Wide-Angle Zoom Lens Selection For Canon 20D – Tamron 11-18mm

I recently bought a super wide-angle zoom lens for my 20D for photos like this. It’s really wide! More samples at the end of the post.

It was not an easy task/ decision:

Crop Body (Digital Rebel/400D, 30D) owners struggled to find super wide-angle lenses, because a 17-40mm lens becomes a 27-64mm (=effective focal length) on a Canon crop body due to the smaller sensor size compared to a full frame sensor camera like the 5D. That’s handy for telephoto (as 200mm becomes 320mm) but not good for wide-angle lenses originally designed for 35mm (full frame) cameras.

The lens manufacturers addressed the issue by designing lenses especially for crop bodies. These lenses are smaller and have less weight than their full frame counterparts. On the other hand, these can be only used on crop bodies, not on full frame cameras.

After scanning the market I short-listed 2 lenses

• Canon EF-S 10-22mm f/3.5-4.5 USM
• Tamron SP 11-18mm f/4.5-5.6 Di-II LD Aspherical (IF)

Here is the justification

• I like to travel light. The Tokina (12-24) and Sigma (10-20) products are out of the list for that
• I do not care (too much) that these lenses do not work on a full frame sensor camera. If I upgrade later, the lens stays with my 20D … on sale or as a backup

It is a pretty tough choice between the two

• The Canon gets great reviews, the Tamron gets good reviews
• The focal range of the Canon is much larger
• The Canon lens is faster (aperture-wise)
• The Tamron costs 530 US$ (including a lens hood) and the Canon costs 675 US$ (no hood). An original Canon hood will set you back an other 40 US$

I finally bought the Tamron, because

• The price difference matters for me. If money would not matter, well, I get the Canon
• I guess that the difference in focal length won’t be relevant for my main applications of this lens. Landscapes and architecture. One review that made the comparison suggested that. But you never know until you try ...
  
• Also the lens speed does not really matter for my applications. The majority of times I am between f8 and f16
• Due to the shorter focal length and slower speed, the Tamron is even smaller and lighter … marginally

Image quality of the Tamron 11-18mm

• Colours are great, sharpness is good
• Barrel distortion and chromatic aberrations are noticeable in the corners of the image (see 100% crop sample below)
  

I really would love to have the Canon - at least for a few days or so - to compare the image quality. Unfortunately I don’t ;-)

Here is an “extreme sample” with 100% crop, no Photoshop manipulation.Purple fringing along the left side white column is clearly visible. It is not that drastic in all photos, but happens quite regular.








More Samples:





In case you consider buying a wide-angle lens for a crop body camera, I recommend reading the following links:

http://www.digi-darkroom.com/showthread.php?t=18242
http://www.kenrockwell.com/tech/digital-wide-zooms/comparison.htm
http://www.kenrockwell.com/tamron/1118.htm
http://www.kenrockwell.com/canon/1022.htm
http://www.luminous-landscape.com/reviews/lenses/Canon-10-22mm-test.shtml
http://www.luminous-landscape.com/reviews/lenses/tamron%2011-18mm.shtml
http://www.photozone.de/8Reviews/lenses/tamron_1118_4556/index.htm