[New test photos released] Leica Summicron 35/2 Eight Element copy made in China

[james.liam]

Wow! The way the second tree from the right, along with the background behind it, goes out of focus is really disappointing.

De-centered elements

 

[KEVIN-XU 愛 forever]

Hey guys, I am sorry for my absence in the past few months. I was swamped in the past few months. And will be most likely so toward the new year. I have my own job and business to do, which consumed most of my time and energy. But still, I am doing my best trying to fulfill all the orders been placed for the first batch. I hope everybody will get the lens around the new year.

I will share more information regarding the light lens labs' project where when I get the chance.

Best wishes,
Kevin

 

[KEVIN-XU 愛 forever]

Yes, this happened with my black lens too. Kevin sent it back as he was not satisfied with it. I also did not ask him what was wrong with the lens.

Hi Raid,

The focusing barrel of your lens is a little bit stiff and there is a minor cosmetic imperfection on your lens. Nothing major. Most importantly, I need to make sure it is a useable lens and focus correctly on my Leica M10 at least.

Kevin

 

[KEVIN-XU 愛 forever]

So far, all of the lenses that I returned were having cosmetic imperfections or stiff aperture ring/focus barrel. I haven't noticed any optical issues before.

I will work with Ron and see what we can do in that case.

 

[KEVIN-XU 愛 forever]

Hi,
I received one of the early black paint samples and it was not perfectly reaching infinity on a RF properly calibrated M10. Luckily my local Leica shop technician adjusted the lens for me.
I did mention it to Kevin back then.

Sorry!!! I must be missed your email... Glad to know that you could find a solution.

 

[rscheffler]

I think this is quite normal with fast wide angle lenses of 60 years old. The focal plane of the outer corners of Leitz 35mm lenses sixty years old are often completely out of focus. That's the charm of old lenses. It is then as if the focal plane in the extreme corners is bent forward, so that something becomes sharp that is not set at all. I think this is also the case here. At larger apertures, this phenomenon disappears completely because of the shallow depth of field. Then everything in the corners becomes unsharp. If this effect is undesirable for you, you should buy a modern aspherical lens with a perfectly flat field of focus.


Erik.

It's one thing if you know that's how the lens performs.

Based on the prototype sample photos earlier in this very long thread, as well as the results Ashwin Rao has posted, I didn't see any indication of extreme central focus shift. Ashwin uses the replica on an M9M and has told me he is confident to use it all apertures with the RF (given the camera has no live view capability). I can't say the same with my copy unless shooting wide open or at f/11.

 

[rscheffler]

De-centered elements

Maybe, but I'm seeing very strong "W" field curvature with my copy. With a row of trees like in that example, at a diagonal, if focused on the near one at the left third, the center one would fall within the field curvature bending away from the camera to form the middle 'peak' of the "W," but the next one in the right third would be out of the field curvature in the right 'valley' of the "W" and therefore much softer. With my copy, f/4 through f/5.6 most clearly exhibit this wavy field curvature.

One way to understand the degree of field curvature if your copy is similar to mine, is to shoot something boringly uniform but textured, like a lawn or an expanse of gravel, down at an angle, through the full aperture range. Bring the photos into Photoshop and apply the Find Edges filter (found under Stylize). As the lens is stopped down you'll see a distinctive "W" begin to appear and become quite noticeable at f/4 and f/5.6. You'll also notice that it shifts away from the camera as the lens is stopped down. Depth of field begins to mask it at f/8, and it's pretty much gone by f/11.

I also agree now with earlier comments that film shooters using this lens may not see the problem as easily, depending on what the end destination is for their images. I made some 10" prints (from digital) to compare images at f/4 that were rangefinder focused (and soft in the center) against those that were live view focused at f/4. The printed live view images do show better central sharpness, but depending on the subject content, one might have to look pretty closely to see this. Smaller prints certainly would mask the problem even more. But for me, viewing full images on a 27" iMac, I can definitely see the central image softness and truthfully, it really bothers me. Especially when the center is properly focused and reveals just how sharp the lens is stopped down (if focused correctly).

