My Take on Image Comparisons on the Web

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To me, the practice of placing images, that have made with cameras and lenses being tested and reviewed, onto the Web for the reasons of making valid comparisons is worthless, with a couple of exceptions.  Let me tell you why.

First, when you are considering purchasing a new camera or lens, the best place to look for reviews, information, tests and comparisons in on the Internet.  The Internet is a wonderful resource!  There are many, many sites that provide that service.  But the Web has limitations and you have to understand that in order to help yourself make informed decisions.

Let me give you a couple of examples from the past that highlight similar problems.  When CDs first appeared, all the morning TV talk shows had individuals on who would espouse how great the sound from the CD was compared to cassette tapes and vinyl albums, which were the norm at the time.  But, they didn't play them, and at first you don't understand why because you want to hear it.  When they explained there was no way to hear the difference over the poor audio on your television set, I immediately understood.  Playing a CD over the TV wouldn't make a difference at all.  So, they just showed the CD players and explained why the sound was so much better.

When DVDs came out, all the morning TV talk shows touted how great the experience would be viewing the movies from DVDs versus the old videotapes.  I wanted to see the difference, but they wouldn't show it, because our TVs would not reproduce the DVD quality over cable or the air.  I immediately understood.  So, they just showed the DVD players and explained why they were much better than videotapes.

When HD televisions first appeared--large, thin, great color, digital, sharp picture--the shows were agasp at how detailed and great the picture on the TV was.  The TV anchors even talked about how the flaws in their faces, in spite of makeup, could now be seen and that they would have to change how make up was applied.  I wanted to see it!  But they only showed the TV with no picture as there was no way my standard definition TV could possibly show me the high quality of HDTVs.  Starting to get the picture?  So, they just explained why it was better than standard definition TV.

When a new camera or lens is released, raved about, tested and reported, the reviewers most often place images on the web showing how great the new piece of equipment is and what great images you will make with it.  But can you really see the intricacies described that you want to see for yourself when viewing those images on the web?  Mostly not.

I normally don't pay much attention to the images posted but mostly rely on the reviewers words and descriptions.  That being said, there are sites that test each camera or lens exactly the same way and, because the methodology and equipment is exactly the same, one can make a valid comparison of the new gear versus the previously tested gear.  Now, if you have a piece of gear they have previously tested and have used that gear extensively, you know from your experience what you can expect from your gear and can then compare what the reviewer or charts say about the new released gear.  If the numbers for resolution, distortion, noise, chromatic aberration and vignetting (shading) are better, you know that the new lens or camera body will better than the one you currently have.  If the numbers for a new camera body, tested exactly the same way as your current camera body, are better, you can form an opinion as to how much better the new one is and understand what differences there are.

After that, there is not much you can discern by looking at images on the web, with a couple of exceptions.

First, most images posted are jpegs and rendered small.  Not good.  There is no way to make a valid conclusion after an image has been processed by the camera's software.  All software is written differently and it is comparing apples to oranges.

Second, you are viewing images on your monitor at 72 or 96 dpi.  Not much resolution for trying to truly see how good of an image can be produced.  Even on an iPad, it is not much better.

Third, most monitors are not color calibrated so  you probably won't be able to detect the subtleties of color reproduction.

Fourth, sometimes they give you the option of downloading RAW files.  That is good.  If you download the RAW files, you can then look at the files on your own computer at whatever magnification you feel is necessary to compare the two RAW images.  A bit better as you have much more control of the comparison.

Fifth, often times reviewers show RAW files (or jpegs) right out of the camera and draw a conclusion that one camera is better than the other.  I don't believe that is valid as I don't know of anyone that uses a RAW file, unedited in any way, directly from the camera, as their final image.  I think the valid comparison comes when you try to make the best image you can from each, then compare the finished images.  Why?  Camera manufacturers build in different software parameters that sometimes process even RAW images without you even realizing it.  My Olympus OMD does that in lens distortion, vignetting and chromatic aberration corrections, even in the RAW files.  There is no way for me to turn that off.  Same with jpeg files.  Different settings in different cameras, even when both are set to "0" or null, can produce hugely different files in the area of contrast, saturation, sharpening, etc.  Manufacturers make their decisions on how their standard files will look, based upon what they think will make their images look best to their customers.  It then looks like one camera's images are much better than the other's, when both images in most comparisons, RAW or jpeg, can be matched precisely with a bit of fine tuning in Lightroom, Aperture, GIMP or Photoshop or other image editing software.

Lastly, you may be able to make some sense of distortion in a lens, however, refer to the previous paragraph, and realize that the camera's software may be manipulating the distortion even in the RAW files.  But distortion can be corrected easily in image editing software also.

I believe the only way to make a valid comparison is to take two identical images under identical conditions, make the best final image out of each and then see which one you like better.  You can't do that by looking at two posted images on the web.

Thanks for looking.  Enjoy!

Dennis Mook


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