speedbird128
Posts: 1562
Joined: Tue Oct 28, 2003 2:30 am

When Is It "Too Much" Dust In Your Lense...

Tue Nov 29, 2005 6:04 pm

Hi happy people,

I have a Sigma 80-400EX Optical Stabalised lense, and it's around 6 months old now.

I was giving all my gear a thorough cleaning the other day, and I have noticed a couple of dust specks inside the lense.

They are not visible on the photographs I take - or at least I can't see them  Wink.

At what point does it become too much dust- is that when you see the specks on the shots??

Thanks for any info

Cheers
Bryan
A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7
 
QANTAS077
Posts: 5177
Joined: Wed Jan 14, 2004 5:08 pm

When Is It "Too Much" Dust In Your Lense...

Tue Nov 29, 2005 6:10 pm

Quoting Speedbird128 (Thread starter):
At what point does it become too much dust- is that when you see the specks on the shots??

it's usually the dust on your camera sensor that's the problem when you review your images, my lens has a bit of dust on it and i have recently cleaned my sensor and i have no dust spots.
 
speedbird128
Posts: 1562
Joined: Tue Oct 28, 2003 2:30 am

When Is It "Too Much" Dust In Your Lense...

Tue Nov 29, 2005 6:14 pm

Quoting QANTAS077 (Reply 1):
it's usually the dust on your camera sensor that's the problem when you review your images, my lens has a bit of dust on it and i have recently cleaned my sensor and i have no dust spots.

It's the same scenario for me wrt the sensor - obviously because the dust blocks light reaching the sensor and thus causing spots it's more critical to keep clean.

I was just wondering at what point do I send my lense off for a cleaning?
A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7
 
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derekf
Posts: 888
Joined: Tue Feb 20, 2001 4:05 am

When Is It "Too Much" Dust In Your Lense...

Wed Nov 30, 2005 4:58 am

I had some interior dust on my Sigma 170-500 and was told it was fairly common on lenses like that and that it would make very little difference to the photos. I certainly didn't see any difference.
Sigma were going to charge around £80 plus postage to clean it so I didn't bother.
Zooming out in dusty conditions causes suction apparently.
I did find some useful info by searching Google though.
Hope this helps

Derek
Whatever.......
 
petertenthije
Posts: 3309
Joined: Tue Jul 10, 2001 10:00 pm

When Is It "Too Much" Dust In Your Lense...

Wed Nov 30, 2005 5:34 am

If you put your longer lenses against a chain link fence, the fence will be largely (or even totally if the zoom is long enough) filtered out. Same goes with the dust spots on the lense. The reason the spots on a film/sensor show is because they are at the end point. The sensor can not "look around" it, and will therefor show it.

If you use a very low aperture (or high, whatever, i keep mixing them up) the spots might show up though. But only the larger ones. I'd be surprised if a grain of sand would show.
Attamottamotta!
 
speedbird128
Posts: 1562
Joined: Tue Oct 28, 2003 2:30 am

When Is It "Too Much" Dust In Your Lense...

Thu Dec 01, 2005 2:16 pm

Quoting Petertenthije (Reply 4):
The reason the spots on a film/sensor show is because they are at the end point. The sensor can not "look around" it, and will therefor show it.

Correct - I use the blue sky at f22 technique to check for CMOS dust spots...

So I guess the few litte dust specks in the lense aren't critical. Goodie  Smile

Thanks for the input

Cheers
Bryan
A306, A313, A319, A320, A321, A332, A343, A345, A346 A388, AC90, B06, B722, B732, B733, B735, B738, B744, B762, B772, B7

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