Sigma 10-20 Lens Test

[Norfindel]

Hello,

I recently buyed a Sigma 10-20 Ex lens and took a few test shots. I would like to know the opinions of other owners of this lens model.

The first test was done at 2.5 meters from the wall, and showed one soft corner, however i suspect the tripod was not parallel to the wall and not too stable, so i made the second test at a greater distance. All the image corners are at 100% zoom.

First Test
----------

This is a reduced view of the wall (just to show how the entire picture looks):



Those are the corners of the image taken at f/4:



Those are the corners of the image taken at f/8:



Those are the corners of the image taken at f/16:



Second Test
-----------

This time, i shooted a wall across the street at 6 meters aprox.

This was shot to test the upper edge of the image, followed by the upper left/upper middle/upper right zones at different apertures:









This was shot to test the middle areas of the image, followed by the left/center/right zones at different apertures:









I tried to test the lower edge, but as the sun was directly on the frame it flared, so i decided to only shoot that image alone:





Finally, this is an image taken from my house roof at dawn (not a lens test):

[Photo-John]

This is excellent test material, Norfindel. I really like the way you've built your sample images. You should also take a look at the wide-angle lens discussions we've been having on the Canon forum and add a link to this post.

Please also post a review for the Sigma 10-20mm lens in the reviews. And make sure to include a link from your review to this post so that people can see your samples.

Read and write reviews for the Sigma 10-20mm >>

Thanks in advance for the review!

[Norfindel]

Thank you, the images of the details are done by a script (it cost me several hours to make but finally done it). In case anyone want to use it, it's at the end of this post.

The script always takes 9 squares of 2 centimeters each, so you can change the image size (without resampling) to choose how big you want the target image. The text at the lower right of the image is by default "Lens Test", or whatever you enter in IPTC Core -> Title on adobe bridge, or similar application.

This is the script:


//
// Crea un documento que contiene el detalle de los bordes de la imagen al 100%, el
// resultado son 9 cuadrados de 2cm x 2cm cada uno.
//
// El nombre del documento creado es "Lens Test" ó el valor que haya en IPTC Core -> Title
// Un marco gris es creado y los datos EXIF y el nombre del documento se ponen en el.
//

// enable double clicking from the Macintosh Finder or the Windows Explorer
#target photoshop

// in case we double clicked the file
app.bringToFront();

var firma = "Lens Test"

// No mostrar ningun tipo de dialogo
//var saveDialogs = displayDialogs
//displayDialogs = DialogModes.NO

var originalRuler = app.preferences.rulerUnits
app.preferences.rulerUnits = Units.PIXELS

var saveColor = backgroundColor

backgroundColor.rgb.red = 128
backgroundColor.rgb.green = 128
backgroundColor.rgb.blue = 128

// docRef = active document
var sDoc = app.activeDocument

var exifData = ExifInfo(sDoc, "Model") + " - " + ExifInfo(sDoc, "Focal Length") + " - " + ExifInfo(sDoc, "Shutter Speed") + " - " + ExifInfo(sDoc, "Aperture Value") + " - ISO " + ExifInfo(sDoc, "ISO Speed Ratings")

if (sDoc.info.title > "") firma = sDoc.info.title

// El primer numero es el tamano en milimetros de la seleccion
var selectionWidth = 20 / 25.4 * sDoc.resolution
var selectionHeight = 20 / 25.4 * sDoc.resolution
var separation = 1 / 25.4 * sDoc.resolution

var tDoc = app.documents.add(selectionWidth * 3 + separation * 2,
selectionHeight * 3 + separation * 2,
sDoc.resolution, firma, sDoc.DocumentMode, DocumentFill.BACKGROUNDCOLOR)

// Le asigno el mismo perfil de color que al source document
tDoc.colorProfileName = sDoc.colorProfileName

// Borde superior izq
var sX = 0
var sY = 0
var tX = 0
var tY = 0
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Borde superior central
sX = (sDoc.width - selectionWidth) / 2
sY = 0
tX = selectionWidth + separation
tY = 0
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Borde superior der
sX = sDoc.width - selectionWidth
sY = 0
tX = tDoc.width - selectionWidth
tY = 0
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Central izq
sX = 0
sY = (sDoc.height - selectionHeight) / 2
tX = 0
tY = selectionHeight + separation
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Central medio
sX = (sDoc.width - selectionWidth) / 2
sY = (sDoc.height - selectionHeight) / 2
tX = selectionWidth + separation
tY = selectionHeight + separation
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Central der
sX = sDoc.width - selectionWidth
sY = (sDoc.height - selectionHeight) / 2
tX = tDoc.width - selectionWidth
tY = selectionHeight + separation
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Borde Inferior izq
sX = 0
sY = sDoc.height - selectionHeight
tX = 0
tY = tDoc.height - selectionHeight
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Borde Inferior medio
sX = (sDoc.width - selectionWidth) / 2
sY = sDoc.height - selectionHeight
tX = selectionWidth + separation
tY = tDoc.height - selectionHeight
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Borde Inferior der
sX = sDoc.width - selectionWidth
sY = sDoc.height - selectionHeight
tX = tDoc.width - selectionWidth
tY = tDoc.height - selectionHeight
CopyRectangleTo(sDoc, tDoc, sX, sY, tX, tY, selectionWidth, selectionHeight)

