VIRB

If you are looking for an inexpensive ultra-wide lens for a full frame Canon camera, this is one to consider. I've been content using one with my 5D for the past few months.

I usually find 24mm wide enough on the 5D, but I wanted the option to go wider without spending a great deal. The Tamron SP AF17-35MM F/2.8-4 was my least expensive ultra-wide option, but there wasn't much information available online regarding its performance on full frame cameras. The reviews that did exist said that it performed extremely well on crop bodies and not so well on full frame. At $299 shipped from Norman Camera (one of my favorite stores), I decided to gamble on this lens.

Here are some observations with accompanying photos. All were taken on the 5D at ISO 100, auto-WB, RAW processed in C1 (Magne hi-sat profile), "standard" sharpening in C1 with no subsequent sharpening in PS except for Smart Sharpen amount 30, radius 0.2 on the resized photos (not the 100% crops). No light falloff, distortion, or CA fixed in post, except as indicated.

The Tamron SP 17-35mm f2.8-4 Di has good center sharpness at all apertures and focal lengths.

17mm, f2.8:

100% crop:

After Photoshop vignetting tool:

17mm f2.8 again:

100% crop:

17mm f2.8:

Center crop:

Bottom border crop:

The above wide open at 17mm shots show the worst light falloff that this lens has to offer. Here's an example to see how light falloff really isn't an issue at f4:

Center 100% crop:

Here are some 100% crops to show you the stopped down corner performance, both in terms of CA and softness in the extreme corners, all at 17mm.

f8:

f11:

f16:

Here's the full res version (large) from which the f11 crop above was derived (large).

A few resized family snaps:
f14, 17mm:

f14, 17mm again:

f14 again, this time at 35mm

Here's the full-res version of that shot (large).

f4, 17mm (soft corners apparent even at this size):

f4, 17mm again (can again make out the soft corners):

A few more thoughts about this lens...

Barrel distortion is pronounced compared to the pricier lenses in this range. I don't mind this for three reasons. 1) I'm getting this lens for cheap =). 2) Barrel distortion is easily fixed in post with minimal resolution penalty since the center area is downsampled to accomplish this (unlike pincushion which requires upsampling of the middle with marked resolution penalty. 3) A little barrel distortion can actually make people's heads look more normal when they are towards the edge of the frame.

Summary of findings:

Sharpness: Great in the center, acceptable (to me) in the edges and near corners, and downright smeary in the extreme corners until f8.

Color: Seems neutral or even a bit cool. Doesn't seem as saturated as my other lenses but I think I can make this happen in post.

Contrast: Not as contrasty as some lenses, but with some stopping down and appropriate post-processing the results are excellent.

Flare - Average performance, not terrible.

Lateral CA - It's there. I can deal with it =).

Autofocus hunts a bit in low light (not excessive). I was hoping AF would be as fast as it is on the Tamron 17-50 (which doesn't hunt at all on a 30D in low light)

Distortion: pretty significant barrel in the wider focal lengths

Bokeh: Not very good, but I don't consider this as important in a superwide

Build: Very solid. Smooth ring movement. Typical Tamron SP series build.

Form: Nice and light/compact. Similar size/weight to the Canon 85/1.8 prime.

Cost/value: Least expensive superwide zoom. Less expensive than any of the options for crop cameras. Valuable focal length range for crop or full frame.

Speed: Most of the frame is sharp at f2.8 - a real plus!

A final example, taken through my office window (Click here to see the full-size version):

If you decide to buy the the Tamron 17-35 and this user review has helped you, you can help me by purchasing from Amazon after going there via the link below.

Visiting the Amazon page using that link doesn't change your price but makes it so that Amazon shares a bit of the profits with me. I can honestly recommend Amazon for photography gear. In addition to competitive prices, they have great customer service and one of the best return policies around (though if the item is being sold on Amazon by a third paty seller, then the return policy of that seller would apply).