Someone who performs outstanding optical testing...

I've known of the Lensrentals blog for some time, now.  Yet it's only very recently that I came to more fully understand and appreciate what Dr. Roger Cicala has to say. 

I enjoyed reading Dr.Cicala's comments on prime lenses and think his conclusions are interesting.  Of course I'm now considering adding a Sigma 30mm f/1.4 DC Contemporary lenses to my always too long list of optics that I might _have_ to have.

Dr. Cicala's conclusions were based in this article on traditional MTF measurements.  That is, contrast measurements were made along a single 2D line.  No attempts were made to account for optical field curvature in a 3D space.

Then I came across a current article and it really caught my attention.  Roger writes about integrating MTF information in a way that goes beyond simple flat field measurements.  

This is wonderful in the way the information helps one "see" how lenses behave in three dimensions. I think what Dr. Cicala & Co are now doing is ground breaking. I love it!

Additionally, I appreciate is that he clearly states that he is _not_ testing for out of focus rendition.  His tests might at best remotely hint at how out of focus regions can be rendered, but that is an area he is currently leaving to others.

Which leads me to something I read some years ago.  This was something that David Duncan Douglas wrote about when he first encountered Nippon Kogaku lenses.  His story, in general, is very well known.

M.Douglas' colleague made a nicely sharp image and was asked what lenses he was using.  M. Douglas' glass was designed and manufactured by Leitz and Zeiss and he was finding his lenses were rather soft and unremarkable compared with the photo his colleague had made.

On his first visit to Nippon Kogaku (now Nikon) they used a display method where one could clearly see and evaluate the performance of a lens.  A lens projector was the display method.  The way it worked was to have a grid image projected onto a screen through a lens.  As a lenses focus ring was turned a person could judge for themselves not only resolution, but _how an optic transitioned from out of focus into focus and back out of focus_.

There is a standard, albeit subjective, method for considering out of focus rendition of optics as well as "sharpness". Lens projectors are still used today for evaluating lenses used in cinema.  In fact, at least one testing lab has added out of focus rendition information to their web pages. 

Coming back to Dr. Cicala's lens tesing, I wish I had access to the kinds of equipment he uses.  Lens Rentals looks at the latest generation lenses.  I'd like to see how the old manual focus Nikon Nikkors behave.  There would be a lot for me to learn.

Both methods (MTF in 2D/3D and grid image projection) do not take into account the image recording materials.  These methods consider only the lenses.  I will leave the pros and cons of this for perhaps another time.  

Until then, and only if you're really interested in the subject and haven't already encountered Lens Rentals blog, consider what Dr. Cicala has written.