Dust inside lenses.....................

[diego_alonso]

Please can anybody tell me why some microscopics dust appears inside

lenses and if it afect the image? since what size enlargment?.

Thank you very much.

[thebigfish]

Dust gets into your lenses because of it is pulled in by the action of the lens

moving in and out which creates a little vacuum inside the lens. Especially

with zoom lenses. Dust particles affect the image depending on how close

they are to the focal plane. The closer they are, the more they affect the

image. They can also contribute to flare in bright light conditions. If it's an

expensive lens, you might want to have it cleaned. If it's not, it probably

doesn't matter much.

Thanks

Brian

www.brianhallett.com

[nick_fuegi]

Hi Diego,

 

I have a Canon EF 135mm soft-focus lens. For those of you who aren't familiar with the lens. It is extremely sharp and focuses as any other lens. If desired, it also has the ability to slightly offset the focus to one of two settings to soften the image.

 

My lens is full of dust and worse still FUNGUS spots, up to 4mm accross. They are further back than behind the front element (I can't tell exactly how far without total disassembly - a VERY risky business). You can only see one tiny spot on the final image. Which only requires one click of the clone brush to remove.

 

The effects of the dust seem to decrease as aperture increases. If you shoot at f4 - f5.6 there is no effect. Down to F11 I have seen hardly any effect at all (the one spec mentioned above) and I never have cause to shoot as smaller than f11 with this type of lens.

 

I'm not certain whether dust affects wide or telephoto lenses more than the other. There must be a difference though. Anyone know?

 

Hope that helps.

 

Regards,

 

Nick

[mark_bouquet1]

Nick's right that the dust gets sucked into the lens as you focus, or zoom. The solution, though it might be too late in your case since you're already asking this question, is to be meticulous about keeping dust off the exterior of the lens, before it can get inside.

 

I have several brushes for this purpose, which I employ regularly after each day's use, before putting my cameras away. One brush has very soft bristles, to be used ONLY for cleaning lens surfaces. Another brush has stiffer bristles, and I use this to clean the exterior surfaces of lenses and camera bodies. I don't think compressed air or blowers are such a good idea because they'll force the dust into the lens, rather than pushing it off.

 

It's also important to keep any cases and camera bags meticulously clean by vacuuming them out regularly. My personal opinion is that cotton camera bags, like Domke's for example, are ultimately a bad idea because they naturally and inevitably shed lint, unlike synthetics. This is too bad because the cotton ones are nicer tactily and aesthetically. (JMHO)

 

The payoff for this extra effort is lenses that stay clean. I have five lenses, all purchased new by me, some nearly 20 years old, and none of them have any visible dust inside.

[diego_alonso]

Thanks to All, your answers are very helpfull. I will send to clean them then be more carefull.

Thank you very much.