[Scythels]

Regarding the opera house image, it is certainly a poor image but imatest suggests the resolution is about 1/3rd that in the center - I am doubtful of that simply because of the flags that go up in design when that is the case (aberration plot scale would need to vary considerably as you move towards the center for example).  It also looks like a simple defocus, so astigmatism and chromatic issues seem to be the issue.  Certainly a bad performance, but imatest suggests it is more awful than it is, imo. 


Regarding computed MTF tests - Optical Design Software produces exceedingly accurate MTF charts - the software prediction will be within 1% of a well assembled lens on a real MTF bench.  I am quite adamant about this, but the reason will come into view soon enough. 

 

Some variables that go into the disparity between reality and software:

 

* ODS defaults to MTF at best focus for each plane, so this makes the lens look better than it really is.  I.e it removes astigmatism in the form of a mismatch between the focusing position of the meridonal and sagittal planes. 

 

* ODS MTF plots tend to be weighted 1:2:1 for red:green:blue, reality is not always in this ratio (though this is done to mimic the eye)

 

* ODS plots are for the nominal design.  Nominal designs are never manufactured - there is some manufacturing tolerance in all cases.  At times it is quite large. 

 

* ODS plots are for the bare lens, the sensor can have a rather enormous impact on the performance in many cases.