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Front-End Filter Improves Corner Smearing
  
 
Maknof
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p.92 #1 · p.92 #1 · Front-End Filter Improves Corner Smearing


In EU, local vat plus customs duties and fees for a total of about 25%


Oct 24, 2017 at 07:27 PM
Mathieu18
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p.92 #2 · p.92 #2 · Front-End Filter Improves Corner Smearing


Wondering if anyone knows the best place to order a Opto Sigma 5000mm PCX for shippment to the US? Global site or European Site? Or anyone have one they're no longer using? Need it for Contax G lenses on a Kolari UT. Have a 1500mm setup if anyone wants to swap. Great on the stock stack.


Oct 24, 2017 at 08:28 PM
GMPhotography
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p.92 #3 · p.92 #3 · Front-End Filter Improves Corner Smearing


I would wait to see what Fredís test reveal and mine with the PCX 4000 for the CV 35 1.7 and the 28 Ultron F2. Iím just testing the 28 myself

We both also posted links to order these a couple times now. Not sure you saw that



Oct 24, 2017 at 08:31 PM
Mathieu18
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p.92 #4 · p.92 #4 · Front-End Filter Improves Corner Smearing


Derek convinced me with his tests on the G28, but a few more days might not hurt.

I did know they were out there but itís hard to find in 92 pages. Finally found one Haruhiko posted so sent them an email. Thanks as always!

GMPhotography wrote:
I would wait to see what Fredís test reveal and mine with the PCX 4000 for the CV 35 1.7 and the 28 Ultron F2. Iím just testing the 28 myself

We both also posted links to order these a couple times now. Not sure you saw that




Oct 24, 2017 at 09:17 PM
scrappydog
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p.92 #5 · p.92 #5 · Front-End Filter Improves Corner Smearing


Mathieu18 wrote:
Wondering if anyone knows the best place to order a Opto Sigma 5000mm PCX for shippment to the US? Global site or European Site? Or anyone have one they're no longer using? Need it for Contax G lenses on a Kolari UT. Have a 1500mm setup if anyone wants to swap. Great on the stock stack.


I ordered direct from their website. They are based in California, I think. Here's the link if you don't have it:
https://www.global-optosigma.com/en_us/Catalogs/gno/?from=page&pnoname=SLB-P%28%CF%8630%EF%BD%9E%CF%8650%29&ccode=W3043&dcode=W3043-2&gnoname=SLB-50-5000PM



Oct 24, 2017 at 09:50 PM
hanay78
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p.92 #6 · p.92 #6 · Front-End Filter Improves Corner Smearing


Hello,

I just tried zm 25mm with planoconvex SLB-50-1500PM in a sony a7rii. I am contacting you because is the first time I played with rangefinder optics and somehow i am doubtful about the results of my test.

I noticed that the lens somehow changes the rendering of the objective. A very small but noticeable decrease of resolution appears. Also things became a little bit (very little) more yellow.

Corners got also improved

The objective is tiny, and this I like. But somehow I am spending around 1000Ä (objective + adapter + lens + small things) and this is the price of used batis 25mm.

I understand the vigneting is associated with rangefinder optics. Can you say something about it? it is more significant than SLR native lenses or this i will also have with batis?

What about final resolution? it is comparable to batis?

Thank you in advance for your help, but I am a newby and need some support.

Regards



Oct 28, 2017 at 06:03 PM
GMPhotography
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p.92 #7 · p.92 #7 · Front-End Filter Improves Corner Smearing


I think on the 25 you want the front filter curve facing towards sensor


Oct 28, 2017 at 06:17 PM
DavidBM
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p.92 #8 · p.92 #8 · Front-End Filter Improves Corner Smearing


hanay78 wrote:
Hello,

I just tried zm 25mm with planoconvex SLB-50-1500PM in a sony a7rii. I am contacting you because is the first time I played with rangefinder optics and somehow i am doubtful about the results of my test.

I noticed that the lens somehow changes the rendering of the objective. A very small but noticeable decrease of resolution appears. Also things became a little bit (very little) more yellow.

