What is this ring showing on my lens?

Started 8 months ago | Questions
Sagnet New Member • Posts: 7
What is this ring showing on my lens?

Hi guys! Just bought the EOS 90D, which was an upgrade from my EOS 650D (Rebel T4i). I have some old lenses I'm planning to use with the 90D. One of them is a Sigma 50mm 1.4. However, when shooting with this wide open on the 90D, there is a circle showing. What is this? The aperture, or something else?

It only shows at 1.4, it goes away when stopped down to 1.6. It does not show on my 650D at 1.4. I find this strange, as both cameras are APS-C format.

ANSWER:
Canon EOS 90D Canon EOS Rebel T4i (EOS 650D / EOS Kiss X6i)
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Fastfreddy74 New Member • Posts: 14
Re: What is this ring showing on my lens?
2

Try to disable lens aberration corrections in camera, and check if the circle is gone.

It can happen with old lenses on recent camera bodies

selected answer This post was selected as the answer by the original poster.
Ray UK Contributing Member • Posts: 821
Re: What is this ring showing on my lens?
3

Fastfreddy74 wrote:

It can happen with old lenses on recent camera bodies

Not necessarily old lenses but the lens corrections only apply to lenses made by Canon.

S Castle
S Castle Senior Member • Posts: 1,219
Re: What is this ring showing on my lens?

Ray UK wrote:

Fastfreddy74 wrote:

It can happen with old lenses on recent camera bodies

Not necessarily old lenses but the lens corrections only apply to lenses made by Canon.

Yes, plus I seem to recall something about exactly this effect before, and a firmware update from the lens mfr fixed it. I don't remember if it was Tamron or Sigma.

-- hide signature --

Shane

OP Sagnet New Member • Posts: 7
Re: What is this ring showing on my lens?
1

Fastfreddy74 wrote:

Try to disable lens aberration corrections in camera, and check if the circle is gone.

It can happen with old lenses on recent camera bodies

Thanks guys, it was the "Peripheral illumination corr" that did it. Turned it off, and the ring was gone.

For completeness, the lens is the Sigma 50mm 1.4 EX DG HSM.

OP Sagnet New Member • Posts: 7
Re: What is this ring showing on my lens?

Oh, and one more question: Which correction settings are recommended for this kind of older, non Canon lenses? Should I leave any corrections on, like for Chromatic aberration or Diffraction? Or just turn them all off?

Fastfreddy74 New Member • Posts: 14
Re: What is this ring showing on my lens?

Sagnet wrote:

Oh, and one more question: Which correction settings are recommended for this kind of older, non Canon lenses? Should I leave any corrections on, like for Chromatic aberration or Diffraction? Or just turn them all off?

I'd turn off only the corrections that created the issue.

Anyway, lens corrections only affects jpegs, if you shoot raw you'll have to apply it in post production, so it doesn't matter what was set in camera.

John Sheehy Forum Pro • Posts: 24,776
Re: What is this ring showing on my lens?
1

Sagnet wrote:

Hi guys! Just bought the EOS 90D, which was an upgrade from my EOS 650D (Rebel T4i). I have some old lenses I'm planning to use with the 90D. One of them is a Sigma 50mm 1.4. However, when shooting with this wide open on the 90D, there is a circle showing. What is this? The aperture, or something else?

It only shows at 1.4, it goes away when stopped down to 1.6. It does not show on my 650D at 1.4. I find this strange, as both cameras are APS-C format.

The lens is masquerading as some Canon lens in the data it supplies to the camera, which needs different corrections, so in newer bodies that correct for lenses in their JPEGs, you need to disable whatever correction is causing the problem, a real pain in the neck if you switch lenses frequently or urgently.  You will have similar problems with "masquerading" with the IBIS in the R5 and R6; the wrong focal lengths are reported, and the shake corrections can be so wrong in some cases that IBIS causes far more blur than non-IBIS will give.  I have an old Sigma 12-24mm zoom that the R5 sees as an 85mm prime, and with IBIS, you can see the EVF swimming from the excess correction.

CameraCarl Veteran Member • Posts: 7,689
Re: What is this ring showing on my lens?
2

Sagnet wrote:

Oh, and one more question: Which correction settings are recommended for this kind of older, non Canon lenses? Should I leave any corrections on, like for Chromatic aberration or Diffraction? Or just turn them all off?

Turn off all in camera corrections and make whatever corrections you need to make in post processing. I do this on all my cameras even when I am using only Canon lenses. If I'm not mistaken, the in-camera corrections usually only work with jpegs or Canon DPP software, anyway.

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