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

Moderated by: Fred Miranda
Username  

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Sony Forum | Join Upload & Sell

1       2       3              88      
89
       90       91       end
  

Front-End Filter Improves Corner Smearing
  
 
GMPhotography
Online
• • • • •
Upload & Sell: On
p.89 #1 · p.89 #1 · Front-End Filter Improves Corner Smearing


Lol. Love the guinea pig attitude. Go getíem Fred

It may work with our adapters. I think you need a PCX 2500 but wait for the simulation



Oct 03, 2017 at 04:41 AM
Fred Miranda
Offline
Admin
Upload & Sell: On
p.89 #2 · p.89 #2 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
Lol. Love the guinea pig attitude. Go getíem Fred

It may work with our adapters. I think you need a PCX 2500 but wait for the simulation


Anything for nice sunstars.



Oct 03, 2017 at 04:44 AM
sebboh
Offline
• • • • • •
Upload & Sell: Off
p.89 #3 · p.89 #3 · Front-End Filter Improves Corner Smearing


Fred Miranda wrote:
What the heck, I just ordered one. let's see what this puppy can do. I will first try my PCX 5m with it while sending images to Haruhiko for a possible MTF simulation.


way to take one for the team.

has anybody looked at the 28 cron?




Oct 03, 2017 at 04:54 AM
Phillip Reeve
Offline
• • • •
Upload & Sell: Off
p.89 #4 · p.89 #4 · Front-End Filter Improves Corner Smearing


Fred Miranda wrote:
Phillip Reeve wrote:
Fred Miranda wrote:
@BastianK@@@, @sebboh@@@ and @Phillip Reeve@@@,

Have any of you tested the CV 28/2 Ultron with a PCX lens (2m or 2.5m)?
If so, would a short adapter make it reach infinity?

Let me know if someone has this lens. I need some pictures to calculate the perfect PCX for it.
Thanks!
Fred

Bastian sold his copy before this thread was started. But some days ago he thought about giving it a second chance.
[/quote

Based on the lens likely need of a 2m or 2.5m PCX, do you think that infinity could be reached even with our short adapters? There is...Show more
I have no idea. But assuming that the formula posted by artur5 is correct:
artur5 wrote:
Fred, if by longer you mean that the focal length increases then no, itís actually the opposite. When you add a positive diopter element to any lens, the focal of the combo becomes shorter. Itís a basic law of optics. The simplified formula is : F3 = F1*F2/(F1+F2). Where F3 is the final length, F1 is the focal of the original lens and F2 is the focal of the PCX filter.
In this case : F3 = 35*5000/(35+5000) = 34.76
Thatís why youíre able to focus nearer when you use this PCX on your CV 35/1.7. The focal goes from the original
...Show more
A 28 mm lens with a 2500 mm PCX would need a 0.310 mm shorter adapter which is 0.066 mm more than the CV35 needs (0.143 mm for the 2 m). I am traveling right now so I can't measure my adapter which still has some more room. Will be a close call. And I don't know how good the CV28 performs on a thin filter camera. So I look forward to your results

...Show more



Oct 03, 2017 at 04:55 AM
Phillip Reeve
Offline
• • • •
Upload & Sell: Off
p.89 #5 · p.89 #5 · Front-End Filter Improves Corner Smearing


sebboh wrote:
what makes you sure of this? it seems very strange to make a rangefinder lens that couldn't be adjusted. most lenses adjust infinity focus by changing the point at which the helicoid runs into the hard stops (shims are actually pretty rare).


So you think there will be a way to adjust the CV35? Can you elaborate a bit on how this point is changed and how we could find out if that works for the CV35? I would really like to have a helicoid adapter but it only makes sense for me if I can get the CV to work with it.



Oct 03, 2017 at 04:57 AM
sebboh
Offline
• • • • • •
Upload & Sell: Off
p.89 #6 · p.89 #6 · Front-End Filter Improves Corner Smearing


Phillip Reeve wrote:
So you think there will be a way to adjust the CV35? Can you elaborate a bit on how this point is changed and how we could find out if that works for the CV35? I would really like to have a helicoid adapter but it only makes sense for me if I can get the CV to work with it.


yes, it seems extremely unlikely that a rangefinder lens would be designed with no way to correct infinity adjustment. there are a lot of ways to do this, but pretty much all manual focus lenses have a physical stop to keep the helicoid from turning any further at both infinity and mfd (often it is attached to the focus ring) otherwise you could accidentally unscrew the helicoid. many times infinity stop's location is designed to be adjustable for infinity calibration. that is the first place i'd look. unfortunately everybody designs these things a little different. one of the reasons i really like using the rokkor 55/1.7 for my contax g conversion is because this adjustment is so easy on that lens. i have never torn down a voigtlander, so i can't help beyond that at this point...



