Oh Dear!

[Donald]

Right guys - What on earth are those marks.

I've cranked up the contrast to show them. They're not dust bunnies. I am perplexed (to say the least).

Help me out of my misery!

[Shadowman]

Donald,

Looks like spots on the lens or sensor, I usually have to do a good desmudging to remove. Were you changing lenses near water droplets? I would also check front/rear of lens.

[Manfred M]

Donald - what aperture and focal length are you shooting at?

I've seen something similar when shooting an ultra-wide angle lens at a very small aperture setting. The DoF is so large that contaminants on the front element of the lens (or filter?) start becoming distinct. By the way, there are lots of dust bunnies as well.

[William W]

Hiya Donald,

Manfred is on the right track IMO.

What Lens?
What Focal Length?
Any Filters on Lens?
What Aperture?
Where exactly was the sun relative to your camera?

My opinion:

The dark circular shadows are typical of Lens Flare from a W/A lens (more typically from a zoom than a prime) when used at a relatively small Aperture. The key is that the shadows are beautifully circular.

Unlikely that one would see them in the viewfinder or in live view unless really tuned into to finding them.

Typically the sun would be way out of the shot and you'd think it safe, but a strong ray (on yours from TOP CAMERA LEFT) has just penetrated the edge of the lens and bounced back from inside the lens and then bounced back off the inside of the lens's coating (or the inside of a filter) then onto the sensor.

It is possible that this strong ray could have been a reflected from a cloud or come through a cloud.

You should eliminate any intrinsic lens issue if the shadows only are on this one, or a group of similar image(s).


*

AREA "A"

*

AREA "B"

("overlkays" should read "overlays")

WW

[Manfred M]

Bill - when I first saw the image, lens flare is the first thing that popped into my mind, but I have never seen the pattern look anything like what we see in Donald's image.

[William W]

Not exactly the same but a reasonable enough facsimile to further the original diagnosis:

Image 1
JPEG SOOC, shot outside a few hours ago.
EOS 5D MkII,
EF 16 to 35/2.8L @16mm
Clear Filter on lens (excellent quality)
No Lens Hood
Aperture = F/20




*

Image 2.
A conversion to B&W



*

Image 3
Enlarged area top left



***

Note that we see some evidence of Lens Flare in the Colour, but not necessarily the formed clouded circles or anuli.

Note we see some evidence of both a pattern of clouded circles and also a pattern of clouded anuli in the converted B&W. image

NOTE - I purposely made a technically poor B&W to make it easier to illustrate one result of Lens Flare. (replicated a DEEP YELLOW Filter)

I do NOT suggest that Donald's B&W conversion was poor: but I just point out that (as I mentioned) he would not likely have noticed anything in the Viewfinder, or in the Live View image.

It would be interesting to note if Donald did NOT notice the circular shadows in the Post Processing when viewing the Colour Versions and only noticed the circular shadows after the B&W conversion.

WW

[fatehproductions]

Not exactly the same but a reasonable enough facsimile to further the original diagnosis:

Image 1
JPEG SOOC, shot outside a few hours ago.
EOS 5D MkII,
EF 16 to 35/2.8L @16mm
Clear Filter on lens (excellent quality)
No Lens Hood
Aperture = F/20




*

Image 2.
A conversion to B&W



*

Image 3
Enlarged area top left



***

Note that we see some evidence of Lens Flare in the Colour, but not necessarily the formed clouded circles or anuli.

Note we see some evidence of both a pattern of clouded circles and also a pattern of clouded anuli in the converted B&W. image

NOTE - I purposely made a technically poor B&W to make it easier to illustrate one result of Lens Flare. (replicated a DEEP YELLOW Filter)

I do NOT suggest that Donald's B&W conversion was poor: but I just point out that (as I mentioned) he would not likely have noticed anything in the Viewfinder, or in the Live View image.

It would be interesting to note if Donald did NOT notice the circular shadows in the Post Processing when viewing the Colour Versions and only noticed the circular shadows after the B&W conversion.

WW

Yes I do agree with you.

[Donald]

Dear all - Many thanks. I think you have quelled my panicking chest (to mix my metaphors)!

What Lens? 24-70
What Focal Length? 70
Any Filters on Lens? Yep. UV filter that always stays on + (5-stop + Variable Graduated ND)
What Aperture? f16
Where exactly was the sun relative to your camera? Top right facing the camera

and additional bit of info - Exposure? 301 seconds.

It is possible that this strong ray could have been a reflected from a cloud or come through a cloud.

The reason that I didn't think lens flare is that I did an equally long exposure facing the other way so that the sun was behind me. But in that image the one 'spot' I can see is where there is a very bright cloud and/sky such that I thought it might blow that part of the frame.

[William W]

. . . Any Filters on Lens? Yep. UV filter that always stays on + (5-stop + Variable Graduated ND) . . .

OK. It is possible that there could have been a lot of a bouncing light flare between those filters.

*

Mixing metaphors is a talent, not a curse.

WW

[Donald]

Many thanks for your help on this, Bill.

ps:- I've just cleaned the UV filter which was awful, but also the sensor.

[Manfred M]

70mm focal length is far too long for the effect I wrote about to be happening.