 

[Erik van Straten]

I also agree now with earlier comments that film shooters using this lens may not see the problem as easily, depending on what the end destination is for their images. I made some 10" prints (from digital) to compare images at f/4 that were rangefinder focused (and soft in the center) against those that were live view focused at f/4. The printed live view images do show better central sharpness, but depending on the subject content, one might have to look pretty closely to see this. Smaller prints certainly would mask the problem even more. But for me, viewing full images on a 27" iMac, I can definitely see the central image softness and truthfully, it really bothers me. Especially when the center is properly focused and reveals just how sharp the lens is stopped down (if focused correctly).

It surely is sharp, but you'll have to take into account that this is a sixty year old design and not made for digital use. On film the lens performs more than satisfactory. Of course the lens can be used on a digital camera, but the lens cannot be expected to be optimized for digital use.
If the problem you mentioned only occurs with the copy you have, it should be resolved.


Erik.

 

[Erik van Straten]

This is how my copy performs on a sixty year old Leica M2.

gelatine silver print (LLL8 35mm f/2) leica m2

Erik.

 

[yossi]

I think this is quite normal with fast wide angle lenses of 60 years old. The focal plane of the outer corners of Leitz 35mm lenses sixty years old are often completely out of focus. That's the charm of old lenses. It is then as if the focal plane in the extreme corners is bent forward, so that something becomes sharp that is not set at all. I think this is also the case here. At larger apertures, this phenomenon disappears completely because of the shallow depth of field. Then everything in the corners becomes unsharp. If this effect is undesirable for you, you should buy a modern aspherical lens with a perfectly flat field of focus.


Erik.

The fact is: I also took a shot of the trees using the original Summicron 8E (image attached below). The image does not show the same behaviour as the replica, especially for the last tree on the right.

To my untrained eyes, the replica seems to be sharper on the left most tree but exhibits wavy plane of focus towards the right frame. Not so for the original 8E. The defocusing is gradual and natural. The last tree on the right is clearly out-of-focus.

I suspect that the replica lens must have been tweaked optically to get sharper/higher contrast wide-open and (maybe) in the process the curvature of field got impacted somewhat. This is just my guess, and I cannot be very sure as I have no knowledge as to what exactly the replica's design consideration was.

 

[Erik van Straten]

The fact is: I also took a shot of the trees using the original Summicron 8E (image attached below). The image does not show the same behaviour as the replica, especially for the last tree on the right.

Thank you for showing this!

That is very interesting. I must say that the picture with the "real" 8E looks very much as I anticipated: in fact there is only sharpness in a large spot in the middle of the image. Stopping down brings sharpness over the whole field. That is indeed how I know the original 8E.

I will make some tests with my LLL8 to see if it acts the same as yours, but that will take some time. Earlier I did not check my LLL8 on this point.

Erik.

 

[raid]

Hi Raid,

The focusing barrel of your lens is a little bit stiff and there is a minor cosmetic imperfection on your lens. Nothing major. Most importantly, I need to make sure it is a useable lens and focus correctly on my Leica M10 at least.

Kevin

Thank you Kevin. You took care of it, and I got from you a beautiful lens.

 

[raid]

Thank you for showing this!

That is very interesting. I must say that the picture with the "real" 8E looks very much as I anticipated: in fact there is only sharpness in a large spot in the middle of the image. Stopping down brings sharpness over the whole field. That is indeed how I know the original 8E.

I will make some tests with my LLL8 to see if it acts the same as yours, but that will take some time. Earlier I did not check my LLL8 on this point.

Erik.

In my basic comparisons between the Summicron and the replica I did not identify any issues.

 

[D&A]

Hi,

These are two test images I took with the replica lens when 1st received months ago, The 1st image taken wide open at f2 (focused on the tree trunk) and the second image taken at f4 (also focused on the tree trunk). As seen in both images, the tree trunk, although sharp at f2, sharpens up even more at f4. Looking at the grass both adjacent to and behind the tree trunk, it doesn't appear there is any appreciable focus shift nor does the tree trunk lose sharpness when the lens is stopped down from f2 to f4.

If I look at the textured concrete driveway and the grass just in front of it....in both images, the grass tends to lose sharpness gradually as it trails off into the distance (in both shots). It doesn't appear to sharpen up at some point as it gets further away from the point of focus and then goes out of focus again as shown in the multiple tree image posted earlier.

Keep in mind these shots were taken months ago in general testing of the focus of the lens and not specifically testing for wavy field curvature.

