Tag Archives: compare

Canon 24-70mm f/2.8 L II vs. 24-70mm f/4L IS vs. 24-105mm f/4 L IS (and more?)

Anyone who spends any time in photography forums discussing Canon lenses has seen this topic come up regularly: the comparisons between the 24-70 and 24-105mm L zoom options. If you follow this subject you are familiar with posts asking which of these lenses is “best” or claiming that one or another is great and the others are poor, and with the ensuing debates. Rather than re-writing what I have to say about this every time the subject comes up, I thought I would post once here and then link back to this article.

(Update 1/4/13: Things have changed in significant ways since I first posted this review back in 2011 – primarily with the introduction of two newer Canon 24-70mm L zooms. I have made a few updates to this post to reflect those changes. I have now had the opportunity to use the updated Canon EF 24-70mm f/2.8L II lens. It is also a very fine lens and a great performer. In addition, there is now a Canon EF 24-70mm f/4.0L IS USM lens as well, and the Canon 24-105mm f/4L F/4.0L IS lens is still available. Canon shooters have an over-abundance of good lenses that cover the 24mm to whatever-mm focal length range at this point. All three of these current lenses are excellent options and the functional differences among them now are the primary basis for selecting one over the others. If you need f/2.8 and are OK with a smaller focal length range and not having IS, the 24-70mm f/2.8 could well be your choice. If you can get along without f/2.8, are OK with the smaller focal length range, would like IS, can make use of semi-macro capabilities and want a smaller lens, then the 24-70mm f/4 IS lens can be a great option. If you don’t need f/2.8,  but do value image stabilization and a significantly larger focal length range, the 24-105 is a wonderful choice. )

(Update 1/8/15: And now there is yet another lens in this general category from Canon, the EF 24-105mm f/3.5-5.6 IS STM Lens. I have incorporated some information about this option below.)

Continue reading Canon 24-70mm f/2.8 L II vs. 24-70mm f/4L IS vs. 24-105mm f/4 L IS (and more?)

A Test: Correcting Perspective in Post-Processing

Earlier today I saw a post in which the author stated that correcting for perspective in post-processing would lead to serious problems:

There is quite a bit of loss in image definition if you do a significant amount of correction for converging verticals in an image editor. You can get far better results with a view camera or a tilt/shift lens. If you only photograph for the web, then maybe the image editor approach is ok, but for reasonably large prints?

While that point of view is widely held and often repeated, in my experience a blanket statement like this is not totally correct – it may come down to the definition of “significant.” I find that in many cases the degradation of the image is so small as to be insignificant or even invisible at 100% magnification, and it is most often completely invisible even in fairly good size prints. (This is not to suggest that those making severe corrections, in architectural photography for example, would not be better served by using a tilt/shift DSLR lens or a MF or LF system.)

Rather than just accepting statements like this, I like to test them. In the past I’ve tested and written about the option of correcting for lens distortions in post- processing: A Test: Correcting Lens Distortion in Post Processing. Here I want to extend this concept to using post-processing techniques for the correction of perspective distortion and for leveling the image.

The photograph I’ll use was shot handheld using a full-frame Canon 5D with the EF 35mm f/2 lens, one of my favorites for street photography. First a small version of the final photograph:


Borch’s Iron Works and Machine Shop – old metal shop building in the downtown area of San Jose, California. © Copyright G Dan Mitchell – all rights reserved.

Next is the same image with the same post-processing, except that the corrections to horizontal alignment and perspective have been left out:


Borch’s Iron Works and Machine Shop – old metal shop building in the downtown area of San Jose, California. Uncorrected version. © Copyright G Dan Mitchell – all rights reserved.

Yup, that’s what happens when you shoot street and shoot handheld. ;-)

In this example we can clearly see several problems that need fixing. First, the image is not level – it tilts down to the right. Second, the vertical lines begin to converge toward the top of the image. Third, since the camera’s sensor was not perfectly parallel to the building wall, the right side of the building recedes and gets smaller as the horizontal lines become closer together toward the right edge.

In my view, the uncorrected version of this photograph is not usable. On the other hand, I’m not likely to start doing street photography with a tripod and a tilt shift lens any time soon! Correction in post seems to be a reasonable option. (And, to cut to the chase, the corrected version seen above really does make a nice print.)

The next image includes two versions of roughly the same section of the photograph at 100% magnification. The crops come from the lower left area of the full image and include the conduit on the wall in the area in full sun. I could have used a section from all the way in the corner, but given the low contrast in that area the difference between the samples would be even harder to see – so I’ll stick with the section where the conduit provides a more visible contrast and frame of reference. Depending on your monitor, this resolution is equivalent to looking at a small section from a print that would be perhaps 50″ or 60″ wide. (Hint: that would be a very big print for a DSLR original – significantly larger than almost anyone ever produces! Made many 60″ x 40″ prints recently?)


100% magnification from lower left area of ‘Borch’s Iron Works and Machine Shop’ – two versions. © Copyright G Dan Mitchell – all rights reserved.

I believe that if you know what to look for and you  inspect this 100% crop very closely you can detect a small difference in the “sharpness” of the two photographs – but it is quite subtle even when viewed at 100%. In practical terms, however, this tiny effect that is just barely visible under close inspection at 100% in side-by-side comparisons on the screen is entirely insignificant in a print. Even with a very close inspection it would be quite invisible in a print of, say, 18″ x 24″ and probably even larger. Bottom line: Both would produce very sharp prints at very large sizes and essentially no one would comment that one is sharper than the other… though quite a few might notice that the corrected image looks a whole lot less distorted in the spatial sense.

Note: Article text edited/updated for clarity on 4/27/13.

This reinforces my belief that any degradation to the image quality that occurs when lens distortion, perspective, and/or horizontal level are corrected carefully during the post-processing stage can be very minimal and in the majority of situations will be invisible in prints.


G Dan Mitchell is a California photographer and visual opportunist. His book, “California’s Fall Color: A Photographer’s Guide to Autumn in the Sierra” is available from Heyday Books and Amazon.

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Using Prints to Test Four Canon DSLRs

Miles Hecker has posted interesting test results in his Canon EOS big guns image quality shootout:

As some of you know, I am a landscape photographer. I migrated to full frame digital SLR’s from medium format film. I used to shoot 6×4.5, 6×7 and 6×9 film with the end product being prints of 20″x30″ and larger. As such, I chose to investigate only one area of the 5Dmk2 in this exercise, overall image quality or IQ for short. For this test, I decided to construct a still life with a wide range of color, lots of detail and very controlled lighting to obtain what for me are valid results.The test would produce 100% crops for pixel peeping. The final analysis of IQ however would be made using real life obsevers and detailed sections of 16″x24″ and 20″x30″ photographic prints.

What I like about his test methodology is that it eliminates the very difficult issue of normalizing on-screen tests of cameras with different sensor sizes and photosite densities but doing something that I have felt would make the most sense, comparing large prints from the different test cameras. In this case he tested the Canon EOS 1DsM3, 5D2, 5D, and 50D. 

I won’t spoil the fun by telling you the results here, but let’s just say I’m not at all surprised at the results.

Canon EOS 5D

Having used my Canon EOS 5D extensively for about two years, I figure it is about time for me to write up something about my experiences with and impressions of this camera. Rather than try to compete with the existing camera review sites and post a bunch of technical specifications and test results, I’m going to focus on aspects of the camera that may give a better general idea of its strengths and weaknesses and of situations for which it is best adapted. Continue reading Canon EOS 5D