Strange Glow

I just found this site the other day and have already gotten tons of information from it.

Yesterday I received a Rebel Xsi/450D which I had just purchased on ebay. I put my Canon lens (EF75-300mm f/4-5.6 IS USM) on and went out to take a few test shots (and to bust my son for not wearing eye protection while using a weed-eater). On a couple of the photos, when I zoom in close my son seems to be emitting a glow, I've never noticed that effect before (I've been using this same lens on my 300D Rebel since I purchased it new).

This shot was taken at 75 mm, f4.0, 1/500 sec, ISO 800, shot in RAW, and I use a Canon UV filter (I've heard some smart people say don't use a UV filter, but I often shoot sports where it's dusty so have always left it on).

Any thoughts on why I'm seeing this? Thanks.

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It looks like there is some sun coming through the tree branches which is causing the glow. The sun shine is causing overexposure in certain parts of the photo.

Purple fringing.

This is Chromatic Aberration (CA).

Most kit lenses (and other inexpensive ones) suffer from it. This is the difference of a less expensive lens from a more expensive one.

Lightroom and Darktable have data bases for lenses and will correct lens distortion and CA. It works quite well, but you have to shoot RAW.

Below is an example (it's mostly green) before correction. It left a little bit of magenta, which can be taken care by the pixel editor. Left is before correction, right is after.

Yep, chromatic aberration, most visible on sharply-edged high contrast locations in the picture.

MakisM1 wrote in post #14558406
This is Chromatic Aberration (CA).

Most kit lenses (and other inexpensive ones) suffer from it. This is the difference of a less expensive lens from a more expensive one.

I never really thought of this particular lens as "inexpensive" (at least not according to my wallet) - thanks for breaking my bubble . But ok, from what I just looked up on Wikipedia on purple fringing and CA that makes sense as I rarely shoot with this lens wide open with direct sunlight on the subject.

groundloop wrote in post #14558420
I never really thought of this particular lens as "inexpensive" (at least not according to my wallet) - thanks for breaking my bubble .

Believe me, I feel your pain... I bundle my EF-S 18-200 ($699 list @B&H) in the 'inexpensive' category. I am trying to use a euphemism for 'cheap(er)' design/construction, it does not really describe the price of the lens. Just as much as L-lens does not mean Luxury-lens.

But to put things into (Canon's) perspective:

The EF 70-300 L f4-5.6 costs $1499

The EF 70-300 DO (non-L) costs $1309

The EF 70-300 non-DO costs $549

I have a feeling that from the DO (I think it stands for Diffraction Optics) and up, CA will not be a problem...

But hey, if you can correct the problem with software, the price difference is in your pocket!

PS: Check whether the software that comes with Canon (EOS Utility etc) can do lens related corrections. Unfortunately this software doesn't work right off the bat with Linux, so I am not familiar with it.

MakisM1 wrote in post #14558467
PS: Check whether the software that comes with Canon (EOS Utility etc) can do lens related corrections.

I had been using Phase 1 for processing RAW photos shot with my 300D. To avoid buying new software when I upgraded to the 450D I decided to give Canon's Digital Photo Pro a try, and I have to say that the latest version is pretty decent (especially since it's free). It does include lens correction, but unfortunately my lens isn't in the database.

CA can show up on very expensive lenses as well... particularly those with apertures of f/1.2 and f/1.4

Several people have mentioned common distortions. However, something you did has contributed quite a bit to making the distortions much worse than normal. The EXIF on your images indicates you shot at ISO 800, 1/500 sec and f/4. The basic bright sun exposure for ISO 800 would be 1/800 sec at f/16, perhaps f/11 if you wanted to pull detail out the green surrounding. So you are about 3-1/2 stops overexposed. I would review what you are doing for determining exposure.

Blown highlights.

Don't forget about the Purple Fringe MONSTER ---- The 85mm f/1.2 L and retails for 2,200 bucks. This isn't a problem just reserved for cheap lenses.

jwcdds wrote in post #14558810
CA can show up on very expensive lenses as well... particularly those with apertures of f/1.2 and f/1.4

Yes, my 70-200 f/2.8L IS Mk1 shows it sometimes....

groundloop wrote in post #14558420
I never really thought of this particular lens as "inexpensive" (at least not according to my wallet) - thanks for breaking my bubble . But ok, from what I just looked up on Wikipedia on purple fringing and CA that makes sense as I rarely shoot with this lens wide open with direct sunlight on the subject.

Expensive lenses do it too in varying degrees, as Julian points out. It is not directly tied to the price tag of the lens. It is just that the more expensive lenses seem to have more of the necessary coatings to help reduce this. Just stop the lens down, and it should go away, or you can edit it out.

jack880 wrote in post #14569584
Yes, my 70-200 f/2.8L IS Mk1 shows it sometimes....

My 80-200 magic drainpipe too, in high contrast situations eg: in a very sunny day.