Oct 03, 2017 at 05:14 AM
Gary Clennan
Offline
• • • • •
Upload & Sell: On
p.89 #7 · p.89 #7 · Front-End Filter Improves Corner Smearing


sebboh wrote:
way to take one for the team.

has anybody looked at the 28 cron?



I've got one but don't own any filters (yet). This would be a great lens to have perform well on the A7RII....



Oct 03, 2017 at 02:04 PM
Fred Miranda
Offline
Admin
Upload & Sell: On
p.89 #8 · p.89 #8 · Front-End Filter Improves Corner Smearing


Phillip Reeve wrote:
A 28 mm lens with a 2500 mm PCX would need a 0.310 mm shorter adapter which is 0.066 mm more than the CV35 needs (0.143 mm for the 2 m). I am traveling right now so I can't measure my adapter which still has some more room. Will be a close call. And I don't know how good the CV28 performs on a thin filter camera. So I look forward to your results


That's my thoughts exactly. I'm really hoping for a CV 28 FE or Loxia 28 but perhaps the Ultron M will work.



Oct 03, 2017 at 02:16 PM
Gunzorro
Online
• • • • •
Upload & Sell: On
p.89 #9 · p.89 #9 · Front-End Filter Improves Corner Smearing


Fred Miranda wrote:
More...


Looks pretty convincing that the added filter provides better IQ.

The question is: why don't manufacturers incorporate such a corrective lens as part of the design for appropriate lenses? Lazy? Ignorant? Penny-pinching?



Edited on Oct 03, 2017 at 03:58 PM · View previous versions



Oct 03, 2017 at 02:29 PM
Gunzorro
Online
• • • • •
Upload & Sell: On
p.89 #10 · p.89 #10 · Front-End Filter Improves Corner Smearing


sebboh wrote:
one more data point for everyone, a lens everybody hates, the contax g 35/2 planar on a stock a9 vs stock a9 + 5m pcx filter vs kolari UT a7:
http://c1.staticflickr.com/5/4504/37426657712_09dfcb19d3_o.jpg
full sized

there is virtually no difference between with the filter or without, i would think i exported the same photos twice except for slight differences in framing/foliage movement. the kolari mod shows marketed improvement in the midzone and inward field curvature towards the corners (left corner is much closer than the right corner).



Really nice comparison format!



Oct 03, 2017 at 02:30 PM
 

Search in Used Dept. 



GMPhotography
Online
• • • • •
Upload & Sell: On
p.89 #11 · p.89 #11 · Front-End Filter Improves Corner Smearing


sebboh wrote:
yes, it seems extremely unlikely that a rangefinder lens would be designed with no way to correct infinity adjustment. there are a lot of ways to do this, but pretty much all manual focus lenses have a physical stop to keep the helicoid from turning any further at both infinity and mfd (often it is attached to the focus ring) otherwise you could accidentally unscrew the helicoid. many times infinity stop's location is designed to be adjustable for infinity calibration. that is the first place i'd look. unfortunately everybody designs these things a little different. one of the reasons i
...Show more

On the VC 35 there are shims inside the rear element you can get too. What that would do is still unclear as my adapter goes to infinity so have not gone any further in exploring that. When I tore down the 28 ultron actually tore it completely down almost I did not see any shims or a way to adjust the helicod. Now Iím not sure what I was looking for either. Itís not what I do everyday. Now when I shot Medium Format tech cam lenses there was a way to adjust infinity. You pulled back the rubber focusing ring and usually there where 3 screws you could loosen and adjust the helicod that way and I did that for every lens I had for infinity at the hard stop.

Now I certainly could have missed something on the Ultron 28 and a way to adjust it. We maybe okay with front filter and the adapter we are using for the CV 35 1.7 the K&F.

On my setup with the PCX 5000 Iím right at the beginning of the infinity symbol which still leaves a lot of room for infinity. Now itís possible with a stronger PCX 2500 that we may still have enough room.

What Fred needs is a PCX 2500 to try out with his adapter which BTW is exactly the same spot on our 35 1.7 spot. Be nice if someone had one to lend him to find out if it works.

But if there is a way to adjust the 28 Ultron I would love to know about it.



Oct 03, 2017 at 02:35 PM
Fred Miranda
Offline
Admin
Upload & Sell: On
p.89 #12 · p.89 #12 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
On the VC 35 there are shims inside the rear element you can get too. What that would do is still unclear as my adapter goes to infinity so have not gone any further in exploring that. When I tore down the 28 ultron actually tore it completely down almost I did not see any shims or a way to adjust the helicod. Now Iím not sure what I was looking for either. Itís not what I do everyday. Now when I shot Medium Format tech cam lenses there was a way to adjust infinity. You pulled back the rubber
...Show more

I would like to confirm the PCX strength before purchasing it. So, it may take a while to find out.



