Some of my photos on covers:
Not long ago, I happened to have three of Canon's four 400mm lenses on hand at the same time. I thought it would be interesting to compare image quality of these three lenses, with and without the use of the 1.4x telextender.
The models tested were the Canon EF 400mm DO (diffractive optics) IS f/4; the Canon EF 400mm f/5.6 (non-IS); and the Canon EF 100-400mm IS f/4.5-5.6. Although I would have been interesting to also include the massive Canon EF 400mm IS f/4, it is simply too large a lens for my use. This comparison was done specifically because I'm always looking for portable, lightweight 400 lenses that will also function with a 1.4x telextender.
All of the photos were shot using a Canon 30D, tripod mounted. No post processing was done to any of the images, and internal camera sharpening was set to Picture Style Standard (which has a sharpening level of 3). ISO setting was 400. If the lens had IS (image stabilization) it was turned off. The telextender was the KenkoPro 1.4x (in past tests between the Canon 1.4x and this KenkoPro, I've found no differences in image quality, and I tend to use the KenkoPro because it is a bit smaller and lighter).
In addition to the difference in sharpness, the test also yielded a few other surprises -- such as the level of contrast each lens produces; differences in saturation; and even differences in focal length. Theoretically they are all 400mm (or 560mm with the multiplier) but the 100-400 yielded "smaller" images. That is, they appear to be about 390mm (or, if its images really are 400mm, then the other two lenses produce slightly "larger" images). Not a big deal, really, but interesting to see.
Some of the differences in saturation, brightness, and contrast are no doubt due to the fact that the scene was shot outdoors, and so the light wasn't absolutely constant. I did try to shoot the entire sequence in rapid succession to minimize changes in light -- the whole process took about one-half hour to complete.
I won't keep you waiting. The results may surprise some, at least if you base your assumptions upon the old adage that "you get what you pay for" because the least expensive of these lenses produced the best images!
The "forgotten" 400 lens -- forgotten because the EF 400 f/5.6 is pretty low-tech and has no image stabilization -- yielded the sharpest images both without and with the telextender. It was followed closely by the 100-400 IS (which is my favorite all-round wildlife lens). The differences between these two lenses is very slight, but it is clearly there. As with most things in life, you make choices that have trade-offs -- the zoom lens is slightly less sharp, but is more versatile because of the zoom feature, as well as the fact it makes a better low-light lens thanks to image stabilization.
This is the second time I've had the chance to use the 400mm DO, and these tests, and a week of field use photographing nesting peregrine falcons, confirmed what I experienced the first time I used this lens -- it is not as sharp as I would like. You'll note in the test photos that you won't see any shots taken with this lens at f/4 -- wide open. That's because I couldn't produce a single photo that was even close in quality to those of the other two lenses unless shot at f/5.6 (w/o the multiplier) or f/6.3 (with the multiplier). At f/4, the images from this lens are simply unacceptable to me. At f/5.6 and f/6.3 they are merely OK. I did not test other apertures because the only reason I would consider purchasing this lens is to have a faster aperture than that provided by the other lenses.
The links to the test images are found below. Each will open in a new window, so you can open them all and go back and forth between them for comparison's sake. They are fairly large is size, so if you have a slow internet connection, be patient.
The "100% crop" images simply means that, while in Photoshop, I zoomed into the image to "actual pixels" (100%) then cropped that section of the photo out of the full frame. On each of the first three test pages below you'll find two full frame photos, one without, one with, the telextender, and then two "100% crop" images -- again, one without, one with, the telextender.
Canon EF 400 (non-IS) f/5.6, all test images HERE.
Canon EF 100-400 IS f/4.5-5.6, all test images HERE.
Canon EF 400mm DO IS, all test images HERE.
And last, a comparison of 100% crop images (without the telextender) from all three lenses on one page is HERE.
The Canon EF 400 f/5.6 is one sharp little lens, and the cheapest (about $1000) of the bunch. I wish it had image stabilization because I tend to do a lot of hand-held photography, but despite that, I don't think anyone out there could ever seriously complain about the quality of images this lens is capable of producing.
The Canon EF 100-400 IS f/4.5-5.6 is nearly the equal of the EF 400 f/5.6, and in my estimation, is more versatile because the zoom feature allows you to compose an image without moving, and the IS means you can get by in low light situations with a lower ISO setting. You've probably read elsewhere on my website that this is my favorite all-round wildlife lens, and these tests haven't changed my mind. At about $1500, this lens is a bargain. Consider renting this lens if you have only an occasional need, or would like to try it out before purchasing.
The Canon EF 400 DO IS is a real disappointment to me. Considering this lens sells for in excess of $5000 USD, it should yield better results. The diffractive optics was designed to reduce the size and weight of a 400mm f/4 lens -- and it has. But image quality was also reduced, and considering I needed to shoot this lens at f/5.6 or f/6.3 to get results comparable to the other two lenses, spending nearly $4000 more for an f-stop of f/4 that I can't use seems more than just silly. The less-than-stellar optical performance of this lens becomes even more apparent when using a telextender. Without the extender, and at f/5.6, this lens produces OK results. But I personally consider it virtually unusable with an extender. Your gas mileage, as they say, may vary, and I'm sure there are photographers out there who will swear by this lens.
On The Telextender Function
The f/4 lens does work nicely with the 1.4x telextender (image quality aside). It focuses fast and accurately. When using an extender with the other two lenses, at least if you're not shooting a Canon "1" series pro body, you need to use the old "tape the pins" trick to enable autofocus. Of the two lenses, the 100-400 functions better with the extender than the fixed focal 400 f/5.6, which tends to hunt a bit more. Neither would be suitable for use on fast moving objects, but work fine on stationary or slow moving subjects.
The "Other" 400 -- the 300mm f/2.8 plus 1.4x extender
Another option to consider is the superb Canon 300mm f/2.8 Mark II lens. When you add a 1.4x extender, you end up with a 420mm f/4 lens. While I did not have this combination when I did the above tests, I can tell you from personal experience that I believe this combination produces results that would have put it in first place for image quality. In addition, even when using the 1.4x on the 300, the autofocus speed is superior to the 400 f/5.6 and the 100-400 without extender. I routinely shoot birds in flight with this combo.
It is also a very manageable lens combination to hand hold. It has superior image stabilization to the 100-400 (and of course, the 400 f/5.6 has none). Last, it works very well with the 2x multiplier, yielding a 600mm f/5.6 lens. While image quality suffers a little bit with the 2x, the results are more often than not very, very good, and sometimes downright excellent, depending upon the aperture used (f/8 yields stunning results).
As I've stated elsewhere, I'm not a pixel peeper. I let my editors determine if my images are good. The fact that I've sold many images taken with the 300 and 2x combo tells me that it produces fine quality photos. If you doubt that, that's OK. But don't doubt the fact that as a 420mm lens it is superior to any of the above 400mm lenses. Keep the 300 f/2.8 in mind when you are shopping for a "400mm" lens.
You won't be disappointed...except perhaps in the price. You can usually pick up a clean copy of this lens used for about $3600, and new for about a thousand dollars more. However, Canon has recently announced a Mark III version will be released in 2011, and that lens is going to be several thousand dollars more. It is going to have to be one hell of a lens to be superior to the Mark II, which is widely accepted to be perhaps the sharpest, fastest focusing lens Canon has produced.