Home · Register · Software · Software · Join Upload & Sell

  

  Previous versions of HaruhikoT's message #13751769 « Front-End Filter Improves Corner Smearing »

  

HaruhikoT
Offline
Upload & Sell: Off
Front-End Filter Improves Corner Smearing


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.

[Update Oct.15] I did small update on my model and now I confirmed Reversed 1.5m PCX(SLB-50-1500PM) for both G Biogon 21mm and 28mm is optimal.

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!

To prove the theory, I purchased a f=1.5m lens \"SLB-50-1500PM\" and a f=2m lens \"SLB-50-2000PM\" from Japanese lens supplier SIGMA-KOKI.
Both are 3mm thick, 50mm diameter and AR-coated. $85-$90 each.
You can order here:
http://www.global-optosigma.com/en_jp/Catalogs/pno/?from=page&pnoname=SLB-P%28%CF%8630%EF%BD%9E%CF%8650%29&ccode=W3043&dcode=W3043-2

I show examples of modification. Easy and non-destructive.

Contax G Biogon 21mm:
Attach 55-52mm stepdown adapter, put the 1.5m lens into the 52mm thread and clamp it with 52mm ring.
I got the 52mm ring by disassembling this:
https://www.amazon.com/AmazonBasics-UV-Protection-Lens-Filter/dp/B00XNMWCF8



Contax G Biogon 28mm:
Attach 46-55mm stepup, 55-52mm stepdown, put the 2m lens into the 52mm thread and clamp it with 52-55mm stepup adapter.






Dec 19, 2016 at 03:06 PM
HaruhikoT
Offline
Upload & Sell: Off
Front-End Filter Improves Corner Smearing


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.

[Update Oct.15] I did small update on my model and now I confirmed Reversed 1.5m PCX for both G21/G28 is optimal.

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!

To prove the theory, I purchased a f=1.5m lens \"SLB-50-1500PM\" and a f=2m lens \"SLB-50-2000PM\" from Japanese lens supplier SIGMA-KOKI.
Both are 3mm thick, 50mm diameter and AR-coated. $85-$90 each.
You can order here:
http://www.global-optosigma.com/en_jp/Catalogs/pno/?from=page&pnoname=SLB-P%28%CF%8630%EF%BD%9E%CF%8650%29&ccode=W3043&dcode=W3043-2

I show examples of modification. Easy and non-destructive.

Contax G Biogon 21mm:
Attach 55-52mm stepdown adapter, put the 1.5m lens into the 52mm thread and clamp it with 52mm ring.
I got the 52mm ring by disassembling this:
https://www.amazon.com/AmazonBasics-UV-Protection-Lens-Filter/dp/B00XNMWCF8



Contax G Biogon 28mm:
Attach 46-55mm stepup, 55-52mm stepdown, put the 2m lens into the 52mm thread and clamp it with 52-55mm stepup adapter.






Dec 19, 2016 at 03:01 PM
HaruhikoT
Offline
Upload & Sell: Off
Front-End Filter Improves Corner Smearing


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!

To prove the theory, I purchased a f=1.5m lens \"SLB-50-1500PM\" and a f=2m lens \"SLB-50-2000PM\" from Japanese lens supplier SIGMA-KOKI.
Both are 3mm thick, 50mm diameter and AR-coated. $85-$90 each.
You can order here:
http://www.global-optosigma.com/en_jp/Catalogs/pno/?from=page&pnoname=SLB-P%28%CF%8630%EF%BD%9E%CF%8650%29&ccode=W3043&dcode=W3043-2

I show examples of modification. Easy and non-destructive.

Contax G Biogon 21mm:
Attach 55-52mm stepdown adapter, put the 1.5m lens into the 52mm thread and clamp it with 52mm ring.
I got the 52mm ring by disassembling this:
https://www.amazon.com/AmazonBasics-UV-Protection-Lens-Filter/dp/B00XNMWCF8



Contax G Biogon 28mm:
Attach 46-55mm stepup, 55-52mm stepdown, put the 2m lens into the 52mm thread and clamp it with 52-55mm stepup adapter.






Dec 19, 2016 at 02:44 PM
HaruhikoT
Offline
Upload & Sell: Off
Front-End Filter Improves Corner Smearing


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: http://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!

To prove the theory, I purchased a f=1.5m lens \"SLB-50-1500PM\" and a f=2m lens \"SLB-50-2000PM\" from Japanese lens supplier SIGMA-KOKI.
Both are 3mm thick, 50mm diameter and AR-coated. $85-$90 each.
You can order here:
http://www.global-optosigma.com/en_jp/Catalogs/pno/?from=page&pnoname=SLB-P%28%CF%8630%EF%BD%9E%CF%8650%29&ccode=W3043&dcode=W3043-2

I show examples of modification. Easy and non-destructive.

Contax G Biogon 21mm:
Attach 55-52mm stepdown adapter, put the 1.5m lens into the 52mm thread and clamp it with 52mm ring.
I got the 52mm ring by disassembling this:
https://www.amazon.com/AmazonBasics-UV-Protection-Lens-Filter/dp/B00XNMWCF8



Contax G Biogon 28mm:
Attach 46-55mm stepup, 55-52mm stepdown, put the 2m lens into the 52mm thread and clamp it with 52-55mm stepup adapter.







Oct 05, 2016 at 02:43 PM
HaruhikoT
Offline
Upload & Sell: Off
Front-End Filter Improves Corner Smearing


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!

To prove the theory, I purchased a f=1.5m lens \"SLB-50-1500PM\" and a f=2m lens \"SLB-50-2000PM\" from Japanese lens supplier SIGMA-KOKI.
Both are 3mm thick, 50mm diameter and AR-coated. $85-$90 each.
You can order here:
http://www.global-optosigma.com/en_jp/Catalogs/pno/?from=page&pnoname=SLB-P%28%CF%8630%EF%BD%9E%CF%8650%29&ccode=W3043&dcode=W3043-2

I show examples of modification. Easy and non-destructive.

Contax G Biogon 21mm:
Attach 55-52mm stepdown adapter, put the 1.5m lens into the 52mm thread and clamp it with 52mm ring.
I got the 52mm ring by disassembling this:
https://www.amazon.com/AmazonBasics-UV-Protection-Lens-Filter/dp/B00XNMWCF8



Contax G Biogon 28mm:
Attach 46-55mm stepup, 55-52mm stepdown, put the 2m lens into the 52mm thread and clamp it with 52-55mm stepup adapter.







Oct 04, 2016 at 12:15 PM





  Previous versions of HaruhikoT's message #13751769 « Front-End Filter Improves Corner Smearing »