Here I repost my previous report.
---
While Kolari mod is great solution for wide-angle rangefinder lens users,
personally I still hesitate to modify my A7 because such unofficial mod voids Sony\'s warranty.
Here I would like to introduce another solution to fix corner smearing issue.
I believe Astigmatism is the principal cause of corner smearing.
[Update Dec.19] In some lenses like ZM35/1.4, field curvature is severer than astigmatism. The PCX solution improves both astigmatism and field curvature significantly.
I tried some optical simulations and found that a plano-convex lens placed in front of the WA RF lens can control astigmatism.
I use OSLO free edition: http://www.lambdares.com/oslo-university-program
For simplicity, simulation use perfect lens instead of complicated actual lens design.
I think symmetrical lens design such as Biogon matches this simplified simulation, but retrofocus design does not.
[Update Oct. 5] Now my model can also handle retrofocus-type (asymmetric design) lens.
Astigmatism at Extreme Corner:
21mm f2.8 with 1.8mm thick cover glass (Original A7): 0.6mm.
21mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.25mm.
1.5m plano-convex in front of 2.8/21 with 1.8mm glass: 0.14mm.
28mm f2.8 with 1.8mm thick cover glass (Original A7): 0.4mm.
28mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.18mm.
2m plano-convex in front of 2.8/28 with 1.8mm glass: 0.07mm.
So theoretically, this front-end filter solution outperforms Kolari/Leica in terms of astigmatism!
Here I repost my previous report.
---
While Kolari mod is great solution for wide-angle rangefinder lens users,
personally I still hesitate to modify my A7 because such unofficial mod voids Sony\'s warranty.
Here I would like to introduce another solution to fix corner smearing issue.
I believe Astigmatism is the principal cause of corner smearing.
[Update Dec.19] In some lenses like ZM35/1.4, field curvature is severer than astigmatism. The PCX solution improves both astigmatism and field curvature significantly.
I tried some optical simulations and found that a plano-convex lens placed in front of the WA RF lens can control astigmatism.
I use OSLO free edition: http://www.lambdares.com/oslo-university-program
For simplicity, simulation use perfect lens instead of complicated actual lens design.
I think symmetrical lens design such as Biogon matches this simplified simulation, but retrofocus design does not.
[Update Oct. 5] Now my model can also handle retrofocus-type (asymmetric design) lens.
Astigmatism at Extreme Corner:
21mm f2.8 with 1.8mm thick cover glass (Original A7): 0.6mm.
21mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.25mm.
1.5m plano-convex in front of 2.8/21 with 1.8mm glass: 0.14mm.
28mm f2.8 with 1.8mm thick cover glass (Original A7): 0.4mm.
28mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.18mm.
2m plano-convex in front of 2.8/28 with 1.8mm glass: 0.07mm.
So theoretically, this front-end filter solution outperforms Kolari/Leica in terms of astigmatism!
Here I repost my previous report.
---
While Kolari mod is great solution for wide-angle rangefinder lens users,
personally I still hesitate to modify my A7 because such unofficial mod voids Sony\'s warranty.
Here I would like to introduce another solution to fix corner smearing issue.
I believe Astigmatism is the principal cause of corner smearing.
[Update Dec.19] In some lenses like ZM35/1.4, field curvature is severer than astigmatism. The PCX solution improves both astigmatism and field curvature significantly.
I tried some optical simulations and found that a plano-convex lens placed in front of the WA RF lens can control astigmatism.
I use OSLO free edition: http://www.lambdares.com/oslo-university-program
For simplicity, simulation use perfect lens instead of complicated actual lens design.
I think symmetrical lens design such as Biogon matches this simplified simulation, but retrofocus design does not.
[Update Oct. 5] Now my model can also handle retrofocus-type (asymmetric design) lens.
Here are the results.
Astigmatism at Extreme Corner:
21mm f2.8 with 1.8mm thick cover glass (Original A7): 0.6mm.
21mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.25mm.
1.5m plano-convex in front of 2.8/21 with 1.8mm glass: 0.14mm.
28mm f2.8 with 1.8mm thick cover glass (Original A7): 0.4mm.
28mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.18mm.
2m plano-convex in front of 2.8/28 with 1.8mm glass: 0.07mm.
So theoretically, this front-end filter solution outperforms Kolari/Leica in terms of astigmatism!
Here I repost my previous report.
---
While Kolari mod is great solution for wide-angle rangefinder lens users,
personally I still hesitate to modify my A7 because such unofficial mod voids Sony\'s warranty.
Here I would like to introduce another solution to fix corner smearing issue.
I believe Astigmatism is the principal cause of corner smearing.
I tried some optical simulations and found that a plano-convex lens placed in front of the WA RF lens can control astigmatism.
I use OSLO free edition: http://www.lambdares.com/oslo-university-program
For simplicity, simulation use perfect lens instead of complicated actual lens design.
I think symmetrical lens design such as Biogon matches this simplified simulation, but retrofocus design does not.
(Update in Oct. 5: Now simulation can also handle retrofocus: https://www.fredmiranda.com/forum/topic/1453834/1#13753135
)
Here are the results.
Astigmatism at Extreme Corner:
21mm f2.8 with 1.8mm thick cover glass (Original A7): 0.6mm.
21mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.25mm.
1.5m plano-convex in front of 2.8/21 with 1.8mm glass: 0.14mm.
28mm f2.8 with 1.8mm thick cover glass (Original A7): 0.4mm.
28mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.18mm.
2m plano-convex in front of 2.8/28 with 1.8mm glass: 0.07mm.
So theoretically, this front-end filter solution outperforms Kolari/Leica in terms of astigmatism!
Here I repost my previous report.
---
While Kolari mod is great solution for wide-angle rangefinder lens users,
personally I still hesitate to modify my A7 because such unofficial mod voids Sony\'s warranty.
Here I would like to introduce another solution to fix corner smearing issue.
I believe Astigmatism is the principal cause of corner smearing.
I tried some optical simulations and found that a plano-convex lens placed in front of the WA RF lens can control astigmatism.
I use OSLO free edition: http://www.lambdares.com/oslo-university-program
For simplicity, simulation use perfect lens instead of complicated actual lens design.
I think symmetrical lens design such as Biogon matches this simplified simulation, but retrofocus design does not.
Here are the results.
Astigmatism at Extreme Corner:
21mm f2.8 with 1.8mm thick cover glass (Original A7): 0.6mm.
21mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.25mm.
1.5m plano-convex in front of 2.8/21 with 1.8mm glass: 0.14mm.
28mm f2.8 with 1.8mm thick cover glass (Original A7): 0.4mm.
28mm f2.8 with 0.8mm thick cover glass (Kolari/Leica): 0.18mm.
2m plano-convex in front of 2.8/28 with 1.8mm glass: 0.07mm.
So theoretically, this front-end filter solution outperforms Kolari/Leica in terms of astigmatism!