*** One thing I noticed in many many test shots I've taken is what appears to be fairly extreme field curvature at the extremes of the frame. In both images posted, look at the very very top right hand corner (and to a lesser extent at the upper left hand corner of the images). The tree branches and leaves in these locations are well out of the depth of field and yet they sharpen up extensively (very sharp). Yet adjacent trees next to these are blurred as they should be. I've noticed this is consistent in many series of test images I've taken. I don't recall ever seeing this when I owned the original Leica 8 element. Still I don't see evidence of the "W" pattern of sharpness/depth of field as previous described but I would have to test for it specifically (heavy rain/snow today).

A general comment about optics from what I learned over the years, and from some optical lens designers....is that regarding increasing center sharpness in designing a lens, I've learned this can be optically done by lens designers but that often introduces wavy or other forms of distortion (including field curvature)...unless optically corrected, especially with today's computer designed optics.

OK, below are the two test images I described. Taken with a Leica M9 and repeated with two other M9 bodies, so these results were consistent. I still believe this lens is a major achievement and a notable lens in construction and performance. I'm sure it can be tweaked at some point if its desired to bring it even closer to the signature of the original 8 element. Both the maker/designer of the lens should be thanked for his endeavor and also to Kevin for his hard work (having many other responsibilities, in making the opportunity possible to acquire the lens.

Note 1st image is taken at f2. 2nd image taken at f4. You can click on each image once to enlarge for better detail.

Dave (D&A)

 

[Erik van Straten]

Yes, this is the effect I was trying to point out in words above. This is quite normal behaviour for old lenses. Above all the Canon 35mm f/1.5 has this effect.

A Leica lens with this strange behaviour too is the "222XXXX" Summilux 35mm f/1.4, the first series non-steelrim 35mm Summilux. My example, the 2221365, shows this effect strongly.

I did not see it on my LLL8, a prototype.

Erik.

 

[raid]

Yes, this is the effect I was trying to point out in words above. This is quite normal behaviour for old lenses. Above all the Canon 35mm f/1.5 has this effect.

A Leica lens with this strange behaviour too is the "222XXXX" Summilux 35mm f/1.4, the first series non-steelrim 35mm Summilux. My example, the 2221365, shows this effect strongly.

I did not see it on my LLL8, a prototype.

Erik.

The Canon 35/1.5 has been called "a dog" for many years. It depends how you use this lens. If your main focus point is in the center, the image comes out nicely. Do you agree, Erik?

 

[rscheffler]

In the three attached images, even at the max 500 pixel size allowed by the forum, I think you can see how field curvature develops with my copy of the replica.

This is just a can placed on a gravel covered area and focus was on the can. The Find Edges filter was applied in Photoshop to essentially produce a 'focus peaking' effect to show the area of highest contrast, and therefore most likely plane of focus.

At f/2, rangefinder focus is accurate (enough) on the can.
At f/2.8 the wave becomes more apparent
At f/4 the wave is very evident and focus at the center of the image has shifted behind the can enough that it is out of focus when the full image is viewed on a 27" non-retina iMac.

I will reiterate that the MTF and field curvature documentation included with the replica indicates some waviness of field curvature is inherent in the design.

That said, and as previously stated, the severity of field curvature I'm seeing in images from my copy was not evident in images posted earlier in this thread from prototypes, nor do I see the effect in images from Ashwin Rao's copy.

Not included here, but also tested was my Canon 35/2 LTM. Yes, it too has similar field curvature. The big difference though, is that as the lens is stopped down, the majority of the curvature remains in the depth of field and the center never becomes obviously soft due to focus shift.

I'm still collecting suitable sample images to present at full resolution, for which I will provide a link in the next day or so.

 

[raid]

If the replica of the Summicron is a true replica, and if the Summicron does not have such characteristics, is the replica a poorly designed lens then? Is it over-corrected?

 

[rscheffler]

Maybe not, because the prototype sample images seemed to be very close to the original. It might be a matter of tweaking the alignment/spacing of the optics? Or something has changed between the prototypes or early production samples and what is shipping now.

 

[james.liam]

If the replica of the Summicron is a true replica, and if the Summicron does not have such characteristics, is the replica a poorly designed lens then?

"True" replica is a tough one, except as made by Leica, like the new/old 28 Summaron. They have the formulae for the original glass and can concoct alternatives that will provide the performance you'd expect from a facsimile. LLL, reverse engineered (a speciality of the PRC fraught with its own issues) and did the best they could for $500. You cannot over-expect from this experiment.