How much can a lens take before it effects IQ:::

[hoffy]

I found this on another forum:

Dirty Lens Article

Very interesting indeed.

[Kym]

Front of lens - yeah!

Try specs of dust on the rear element

[Seesee]

Hmmmmmmmm.......might just go out the back and hit the front element of my 300 f2.8 and see if it's true ....back in a mo..........................


Nah seriously, it does take a lot of muck on the glass to have any effect, I even have a large scratch on the back element of my Tammy 28-75 with no adverse effects which did surprise me.

[arthurking83]

IN GENERAL you really only start to notice the affects of scratches and dust on lens elements if two conditions exist.... shooing into a light source(haze or loss of contrast) and stopping down to apertures like f/11 in some cases and smaller.. I've generally found f/16-f/22 to be apertures to avoid if your lens has dust on it.

usually, bad technique, misfocusing, bad tripod, lack of mirror lockup(if the bad tripod is still being used), placing one's fingers in front of the lens element (such as when handholding Cokin GND's ) .. all contribute to more loss of IQ, than a few scratches and/or some dust and haze will.

[Analog6]

This is all well and good, but if a lens has been treated carelessly and allowed to get scratched and marked, then there may be inside damage invible to the eye. So on the buying front, I'd go for the well cared for lens every time.

I've often noticed an incredible amoount of muck on mine while out shotting in windy /dusty conditions, but as you say, it does not seem to effect the photos.

[BLWNHR]

The truely is interesting. I know I'm not a clean nazi when I'm out and about. I don't set out to get my gear dirty, but if I get a collection of dust or rain mist on the front element I typically leave it until I can get home and clean it methodically and properly.

On a side note that lens has terrible vignetting.

[pollen]

I found this quite interesting: http://www.lensrentals.com/news/2008...ment-scratches

Lens scratches and dust won't directly manifest itself on the photograph, but they will indirectly through increased flare and reduced contrast

[benixau]

Cool
This also hold true for filters btw.
The fine scratches they take don't show up in any photo - I know, I've pixel peeped to try and see them. For the record, my lenses come out of the box and get a hoya UV on them before I even put them on the camera, so if they were going to be scratches anywhere they'd be on the filter.

Also consider that a reflex lens has a huge centre area that it can't see through and yet there's no black circle in the middle.

[degarr]

I found this quite interesting: http://www.lensrentals.com/news/2008...ment-scratches

Lens scratches and dust won't directly manifest itself on the photograph, but they will indirectly through increased flare and reduced contrast

That is quite amazing, I was expecting to see some minor damage

[Dawixe]

Interesting read.