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Front-End Filter Improves Corner Smearing
  
 
hiepphotog
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p.3 #1 · p.3 #1 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
I'm interested in a the ZM 35 1.4 filter for it. I have a stock A7r II. Just point me to the correct filter solution and I'll buy it.


Guy, can you lean on any of your Zeiss contact to get the exact exit pupil distance? That would greatly help pinpoint the more exact filter solution.



Oct 07, 2016 at 05:11 PM
nehemiahphoto
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p.3 #2 · p.3 #2 · Front-End Filter Improves Corner Smearing


hiepphotog wrote:
I have no doubt Rich . I'm hopeful with this mod.


I an with Guy and Hiep...I'll try the optimal adapter for the g21, just need to know what it is




Oct 07, 2016 at 05:22 PM
HaruhikoT
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p.3 #3 · p.3 #3 · Front-End Filter Improves Corner Smearing


hiepphotog wrote:
For the filter case, that is a huge drop in the center performance with the PCX filter (plano-convex instead of plano-concave). How does the 8m filter work on the stock camera? I'm surprised to see that the Lux 35 seems to perform less well using the PCX than the Kolari mod. Your real-life G 21 test shows that the PCX mod works wonderfully with one of the toughest lenses out there and the result is even better than the Kolari.

As most people here are interested in teh ZM 35/1.4, can you rerun the simulation with the ZM 35/1.4 instead? I
...Show more

8m is too weak (Shorter FL has stronger effect) for stock camera.
Gradually I'm going to recognize, the PCX method is great but not always outperform Kolari.
Even G21, if you look closer, you may notice my test sample using PCX has some strange softness at medium area (neither corner nor center). Kolari+G21 may not sharp at extreme corner, but I expect its sharpness is better than PCX at the center and medium area.
PCX+Kolari will be always best.

I know many people would like to know ZM35/1.4's result, but unfortunately I can't find its exit pupil distance (zeiss doesn't open it) so I can't run accurate simulation.



Oct 07, 2016 at 05:33 PM
GMPhotography
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p.3 #4 · p.3 #4 · Front-End Filter Improves Corner Smearing


I found some data

http://www.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter/

Than I found this

The Voigtlander 15mm f/4.5 Heliar M mount, Zeiss ZM 15mm f/2.8 Distagon, Zeiss ZM 21mm f/2.8 Biogon, Leica-M 28mm f/2.8 ASPH Elmarit, and Zeiss ZM 35mm f/2.8 Biogon all have exit pupil distances of less than 30mm.

A number of other rangefinder lenses have exit pupil distances of less than 50mm, but particularly notable are the Voigtlander 35mm f/1.2 and 50mm f/1.5, both of which have wide apertures in addition to short exit pupil distances. Obviously, stopping these lenses down will help minimize the effects of sensor stack if you just have to shoot them on an m4/3s camera.



Oct 07, 2016 at 05:48 PM
GMPhotography
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p.3 #5 · p.3 #5 · Front-End Filter Improves Corner Smearing


These three caught my eye they don't list the ZM but

Leica-M 35mm f/1.4 ASPH Summilux 40.50

Voigtlander 35mm f/1.2 M 44.5

ZM 35mm f/2.0 Biogon 34


I would assume for the ZM maybe 40?

Lets call it a guess.

Edited on Oct 07, 2016 at 05:55 PM · View previous versions



Oct 07, 2016 at 05:51 PM
GMPhotography
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p.3 #6 · p.3 #6 · Front-End Filter Improves Corner Smearing


Now just in case you are thinking of your ZM 50mm 1.5 Sonnar. Here is the VC 50 1.5

Voigtlander 50mm f/1.5 M 49.16. I would think that be very close



Oct 07, 2016 at 05:54 PM
freaklikeme
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p.3 #7 · p.3 #7 · Front-End Filter Improves Corner Smearing


I'm in, or will be once I hear back from Sigma-Koki on the quote. My goal is to make the Elmarit 24 ASPH usable on the a7rII. I picked up an e55/series VII filter holder. The diameter should be good since the series VII filters have a 50.8mm diameter, but I'm guessing from the looks of it I'll have to pad the inside of the frame a little since the filter frames are thicker than these optics. It should make it easier to switch out the optics in testing (1.2m, 1.5m, 2m) and I can probably dig up some Copal 3 spacers if I need to fine-tune the distance between the optic and the lens.

