UV ?

[colinbm]

Some of my UV / Protection Filters don't cut UV, why ?

So I purchased a new release Manfrotto Outdoor UV Filter.

https://www.digitalc...-uv-filter-77mm

I was disappointed again that this one didn't cut UV either....?

 

First image is of todays full sunlight.

Second image is with the Manfrotto Outdoor UV Filter.

 

 

[Andy Perrin]

Indeed, I think many people have reported that so-called UV filters don't do much UV cutting. It seems this one cuts nothing!

[dabateman]

When most of the world switched from film, (very UV sensitive) to digital (not really UV sensitive at all), these filters main use became front of lens protection. So can be made of any cheap glass with a coating and most users will not notice.

Except they will cause problems with image quality. Flare, CA, ghosting, coma, many problems people complain about are caused by the junk protection filter placed infront of the lens.

 

We had a couple theads on good 400nm blocking. I still like tiffen 2A. But can't be too old. I got a Tiffen 2A series C filter, which is 21mm in diameter to drop into a 25mm ring. The thing is from 1952 and leaks UV like crazy.

[JMC]

Colin,

 

Welcome to the murky world of product claims. Not all UV filters block UV, or at least not the UV that they need to block to be of use to photographers.

 

There's a nice review of some of them here (although a few years out of date now) - https://www.lensrent...r-spectrograms/

[colinbm]

I was surprised, & with all the hype on the Manfrotto packaging too....!

[Stefano]

Probably, as someone said above, in the digital era you don't need to cut UV and your UV filter is for protecting the lens, but the name remained the same, just like tinfoil, that was made out of tin once, and now it is made of aluminium, but it is still called tinfoil (also in Italian).

[JMC]

Yeah, but don't expect all internal filters to properly cut the UV. I've found on Canons especially, from looking at the internal filters, that some of them let a significant amount of light in at around 365nm.

 

Some of us still call Al foil, tinfoil, here in the UK too.

[bvf]

Here's a photo I took of a few Hoya filters using the tri-colour UV technique.

 

It shows that the Hoya UV© [i can't stop bracket-C-bracket being converted to copyright here!] filter does little in the way of UV absorption, at least not in UVA - not much more than the Lens Protector filters which have appeared recently. The yellowish colouration indicates slightly increasing absorption as you go down the UVA wavelengths.

 

On the other hand, the UV(0) filter seems to be effective at blocking UV across the UVA range.

 

Just for fun, I've added a similar image showing how (in)effective Cheap-from-China safety glasses advertised as providing UV protection are. (I was also surprised that the Uvex glasses let quite a lot of UVA through too.)

 

 

[colinbm]

Thanks Bernard, I'll see if I have a Hoya UV(0) & 81B...?

[bvf]

The 81B was just a random filter I found in drawer rather than a UV-cut filter. (I think it's for colour temperature conversion - I just used it in this image because it was very light, like the UV filters).

[Damon]

Jonathan I tend to agree. My unmodified off the shelf Canon 1D Mark IV can take UV pics.

[OlDoinyo]

I did a test a few years ago wherein I demonstrated that a so-called UV-haze filter was a better UV transmitter than all but one of my lenses (the Steinheil!) I got a chuckle out of that. Even the slightly stronger "Skylight" filters let some UV through, though they might have been of some slight optical value.

 

I think that, in the days of color film, UV was perceived as a problem (especially if the film was not overcoated.) Clever merchants then peddled a ''solution" without bothering to test if it actually worked, and nobody questioned anything. In some cases, especially after 1970 or so, the lenses in use passed very little UV anyway, so it turned out that there was not much of a problem to solve. There was never an issue with B&W film because it was typically used with colored filters that were themselves UV-opaque. The habit of putting a clear filter on the front of the lens "for protection" persisted into the digital age--and some filters were simply marketed as "clear" with no claimed optical effect.

[colinbm]

I would have thought, hoped, that Manfrotto coming late into the filter business, with its good reputation, & all the hype on the packaging, that it would have put out a UV / Protection Filter with better lab specs then this.

[Cadmium]

Here's a photo I took of a few Hoya filters using the tri-colour UV technique.

 

It shows that the Hoya UV© [i can't stop bracket-C-bracket being converted to copyright here!] filter does little in the way of UV absorption, at least not in UVA - not much more than the Lens Protector filters which have appeared recently. The yellowish colouration indicates slightly increasing absorption as you go down the UVA wavelengths.

 

On the other hand, the UV(0) filter seems to be effective at blocking UV across the UVA range.

 

Just for fun, I've added a similar image showing how (in)effective Cheap-from-China safety glasses advertised as providing UV protection are. (I was also surprised that the Uvex glasses let quite a lot of UVA through too.)

 

 

 

Bernard, I would have to strongly disagree with you about the Uvex glasses (Amber MPN: S0290X), because those block UV entirely, I have tested them.

