Vignetting with the EF-S 10-22...caused by lens hood?

[baboymo]

Take a look at the vignetting at 10mm with the lens hood on.

http://home.earthlink.net/%7Epixelshift/images/CRW_2370.jpg
http://home.earthlink.net/%7Epixelshift/images/CRW_2371.jpg

Unfortunately I forgot to test it out without the hood. Could this be a characteristic of the lens? What do you guys think?

[drisley]

I honestly don't see much. I guess it is there a little bit.
With such a wide angle, vignetting could be very possible.
If you use photoshop and shoot raw, you can correct vignetting very easily.
It can also be corrected on jpgs too.

[Toogy]

Are you using a UV filter at all? I have noticed VERY slight vignetting at 10mm with my UV filter (Hoya super Pro-1), but it doesn't really bother me, like drisley said, easily fixable.

[DaveG]

I don't see vignetting in either photo. I think that what you are seeing is the naturaly darker sky when you move away from the centre and the light source. The 10-22 is so wide that it looks like fall off/vignetting when it really is the density of the sky changing.

[Dante King]

I dont see it either.

[raylks]

I don't see it either

[COKE CAN]

What is vignetting?

[mr.photoguy]

It could be just the contrast in the sky...

Do a with/and without shot.

[cfcRebel]

What is vignetting?
I had the same question. I found this:

vi·gnette (vĭn-yĕt') http://www.gurunet.com/content/img/pron.gif
n.

A decorative design placed at the beginning or end of a book or chapter of a book or along the border of a page.
An unbordered picture, often a portrait, that shades off into the surrounding color at the edges.

A short, usually descriptive literary sketch.
A short scene or incident, as from a movie.

tr.v., -gnet·ted, -gnet·ting, -gnettes.

To soften the edges of (a picture) in vignette style.
To describe in a brief way.
[French, from Old French, diminutive of vigne, vine (from the use of vine tendrils in decorative borders). See vine (file:///C:/Documents%20and%20Settings/All%20Users/Application%20Data/GuruNet/GuruNetCache/atomicalookup_1555_[V0105600]).]

[DaveG]

In photographic terms vignette can be used to describe light fall off in the corners or the edges of an image; or where the edges get blocked by something like a lens hood. I'm not sure if the denotation is correct and a dictionary will shed some like on that, but that's what the commonplace connotation is now, and it usually takes twenty years for that meaning to show up in a dictionary.

Vignetting caused by a lens hood is one thing and its cure simple: don't use THAT shade. But fall off is something else and worth talking about I think.

All lenses will have fall off, the light just has to travel farther to reach the edge of the film/sensor than the middle. When it goes farther, it's weaker so there's less of it to be recorded by the sensor.

This is much more noticeable on wide angle lenses. Lenses make an image circle, a disk of light that covers the size of the sensor. The EF-S lenses not only won't fit on the 1DS Mark 2 body but even if they did their coverage on that bigger sensor would be a circle. In large format (4x5) photography a typical lens has a huge image circle. That's because those cameras allow the photographer to move the film rectangle shape around inside that circle. That way they can use tilts and swings (change the plane of depth of field); rises (reduce the "falling over backwards" look in images of buildings); and other camera movements.

When I use one of my LF cameras I can see fall off when I get close to the edge of the image circle. With my 8x10 I've run out of image circle and had a black strip on the bottom of my neg. The EF-S lenses will have an image circle just big enough for the 20D sized sensor so you are always going to be seeing close to the edge of that lenses' coverage.

To correct fall off and other distotions go to the PTLens site and download the free (and brilliant) PTLens Photoshop plugin. http://epaperpress.com/ptlens/index.html

PTLens corrects for distortion for many Canon lenses, including barrel and pin cushion distortion, and of course vignetting. The vignetting fix will lighten the corners and does so very well. Ironically I almost always slightly darken the corners of my images as a way of framing the subject, so a little bit of fall off saves me some time! But each to their own.

[cfcRebel]

I appreciate you took time to explain this. I have definitely learned alot. Thanks David.
One silly question: Would a round sensor, as opposed to square, alleviate or reduce the likelihood(not eliminate) of the fall off? I guess it doesn't matter, especially when an image circle is way too big for the sensor.

[Tom W]

David is correct. Sometimes, the vignetting that can occur from a lens hood or filter is referred to as "hard" vignetting. It is a physical blocking of the light and is pretty obvious.

The other type of vignetting is referred to as "optical" vignetting. This is a natural phenomenom that occurs in lenses, and is more visible and more prevalent on wider angle lenses. It is as Dave describes, but it also has to do with the angle with which the light passes through the lens.

The way lenses are designed optically, closing down the center of the lens results in a darker picture rather than a reduction of the diameter of the image circle. That is by design and is why the diaphram can be closed or opened to adjust the aperture (f-stop). But with wide angle lenses, as the angle of light approaching the lens increases away from straight-on, the light rays don't travel through the lens straight, so they don't get the benefit of the full diameter of the lens elements.

Pick up a lens, remove both the front and rear lens caps, and look straight through the lens from the front (as though looking into the camera). What do you see? A nice round ring in the middle. But start angling the lens so that you aren't looking straight through it any more, but at an angle and the ring goes from O to (). That is basically the light being "chopped off", but it is happening in the middle of the lens somewhere between where the diaphram is and the front of the lens, so instead of chopping the side off your image, it merely darkens the corners of the image. (remember that the lens is designed so that the diaphram acts like a "light valve" darkening the whole image rather than just reducing the size of it).

Here's where stopping down comes in handy. Most wide-angle lenses will exhibit some optical vignetting at wide apertures, even if it is barely visible. But as you stop down, that vignetting disappears. Why? Because as you reduce the size of the diaphram by stopping down, you decrease it until the diameter of the diaphram hole is small enough to fit within the () shaped hole that incoming light produces when the angle is wide. In other words, o fits inside (), whereas O does not. In other words, the wide-open aperture experiences light-falloff towards the edge while the stopped down aperture does not.

[Jon]

Agreed - that's in all probability typical ultra-wide-angle light fall-off.