# EF-M 22 f/2 - sky phenomenon or bug?



## Deleted member 378664 (Jan 22, 2017)

Hello,

has anyone seen such a kind of ring in the sky before?
Is this a sky phenomenon due to certain light/weather conditions (I guess not, the two examples pictures were taken with different orinentation)?
#1 no adjustments (imported in LR and exported to jpg with 860px at the long edge)






#1 extrem adjustments to emphasize the phenomenon





#2 no adjustments (imported in LR and exported to jpg with 860px at the long edge)





#2 extrem adjustments to emphasize the phenomenon





Has anyone an explanation for this behaviour?
I never have seen this with pictures taken with the EOS-M. The samples above are made with the EOS-M5. They are out of a series of pictures I took that morning. Only these two ones are affected. This is the first time I encounter this kind of strange ring in the sky.


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## bholliman (Jan 24, 2017)

Is the circular pattern around the sun? If so, it might be an atmospheric phenomena called a sun halo, caused by ice crystals in the air and the light angle. I've seen something similar here during extremely cold weather.

Maybe somebody better with science can provide a better explaination.


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## bluenoser1993 (Jan 24, 2017)

Strange that it is only these two photos out of a series affected. Due to the exact symmetry of the flaw in both photos, to me it looks like lens correction over doing it. Almost like the lens profile isn't correct in the camera.


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## rs (Jan 24, 2017)

Try another raw converter. I'd suggest Canon's DPP as it's the only OEM raw converter out there.


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## Deleted member 378664 (Jan 24, 2017)

bholliman said:


> Is the circular pattern around the sun? If so, it might be an atmospheric phenomena called a sun halo, caused by ice crystals in the air and the light angle. I've seen something similar here during extremely cold weather.
> 
> Maybe somebody better with science can provide a better explaination.



I would rule out a sun halo. I was photographing in two different direction during the end of the blue hour right befor sun rise.
The first shot was taken northbound:





the second shot 6 min later eastbound:





I will do another test this morning at the same location. I will take the same photos with different aperture settings. The two shots in question were taken with f/11.

When I open these two pictures in DPP, I can see the same effects.

regards
Frank


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## Sharlin (Jan 24, 2017)

Try disabling in-camera lens correction, especially vignette control (peripheral illumination correction) if it's enabled. This does look like some sort of a bug with the lens profile.


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## Deleted member 378664 (Jan 24, 2017)

Sharlin said:


> Try disabling in-camera lens correction, especially vignette control (peripheral illumination correction) if it's enabled. This does look like some sort of a bug with the lens profile.



OK, I took some photos this morning with apertures from f11 to f2 in 1 stop increments.
I have done each aperture series with different settings regarding in camera lens correction (vignetting, diffraction and ca's). I will analyse it this evening.

I will do the same test with the EOS M again. I never have seen this phenomenon on photos taken with the M. Maybe it is really related to the profiles in the EOS M5.

Frank


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## sanj (Jan 24, 2017)

Some temperature related issue with sensor? I doubt if this is lens related. Maybe try another lens as well and take similar photo and then push in post?


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## Don Haines (Jan 24, 2017)

sanj said:


> Some temperature related issue with sensor? I doubt if this is lens related. Maybe try another lens as well and take similar photo and then push in post?


If it was a linear phenomena, I would tend to blame sensor, for a circular phenomena I would tend to blame lens.

What happens if you turn all lens correction off and try different lenses?


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## Mikehit (Jan 24, 2017)

The circle seems to be symmetrical top-bottom but if it were a lens issue I am not sure why it would appear to be off centre to the right.


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## old-pr-pix (Jan 24, 2017)

Mikehit said:


> The circle seems to be symmetrical top-bottom but if it were a lens issue I am not sure why it would appear to be off centre to the right.


Check the scroll bar under photos... it looks centered to me if I scroll to the center the pix. Seems like the lens and/or lens correction software is involved.


