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

[yossi]

But coatings don't necessarily affect aspects such as focus shift and field curvature.

I received my lens and I have mixed feelings about it when used stopped down because of strong focus shift combined with "W" shaped field curvature. These are my impressions about it with my M240 after both casual photos at various distances as well as putting it on a tripod and doing some careful tests at a range of distances (because of the behavior I noticed in those initial casual photos).

If focused by RF at f/2 and not refocused:

f/2: is kind of glowy due to SA, but sharp enough, which I expected and fully accept, with good flatness of field across the frame.

f/2.8: increases contrast a lot and there seems to be a touch of focus shift, but not much. Center frame sharpness is slightly underwhelming and signs of a mid zone drop in sharpness.

f/4: focus in the center 1/4 to 1/3 of the frame shifts considerably behind the subject while the rest of the frame is pretty sharp with signs of a mid zone dip.

f/5.6: focus in the center shifts even more behind the subject and affects about the center 1/3 of the frame, while the rest of the image remains sharp.

f/8: depth of field begins to recover central sharpness and the outer 2/3 of the frame is good. But central sharpness is still not acceptable, nor as good as the outer 2/3 of the frame.

If I use live view and refocus as the lens is stopped down, the center 1/4 of the frame is sharp and the rest of the image shows considerable field curvature towards the camera. Even depth of field at f/8 is insufficient to recover the mid zone of the image, though the very edges are sharp.

For example a scene nearly at infinity, based on RF focus, f/2 was accurate (as sharp as can be expected). Refocusing with live view at f/4, optimal central focus was with the focus ring at around 10m to get 'infinity' in focus in the center of the image (the rest of the image at that distance is very soft). At f/5.6 optimal near infinity central sharpness had the focusing ring between 5-10m (again, the rest of the image is soft at that distance). At this point, looking through the optical viewfinder, the RF patch was significantly out of coincidence.

I can confidently RF focus my copy at f/2, and with slight front focus, f/2.8. As the lens is stopped down, the "W" shaped field curvature becomes very strong, shifting optimum center sharpness away from the camera and making RF focus placement at f/4 and f/5.6 very difficult without resorting to live view. However, if I RF focus at f/4 or f/5.6 and place the subject in the rule of thirds zone, it will be correctly focused. It would seem the lens's RF calibration is set to cut through the middle of the "W" to keep good average sharpness across the frame but sacrificing the center at f/4-8.

Based on the MTF and field curvature documentation supplied with the lens, it appears "W" shaped field curvature is a characteristic of the lens. What I'm unable to determine from using just my copy is whether its performance is consistent with others, or at the extreme end. In other words, can you RF focus your copy and get a sharply (or acceptably) focused photo of your subject dead center in the frame at f/4 and f/5.6?

Ideally, I would like to use the lens for both wide open character/rendering as well as stopped down use (with good across-frame performance). Maybe it's too much to expect from this era of 35mm design?

Mine is a BP version and I believe it also has some weird field curvature at f4 and f5.6. It is not quite the same as your case though.

I did not use tripod to test focus but some handheld shots show that at f4 and f5.6, the sharpness is not even across the whole frame. At f2, focus is spot on.

Below is a shot at f5.6. Focus was on the first tree on the left (sharp, even a small lizard is clearly visible) but just look at the other 3 trees. The second last one on the right is most unsharp and strangely, the very last one becomes sharper ?!! (click on the image to see a bigger one)

I really don't know what is the cause of this. Maybe someone could enlighten me 🙂

 

[kiemchacsu]

I will check my copy this week, mounted on a tripod for better results.

...
Based on the MTF and field curvature documentation supplied with the lens, it appears "W" shaped field curvature is a characteristic of the lens. What I'm unable to determine from using just my copy is whether its performance is consistent with others, or at the extreme end. In other words, can you RF focus your copy and get a sharply (or acceptably) focused photo of your subject dead center in the frame at f/4 and f/5.6?
...

 

[fbf]

depends on how you interpret the lens. They are fully capable making a better lens than the original 8 elements but the question is how many ppl are interested in a "better" copy lens. I think it's difficult to completely recreate the original lens but they have done a great job so far
They are planning to "upgrade"/ "improve" the current lens so you can bet the 1st batch lens will be very different than the one im getting in a couple of days.

 

[raid]

It was a $500 risk taking project, and it is most likely a very good lens for most lenses received here. It may be a QC issue. If it had been a lens design issue, we would have seen far more people complaining about some aspects of the lenses.