Corners got also improved

The objective is tiny, and this I like. But somehow I am spending around 1000Ä (objective + adapter + lens + small things) and this is the price of used batis
...Show more

If you compare Zeiss MTF charts for Batis and ZM, and then recognise that the ZM performance on Sony, even with the front lens, will be not quite (but almost) as good as the chart says you will get an idea of their relative resolution..



Oct 28, 2017 at 08:50 PM
Samuli Vahonen
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p.92 #9 · p.92 #9 · Front-End Filter Improves Corner Smearing


hanay78 wrote:
Hello,

I just tried zm 25mm with planoconvex SLB-50-1500PM in a sony a7rii. I am contacting you because is the first time I played with rangefinder optics and somehow i am doubtful about the results of my test.

I noticed that the lens somehow changes the rendering of the objective. A very small but noticeable decrease of resolution appears. Also things became a little bit (very little) more yellow.

Corners got also improved

The objective is tiny, and this I like. But somehow I am spending around 1000Ä (objective + adapter + lens + small things) and this is the price of used batis
...Show more
Hi hanay78,

1500mm is wrong front filter for ZM25, it's too strong. 2500mm can generally be considered optimum for ZM25 - I'm sorry that you purchased wrong correction lens because BastianK article contains wrong information (also his links post to post confirming 2500mm good and other link to G21). Generally I would advice not to 100% trust his article or my wiki-page even they are mentioned in the first post of the thread, always check from the actual posts in the thread.

If your colors got affected by the front lens, then you have some defect on your lens. The front lens does not change colors. Please verify in center of image with gray card, if there REALLY is yellow cast then the OptoSigma lens is somehow wrong (we have not heard about such cases in here before).

See simulations in page 67, post #6. And on page 70 are Guy's tests with 2500mm, they should tell you what to expect landscape distance (if you are not familiar of Guy's standard test target, google "site:fredmiranda.com Big Bronco", he has been shooting MANY lenses using the same building - this is needed as on page 70 there are only crops - the other crops are from somewhere else, I don't know how to find whole scene of that, most likely some page of this thread has also it).

As I have all Optosigma lenses from 1500mm to 5000mm I tried ZM25 with 2000mm, 2500mm and 3000mm lenses; 2000mm and 2500mm are about the same, but for boke shooting I would choose 2000mm (slight inward field curvature), but just for landscapes I would use 2500mm. 3000mm was too weak and there was outward field curvature. The best quality I was able to get from lens is combination of using thin filter camera (Kolari v2) and 4000mm.

If you only have 1500mm then definitely you need to have convex surface on the side far away from the ZM25. If you turn the lens so that convex surface is towards the ZM25, then it's equivalent of ~1300mm, and is even stronger, and you would need weaker lens.


Vignetting; You have A7r mkII, which has backlit sensor -> you have much less vignetting than me, and my only advice would have been to use A7-camera with backlit sensor... On the A7r, A7mkI and A7(Kolari v2) vignetting is quite large at f/2.8, but it has not bothered me @ f/5.6.

Samuli



Oct 28, 2017 at 09:00 PM
hanay78
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p.92 #10 · p.92 #10 · Front-End Filter Improves Corner Smearing


Dear David,
i did as you mentioned. Thank you for the suggestion
regards



Oct 28, 2017 at 11:05 PM
 

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hanay78
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p.92 #11 · p.92 #11 · Front-End Filter Improves Corner Smearing


Dear Samuli, thanks for your answer

I like it a lot mechanically ZM lens. Optically... I have doubts. Thats why i wrote the post. I will try to sell the Opto Sigma lenses I bought (I have two because I intended to correct Contac G 21mm too)
I am deceived. Focusing is not nice with Contax G. With this I was pretty deceived with optical performance...

you mean this one I believe
http://www.fredmiranda.com/forum/topic/1453834/69?keyword=big,bronco#13971184
which means very good performance

I also found your table, containing 2500mm was the best. A pity. I should have find it before

I want to try again with another lens. Still in order to keep controlled expenditure: in your opinion, it is worth to go for batis or better to remain here with the new filter?

