DSLR Lens Filter Question

[chrisb1357]

Hi all,

well i have just got 2 Filters for Canon 350D. one is a UV and the other a Polarized. My question is i dont know when to use them as i am new to all this. Does the Polarized filters have a top or bottom as on the outside of the filter it has a silver line on it

Also how do you clean these as one has a finger mark on. Can use the same stuff that i clean my lenses with to clean the filters.

Thanks
Chris

 

[DaveHope]

I'll start by explaining what each is

A UV filters are clear glass and are just there to absorb UV light (similar to Skylight & Haze filters). Most people (myself included) only use them to protect the lens. Who cares if a £20 filter gets broken? But if a £500 lens gets a scratch you're likely to be a bit more upset. You should (IMO) use a UV filter on every lens that you care about

A polarizing filter is used to remove reflections from a surface and to make blue skies darker. They work by only allowing light into the lens from a specific direction. These are great for landscape photos or just general photos outside on a sunny day.

cleaning can be a bit of a challenge. Most cleaning fluids arn't meant for multi-coated glass, Hoya say that you shouldn't use ANY cleaning fluid just your breath and a microfiber cloth.

Hope that helps

 

[chrisb1357]

Thanks for the quick reply.

Well i have stuck the UV One onto my 70-300mm Canon lens as i do alot of outside Aircraft photos so will help protect the lens a bit more.

U say about using a microfiber lens cloth which i have. Should i only use my breath on my lens as well or can i use the fluid.

Thanks
Chris

 

[StewartR]

I'll take up the opposite stance to Dave, just for the fun of it.

1. Why would one pay hundreds of pounds for a precisely engineered, high optical quality lens and then stick a cheap piece of glass in front of it?

2. The more pieces of glass you have stacked up, the greater the potential for internal reflections which will appear on the image as lens flare.

3. There have been reports of cheap UV filters causing problems with autofocus systems, and also of producing really ugly bokeh (OOF blur).

Obviously, if you're shooting something like paintball then some protection on the front of the lens is a very good idea. But some people find that using lens hoods tends to prevent marks and scratches on their lenses, because the front element is then recessed into the hood, so there's no need for a protective filter. (And using a hood is a good idea anyway, because (a) it reduces flare, and (b) it makes your lens look bigger!)

 

[CT]

I'm with Stewart on this, I hate sticking bits of glass in front of my lenses unless it's essential, but I always use a lens hood. If I was in a particularly wet or dusty environment then I probably would use a UV filter, and to be fair Canon recommend one in the wet to complete the weather sealing properties on their weather proofed lenses.

Dave has explained what the polariser does, but you may still be wondering how to use it. Fit the polariser to your lens then look through the viewfinder. Rotate the filter as you look through the viewfinder and you should see a marked reduction on reflections off surfaces you can see in the viewfinder. You can easily practice this on any reflections in the room where you are.

The instructions for polarisers always say that they eliminate or reduce reflections from non metallic surfaces, which I've always had trouble understanding because they clearly do have an effect even on some bare metal surfaces.

Using the polariser to deepen a blue sky is a bit different and it works best at an angle of about 90 degrees to the Sun. Rotate the filter to the position where you see the optimum darkening of the sky (through your viewfinder) for the best result.

Polarisers are also excellent for reducing reflections when taking shots over water.

 

[CT]

U say about using a microfiber lens cloth which i have. Should i only use my breath on my lens as well or can i use the fluid.

Thanks
Chris

All I've ever used to clean lenses with is my hot breath and a nice soft cloth. There's no harm in using a lens cleaning cloth, but if you use the fluid, use it sparingly and apply it to the cloth first - never directly to the lens as it can be strong enough to remove the lens coating.

If you get a fingerprint on the lens don't let it lay there, remove it ASAP as acid in fingerprints can also etch into the lens coating. It varies enormously from one person to another, but any engineer will tell you some people can rust metal just by handling it!