 

[raid]

It was a $500 risk taking project, and it is most likely a very good lens for most lenses received here. It may be a QC issue. If it had been a lens design issue, we would have seen far more people complaining about some aspects of the lenses.

 

[james.liam]

One wonders how much of the focus shift is apparent because everyone is testing it out on a digital sensor instead of film. I would be more worried about decentered elements given its modest cost and inconsistent QC.

 

[rscheffler]

^^rscheffler, interesting examination and analysis ^^

It would be good to find out if your observations are typical of the replica production... Or for that matter typical of the original 8-element Summicron. As to the latter I don't think so, though I have not closely studied its behavior in the way you did. But I've had my Summicron v.1 since new in 1968 and have not noted anything like this in normal usage.

As recently as Sept 2019 I used it exclusively on a vacation trip to the Canadian Rockies with my Leica M-D 262. See photos in my Gallery with batch numbers 190914 and 191003, numbers representing the date of the last photo in each batch. Or just search for that lens and user= Doug

Hi Doug, thank you very much for understanding my point and your considerate reply.

This is exactly my desire: to determine if this is normal, or abnormal behavior for this lens. And given that it is a very accurate copy of the original, whether it too shares the characteristics I've seen in my copy.

Because I don't have first-hand experience with the original Cron 8E, or access to one for comparison, my hope is that feedback from others here can clarify the level of performance one should expect from the replica.

I had a browse through your more recent 35 Cron gallery images. Within the limitations of resolution they're made available, I cannot see any indication of weak central sharpness similar to what I've seen from my copy of the replica.

I have been in contact with Kevin and he has requested sample images to share with Mr. Zhou for feedback and to determine a course of action. I will provide a link in a future post for others here to also access those images and provide their feedback.

Unfortunately in this situation, Kevin is 'stuck' in the middle, as a go-between and likely cannot make immediate, independent decisions.

Lastly, I downloaded the comparison photos between the replica and the original Cron 8E by Ashwin Rao, posted earlier in this thread and available on Flickr. In his set is a sequence of photos of a man, shot at each aperture from wide open through f/16. In none of those images, from either lens, is there any indication of poor central sharpness. This is the opposite to what I see with my copy and provides some indication that the performance of my copy is not optimal.

 

[raid]

I also believe this is a QC issue in some lenses. Will you mail the lens back?

 

[oldwino]

My copy, one of the first ones with flint glass, seems pretty good across the field. I've not noticed any excessive field curvature. Now, I've shot mine solely on film, and these issues may be more pronounced on digital.
I find the lens has a "flatter" look to it than I prefer - but that would be true for the original as well, I suspect. My 35 Summaron was the same way - sharp, but low contrast. I find myself using my LTM nikkor far more often, in spite of that lens' shortcomings (namely, very busy bokeh). The LLL 35 does look great on my M2...
Maybe I should buy one of the new Ultrons...;-)

 

[rscheffler]

Mine is a BP version and I believe it also has some weird field curvature at f4 and f5.6. It is not quite the same as your case though.

I did not use tripod to test focus but some handheld shots show that at f4 and f5.6, the sharpness is not even across the whole frame. At f2, focus is spot on.

Below is a shot at f5.6. Focus was on the first tree on the left (sharp, even a small lizard is clearly visible) but just look at the other 3 trees. The second last one on the right is most unsharp and strangely, the very last one becomes sharper ?!! (click on the image to see a bigger one)

I really don't know what is the cause of this. Maybe someone could enlighten me 🙂

Thanks for the high-rez sample image.

The MTF documentation provided with the replica indicates that there is some degree of "W" shaped field curvature inherent in its optical performance. I believe this is what is seen in your image and likely is not quite as severe as that exhibited by my copy.

My question to you is: if you were to put one of those trees in the center of the image, or a person, or any object, and photograph it at f/4 or f/5.6, is it acceptably in-focus?

With my copy it is not.

However, if I focus and recompose, putting the subject roughly in the rule of thirds zone, it will be sharply focused at all aperture values. It's only when I place the subject in the center 1/4 to 1/3 of the image, that focus in the range of f/4-f8 ends up well behind the intended point of focus and depth of field is insufficient to compensate. Yet that same scene, if shot at f/2, would be in focus in the center of the image.

 

[rscheffler]

I will check my copy this week, mounted on a tripod for better results.

Thank you, I look forward to your results.