// Hago un marco gris para la foto
var borderSize = tDoc.width * 0.03
tDoc.resizeCanvas(tDoc.width + borderSize, tDoc.height + borderSize)
tDoc.resizeCanvas(tDoc.width, tDoc.height + borderSize, AnchorPosition.TOPCENTER)


// A partir de aca, pongo la informacion exif en un textlayer
var textColor = new SolidColor;
textColor.rgb.red = 0;
textColor.rgb.green = 0;
textColor.rgb.blue = 0;


// Pongo los datos EXIF
var newTextLayer = tDoc.artLayers.add();
newTextLayer.kind = LayerKind.TEXT;
newTextLayer.textItem.font = "ArialMT"
newTextLayer.textItem.contents = exifData
newTextLayer.textItem.position = Array(borderSize/2, tDoc.height - borderSize/2);
// Seteo el alto del texto (tengo que pasar de pixels a puntos)
newTextLayer.textItem.size = borderSize / tDoc.resolution * 58
newTextLayer.textItem.color = textColor;

// Pongo la firma
var newTextLayer = tDoc.artLayers.add();
newTextLayer.kind = LayerKind.TEXT;
newTextLayer.textItem.font = "ArialMT"
newTextLayer.textItem.justification = Justification.RIGHT
newTextLayer.textItem.contents = firma
newTextLayer.textItem.position = Array(tDoc.width - borderSize/2, tDoc.height - borderSize/2);
// Seteo el alto del texto (tengo que pasar de pixels a puntos)
newTextLayer.textItem.size = borderSize / tDoc.resolution * 58;
newTextLayer.textItem.color = textColor;


app.preferences.rulerUnits = originalRuler
backgroundColor = saveColor

//displayDialogs = saveDialogs

newTextLayer = null
borderSize = null
saveColor = null
a = null
sX = null
sY = null
tX = null
tY = null
sDoc = null
tDoc = null
firma = null



function ExifInfo(document, tag)
{

var result = ""

for (var a = 0; a < document.info.exif.length; a++)
{

if (document.info.exif[a][0] == tag)
{
result = document.info.exif[a][1]
break
}
}

return result
}


function CopyRectangleTo(sDoc, tDoc, sX1, sY1, tX1, tY1, w, h)
{
// Activo el Source Document
app.activeDocument = sDoc

var sX2 = sX1 + w
var sY2 = sY1 + h

var shapeRef = [
[sX1,sY1],
[sX2,sY1],
[sX2,sY2],
[sX1,sY2],
[sX1,sY1]
]
sDoc.selection.select(shapeRef)
// Copio el cuadrado que seleccione
sDoc.selection.copy()

var tX2 = tX1 + w
var tY2 = tY1 + h

// Activo el Target Document
app.activeDocument = tDoc

// Selecciono el area para hacer Paste Into
shapeRef = [
[tX1,tY1],
[tX2,tY1],
[tX2,tY2],
[tX1,tY2],
[tX1,tY1]
]
tDoc.selection.select(shapeRef)

// Paste into
tDoc.paste(true)
}

[Photo-John]

Thanks for the script! I have no idea how to implement it. But I'm going to give it a shot. Maybe it can become a standard for testing on the site. I appreciate your effort and your willingness to share. The output format is very, very good.

[another view]

Pretty impressive post you've got there! I have the lens but haven't used it a lot yet. I have been very surprised with mine at how little flare there has been. I figured a 10mm zoom would be horrible here but I'm impressed. This is the first fairly wide lens I've had good luck with on digital. I've never done anything formal to test distortion or anything else other than to take a few shots to make sure that the focus is on and everything is working right.

Here's that shot with the sun in the frame. It was a RAW file that I lightened and also boosted the saturation a bit, plus I used fill flash for the foreground. The water would blow out on any media (neg or slide film, digital) and I expected some flare. Not bad, I'd say and it was all the way out to 10mm.

[Norfindel]

Thank you again.

John: The script is for adobe photoshop cs2, it's just a text file with the name LensBorderTest.jsx (any name will do, just the extension must be .jsx).
I just made an action in photoshop that changes the image size to 8 or 12 centimeters height (keeping proportions, and without resampling). This just changes the image dpi to match the output size, and won't touch any pixel, then File --> Automate --> Scripts, and select the script to run.

another view: nice picture, i think that using curves in photoshop could bring the contrast up nicely. Also, i found "shadows and highlights" to be really good to balance the brightness of all the areas in the image.
The last image of my post is taken in raw. All the trees and houses looked fairly dark, but playing with shadows and highlights do the trick.
It's said than the canon 10-22 is even better in flare resistance, distortion, and sharpness, but some u$s 200 more, and doesn't even come with the hood. I'm won't do a lot of 1 meter wide prints, so i think the sigma is a good choice.
The lens mechanical construction looks good to me, the only really bad thing about this is the lens frontal cap. It's really horrible, just a piece of low-quality plastic that doesn't even locks securely in place. I'm currently looking for a replacement cap.

[another view]

Thanks - my shot is a RAW file and I just did a quick Photoshop on it. It could use a bit more contrast but these kind of shots usually have fairly low contrast so I wouldn't want to add much to it. I've never been much of a fan of the S&H tool - the results I've had with it have made it look pretty obvious that I used it, and that's a bad sign... My lens cap fits OK, maybe it's a different version (bought the lens earlier this year).