Improvement of peripheral image quality

Optical lenses are under development all the time to accomplish superb performance in sharpness and resolution eliminating aberration and distortion, regardless to say that optical lens manufacturers in our country are second to none.

Generally, image quality is better near the center of picture than that of four corners, this principle does not change even now after 100 years later from its invention, though not a few researching and development had been done in the engineering field including some adjustment in image adjustment in software.

Then it might be a smart way to use the lens using only the center area, iris closure is one way and apply larger format lens on the smaller format might be better, do full frame lens on APS-C format would be expected better result.

How about utilize 645 format lens on 135 full frame? Probability might be high if the same theory is invited on larger format lenses.
No complicated theory or study are required to progress in image quality.

As a many 645 lense are now fire sale state in Yahoo Auction, my tentacles with bad habit start to wriggle, to tell the truth, Mamiya Sekor Zoom 105~210 for 645 format was bid and payed 980 yen already. It will be at my hand tomorrow?

Also, extension rings are on the way to me for mounting adapter flange formation both for SONY-E and Fujifilm GFX.
My storebox is almost fully occupied by modified lenses, so now is time for refraining from it.