Filter Question.

[Douglas Joseph]

Hello, comrades.

I just recently bought a UV filter, which cost a mere twenty dollars (basically acts as a lens cap). However, I have noticed that there has been less haze while shooting with my XL2 now. I was thinking about buying the FS-72U Filter Set, which includes: Neutral Density (ND8), polarizing and ultra-violet filters; usually sells for around hundred dollars. Do you think there will be much difference between the UV filter I just bought, and UV filter included in the set? I'm sure there is a diffence, it's just I have done barely any research for UV filters. Also, have any of you purchased the FS-72U Filter Set, and was it worth it? Any help which can be provided will be greatly appreciated.

Thanks, in advance.

D.C. Joseph.

[Tom Hardwick]

You've bought a beautiful 12 element, 10 group lens that Canon have applied their best multi-coating to. They need to with so many glass elements all in a row. Now what have you done? You've added another element to the lineup - a $20 72 mm UV filter. I'll bet you a dollar to a donut it's not coated in the slightest. Does it even have a maker's name you recognise?

Now ask yourself this, Doug. If Canon's advertising for the XL claimed that it has a 13 element zoom and the front element was completely uncoated, how would you feel? Rightly disturbed, I should think.

Remember that anything you screw into the front of your zoom (filter, wide-angle converter, etc) forms a new front element, and the coating on this element has to be the very best you can afford.

I have a test I show people. I have an uncoated UV and a S-HMC Hoya, and within 2 minutes I can have them skimming their ucoated UV out over the lake. Think on this.

tom.

[Alec Lence]

Are you saying that he would be better off shooting without a UV filter should he not be able to afford top of the line?

(I know this sounds smartassish but I can't think of a better way to word it, my apologies, I legitimately would like to know :-)

[Douglas Joseph]

Tom, now, are you saying the 20x optical zoom lens already has a coating on it which will protect it from UV rays, no? Because from what I can gather, you're saying that my lens already has a coat which protects it. Forgive me, I am ignorant.

[Pete Bauer]

Hi Douglas,

The end-purpose of the coatings on the lens elements is not really for the UV filtering, but rather to reduce internal reflections and other nasty optical effects that otherwise can't reasonably be engineered out of a multi-element system.

Placing a relatively inexpensive UV filter on the front helps protect the front element from damage -- better a $20 filter gets scratched than your front element! I personally keep a UV on at all times, unless making occasional use of my circular polarizing filter and rarely a neutral density filter. There is some truth to the rule of thumb that you get what you pay for. A UV filter will also help reduce haze in outdoor long shots, thus giving the image a slightly sharper, richer look. Indoors it probably is no more than a lens protector.

As Tom was saying, a super-cheap, uncoated filter will of course have some negative effect on your image. But a quality coated filter will have very much less negative effect, in most shooting circumstances not noticeable. Some folks invest in matteboxes, but for those of us who just use screw-on filters, it is probably worth making sure you get filters of good optical quality.

I'm not familiar enough with different brands to make a real comparison-based recommendation, but you shouldn't have to break the bank to get a decent UV filter.

[Tom Hardwick]

First off Alec, no offence taken at all. All glass absorbs UV, so adding another UV filter in front of the 12 elements you already have (plus the three prisms and the OIS elements) is pretty unnecessary. SD DV footage is pretty crude, low res stuff, and any difference that Pete describes has passed unnoticed by me for many years.

Doug, the multi-coating is applied to make sure (nearly) all the light that hits the glass surface passes through the element. An uncoated element reflects and refracts about 8% of the light. This is not about UV transmission, it's about flare levels.

Right. Do treat your front element as a vulnerable piece of glass. It's mighty expensive to replace, though in the XL2 it's the plane-parallel VAP we're talking about. (not on the 3x widie, BTW). Use and treat a UV filter as mechanical insurance protection, nothing more. You're adding two extra glass surfaces and for what? If it's to keep out chemicals, cement dust, rain and children's pokey fingers - fine.

But any added glass must by definition very slightly reduce the image quality, it's the law of the land. So, if you feel you must, make sure you get a super multi-coated filter, because as I say, I have a test that I show folk that really surprises them - most people don't realise the damaging effects of shooting in high contrast situations (not necessarily against the light) that an uncoated filter brings to the party.

And most certainly remove said filter when you fit a converter lens. This is tom's law.

tom.

[Alec Lence]

Tom, thank you for the response, that cleared up my question.

I was taking a look at some of Tiffen's "Film Look" kits. Not because I want a "film look," I really don't care, story before technique for me, but because I liked what I read about some of the effects the filters have. If they lower my image quality, however, I don't see any purpose in spending hundreds of dollars on varying filters. Unless softening an image and diffusing light are one and the same with lowering image quality, what is your honest opinion of these screw-on filters?

Thanks again

[Tom Hardwick]

The thing to remember when using filters is that, "filters add nothing, they only take away" This is not strictly true because the add small amounts of flare and (hopefully) large amounts of artistic interpretation. But in reality they're taking away (colours and light and sharpness).

And once this is done, it's done. It's very difficult indeed to reclaim that lost information, and best to consider it gone. However, if you shoot for real and filter in post at your leisure it gives you artistic opportunities denied you out in the field. You have time and your output monitor to change, test, and change again. You can add filters to filters, and vary them over time.

Some optical soft focus filters do an excellent job in that they keep a sharp image and overlay it with gentle flare. There are Canopus filters that do a remarkably similar job, and of course are scalable at the same time. Some cross screens (often incorrectly called 'glitter' filters) add 6 or 8 point stars to every highlight, and these are very difficult indeed to add in post, especially to rippling water.

So it's a see-saw. Some filters such as polarisers are best applied to the lens, others such as graduated are better left to post production. As with all artistic mediums, chop and change to tell your story, and don't get too hung up about the very last of the technical nuances.

tom.

[Ash Greyson]

The main use for a UV filter IMHO is protection, HOWEVER, as noted, anything but a nice filter will degrade the image. Dont put 86 octane in your Ferrari. A decent UV filter will retail for $79+ You can find them on eBay for less, Hoya filters are generally pretty good. Whatever you do, do not buy one of those cheap junky kits...100% crap.


ash =o)

[Tom Hardwick]

Generally I'd go with Ash's thoughts, that the 'filter sets' are generally not up to much. I don't know the quality of the FS-72U Filter set that Doug was referring to (opening post), but a colleague of mine bought the Panasonic 'standatd filter set' for his DVX100A and they were beautifully made and really superbly coated. Fitted to the camera they were invisible.

My only reservation was that the filters didn't have front filter threads of their own. Not that I'd want to stack filters (a general no-no) but there are times when I need the thread continuing.

tom.

[Ash Greyson]

I agree, I would get filters that will stack...


ash =o)