Dust or damage to front element of my lens?

A

Alllfff

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Edit My Images
Yes
I have recently asked about glares and artifacts in my night photographs. However the more I looked into my photographs the more I notice, that from my Sigma 10-20 all images with F/ higher than say f/13 show three spots exactly at the same spot.

So I played around with the lens for a bit and took some photographs in different settings. The marks were there all the time as you can see from the attached photograph. I properly examined the lens and found those three dots that most likely cause the marks on the photographs, please see last three images attached, the spots are circled. These spots appear to be on the inside of the front element.

I looked into historical photographs with the same lens and similar settings and found out the dots havent moved since at least 2009, I have the lens since june 2008.

Please tell me your opinion, are those dust specs that are just that well attached to the front element and are possible to get somehow cleaned even if it means taking the lens to service for complete servicing? or is it some damage?


Thank you very much for all your help
lensdefect.jpg
 
"These spots appear to be on the inside of the front element."

Yes I can, they are inside...
 
I am betting that it is dust on your sensor, dust on the lens will not show up.
 
Correct me if I'm wrong here but
a) the spots show only with this lens
b) if they were on the sensor they wouldn't change apperance with changing lens settings.
c) I can see matching pattern of three dots on the front element of the glass of this one lens WITHOUT it even being connected to the camera
 
Alllfff said:
Correct me if I'm wrong here but
a) the spots show only with this lens
b) if they were on the sensor they wouldn't change apperance with changing lens settings.
c) I can see matching pattern of three dots on the front element of the glass of this one lens WITHOUT it even being connected to the camera
Click to expand...

A, try shooting a white piece of paper at f20 or higher with a different lens and see if they are showing. Best to do auto levels in ps or similar

B, they will change with different lens settings, probably will not show f4 f5.6 start to show a little more with increasing f number till they become very blooby looking at f22.

C, don't forget the image when projected onto the sensor is upside down, and I can't renber if reversed left to right as well.

The reason I say it won't show up is explained in the link below

http://www.lensrentals.com/blog/2008/10/front-element-scratches

Hope this helps.
 
Looks to me like they're marks/dust on the inside of the front element (even though I've read the lensrentals info).

Do you purposefully take photo's at f/13 or above ?
 
Ok just looked at the photos, I was posting on my phone and couldn't see the photos, the photos you have posted it is lens flare no doubt about it, it is also possible that marks on the lens may cause it, and just a thought it's not the lens coating chipped.?

I have also looked at the other thread and it is definitely lens flare
 
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WOW, ladies and gentlemen please sit down...
I just took a photo of the spots with my macro lens...

What does this look like to you? I knew sigma was cheap, but that cheap?!
dsc0566bo.jpg


To all of you that say dust inside the lens shouldnt influence the image, I agree! From my degree in nanotechnology, dust probably wouldnt but bubble(s) most certainly could?!
 
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Alllfff said:
WOW, ladies and gentlemen please sit down...
I just took a photo of the spots with my macro lens...

What does this look like to you? I knew sigma was cheap, but that cheap?!

To all of you that say dust inside the lens shouldnt influence the image, I agree! From my degree in nanotechnology, dust probably wouldnt but bubble(s) most certainly could?!
Click to expand...

Well, I I believe you may have found your problem. Get in touch with sigma, may be out of warranty but they may well sort it out.
 
Alllfff said:
WOW, ladies and gentlemen please sit down...
I just took a photo of the spots with my macro lens...

What does this look like to you? I knew sigma was cheap, but that cheap?!
dsc0566bo.jpg


To all of you that say dust inside the lens shouldnt influence the image, I agree! From my degree in nanotechnology, dust probably wouldnt but bubble(s) most certainly could?!
Click to expand...

That was some piece of inspiration you had to take a photo with a macro lens. :clap:
 
It's a shame that you have this defect... but I just wanted to add that f13 is a little extreme.

Even at the longest zoom setting of 20mm an aperture of f8 will give you DoF from just over 5ft to infinity. At the wider end f4 will get you about the same DoF. If you're using smaller apertures for time reasons or specifically need f13+ or if these bubbles (?) catch direct light and show up then it's an issue but for more normal use maybe you could use slightly wider apertures.
 
If that's under warranty, get it back to them ASAP. In fact... under the sale of goods act, I reckon you could get that replaced even out of warranty.. that's clearly not fit for purpose.
 
That's pretty poor I'd contact sigma they are generally pretty reasonable and should really replace such a rubish piece of workmanship even if though it's out if warranty. It will help if you are the first owner and still have the invoice.
 
Pookeyhead said:
If that's under warranty, get it back to them ASAP. In fact... under the sale of goods act, I reckon you could get that replaced even out of warranty.. that's clearly not fit for purpose.
Click to expand...

I agree.
 
I have contacted Sigma and they invited me to send it over but they would quote a price on the repair since it is out of warranty (4 years old)...what do I do now?

It was actually my only buy from Jessops, all other lenses I had from ebay, B&H, and gumtree. This one was from Jessops...

Yes I could open up the lens and use apertures smaller than f/13 but why should I limit myself plus these apertures were used for the time reasons.

Pookeyhead, do you have experience with such situations with "the sale of goods act"? I could use some tips there if I decide to go that way.

Thank you everyone for your kind words and tips! Much appreciated!
 
Alllfff said:
WOW, ladies and gentlemen please sit down...
I just took a photo of the spots with my macro lens...

What does this look like to you? I knew sigma was cheap, but that cheap?!

To all of you that say dust inside the lens shouldnt influence the image, I agree! From my degree in nanotechnology, dust probably wouldnt but bubble(s) most certainly could?!
Click to expand...

Sigmas arnt really cheap either!
 
Alllfff said:
I have contacted Sigma and they invited me to send it over but they would quote a price on the repair since it is out of warranty (4 years old)...what do I do now?

It was actually my only buy from Jessops, all other lenses I had from ebay, B&H, and gumtree. This one was from Jessops...

Yes I could open up the lens and use apertures smaller than f/13 but why should I limit myself plus these apertures were used for the time reasons.

Pookeyhead, do you have experience with such situations with "the sale of goods act"? I could use some tips there if I decide to go that way.

Thank you everyone for your kind words and tips! Much appreciated!
Click to expand...

After 4 years with a defect like that it really should have been spotted earlier so Sigma would be within their rights not to repair / replace free of charge IMO, even though the lens wasn't fit for purpose from the outset.
 
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