Regards




Oct 28, 2017 at 11:25 PM
GMPhotography
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p.92 #12 · p.92 #12 · Front-End Filter Improves Corner Smearing


From memory and itís getting shorter Iím pretty sure I used a 2500 on the ZM 25 which is a very nice lens. Iím sure my tests are on the board somewhere.


Oct 28, 2017 at 11:37 PM
Mathieu18
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p.92 #13 · p.92 #13 · Front-End Filter Improves Corner Smearing


The 1500mm should be correct for the G21 on a stock sensor. If you want, PM Sebboh on here, he has a method to convert a G21 into an M mount lens via a Rokkor 55mm and some custom machines plates, I think he has a couple extra plates right now but not sure. Otherwise if you hate that G21 too much PM me a price for the lens and filter, I can live with them!

hanay78 wrote:
Dear Samuli, thanks for your answer

I like it a lot mechanically ZM lens. Optically... I have doubts. Thats why i wrote the post. I will try to sell the Opto Sigma lenses I bought (I have two because I intended to correct Contac G 21mm too)
I am deceived. Focusing is not nice with Contax G. With this I was pretty deceived with optical performance...

you mean this one I believe
http://www.fredmiranda.com/forum/topic/1453834/69?keyword=big,bronco#13971184
which means very good performance

I also found your table, containing 2500mm was the best. A pity. I should have find it before

I want to try again with another lens. Still
...Show more



Oct 29, 2017 at 03:02 AM
Samuli Vahonen
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p.92 #14 · p.92 #14 · Front-End Filter Improves Corner Smearing


hanay78 wrote:
I like it a lot mechanically ZM lens. Optically... I have doubts. Thats why i wrote the post. I will try to sell the Opto Sigma lenses I bought (I have two because I intended to correct Contac G 21mm too)

G21 needs 1500mm(reversed).

hanay78 wrote:
I am deceived. Focusing is not nice with Contax G. With this I was pretty deceived with optical performance...

Contax G adapters turn the skrew originally intended for autofocus motor in G-series camera bodies = focus feeling is not nice. There are significant differences between adapters, I have tried >5 different eBay adapters, Ulata and expensive Metabones - more or less everything else than Ulata and Metabones has turned out to be really really bad, and even Metabones is really bad and only Ulata seems to be somewhat useful what comes to "focus feeling".

And if you shoot on winter (and your winter has below water freezing temperatures), be prepared that focusing gets worse or impossible. Two of my eBay adapters completely stop turning on winter shooting, and rest of the adapters get much worse compared how they were in summer.

If I would not be shooting 99% from tripod, I would do similar conversion, which sebboh has done to his G-series lenses. For me it's beneficial to shoot slowly, and I would not mind if shooting would be as slow as with large format gear = I'm fine with the crappy feeling and spending 5s for focusing instead of 1s is irrelevant for me.

hanay78 wrote:
you mean this one I believe
http://www.fredmiranda.com/forum/topic/1453834/69?keyword=big,bronco#13971184
which means very good performance

Yes those are the page 70 tests I referred.

hanay78 wrote:
I want to try again with another lens. Still in order to keep controlled expenditure: in your opinion, it is worth to go for batis or better to remain here with the new filter?

I'm wrong person to answer "which is better"-questions. I do not believe lenses can be described with adjectives like "better", as everyone has different preferences. I select and evaluate lenses based on rendering styles, not how well they perform in pixel peeping. My criteria to evaluate lens is (more or less in this order):
- how they render focus plane (contrast of different frequency detail, color rendering, how much more focus plane has contrast compared to boke)
- how they render boke on various focus distances, my interest mostly to medium distances, any lens does nice boke in flower shots (how buzy/distracting boke is, which is affected by boke highlight light concentration and shape(aperture & catseye-behaviour), double lining and astigmatism and to some extend LoCa/boke-CA)
- how they render transition from DOF to boke + how fast the transition happens
- focus plane shape (field curvature & astigmatism - this is actually more important for boke; to not get something into focus what is not supposed to be in focus - I shoot landscapes f/5.6-11 and there this almost never is an issue, I don't do astro-photography)
- how much boke is larger in corners due to mechanical vignetting (this actually should be inside previous point, same stuff)
- color defects (CA in it's many forms, image edge/corner color issues due to large ray angle)
- flare performance (overall contrast reduction, behaviour when sun in the frame or close to it)
- how sharp lens is in pixel peeping (not actually selection criteria, I just need lens to be sharp enough)