The only way you are seeing anything through those is with visible and above light.

 

Don't believe me? How about this masked man:

https://www.ultravio...dpost__p__30689

 

Or this, this is even better:

https://www.ultravioletphotography.com/content/index.php/topic/2614-uv-eyewear-protection-upgrade/page__p__19704__hl__+uvex%20+amber__fromsearch__1#entry19704

 

Yep, something wrong with your test, Bernard, better figure that out, no UV gets through those amber Uvex shades, man.

[bvf]

Cadmium - I know the filters don't leak visible or IR, I've been through that a number of times. I made that image early on in my tri-colour UV period, so it's possible there was something wrong with the technique as applied to that image. I'll repeat the experiment and let you know.

 

BTW, I just tried putting the Uvex glasses in front of my full-spectrum camera with a Baader U, and I could still see a faint image.

[Cadmium]

Fresh from the laundry room...

The right pic may look darker exposed, but these have the same exact settings, and the same white balance.

PS: Where did you get your Uvex from? Stephano wanted some, but the place I got mine doesn't ship internationally.

 

[OlDoinyo]

The Baader has a small IR leak--we have documented that. It is possible that that is what is going through your eyeshades and being recorded.

[bvf]

I didn't use the Baader U for the shot of the glasses - it was just a quick check I did today. For the original shot I was using my tri-colour set (380BP20, 345BP25, 315BP25). I have not been able to record any leakage through these.

[Cadmium]

The Baader U doesn't leak anything enough to show up in anything usual, the worst out of band OD is has it about 4/4.5 OD and up in the higher IR range, so any thing you might push would make something black look gray instead of warmer brown.

Bernard, the shot you show of the Uvex glasses is simply misleading. The UVB200 has enough UVB in it to show up. Your shots show a very easy to see through Uvex.

I understand you have tested your UV bandpass filters for out of band leaks, but I am very mistrusting of your setup, because unless you use extended exposures times there would be no way to get that kind of UV illumination through the Uvex glasses at any of your UVA or UVB range. I have never questioned your tri-band filters before, but I seriously do now. Your example makes the Uvex look like a pair of budget sunglasses, and I know they work very well for blocking UV. In fact, they are the best UV blocking eye wear I have ever found.

Where did you purchase them from?

I can't find any way to make them look like your example.

I will try the same using my 8mm thick non glued U-340 stack later on, that have extended range into the UVB when mounted on the UV-Nikkor. That is the best I can think of.

[Stefano]

Maybe a diffraction grating test can help? Sunlight and discharge lamps have well-known lines (absorption in the former, emission in the latter), so you can see if there are visible light leaks (and even at which wavelengths). "Stacking" the Uvex glasses with Bernard's bandpass filters and a diffraction grating may give us some information.

[Andy Perrin]

I have a pair of S0290X.

 

Both shots are F/8, ISO6400, 1/25", S8612 1.75mm + UG11 2mm:

 

Control shot (no UVEX):

 

With UVEX in front of filter:

 

I also tried shooting directly into the sun with UVEX on (F/8, ISO12800, 1/25"):

[Cadmium]

I tried shooting with the U-340 8mm stacks, glued and non glued, and they both see nothing except a faint image of the UVB200 and only if I extend the exposure time into the twilight zone.

The U-340 8mm extends lower than the Baader U's ~320nm reach, down below 300nm (with less upper UVA).

Using the same exposure as the control shot is much more realistic and less misleading.

I can post the U-340 shots if you like, but they look the same as the Baader U shots I posted, but they require longer exposure times due to the lack up higher UVA and less camera sensitivity to UVB.

[Stefano]

It is still day in America, night here.

 

UG11 (2 mm) blocks a bit lower than 400 nm. I wonder how Bernard's 380BP20 filter behaves. Judging from the brown color, this is the filter that is letting more light in with the goggles.

[Cadmium]

It is still day in America, night here.

 

UG11 (2 mm) blocks a bit lower than 400 nm. I wonder how Bernard's 380BP20 filter behaves. Judging from the brown color, this is the filter that is letting more light in with the goggles.

 

Stefano, I think Baader U and U-340 8mm pretty much cover any possible range of Bernard's Tri-UV filter range.

I am very satisfied with the Uvex, but not with Bernard's example of them. That shot is simply very strange.

Unless someone used an extremely long UV exposure, and not such a high ISO as I used (to hand hold the shots), then I can't see how his Uvex example could look how it does,

also, even the white back ground, looks optimally exposed, not overly bright, yet the Uvex looks exposed properly also, so I would not think using an extremely long exposure to push the Uvex would show an optimally exposed background.

So I am wondering about those filters now.

[Stefano]

2 mm GG420 cuts right at 400 nm. If Bernard has it, he could use it to test his filters.