Oct 03, 2017 at 03:26 PM
Fred Miranda
Offline
Admin
Upload & Sell: On
p.89 #13 · p.89 #13 · Front-End Filter Improves Corner Smearing


Gunzorro wrote:
Looks pretty convincing that the added filter provides better IQ.

The question is: why don't manufacturers incorporate such a corrective lens as part of the design for appropriate lenses? Lazy? Ignornant? Penny-pinching?



These lenses are Leica M-mount and therefore not designed for the Sony sensor. We are adding front lenses to mitigate induced field curvature and astigmatism caused by the thicker stack.

The designers were not lazy or ignorant. We are the ones that are crazy!



Oct 03, 2017 at 03:30 PM
GMPhotography
Online
• • • • •
Upload & Sell: On
p.89 #14 · p.89 #14 · Front-End Filter Improves Corner Smearing


Fred Miranda wrote:
I would like to confirm the PCX strength before purchasing it. So, it may take a while to find out.



Yea it could be a PCX 2000



Oct 03, 2017 at 03:32 PM
Fred Miranda
Offline
Admin
Upload & Sell: On
p.89 #15 · p.89 #15 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
Yea it could be a PCX 2000


Ultimately, I'm hoping for a Loxia 28 but perhaps this CV 28/2 Ultron will work and be great at f/5.6 for landscape work.
I should get the lens tomorrow and will send the pictures of it right away for a possible simulation over the weekend or sooner.



Oct 03, 2017 at 03:45 PM
rji2goleez
Offline
• • • • •
Upload & Sell: On
p.89 #16 · p.89 #16 · Front-End Filter Improves Corner Smearing


Fred Miranda wrote:
Ultimately, I'm hoping for a Loxia 28 but perhaps this CV 28/2 Ultron will work and be great at f/5.6 for landscape work.
I should get the lens tomorrow and will send the pictures of it right away for a possible simulation over the weekend or sooner.


With such a strong desire to find a suitable 28mm, I still think the Leica R 28/2.8 II is a great choice. And it gets AF from a TAP. Great rendering.



Oct 03, 2017 at 03:54 PM
Gunzorro
Online
• • • • •
Upload & Sell: On
p.89 #17 · p.89 #17 · Front-End Filter Improves Corner Smearing


Fred Miranda wrote:
These lenses are Leica M-mount and therefore not designed for the Sony sensor. We are adding front lenses to mitigate induced field curvature and astigmatism caused by the thicker stack.

The designers were not lazy or ignorant. We are the ones that are crazy!


Ha-ha!

Well, I'm certainly an ignorant one!

Thanks for the reminder, Fred -- about the M-mount, not the ignorance.



Oct 03, 2017 at 03:57 PM
GMPhotography
Online
• • • • •
Upload & Sell: On
p.89 #18 · p.89 #18 · Front-End Filter Improves Corner Smearing


No your not itís just something you did not know about. We all learn everyday no matter how experienced you are or not. Every single one of us at one time or another took their first image. Itís all a learning curve until they close the lid on you.


Oct 03, 2017 at 04:00 PM
Fred Miranda
Offline
Admin
Upload & Sell: On
p.89 #19 · p.89 #19 · Front-End Filter Improves Corner Smearing


rji2goleez wrote:
With such a strong desire to find a suitable 28mm, I still think the Leica R 28/2.8 II is a great choice. And it gets AF from a TAP. Great rendering.


I tried the R 28/2.8 II and agree with the beautiful color rendering. However, sunstar rendering is lacking and the corners only show good resolution at around f/8 or f/9. (Similar performance to ZF 28/2). LaCA is very apparent as well.
This lens was well regarded in the past but for today's high MP sensors, I believe it's lacking for its price premium.
It's also a bit heavy for a 28/2.8 at 545g (with dumb adapter). With TAP, the weight goes to 650g! (it needs an extra LR-M adapter)



Oct 03, 2017 at 04:09 PM
sebboh
Offline
• • • • • •
Upload & Sell: Off
p.89 #20 · p.89 #20 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
When I tore down the 28 ultron actually tore it completely down almost I did not see any shims or a way to adjust the helicod. Now Iím not sure what I was looking for either. Itís not what I do everyday. Now when I shot Medium Format tech cam lenses there was a way to adjust infinity. You pulled back the rubber focusing ring and usually there where 3 screws you could loosen and adjust the helicod that way and I did that for every lens I had for infinity at the hard stop.

...

But if there is a way
...Show more

do you happen to remember how the focus ring on the 28 ultron was attached to the helicoid?




Oct 03, 2017 at 04:35 PM
1       2       3              88      
89
       90       91       end






FM Forums | Sony Forum | Join Upload & Sell

1       2       3              88      
89
       90       91       end
    
 

You are not logged in. Login or Register

Username     Reset password