Generally I see camera forum people valuating their criteria differently, and it seems pixel peeping/sharpness is very important to majority of people when they select lenses. There rarely has been topics on forums, where these are discussed directly and I base my opinion to discussions about new lenses etc. we have had here and other camera forums on past 15 years I have actively followed them. Due to my different criteria than majority of people I don't answer these "better"-questions directly.

I do not like Tamron/Zeiss Batis 25 rendering style at all, so for me it's irrelevant how good it is for pixel peeping. Also for pixel peeping I do not know why Batis 25 would be better than ZM25, but I have only pixel peeped ZM25 with 36Mpix A7r, where it clearly exceeds sensors resolution - I have hard time believing that it magically would be super crappy on 42Mpix. Personally I would never select Batis 25 over ZM25, unless I would need autofocus for the shoot.

Samuli



Oct 29, 2017 at 07:09 AM
hanay78
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p.92 #15 · p.92 #15 · Front-End Filter Improves Corner Smearing


Hello Samuli,

thanks for your answer!

I am not a pixel peeper. As I said I was deceived because the experiments i did with the filter were not successful. But probably this is due to the fact I was using the wrong lens.

Maybe the copy I had from ZM 25 was not the best. I have send it back, due to a non smooth focusing. So, I was not lucky at all.

That said, about the better issue:

I never have had the batis in my hand. I do not know how good it is, or how it renders. Both batis and zm are zeiss which means results must be excellent and prices are according. I like the compactness of ZM and do not like size of Batis. So my deccision of buying ZM and correction lens was based on this. I do not believe I will need autofocus in a 25mm lens

The 2500mm lens may render the lens accurate. I hope without yellowish issues. Still, there is the vigneting issue. This is very significant at f2.8.

Pros and cons money is similar that is the issue that motivate my question. If you have the lens from former times it is different, but I am buying...

Concerning the lens and montage. I find your table and the information contained there most informative. I have a couple of doubts.

a) I was not able to identify the bulbous side of the lens. I tried both possibilities until i found the best direction.

b) I went to a local camera repair shop i i distroyed several old filters making trials. When you said you use a empty filter (glass removed filter), the retention ring is too high to retain the lens, located a couple of mm lower. did you put something in between or how did you did?

c) Elpro 3 or 4. Do dey have different diameters? 52, 55....? In case they have different sizes, are elpro 3 or 4 of the same size equal for our purposes or do they differentiate?

Thank you very much again



Oct 29, 2017 at 05:06 PM
Samuli Vahonen
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p.92 #16 · p.92 #16 · Front-End Filter Improves Corner Smearing


I see hesitation between lines you write... maybe you should try the Batis 25, it's much "easier" choise, and if you don't care about the Tamron design rendering style it may turn out great lens for you. There is no point to force yourself to buy something you don't want. Lenses will not shoot great photos, you do, but if you feel unconformatable with you lens choices it most likely will have negative effect to your creativity.

For vignetting; do you use some weird settings that Lightroom (or other similar software) automatically assigns lens correction profiles to your other lenses, but it naturally didn't for ZM25 as the software could not see from EXIF what lens it is? Also there are some correction options in camera settings. (asking these as I do not know do you have previous experience of alternative lenses - I know these questions are really stupid, maybe even offending, if you are experienced alternative lens shooter - ZM25 should not have significantly larger vignetting in A7mkII with it's backlit sensor than other 24/25mm lenses, so I'm finding your worry about vignetting weird)

hanay78 wrote:
a) I was not able to identify the bulbous side of the lens. I tried both possibilities until i found the best direction.

