Lens coating/ protection

[jkirkegaard]

Hi,

I have always used a UV-filter on my film cameras. When I moved on to the digital format, I still put the Filter on the lens to protect it. However, I've heard that putting any extra glass in front of the lens will degrade the final image. I have tested it and it's correct, the UV-filter degrades the image just a little bit. so I thought about putting "Protective filter" on the lens. However, this should also degrade the image (haven't tested it).

The lens hood should provide good protection, however wiping the lens front glass so often - wouldn't that eventually destroy the protective lens coating which the glass is covered with? Much easier with a Filter, I can just buy a new one.....

 

[adartsesirhc]

I don't know what you're referring to by a protective filter... I'm pretty sure you just mean a UV filter.

It's true that any filter will degrade your image quality, but better ones will do so less noticeably. I use Hoya SHMC filters. One way to go about it is to leave the filter on almost all the time, except for when image quality really matters to you.

If my camera is off, then my UV filter is always on (although I suppose the lens cap is just as good). If I'm just taking snapshots or event photos, then my UV filter stays on... especially because of the amount of moving around I have to do, possible obstacles, and all the pointy things that seem to aim at my lens. I really don't care about the small amount of sharpness I lose in these situations.

The only time I take the UV filter off is if I'm shooting something I really care about, in which case the conditions are usually more relaxed, I shoot slower, I have control over what's around me, etc. If you're in the studio, where you know that someone won't be launching projectiles in the direction of your front lens element, then chances are your hood is good enough protection.

Why do you have to wipe the front glass? Hoods and lens caps should keep your fingers off of it, and if atmospheric conditions are bad enough that it's getting dirty just from being exposed while you're shooting, then I would probably keep a UV filter on. But that's just me being extra careful.

 

[Josh66]

The coatings are stronger than you think they are - normal cleaning shouldn't be an issue at all.

How often do you clean your lenses? They don't really need to be cleaned unless there's something on them.

I find that basically the only time I have to clean the front element is when it gets a fingerprint on it, which is rare. Unless one of the kids got into the camera bag when I wasn't looking. Then I'll probably have to clean everything.


The "Protection Filter" (as opposed to the UV filter) should be just a piece of clear optical glass - probably with some anti-reflection coatings. I would expect it to behave pretty much identically to a good UV filter on a digital body.

If you notice degraded image quality with the UV filter, you'll probably notice it with the protection filter too.

Personally, I only use filters when I want to filter the light. I use lens hoods, lens caps, and caution to protect the glass.

A clear filter is good to have for the times that you know crap is going to get on the lens though (that would fall under the 'caution' that I mentioned, lol) - salt spray, sand, mud - stuff like that. Abrasive/corrosive stuff. If you're worried about dust, buy a bulb blower.

 

[KmH]

Not only are front lens element coatings a lot more robust than many realize, so is the front lens element glass.

'Protection' filters are only a fraction as thick as, and not even the same grade of glasss as a front lens element. Many front lens elements are immediately backed by optical aberration correcting additional lens elements.

Check out the front lens glass elements in this photo of a DSLR camera and lens that has been cut in half - File:E-30-Cutmodel.jpg - Wikipedia, the free encyclopedia

 

[jkirkegaard]

Hi adartsesirhc , OIIIIIIO and KmH,

Thank you so much for your advice. I think I will put my UV-filters back in my bag and not worry so much about my front element when the hood is on.

 

[Skaperen]

Hi adartsesirhc , OIIIIIIO and KmH,

Thank you so much for your advice. I think I will put my UV-filters back in my bag and not worry so much about my front element when the hood is on.

UV-filters can serve as the lens protector because they are cheaper to replace. They can also remove the UV effects that degrade SOME shots (removing a blue cast where there should not be any, such as a snow scene). But any filter can add glare and degrade the image from coherent reflections (an effect reduced by multi-coating). Len elements do this, too, with more distortion of the effects. That's one reason prime lenses which usually have fewer elements than zoom lenses, can do better.

I keep the UV filter on for protection purpose unless and until I have a special shot I want to make sure comes out better (and doesn't need the UV filtering).

Tip: You can buy some thin rubber jar openers in a grocery store. Certain types make good grips for cases where filters get screwed on too tight.

 

[TCampbell]

There are a few semi-weather-sealed lenses from Canon which will, in the manual, tell you that if you need the lens to be weather-sealed then it needs to have a filter attached to "complete the weather seal."

However... you generally don't need a UV filter -- certainly you don't need it to block UV light (there's already a UV filter built-into the camera just in front of the sensor.) If you use them, then it'd only be for protection. Even still... the lens isn't as fragile as you might think. See this blog post: LensRentals.com - Front Element Scratches

There are some very good filters which won't degrade an image in any noticeable way. Cheap filters can degrade the image in a pretty easy to notice way.

 

[Garbz]

The last bit of TCampbell's post is quite key. If you take a $20 bit of glass and put it on your $2000 lens you will definitely see degradation. That said a $100 B+W filter doesn't appear to have ever visibly degraded any image I've taken. All filters however can create ghosts in scenarios of extreme contrast. However the only time I come across that is for things like nightshoots, where I have a tripod, in which case my camera is being taken care of, and not just slung around my shoulder or thrown in the dirt / sand so the filter can easily come off in that case.

 

[one90guy]

I only use filters for light control and occasionally special effects. Shooting mainly landscape I never remove the lens cap till ready for the shot. I do keep my lens cleaning kit with me at all times and check front element often. Some much easier to clean lens than sit in front of computer removing little dots.

 

[Garbz]

If you're removing little dots then the front element of the lens is NOT the place you should be cleaning.

Try it. Get a big piece of blutac and stick it to the front of your lens and take a photo. See if you can find a dot. Dots are sensor dust.

 

[jkirkegaard]

Okay,

Thanks everyone.

 

[one90guy]

Removing dots from my WalMart processed film mainly. I never change lens on my digital on a outing and try not to on film cameras. But I am going to try the blutac on my digital, great idea, thanks Garbz

 

[Josh66]

Removing dots from my WalMart processed film mainly. I never change lens on my digital on a outing and try not to on film cameras. But I am going to try the blutac on my digital, great idea, thanks Garbz

In this case, the dots/specs are dust on the film. Not sure about all of them, but the Walmart here dries the film in a very dusty environment - guaranteed dust that has to be cloned out, every time.

Even the dustiest film that I do at home is nowhere near the amount of dust that a strip of film picks up in a Walmart store...

 

[jackmolotov]

dunno,I shoot film, and I get this unwanted blue-ish tint in dirrect sunlight without the UV filter.

I also had one break on me once, and better some 10 dollar filter than a lense.

 

[one90guy]

Dust was not much of a problem doing my own film, but last summer my youngest daughter was getting into film. So I gave her all my developing stuff. She already has a enlarger and collecting every thing to build a dark room. She's using her bathroom now, her skills have passed me right on by.