# Tamron 45mm 1.8 Canon 5d Mark IV



## rpritch (Sep 20, 2017)

I just purchased the Tamron 45mm f/1.8 and I am a bit confused. When shot between f/1.8 and f2.5 there is a black ring around the photo--and I am not referring to vignetting. It is literally a black circle. Can someone please help me trouble-shoot this? The phenomenon does not occur on my 7d mark II.


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## ajfotofilmagem (Sep 20, 2017)

Enter the camera menu (or RAW processing software), and turn off lens correction, this phenomenon should disappear.


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## rpritch (Sep 20, 2017)

Thank you for the help. Could you explain why this is an issue on the 5d mark IV and not the 7d mark ii. I did as you suggested and the issue resolved itself. Is this simply indicative of a programing issue on my camera? Would a firmware update handle the issue? It was a preordered camera that has not been updated since the time of purchase.


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## Ryananthony (Sep 20, 2017)

I believe it is your lens that needs updating, not the camera.


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## Antono Refa (Sep 20, 2017)

rpritch said:


> Thank you for the help. Could you explain why this is an issue on the 5d mark IV and not the 7d mark ii. I did as you suggested and the issue resolved itself. Is this simply indicative of a programming issue on my camera? Would a firmware update handle the issue? It was a preordered camera that has not been updated since the time of purchase.



Canon cameras have profiles that correct lenses' optical imperfections, such as vignetting. Canon includes profiles only for its own lenses, not 3rd party lenses. In order to work as smoothly as possible, 3rd party manufacturers make the lenses pretend to be a similar Canon lenses.

Problems arise because the lenses are similar, but not identical. In this case the Tamron 45mm vignettes differently from whichever lens it pretends to be, so the body applies the wrong amount of vignette correction, causing the ring to appear.

As can be seen in the photo, the vignette appears on the edge of FF image. Apparently the vignetting is close enough in the center of the image for the correction to work for the problem not to occur on crop (APS-C) sensors.

A firmware upgrade will not solve the problem, because Canon does not include profiles for 3rd party lenses, so the same profile would be applied, leading to the same effect.


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## rpritch (Sep 20, 2017)

Thank you for such a thorough response. Can I ask why this is not a more common problem then? I scoured the internet for similar situations and the best I could find was a Sigma 50 f/1.4 on a 5d mark iii. Why haven't others had the same experience with this combination?

Thanks again!


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## Drum (Sep 20, 2017)

It has been a widely recorded problem, for a lot of the Sigma Art series lenses. I'm surprised you only found the 50mm having the problem. As said in a previous post its the lens correction setting in the camera that needs to be turned off and not the lens needing an update.


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## rpritch (Sep 20, 2017)

Thanks. Changing the settings worked, so I appreciate your help. I just wanted to get a better understanding as to why this was the case. 

Very helpful, all of you. Thanks again!


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## e_honda (Sep 22, 2017)

I can confirm this same problem also exists on the Tamron 85mm 1.8 VC.


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