1500mm is really easy, I just look reflections (e.g. my roof lamp with 5 bulbs) from boths side of the lens, and it's extreme obvious which side is convex and which planar - most likely I could see it just by viewing the lens from side as 1500mm lens curvature is very visible. For 2500mm it gets much more difficult, you may be able to see it from reflections (I doubt if you didn't see it for 1500mm lens), so most likely you have to hold lens on top of something straight e.g. plastic ruler (do not use metallic, it will scratch your lens...) and observe which side of the lens sits flat on top, and which is the convex side. Also for 2500mm it's very marginal difference for the end result => I would not worry much which direction 2500mm lens "points" as in practice both directions will give almost same results. HINT: If you see difference between directions of 2500mm PCX, then either direction you didn't have lens well centered or it was tilted...

To all my OptoSigma lenses I have the employees of OptoSigma have written the focal length to side of lens e.g. "f = 4000". On all of my lenses, the bottom of this text is the planar side of the lens, and top of the text is convex side. However I do not know a) do they write it to all lenses b) do they care about the orientation when they write it.

hanay78 wrote:
b) I went to a local camera repair shop i i distroyed several old filters making trials. When you said you use a empty filter (glass removed filter), the retention ring is too high to retain the lens, located a couple of mm lower. did you put something in between or how did you did?

Well, I have purchased >35 filters to get FEW working 55mm and 52mm filters, and especially suitable size filter retention rings. I once did think that I found "the perfect 55mm UV-filter" with retention ring inner size 49.8mm. Then I ordered same filters from same seller and they were totally different. So I do not have good method finding suitable 55mm filter, which has correct size retention ring. My method was more or less "place lots of orders for different eBay vendors" for filters, which appear to look good for purpose in eBay image.

On any filter I have assempled I have never needed to "put something in between". You have found some extreme exotic filter if it's originally glass is thicker than OptoSigma lens. I have had exactly oppisite problem; there was not enough thread on some thin filters to hold the retention ring + polarizer/ND-filter on top of OptoSigma PCX-filter as it's thicker than original glass.

hanay78 wrote:
c) Elpro 3 or 4. Do dey have different diameters? 52, 55....? In case they have different sizes, are elpro 3 or 4 of the same size equal for our purposes or do they differentiate?

I do not know, but I'm sure you can find it from google - typically all this kind of info is on Leica-wiki or some other place. I would guess there is no 52mm, as most Leica R-mount lenses have 55mm, but this is just purely guessing, you better find it out yourself. On any of my lenses I do not use ElPro based filter "stack"; it's very thick and causes issues if additional filter are used (I shoot >95% of photos with polarizer).

Samuli



Oct 29, 2017 at 06:55 PM
sebboh
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p.92 #17 · p.92 #17 · Front-End Filter Improves Corner Smearing


Mathieu18 wrote:
The 1500mm should be correct for the G21 on a stock sensor. If you want, PM Sebboh on here, he has a method to convert a G21 into an M mount lens via a Rokkor 55mm and some custom machines plates, I think he has a couple extra plates right now but not sure. Otherwise if you hate that G21 too much PM me a price for the lens and filter, I can live with them!


this is correct, i just ordered a batch of 5 conversion rings to make the g21 into an m-mount lens with a nice rokkor helicoid and a much better mfd. i have 2 of the ring sets left.

the conversion looks like this:















and the conversion rings look like this:





on camera:






Samuli Vahonen wrote:
For vignetting; do you use some weird settings that Lightroom (or other similar software) automatically assigns lens correction profiles to your other lenses, but it naturally didn't for ZM25 as the software could not see from EXIF what lens it is? Also there are some correction options in camera settings. (asking these as I do not know do you have previous experience of alternative lenses - I know these questions are really stupid, maybe even offending, if you are experienced alternative lens shooter - ZM25 should not have significantly larger vignetting in A7mkII with it's backlit sensor than other
...Show more

more symmetric wide angle lenses have inherently more vignetting when stopped down according to zeiss (i forget the explanation), but also lenses that don't transmit identification to the camera won't activate the auto vignetting correction. the contax g 21/2.8 also vignettes quite a lot.



