You should Never use Any filters, except...

[KmH]

Strangely I have never seen plain, optical glass, flat 'filters'.

b+w clear filter | B&H Photo Video

I'm pretty sure Nikon sells clears.

 

[KmH]

A lens cap won't protect you from a kids finger, from a tree branch, or one I put my camera and lenses in quite frequently, strong bursts of sand and salt water. Or what about when you can't use your hood because it interferes with the flash, or the focus assist light? 2 of my hoods are big enough to cause AF to fail in the dark because they block the light.

A lot of people shout from the roves, "It's another piece of glass on your lens, FEAR IT, FEAR IT."

To which I reply, Consider how many elements your lenses have. Glass elements which have been curved, bent, sanded, in all sorts of shapes and by all sorts of machines. Now do you really have so much to fear from a single piece of flat (i.e. far more easy to produce defect free) glass, that is much thinner than most lens elements?

People base their hate often on very cheap filters which do affect image quality quite a lot. But you get what you pay for.

As an engineer I would say do a test and make up your own opinion if the image quality is worth you potentially having a big scratch on your lens. Fortunately I have done such a test for you: http://www.thephotoforum.com/forum/...100830-more-hoya-filter-comparison-tests.html

2 words..........A I R......G A P

 

[Dwig]

I...
IR & ND have their place as well...

Quite correct and thanks for adding the NDs to the list; I forgot them in my long post.

Again, while technically not filters as they affect all frequencies of light uniformly, neutral density "attenuators" are quite useful and in most situations their effect can't be replicated any other way. This applies to both conventional NDs and the graduated ND (AKA GND) attachments.

 

[Moglex]

While we're on it.... another thing that pisses me off is the misuse of 'then' vs 'than'. There are a lot of webbies that use 'then' when 'than' should've been used and vice versa. 'Then' in it's proper use is a descriptive of time, whereas 'Than' is an adjective or adverb of unequal comparison.

/rant

I've never seen that.

It would tend to render what they are saying as gibberish.

"If it was more then that than it was wrong"

 

[Garbz]

The glass in a lens is not flat and the lens is composed of many different elements and element groups. This glass has a meniscus curve.
The idea of using glass with a meniscus curve is that light will pass through the lens and hit the sensor and then bounce straight out through the lens. Putting a filter, like a skylight filter that is generally a screw mount, can wreak havoc. The glass on the filter is most likely not a meniscus curve and light will pass through the filter, hit the sensor and then reflect back on the sensor instead of passing through the filter. Skylight and UV filters are also altering the wavelength of light that hits your sensor. The conversion of photons to pixels by the sensor is based on calculations from pure, natural light. In simple English, changing the light with a UV filter will affect contrast in the final image because the sensor has no way of knowing there is a UV filter on top of the lens. A polarizing filter is the only filter that is acceptable for digital, because achieving the effects of a polarizer in Lightroom or Photoshop is nearly impossible.
-The Photoshop Lightroom Workbook, by Seth Resnick & Jamie Spritzer (founders of D-65.com)

Ok I have a few issues with this passage and I will address them as they are highlighted:
Red: The point of the sensor is to NEVER reflect any light that could be useful. This would be light that is wasted. If you look at your sensor you'll see it has a very light blue colour on an otherwise dark surface. That is it reflecting the top end of the visible red and most of the IR which needs to be cut from the sensor. If useful light is being reflected off your sensor than something is wrong.

A clear example of this is the "hotspots" when people take IR photos. In this case there actually IS light being bounced back out onto the lens. All lenses do this to some extent and the effect is entirely independent on having a filter on the front.

Mind you any filter worth it's salt will have an aggressive anti-glare filter on it. This would mean less than 0.5% of light is reflected and usually this is at a very deep purple wavelength having even less affect on the overall image, as any existence of green or red light would instantly overpower the deep blue which our eyes aren't very sensitive to. But yeah that's beside the point. The original "reflection" off the sensor is incorrect and unless doing IR photography it has zero effect on the image.

Green: UV filters cut out UV, there is no visible effect at all in the visible wavelength. Jump on the the manufacturer's websites and check the datasheets, heck just take the filter and put it on a white piece of paper if you want to prove this. He is right about the Skylight though. That has a very slight pink tint. But who cares. If you're really worried get a "Protector" filter, which passes all wavelengths equally.

Blue:This is a load of absolute crap. The algorithms re-construct the visible image based on the amount of red, green, blue, green. This has absolutely nothing to do with contrast or natural light or any crap like that. The camera records three wavelengths, green twice, and rebuilds the image based on those four points. They don't need to know the presence of any filter. They are optimised to reproduce the visible representation from the visible spectrum they capture. It cuts out the IR using a filter to keep with this principle otherwise they'd just magically software adjust it. In other words what you see through the filter is what it will reproduce, and the only exception to this rule is an IR pass or UV pass filter that is more aggressive that the IR stop filter or the lack of sensitivity of the the camera sensor to UV.

