# RF 24-240mm review



## ajfotofilmagem (Sep 14, 2019)




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## neuroanatomist (Sep 15, 2019)

He claims there is mechanical vignetting at the wide end, which does not seem like something Canon would allow in the design. In another thread, and owner posted a RAW file without correction, showing that the mechanical vignetting is not present. I suspect this reviewer had a filter on the lens while taking the shots where he saw the problem, which leads me to not trust this review.


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## Joules (Sep 15, 2019)

neuroanatomist said:


> He claims there is mechanical vignetting at the wide end, which does not seem like something Canon would allow in the design. In another thread, and owner posted a RAW file without correction, showing that the mechanical vignetting is not present. I suspect this reviewer had a filter on the lens while taking the shots where he saw the problem, which leads me to not trust this review.


Note that the uncorrected image shown by Mr Frost in the video doesn't just show vignetting. It is also noticably wider, a good deal wider than 24mm it seems. I'm not using any filters beyond an ND filter and a CPL. Still, I don't think widening the field of view is a common defect when using filters on wide angle lenses. To support your suspicion that this review is fake because it shows something you don't expect from Canon, could you please show us an example of a filter causing such an effect?

I'm not saying this is a problem or that Canon is ******* for using such means to achieve their design requirements. But it seems like a new design mentality, from Canon at least. And dismissing this review because it shows an effect that somebody else didn't reproduce seems a bit quick, when we don't know the details of how each result was achieved. I posted my suspicion in the other thread.

Explanation of the attachment: I took a screenshot from the corrected and uncorrected frame from the video and put the upper left corner of both versions side by side in Photoshop. I flipped the uncorrected image, so that the part of interest is right next to the other one.


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## koenkooi (Sep 15, 2019)

Joules said:


> Note that the uncorrected image shown by Mr Frost in the video doesn't just show vignetting. It is also noticably wider, a good deal wider than 24mm it seems. I'm not using any filters beyond an ND filter and a CPL. Still, I don't think widening the field of view is a common defect when using filters on wide angle lenses. To support your suspicion that this review is fake because it shows something you don't expect from Canon, could you please show us an example of a filter causing such an effect?
> 
> I'm not saying this is a problem or that Canon is ******* for using such means to achieve their design requirements. But it seems like a new design mentality, from Canon at least. And dismissing this review because it shows an effect that somebody else didn't reproduce seems a bit quick, when we don't know the details of how each result was achieved. I posted my suspicion in the other thread.
> 
> Explanation of the attachment: I took a screenshot from the corrected and uncorrected frame from the video and put the upper left corner of both versions side by side in Photoshop. I flipped the uncorrected image, so that the part of interest is right next to the other one.



As I said in the other thread: 
Have a look at the thread on the Fred Miranda forum. That shows that at 24mm it's a lot wider than 24mm and the camera sets a crop rectangle in the RAW file. If you look at the RAW file with e.g. RAWdigger you'll get the full FoV.


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## neuroanatomist (Sep 15, 2019)

Joules said:


> And dismissing this review because it shows an effect that somebody else didn't reproduce seems a bit quick, when we don't know the details of how each result was achieved. I posted my suspicion in the other thread.


Fair point, thanks for the additional info.

It will be interesting for someone to measure the actual AoVs. If the lens profiles are cropping the resulting images, what are the resulting equivalent focal lengths before and after cropping?


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