Oct 29, 2017 at 07:26 PM
candreyo
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p.92 #18 · p.92 #18 · Front-End Filter Improves Corner Smearing


Hi Sebboh,

I love what you have done with the Biogon 21mm to convert it to Leica M!
Do you know if the rangefinder coupling is accurate regards where the lens is focusing? i.e. on a Leica M camera, say you use the rangefinder to focus at something 5 meters away, does the actual focal plane thru the lens marry up to where you are focusing via the rangefinder?

If so, I'm highly interested in what you needed to buy/ get to do this conversion, as I would love to adapt the Contax 28mm, 45mm and 90mm into rokkor mounts, so they could be used on Leica M and Sony A7 series via TAP.

I know there are companies that sell Gontax G lenses already converted, but they do not look as nice as your conversion using the Rokkor Helicoil, and they are insanely expensive as well.

Kind Regards,

Chris


sebboh wrote:
this is correct, i just ordered a batch of 5 conversion rings to make the g21 into an m-mount lens with a nice rokkor helicoid and a much better mfd. i have 2 of the ring sets left.

the conversion looks like this:
http://c1.staticflickr.com/5/4508/37966344266_416747f5b2_o.jpg
http://c1.staticflickr.com/5/4480/24167959288_6a1fc03644_o.jpg
http://c1.staticflickr.com/5/4494/37966344456_e0c45c0bbf_o.jpg
and the conversion rings look like this:
http://c1.staticflickr.com/5/4477/37966344546_a860f22d4a_o.jpg
on camera:
http://c1.staticflickr.com/5/4446/26243939919_817a40fa93_o.jpg

more symmetric wide angle lenses have inherently more vignetting when stopped down according to zeiss (i forget the explanation), but also lenses that don't transmit identification to the camera won't activate the auto vignetting correction. the contax g 21/2.8 also vignettes quite a lot.





Nov 01, 2017 at 09:51 AM
sebboh
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p.92 #19 · p.92 #19 · Front-End Filter Improves Corner Smearing


candreyo wrote:
Hi Sebboh,

I love what you have done with the Biogon 21mm to convert it to Leica M!
Do you know if the rangefinder coupling is accurate regards where the lens is focusing? i.e. on a Leica M camera, say you use the rangefinder to focus at something 5 meters away, does the actual focal plane thru the lens marry up to where you are focusing via the rangefinder?

If so, I'm highly interested in what you needed to buy/ get to do this conversion, as I would love to adapt the Contax 28mm, 45mm and 90mm into rokkor mounts, so they could
...Show more

thanks! unfortunately contax g lenses are not rangefinder coupled the same way leica m lenses are. it is easy to add rangefinder coupling to a ~50mm lens, but much more complicated to add it to wider or longer lenses (there is a reason those conversions are so expensive). since i'm using these on sony cameras, i've just ignored rangefinder coupling. you would have to use liveview or the distance scale to focus these lenses.

i have also converted the g28, g45, and g90. the rear rings i have left over for the g21 would also work for the g28 however the front rings would either not work or require serious modification since the optical block of the g28 is narrower.



Nov 01, 2017 at 07:21 PM
thrice
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p.92 #20 · p.92 #20 · Front-End Filter Improves Corner Smearing


This question is probably best directed to @HaruhikoT
Would having an aspherical PCX mitigate the mid-field dip? Obviously we want the peak correction in the corners rather than the centre/mid. So a more flattened centre/mid would in theory be superior, if my pseudo-scientific reasoning is correct.

With the correct radii an aspherical PCX might not even affect the infinity focus of the lens, since we just want to pull the edges forward instead of the whole image.



Nov 09, 2017 at 08:30 PM
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