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## Mikehit (Jan 24, 2017)

good point


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## Deleted member 378664 (Jan 24, 2017)

@sanj and @DonHaines:

This morning I only had my 22mm lens with me. I shot with different settings regarding the three possible lens correction parameters.
I guess I will need more time than the few minutes before I go to work to perform a comprehensive series of tests. I will try to do this the oncoming weekend.

Does anyone think the tiny lens hood which I have always on the 22mm lens could be an issue?

Frank


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## sanj (Jan 24, 2017)

So curious now. 
Doubt if it is the lens hood. Really doubt.


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## zim (Jan 24, 2017)

Are you using a filter of any type?


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## Deleted member 378664 (Jan 24, 2017)

zim said:


> Are you using a filter of any type?



no, no filter used.


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## Al Chemist (Jan 24, 2017)

It is not the lens. I noticed the same thing with the 18-150 M and the M5. The pictures were dark subjects against a snow background with sunny conditions. The sun angle was different for different shots. I cannot seem to reproduce it when I try so it happens under certain light conditions and not others. I tend to agree it may well be a lens correction in the firmware. If the sun ever shows up again (It's always Winter and never Spring this year!) I will try turning of the lens correction assuming I can reproduce the phenomenon again. It only showed up a couple of times. Sorry, I didn't keep the images to post.


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## Deleted member 378664 (Jan 24, 2017)

Hi,

I found that it isn't a problem with the camera or the lens. At least this is my assumption:

1st result of my today analysis showed that only the photos taken with f/11 out of a series of f/(11|8|5,6|4|2,8|2) are showing this strange effect when I apply an extreme gradation curve with Lightroom. Independet of the lens correction parameters I used in the camera. Even the photos with deactivated vignetting and/or diffraction correction showed this effect.
2nd result was: In LR I do automatically apply the LR lens profile to each photo during import(development preferences under apply during import).

I deleted my series of test photos from the hard drive and the catalog and reimported the testshots again, but this time without applying the LR profile tp each imported photo.

Applying the extreme gradation curve now didn't reveal this effect.

Conclusion: The LR profile for this lens does not work with f/11. If it is not working with aperture values greater than 11 or with other lenses has to be tested. I limited the series of my testshots to the 22mm lens with the range f/2 through f/11 in one stop increments.

regards
Frank


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## Al Chemist (Jan 24, 2017)

Sunshine today!!!

These were taken moments apart and same processing was used on both. The one titled "on" has the lens aberration correction active. The other titled "off" has this correction disabled. 

I would think that this will be fixed in the first firmware update.


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## Al Chemist (Jan 25, 2017)

I just got around to processing the CR2 files with DPP4 to TIFF and neither image shows the rings. i'm thinking that is because RAW files do not use any of the camera corrections. It would only show up in the JPGs direct from the camera. Is that a correct assumption?


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## Don Haines (Jan 25, 2017)

Al Chemist said:


> I just got around to processing the CR2 files with DPP4 to TIFF and neither image shows the rings. i'm thinking that is because RAW files do not use any of the camera corrections. It would only show up in the JPGs direct from the camera. Is that a correct assumption?


That would make sense....

If that is true, a firmware update could solve the problem.... Also, the camera has limited processing power and as such, the file converter will never be as good as the one in DPP4....


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## Deleted member 378664 (Feb 9, 2017)

Meanwhile I found the rot cause.

Lately I repeated a series of photos at the same location with nearly the same environmental conditons with different f-values in 1 stop increments from f/2 to f/11.
I also varied the different possibilities for in camera lens correction.

The problem occured only with the photos taken with f/11 independently from the in camera lens correction settings.

the fault was my automatically applied lens correction preset during lightroom import.
When I import the photos without the lens correction from LR I don't see those circles.
So it seems to be a problem with the lens correction profile for the 22mm lens in LR espacially with photos taken with f/11.

kind regards
Frank


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