Claiming that the introduction of a UV filter somehow mystically throws these "calculations" out is a load of crap. And if they did I'm sure someone would write a RAW converter method specifically for it. But it doesn't so they don't.

/EDIT:Jon_Are I'm not arguing with you, I'm just saying that what this guy wrote is just outright wrong.

 

[Moglex]

Is grammar really that important?

Yes, because the purpose of language is communication and the correct use of language aids communication and mitigates against confusion.

The problem is not so much with the so called 'grammar nazis' who may make a post once in a blue moon correcting some egregious error so much as with the 'proud to be illiterate' brigade who send the 27 other posts telling everyone that grammar isn't important.

Correcting using grammar has important, its makes those languages easiest for the understand.

 

[Moglex]

Blue:This is a load of absolute crap. The algorithms re-construct the visible image based on the amount of red, green, blue, green. This has absolutely nothing to do with contrast or natural light or any crap like that. The camera records three wavelengths, green twice, and rebuilds the image based on those four points. They don't need to know the presence of any filter. They are optimised to reproduce the visible representation from the visible spectrum they capture. It cuts out the IR using a filter to keep with this principle otherwise they'd just magically software adjust it. In other words what you see through the filter is what it will reproduce, and the only exception to this rule is an IR pass or UV pass filter that is more aggressive that the IR stop filter or the lack of sensitivity of the the camera sensor to UV.

Claiming that the introduction of a UV filter somehow mystically throws these "calculations" out is a load of crap. And if they did I'm sure someone would write a RAW converter method specifically for it. But it doesn't so they don't.

Well said!

The blue section sounded perilously close to new age waffle!

 

[Torus34]

With reference to the IP:

The author's assertion precludes the use of ND and star filters for special effects.

Additionally, if you work with b&w film as I do, the author's advice does not apply. Taking away my filters would remove my ability to selectively adjust gray densities based on color.

 

[Jon_Are]

Jon_Are I'm not arguing with you, I'm just saying that what this guy wrote is just outright wrong.

I understand. I don't know enough about this to even argue either side, that's why I posted it (to learn if it's BS or not).

Now, if you want to argue grammar...

:mrgreen::mrgreen:

Jon

 

[farmerj]

Huked on fonic wurked four me.....

 

[Torus34]

'Now, if you want to argue grammar...'

You leave my Grandma out of this! ;-))

 

[Dwig]

...
The author's assertion precludes the use of ND and star filters for special effects.
.../QUOTE]

Which is the one the the author got correct. ND and Star attachments are not actually filters. A technical discussion of filters would assume that they are not included, though if targeted for novices in the field it should define "filter" properly and list examples of exclusions at the beginning.

 

[astrostu]

...
The author's assertion precludes the use of ND and star filters for special effects.
...

Which is the one the the author got correct. ND and Star attachments are not actually filters. A technical discussion of filters would assume that they are not included, though if targeted for novices in the field it should define "filter" properly and list examples of exclusions at the beginning.

I disagree. I would define a "filter" as anything through which light "filters" -- hence, any front- or rear-lens attachment I would consider it a filter. I could possibly see how a cross-screen you would not consider to be a filter (though I would under my definition), but a ND I think would definitely be considered a "filter" under most definitions since it definitely "filters out" light.

 

[JerryPH]

Any "star" (diffraction, "cross-screen") filters are effects that cannot be duplicated in any easy manner in PS.

I disagree. There are MANY PS plug ins that do that and more. A fast search over on the strobist group or other flickr PS plug-in groups will let you find many that do just that. The demo on youtube I saw last year showed that it was like a 2 click thing... and you had stars anywhere in your pic... lol

That said, I prefer to use filters, just becuase I can.

 

[TamiyaGuy]

Hmmm, to an extent I think he is right, CPLs are quite possibly the best filter to have in your arsenal. But I think he has exaggerated his statement somewhat, I don't think it's the only one you should have. Yes, CPLs are pretty much impossible to replicate in post-processing, particularly the fact that they remove reflections. But there are a few other filters that can't be replicated, too. Neutral Density filters, for example, or Grad NDs (You can take 2 photos then combine them in Photoshop to replicate a GND, but it just doesn't look the same).

Also, while again he's right about the fact that more glass negatively affects image quality, if I took a lot of beach photographs, I sure as hell wouldn't step near a beach until I'd invested in some clear protection filters. Even from my experience, your hands are much less shaky and your body sweats much less when you're wiping the crud off a £30 CPL filter than when you're wiping it off a £300 lens front element .

So, yes. He's right up to a point, CPLs are incredibly useful, but they're not the only ones you should own. All depends on what you want to shoot, too.