Sigma 30mm return it?

Carpy2001

Carpy2001

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520
Name
Andrew
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Hi all, the used Sigma lenses I ordered arrived today.
I noticed a mark on the 30mm, after a quick clean with a lens wipe, it was still there. It looks like it is inside the lens.
I remember someone saying to check for marks on a sensor by shooting stopped down at the sky or light background??, anyway this is what I did. Using a peice of whit paper I took a couple of shot with both lenses at F22, below are the results, the question is, should I return the 30mm?.
This is the first time I have bought a lens apart from the kit lens that came with the camera.
Cheers Andy.

60mm F22 white paper
60mm white paper f22.jpg

30mm F22 white paper
30mm white paper f22.jpg
 
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LongLensPhotography said:
No1 DO NOT shoot anywhere near f22. f8 is really the highest you need to ever use. No2 clean your sensor if you must
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I was just trying to show the mark that is visible inside the lens (when not attached to the camera lol) with the naked eye, if I shine a torch behind the lens you can see it.
Anyway I have emailed the seller some pics, and they have issued me with a returns label and form to fill in saying what is wrong and if I would like a refund or exchange. I went for the exchange lol, second time lucky.
And I also noticed the spot on the lower right hand side (in both images) so maybe a sensor clean is in order.
 
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The odd fleck of dust in a lens is unfortunately quite normal. If you think about it, every time you focus or zoom a lens, it’s effectively pushing or sucking air into the lens body.

If you can only see it at f22, you are almost never going to be shooting that stopped down anyway because the effect of diffraction will make the image very soft.

You can use an online calculator to calculate the diffraction limit for your camera - for my r6ii, it’s around f9/10 and I very very rarely have a need to stop down further than that.

What I’m saying is, in normal use it’s unlikely you’ll ever see it.
 
cuthbert said:
The odd fleck of dust in a lens is unfortunately quite normal. If you think about it, every time you focus or zoom a lens, it’s effectively pushing or sucking air into the lens body.

If you can only see it at f22, you are almost never going to be shooting that stopped down anyway because the effect of diffraction will make the image very soft.

You can use an online calculator to calculate the diffraction limit for your camera - for my r6ii, it’s around f9/10 and I very very rarely have a need to stop down further than that.

What I’m saying is, in normal use it’s unlikely you’ll ever see it.
Click to expand...

Yes, unlikely it maybe, but he will always be looking for it.
 
Shine a torch through the lens if you can see something in there then return if ..if it’s clear it’s likely to be on your camera sensor
 
Just return it - you'll never trust or be happy with the lens in the future, and there's no point in keeping gear you don't want to use.
 
You’re returning the lens now so this is academic.

Dust inside a lens is a fact of life.

It doesn’t affect image quality except in very rare circumstances.

You can’t see it in images as a mark, it just causes slight image degradation due to internal flare, youre far more likely to get worse symptoms by simply using a filter.

That mark on the image? It’s dust on your sensor. Think about it, the mfd on your lens is a foot or more in front of it, how can you ‘see’ something inside the lens?
 
Phil V said:
You’re returning the lens now so this is academic.

Dust inside a lens is a fact of life.

It doesn’t affect image quality except in very rare circumstances.

You can’t see it in images as a mark, it just causes slight image degradation due to internal flare, youre far more likely to get worse symptoms by simply using a filter.

That mark on the image? It’s dust on your sensor. Think about it, the mfd on your lens is a foot or more in front of it, how can you ‘see’ something inside the lens?
Click to expand...
Thanks Phil I will bear that in mind next time. It was just that as soon as I removed the lens cap, boom there it was, like a grey cicular scratch, way inside the lens.
The issue is me I think, once I saw it, and knew it was there, then it was already in my head lol.

Can I ask you please, if it is a mark on the sensor, why it only shows on the 30mm and not the 60mm as shown in the images above?. I can see 1 smallish dot in the bottom right of both images, so that I pressume is on the sensor, but the central mark (blob) is only on the 30mm image .I will try blowing the sensor first and if it is stubborn, then I will get a sensor cleaning kit.

Due to the way I am, this has now made me nervous about buying anymore lenses, this was my first time buying a lens, apart from the kit lens that came with my camera.

As they say " you live and learn", this is not the first mistake I have made, and I am certain it wont be the last lol.

Cheers Andy.
 
Are those test shots crops or whole pictures?

Also, f22 might not be an aperture you use often but you might still want the odd shot at that aperture regardless of the effect of diffraction.

Glad you returned it.
 
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woof woof said:
Are those test shots crops or whole pictures?

Also, f22 might not be an aperture you use often but you might still want the odd shot at that aperture regardless of the effect of diffraction.

Glad you returned it.
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They were full full images, just re-sized for the forum.
 
You’re returning the lens now so this is academic.

Dust inside a lens is a fact of life.

It doesn’t affect image quality except in very rare circumstances.

You can’t see it in images as a mark, it just causes slight image degradation due to internal flare, youre far more likely to get worse symptoms by simply using a filter.

That mark on the image? It’s dust on your sensor. Think about it, the mfd on your lens is a foot or more in front of it, how can you ‘see’ something inside the lens u
Carpy2001 said:
Can I ask you please, if it is a mark on the sensor, why it only shows on the 30mm and not the 60mm as shown in the images above?.
Click to expand...
id assumed the image was a crop centred on a sensor mark.
I have never seen an object in a lens create that effect, genuinely if you put a 2mm square of masking tape on the front element of a lens it won’t show in an image (try it).

So you were definitely right to send it back.
 
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