Help needed - Image spots.

[DMcL]

Belated New Year wishes.

Now, out on a walk last night and noticed a few of my images have these no so cool spots in them. All affected images have been in or around street lighting. It was not raining at the time and my lens is as clean as my eye can tell.

I was using a D7100 with Sigma 17-50 lens, this example was shot at 22mm, 20 sec exposure at F.18.

Any ideas would be welcome.

Thank you.

 

[mikew_RIP]

Looks like they could be reflection from a filter or other lens elements,just a guess.

 

[DMcL]

Didn't use a filter (which reminds me I need to buy a protective one lol). Not sure what an other lens element would be.

 

[Scott Murray]

Looks like dust on the lens.

 

[Horoscope Fish]

Belated New Year wishes.

Now, out on a walk last night and noticed a few of my images have these no so cool spots in them. All affected images have been in or around street lighting. It was not raining at the time and my lens is as clean as my eye can tell.

I was using a D7100 with Sigma 17-50 lens, this example was shot at 22mm, 20 sec exposure at F.18.

Any ideas would be welcome.

Thank you.

Do all the affected shots have anything in common, like using f/18 as the aperture? I'm wondering if that's not some kind of diffraction (for lack of a better word) caused by the small aperture/long exposure combination.

 

[DMcL]

Is there a way of checking for it or doing some sort of test as looking at both ends of lens it looks perfectly fine.

 

[DMcL]

Do all the affected shots have anything in common, like using f/18 as the aperture? I'm wondering if that's not some kind of diffraction (for lack of a better word) caused by the small aperture/long exposure combination.

I see the same spots on images taken at different apertures and different zoom lengths.

 

[Horoscope Fish]

I see the same spots on images taken at different apertures and different zoom lengths.

No idea then... Hope you get it sorted out.

 

[Scott Murray]

Clean both ends of the lens and see if it still appears, also try a different lens and see if it happens. definitely is dust if you ask me.

 

[Scott Murray]

Also please provide other shots at different apertures maybe even take a macro shot of your lens

 

[DMcL]

Okay will try that and report back tonight! Thanks to all

 

[MartinCornwall]

I would agree with Scott, it looks like dust which could be inside the front element, whilst it doesn't show in normal photography it will show up in long exposures at night with bright light sources as in your photo. Here are two examples of when I had a dust inside front element, showing the same spots as in your shot. With most lenses it is easy to unscrew the front element give it a clean and screw back on. Not advisable with the rear element though as there can be electronics involved.

 

[Marcel]

Looks to me like refraction happening inside the lens between different elements. The fact that you used f18 might have made things worse.