Filter Cleaning

[Sam Striano]

Hello,

I was just wondering what some of you guys/gals suggest as far as preparing/cleaning a filter for use?

I just bought a B+W 72MM 010 UV Filter, and they seem to come from the factory less then perfectly clean. What I mean is if i hold it up to my light in the kitchen (100W Spot) you can see all sorts of little specs. I have blown it of with a Rocket Blower and all the loose stuff goes away, be there are still spots, very very small. Are they part of the coating?

I have looked at a few other new B+W filters and they are all the same, so I don't think this is limited to this one. When i look through it in a bright light but not so direct, it is clear as day.

My question is, is the lens on this camera (FX1000) going to pick those up and try to focus on them?

Thanks in advance,
Sam

[Steve Renouf]

Originally Posted by Sam Striano

Hello,

I was just wondering what some of you guys/gals suggest as far as preparing/cleaning a filter for use?

I just bought a B+W 72MM 010 UV Filter, and they seem to come from the factory less then perfectly clean. What I mean is if i hold it up to my light in the kitchen (100W Spot) you can see all sorts of little specs. I have blown it of with a Rocket Blower and all the loose stuff goes away, be there are still spots, very very small. Are they part of the coating?

I have looked at a few other new B+W filters and they are all the same, so I don't think this is limited to this one. When i look through it in a bright light but not so direct, it is clear as day.

My question is, is the lens on this camera (FX1000) going to pick those up and try to focus on them?

Thanks in advance,
Sam

They will be too close to the lense for the camera to be able to try and focus on them.

If you're not working in a vacuum (ie. in the real world) you'll never get an absolutely clean atmosphere, so you'll ALWAYS have stuff on the front. Obviously, we aspire to keep it as clean as possible but it will never be absolutely spotless for more than a couple of seconds. However, those few specs are not going to make any significant difference to the image. If they are on the surface but won't come off by blowing air at them, you could try lense cleaning solution as a last resort. However, if they are entrapped in the multilayer coating, you will never remove them without also removing the coating.

The main result of lots of dust particles on the front elements is a (potential) reduction in contrast due to the refraction of the light scattered by the particles. This would only become a major issue if there really was a lot of dust particles though.

[Luc De Wandel]

Clean the filter thoroughly. As a professional still photographer, I shoot boats at high speed on rough salt waters, and my Canon lenses get full of salt spray all the time. The coatings on these lenses (and filters) are so hard these days that you can clean them thousands of times without any harm. Mind you: not with an abrasive spunge, of course...

This said, dirt or scratches on videolenses (and filters) are more problematic, because of their shorter focal length. Optically, everything is much more critical in the video world. I have a big scratch on the front of one of my 70-200 telelenses, and it does not have any effect on the pictures taken with it. If that would be a videolens, it would certainly cause loss of contrast and possibly flares.