 

[rscheffler]

My copy, one of the first ones with flint glass, seems pretty good across the field. I've not noticed any excessive field curvature. Now, I've shot mine solely on film, and these issues may be more pronounced on digital.
I find the lens has a "flatter" look to it than I prefer - but that would be true for the original as well, I suspect. My 35 Summaron was the same way - sharp, but low contrast. I find myself using my LTM nikkor far more often, in spite of that lens' shortcomings (namely, very busy bokeh). The LLL 35 does look great on my M2...
Maybe I should buy one of the new Ultrons...;-)

Thanks. I think the degree of softness I see with my copy in the center of the image would also be noticeable on film, though I should print one at 4x6 to see how noticeable it is. It should be noticeable in an 8x10" print. I'm not zooming in to 100% and pixel peeping to see the problem in my images.

My current 'go-to' 35mm is the Voigtlander 35/1.7 M version, with which I am extremely happy in respect to optical performance. I was interested in their new 35/2 as a more compact alternative, but wasn't quite won over by its bokeh characteristics. I held off in favor of the LLL replica because the original has always been a lens I've wanted to use, but could not justify the current market value.

Among vintage 35s, I've been happy with the Canon 35/2 LTM, which IMO is a very solid performer when stopped down.

 

[rscheffler]

depends on how you interpret the lens. They are fully capable making a better lens than the original 8 elements but the question is how many ppl are interested in a "better" copy lens. I think it's difficult to completely recreate the original lens but they have done a great job so far
They are planning to "upgrade"/ "improve" the current lens so you can bet the 1st batch lens will be very different than the one im getting in a couple of days.

I appreciate your point.

My desire is for a faithful copy of the original, which all the prototype sample photos posted earlier in this thread pointed towards. This is also what I see in Ashwin Rao's Flickr gallery of the replica compared to the original. It's the reason I signed up for one back in Dec. 2019... Unfortunately I don't think my copy of the replica is consistent with what I've seen in those earlier images.

I do appreciate the 'upgrade' to the equidistant aperture scale spacing on my copy, which includes half-stop clicks.

 

[rscheffler]

It was a $500 risk taking project, and it is most likely a very good lens for most lenses received here. It may be a QC issue. If it had been a lens design issue, we would have seen far more people complaining about some aspects of the lenses.

Yes, I don't disagree.

One wonders how much of the focus shift is apparent because everyone is testing it out on a digital sensor instead of film. I would be more worried about decentered elements given its modest cost and inconsistent QC.

I also believe this is a QC issue in some lenses. Will you mail the lens back?

I suspect there is some QC variation, hence why I'm asking for feedback from other replica users.

I sent Kevin a summary of my initial results and he has asked for images to share with Mr. Zhou in order to determine how to proceed.

I'll also share those images here for feedback, likely in the next day or two.

 

[Erik van Straten]

at f5.6. Focus was on the first tree on the left (sharp, even a small lizard is clearly visible) but just look at the other 3 trees. The second last one on the right is most unsharp and strangely, the very last one becomes sharper ?!!

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.

 

[raid]

I once had a Canon 50/1.2 with a diagonal focus across the images. It went from front focus on left to back focus on right. Only DAG managed to fix the lens. There was a lens element that needed to be positioned differently.

 

[Erik van Straten]

I once had a Canon 50/1.2 with a diagonal focus across the images. It went from front focus on left to back focus on right. Only DAG managed to fix the lens. There was a lens element that needed to be positioned differently.

I know that the Canon 35mm f/1.5 LTM has the effect that I point out above to a very strong degree.

Erik.

 

[raid]

As you said, Erik, this is the charm of some lenses.

 

[james.liam]

I once had a Canon 50/1.2 with a diagonal focus across the images. It went from front focus on left to back focus on right. Only DAG managed to fix the lens. There was a lens element that needed to be positioned differently.

DAG is one of the few with a collimator in his shop. YYe does not have one.

 

[Dan]

Mine is a BP version and I believe it also has some weird field curvature at f4 and f5.6. It is not quite the same as your case though.

I did not use tripod to test focus but some handheld shots show that at f4 and f5.6, the sharpness is not even across the whole frame. At f2, focus is spot on.

Below is a shot at f5.6. Focus was on the first tree on the left (sharp, even a small lizard is clearly visible) but just look at the other 3 trees. The second last one on the right is most unsharp and strangely, the very last one becomes sharper ?!! (click on the image to see a bigger one)

I really don't know what is the cause of this. Maybe someone could enlighten me 🙂

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