With the 5-stop and variable grad plus the UV, you have introduced six additional surfaces for the light to bounce around and off, so the risk of flare goes up significantly. Get rid of the UV in the stack as it adds nothing other than another optical surface that degrades the light hitting the sensor.

[xpatUSA]

Dear all - Many thanks.

What Lens? 24-70
What Focal Length? 70
Any Filters on Lens? Yep. UV filter that always stays on + (5-stop + Variable Graduated ND)
What Aperture? f16
Where exactly was the sun relative to your camera? Top right facing the camera

and additional bit of info - Exposure? 301 seconds.

Somewhat off-topic, but was intrigued by that last number (of a magnitude unheard of in the world of Sigma ).

In terms of exposure value: f/16 and 301 sec implies a scene EV of log2(16^2/301) = -0.2 EV

from https://en.wikipedia.org/wiki/Exposure_value

Adding in your filters which I estimate as 5 plus 1 plus maybe 1/4, it seems that you or your camera thought that the actual scene brightness is about 6 EV. Here's where I flounder - Wiki says that a "typical scene, cloudy bright (no shadows)" is 13 EV, which leaves 7 EV unaccounted for.

Obviously, I must have missed something. ISO?

[Donald]

Somewhat off-topic, but was intrigued by that last number (of a magnitude unheard of in the world of Sigma ).

In terms of exposure value: f/16 and 301 sec implies a scene EV of log2(16^2/301) = -0.2 EV

from https://en.wikipedia.org/wiki/Exposure_value

Adding in your filters which I estimate as 5 plus 1 plus maybe 1/4, it seems that you or your camera thought that the actual scene brightness is about 6 EV. Here's where I flounder - Wiki says that a "typical scene, cloudy bright (no shadows)" is 13 EV, which leaves 7 EV unaccounted for.

Obviously, I must have missed something. ISO?

You lost me at a "scene EV of log 2"

I was using a 5-stop and the Vari-Filter, both from Singh Ray, which I had dialled full up meaning I was getting 8 stops. So, I had 13 stops on the front of the lens.

Is that what you were asking about, Ted

[deanimator]

I just went through an ordeal with dust on my sensor.

It didn't become an issue until I got to 3.5x (using a Minolta 50mm manual reversed onto two sets of extension tubes) after I bought an automated macro rail.

My subjects had the sort of lines radiating from them like the lines from the head of a startled comic strip character.

I thought they were camera movement between exposures/camera advances on the rail, when they were really just dust specks, turned into lines by the stacking software.

[xpatUSA]

You lost me at a "scene EV of log 2"

Sorry - "scene EV of log2(16^2/301)" (where log2 had no space) meant "log to the base two of (f-number squared divided by exposure time)". That is the formula given in the link for a camera exposure value at 100 ISO.

I was using a 5-stop and the Vari-Filter, both from Singh Ray, which I had dialled full up meaning I was getting 8 stops. So, I had 13 stops on the front of the lens.

Is that what you were asking about, Ted

Yes, Donald, I see that my guess at the total filter stops was way, way wrong, shows what I know about filters, eh?

And your 13-stops-worth accounts exactly for that camera setting (surprise).

Thanks for the correction!

[Donald]

I just went through an ordeal with dust on my sensor.

It didn't become an issue until I got to 3.5x (using a Minolta 50mm manual reversed onto two sets of extension tubes) after I bought an automated macro rail.

My subjects had the sort of lines radiating from them like the lines from the head of a startled comic strip character.

I thought they were camera movement between exposures/camera advances on the rail, when they were really just dust specks, turned into lines by the stacking software.

Did you clean it yourself, Dean.

The first few times I took it into a Canon repair shop, but then I thought that I could maybe try it. Nerve-racking at first, but soon felt okay about it and now do it all the time.

[deanimator]

Did you clean it yourself, Dean.

Yes I did.

The first attempt(s) were with supplies found at a local camera store. The results were less than impressive. I just seemed to be moving the dust around.

I had actually already bought better cleaning gear on Amazon, but it had relatively long lead times and the images I was getting with the dust were essentially unusable. So I took a chance and bought what little was available locally.

The cheap (quality wise) stuff didn't get the job done in at least five attempts.

When the good stuff (illuminated loupe, Giotto's blower, Eclipse fluid and Sensor Swab Ultras) arrived, the sensor was clean in one shot.

As with everything else in photography, the better your tools, the easier the task.

[Manfred M]

Donald - I find that running the cleaning cycle on my camera manually 5 or 6 times gets rid of most of the dust bunnies.

When that doesn't work, I resort to a squeeze bulb type blower and that works to get rid all of the dust bunnies about 90% of the time. When that does not work, I use an Arctic Butterfly cleaner (soft, electrostatic-charge nylon brush), I've had to resort to that about once a year, usually in the springtime when sticky pollen cannot be dislodged any other way. I've never had to wet clean a sensor yet.

[Donald]

When that does not work, I use an Arctic Butterfly cleaner

I usually go with the Arctic Butterfly first off. That usually does the trick. I do have 'V' swatches and cleaner fluid for when things are really, really bad, like today.