New ISO 12233 Chart for the new Sigma 50-500 mm APO DG OS HSM Lens?

[shiwanlin]

The ISO 12233 charts provide a good objective evaluation of optical quality of lenses. I am interested in the new version of Sigma 50-500 mm and would like to compare its optical quality with similar zooms from other brands. I wonder if there is any plan to redo the tests for the new Sigma 50-500 mm?

[Bryan Carnathan]

Thanks for the suggestion - I

[Dr Croubie]

i

[shiwanlin]

Thank Bryan.


I find your way of providing the comparison of the ISO charts innovative and very useful - it is the best as far as I concern to actual compare optical quality of lenses. Lens optical quality in practice are relative. E.g. I am evaluating the new Sigma 50-500mm and I want to find out how does it compare to the Nikon and Canon closest equivalents, and Sigma

[Raid]

Bryan


I feel that both the ISO and Flare charts are brilliant and I use them all the time. I attempted to get users on another forum to use these to compare lenses. Much to my surprise they would rather look at the end result, a picture taken by a lens owner, to determine which is the sharpest.


I look forward to the day when there are no Flat Earth societies, when there are no more conspiracy theory web sites and when Donald Trump realizes his hair looks stupid

[Fast Glass]

I attempted to get users on another forum to use these to compare lenses. Much to my surprise they would rather look at the end result, a picture taken by a lens owner, to determine which is the sharpest.

I am too. Are they looking at 100% or downrezed images, if they are looking at the latter then they either don't know very much about photography or have a very one sided view. Also, alens owners pictures are OK as long as they are taken properly. But you cannot compare it to anything side by side so it's not very comprehensive or conclusive.


BTW Bryan,I also love your comparisons. They have settled so many debates on this forum! And there are many people here that have the same opnion on the same lens becuase your charts.


John.

[Raid]

Fast Glass


It’s "here is a shot of a bird,look at how sharp this picture is, what a sharp lens". How sad it is that I cannot ask about PP because somebody might get offended.

[Fast Glass]

Here is a link that you could show to your friends www.juzaphoto.com/article.php.


A referance for the people that don't click on the link.


Down rezing your images softens it because of interpolation (reducing or enlarging an image). To get around that you just sharpen the downrezed image, best to do this in Tiff and save in Jpeg afterwards. At 600/800 pix the image is very small and the pixels are large on your monitor so you cannot see anything close to 100%, even moderate amounts of motion blur or a very soft lens would look perfectly sharp at web size. Of course the larger you print or display on your monitor the more obvious lens softness/motion blur/difraction becomes.


Hopefully that helps,


John.

[shiwanlin]

Leaving the down-sizing issue aside, using random lens owner pictures to compare optical quality of lenses is just not practical. There are too many factors affecting the picture quality. For example, factors like camera shaking, subject motion, quality of light and the subject itself vary so much from picture to picture such that these variations tend to by many factors mask off the objective differences between modern lenses, which are getting diminishingly small. The objective optical quality of a lens puts a limit on the potential of the quality of pictures taken using the lens. Often the quality of pictures realized are far below the potential. To compare the true potential of lenses, factors that affecting the picture quality besides the lens itself must be under control to have meaningful result.