Here's to experimentation.



Oct 07, 2016 at 06:15 PM
GMPhotography
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p.3 #8 · p.3 #8 · Front-End Filter Improves Corner Smearing


freaklikeme wrote:
I'm in, or will be once I hear back from Sigma-Koki on the quote. My goal is to make the Elmarit 24 ASPH usable on the a7rII. I picked up an e55/series VII filter holder. The diameter should be good since the series VII filters have a 50.8mm diameter, but I'm guessing from the looks of it I'll have to pad the inside of the frame a little since the filter frames are thicker than these optics. It should make it easier to switch out the optics in testing (1.2m, 1.5m, 2m) and I can probably dig up some Copal
...Show more

Funny you say that. My Signature under my name at GetDPI for the last several years has been this. Im the author too


Photography is all about experimentation and without it you will never learn art.



Oct 07, 2016 at 06:23 PM
hiepphotog
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p.3 #9 · p.3 #9 · Front-End Filter Improves Corner Smearing


GMPhotography wrote:
These three caught my eye they don't list the ZM but

Leica-M 35mm f/1.4 ASPH Summilux 40.50

Voigtlander 35mm f/1.2 M 44.5

ZM 35mm f/2.0 Biogon 34

I would assume for the ZM maybe 40?

Lets call it a guess.


Unfortunately all lensrental data are eye-balling data from the users. Sometimes, the exit pupil is not right behind the aperture blades.



Oct 07, 2016 at 07:01 PM
GMPhotography
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p.3 #10 · p.3 #10 · Front-End Filter Improves Corner Smearing


Dang


Oct 07, 2016 at 07:06 PM
 

Search in Used Dept. 

        


nehemiahphoto
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p.3 #11 · p.3 #11 · Front-End Filter Improves Corner Smearing


I don't think this helps you guys, but just in case..there's is not way to derive the exit pupil knowing all the other lens specifications? If so I suppose you guys would have already figured it out.







Oct 08, 2016 at 02:52 AM
HaruhikoT
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p.3 #12 · p.3 #12 · Front-End Filter Improves Corner Smearing


Guys having ZM1.4/35,

Could you take a picture like this?
This shot is G21's backside taken by 135mm ZA. You should use relatively long FL to avoid perspective.
Measured barrel diameter is 56mm, Then I've successfully estimated the exit pupil diameter is 8.0mm. G21's technical sheet tells it is truely 8.0mm.

Exit pupil Distance should be equal to the Exit pupil Diameter * F-number.



Haruhiko



Oct 08, 2016 at 05:46 AM
artur5
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p.3 #13 · p.3 #13 · Front-End Filter Improves Corner Smearing


Yes, I think you're right again. If f =2.8 then exit pupil dist= 8*2.8 = 22.4mm. Zeiss gives 22.8mm as the exit pupil distance of G21/2.8, Only 2% of difference, due probably to the aperture not being exactly 2.8 but 2.85 or so.


Oct 08, 2016 at 07:47 AM
HaruhikoT
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p.3 #14 · p.3 #14 · Front-End Filter Improves Corner Smearing


And these are G21 and G28's latest simulation results:

Stock A7, 1.3m PCX is optimal for both G21 and G28, interestingly.
Cameras having optically 0.8mm glass, 4.4m will be best for G21/G28.

Why G21 and G28 are same?
G21's EPD-FL = +1.3mm, that means its exit light angle to the sensor is smaller than its entrance angle 45deg.
G28's EPD-FL = -1.9mm, that means exit angle is larger than entrance angle 37deg.
I think that should be the reason.

Also G21's MTF with PCX 1.3m and 1.5m are quite interesting.
1.5m gets better sharpness than 1.3m at extreme corner, however, 1.3m's medium angle looks better than 1.5m.
In practial medium area is more important than extreme corner, so I think 1.3m is optimal.






