The Zeiss Distagon 21mm Prime vs Canon’s 17-40mm Zoom

| March 24, 2012
zeiss distagon 21mm flower photo

Our first flowers of 2012 shot with a Zeiss Distagon 21mm lens

I admit that taking a close up of our first spring flowers is not quite the broad sweeping landscapes I usually like to shoot with my wide angle lens but it proves an important point. It proves that the extra $1,000 I spent on my new Carl Zeiss Distagon 21mm f/2.8 wide angle lens was worth the money. Why? Because it allows me capture higher quality original images that can be output at larger sizes without having to jump through flaming post-processing hoops. Although the issues I cover in today’s post are not likely to bother anyone that publishes web resolution images, they will rear their ugly heads when images are displayed at higher resolutions.

My stock wide angle lens is the Canon 17-40mm f/2.8L. At $779, it is a very capable lens that I have used to capture some very nice images. What’s more, it is relatively light and is built to last. So what is my beef with the lens? Well, I have become increasingly frustrated lately with  image quality when creating large format prints. In addition to minor vignetting and distortion issues, the chromatic aberration introduced by the lens is irritatingly problematic. What is chromatic aberration? In a nutshell, it is a type of distortion in which there is a failure of a lens to focus all colors to the same convergence point. Chromatic aberration makes itself evident in photographs as “fringes” of color along boundaries of dark and bright parts of an image. What does it look like and how do you control it? Read on.

zeiss 21mm Canon 17-40 comparison

The Zeiss Distagon 21mm f/2.8 and the Canon-17-40mm f/4.0L

To illustrate what I am trying to overcome in image quality, I took two photographs of the lovely crocuses in our garden. One photo was taken with the Carl Zeiss 21mm and the other with the Canon 17-40mm. The images were recorded with the white balance set to daylight and the f-stop at 8.0. Since the Canon is a zoom, I set it to 21mm to mimic the focal length of the Zeiss prime, which is fixed at 21mm.

Starting at the left, look at the first two image slices below. The slices represent the original images that were captured by my Canon 5D Mark II. As the labels indicate, the Zeiss image is on the left and the Canon image is in the center. Even without clicking on the image to see more detail, you can plainly see the problem. The Canon-based image has a garish purple fringe around the crocus petal that I can assure you does not exist in life. As shown in the image inset, at lower resolution you cannot see the fringe. But at a 400% magnification as shown below, or even 100%, the fringing is quite evident and would need to be addressed if the image is to be printed in a large format.

canon 17-40 chromatic aberration

Chromatic aberration screaming on the Canon 17-40mm f/4.0L

The Zeiss-based image contained no chromatic aberration whatsoever. I also noticed that the overall image is “warmer” than the Canon image and contained a much richer spectrum of color and contrast. Frankly, this result should not be all that astonishing. The Zeiss lens is a prime lens. Primes are known to exhibit higher image quality than zooms. And, at over $1,000 more than the Canon, the Zeiss should be better!

So what if you don’t want to pop another grand for the Zeiss? Well there are options. If you shoot your images in RAW format, which I highly recommend, you can use Adobe Camera Raw (ACR) plugin to remove the Lion’s share of the chromatic aberration in images. ACR works in tandem with Adobe Photoshop and other image software programs like Adobe Lightroom to help you “develop” Camera RAW images.

ACR contains lens profiles that can be selected to correct for optical and chromatic distortion. As you can see in the image below, I was able to remove the chromatic aberration in the Canon-based image by simply selecting “Enable Lens Profile Correction” in the Lens Correction tab in ACR. ACR automatically picked the right lens and applied the profile correction!

acr lens profile correction

Correcting chromatic aberration with Adobe Camera RAW

Despite the miracle of ACR, I still prefer shooting with the Zeiss lens to control chromatic aberration. Simply put, I would rather start my post-processing workflow with the cleanest image possible. Although ACR does a great job of correcting for chromatic aberration, the base image still suffers a loss in quality. If you look closely, the remnants of the purple fringing are still present in a desaturated form. There is a light grey outline around the petal. Now look at the petal in the Zeiss-based image. There is a much nicer and color-rich transition between the background and the petal. Plus, the overall color representation is much more pleasant in my opinion.

Ok, I know I am splitting hairs here but that is part of the fun for me. I am interested in the entire process of photography. Sure, making great photographs starts with the eye of the photographer, but it cannot be denied that the quality of the equipment and post processing techniques carry a fair amount of weight in the the final quality of the photograph being made.


Category: Photo Gear Reviews, Photography

Comments (7)

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  1. Dude. This flower shot is impressive. You just keep getting better. Love the facelift you’ve given the blog, too!

    Keep rockin’.

  2. Great article – one thing I might note is that the Zeiss is MF only, which does tend to become a sort of hindrance if you’re not shooting landscapes/etc and need to shoot on the fly – especially as the image quality is so incredible from it. Miss the focus by a hair and you notice, even at f/11!

  3. Rachel Cohen says:

    Really great post and images Lee! Amazing difference between the two lenses!

  4. Lee says:

    Thanks guys and gal! So right Brian. I have not found the MF to be a problem but certainly worth noting if you are shooting on the fly. Thanks for pointing that out.

  5. Chris Wray says:

    Compelling comparison of the two lenses. ACR is an amazing plug-in for CA fixes, exposure restoration and more. But I concur with your observations, the Zeiss lens produces an overall better tonality and color. CA fixes, in my opinion, leave a dingy edge, even though the “neon” glow is removed. Gotta love prime lenses! Zeiss is exceptional.

  6. A.Barlow says:

    Yeah man, the CR on the 17-40 is pretty bad, that’s why I went away from it. I ended up getting the Tokina WA lens and that thing is a tank with better glass than that L lens IMO.

    However, I think it’s almost like comparing apples to oranges. IQ is almost always going to be at least a little better on a prime from everything I have looked at. Plus, Zeiss makes awesome glass – even if it is a bit over priced!

    That program did a pretty good job removing the CA BTW.

  7. Great article to complement an excellent shot!