Haruhiko



Oct 08, 2016 at 09:12 AM
Nanh
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p.3 #15 · p.3 #15 · Front-End Filter Improves Corner Smearing


HaruhikoT wrote:

Guys having ZM1.4/35,

Could you take a picture like this?
This shot is G21's backside taken by 135mm ZA. You should use relatively long FL to avoid perspective.
Measured barrel diameter is 56mm, Then I've successfully estimated the exit pupil diameter is 8.0mm. G21's technical sheet tells it is truely 8.0mm.

Exit pupil Distance should be equal to the Exit pupil Diameter * F-number.

https://farm6.staticflickr.com/5059/29554712694_ce51b2f14d_o_d.jpg


Haruhiko


Quick shot of the zm 35 taken with a 200mm lens. Guess should have closed down a bit to have more dof



Oct 08, 2016 at 09:20 AM
Nanh
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p.3 #16 · p.3 #16 · Front-End Filter Improves Corner Smearing


HaruhikoT wrote:

And these are G21 and G28's latest simulation results:

Stock A7, 1.3m PCX is optimal for both G21 and G28, interestingly.
Cameras having optically 0.8mm glass, 4.4m will be best for G21/G28.

Why G21 and G28 are same?
G21's EPD-FL = +1.3mm, that means its exit light angle to the sensor is smaller than its entrance angle 45deg.
G28's EPD-FL = -1.9mm, that means exit angle is larger than entrance angle 37deg.
I think that should be the reason.

Also G21's MTF with PCX 1.3m and 1.5m are quite interesting.
1.5m gets better sharpness than 1.3m at extreme corner, however, 1.3m's medium angle looks better than 1.5m.
In practial
...Show more

Great work, thanks! One point I would like to note is that I suspect a Kolari modded A7 has a filter stack which is more than 0.8mm thick. This is because with problematic lenses a M9 is a little ahead of Kolari A7s in the corners. My guess is even though the new Kolari IR/UV filter is 0.8mm, there is an additional layer of glass beneath which is sealed onto the sensor and not easily removed.



Oct 08, 2016 at 09:46 AM
HaruhikoT
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p.3 #17 · p.3 #17 · Front-End Filter Improves Corner Smearing


Nanh wrote:
Quick shot of the zm 35 taken with a 200mm lens. Guess should have closed down a bit to have more dof
https://c6.staticflickr.com/6/5073/30101692421_f9261453d1_b.jpg


OK, I estimate Exit pupil diameter = 19.9mm.


I will rerun simulation and will post, please wait



Oct 08, 2016 at 09:48 AM
HaruhikoT
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p.3 #18 · p.3 #18 · Front-End Filter Improves Corner Smearing


This is the ZM1.4/35's result.
Unlike contax G lenses, ZM1.4/35 is the latest released lens for digital, so it must be designed taking the Leica M9's 0.8mm thick glass into account.
Therefore in this simulation, I set the cover glass's thickness to 2.55-0.8 = 1.75mm.
Result shows 2m will be good for stock A7, but still f1.4 seems to be difficult to get usable sharpness.

[Update] The image here was removed because the exit pupil distance I used here was wrong. Now 5m PCX is confirmed as optimal. See my latest posts.


Edited on Dec 19, 2016 at 01:34 PM · View previous versions



Oct 08, 2016 at 10:58 AM
HaruhikoT
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p.3 #19 · p.3 #19 · Front-End Filter Improves Corner Smearing


For ZM1.4/35, meniscus lens instead of simple PCX seems to help sharpness at WO.
However we can get such lens only by custom order so I'm worrying about its cost.

[Update] The image here was removed because I found my model had some flaws to handle meniscus lens and the solution is still under investigation.

Haruhiko


Edited on Dec 19, 2016 at 01:30 PM · View previous versions



Oct 08, 2016 at 12:27 PM
hiepphotog
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p.3 #20 · p.3 #20 · Front-End Filter Improves Corner Smearing


Then the question is how many ZM 35/1.4 users are willing to try out the process so we can meet the MOQ. For a standard size and glass type, custom order piece would not be that bad. Just need to meet MOQ.


Oct 08, 2016 at 03:10 PM
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