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

[raid]

Lovely shots, Raid! I like this lens very much! Like impressionist paintings!


Erik.

Thank you Erik. I like using such lenses once in a while. This is why I bought them. This lens may be "better" with film than with a digital camera (where it gives more natural looking images.) The 3 images that I posted here from the Canon 35/1.5 were taken with film and then the negative was scanned.

 

[D&A]

Sorry for the late response (busy at work and due to very wet weather these few days, no chance to go out to test shoot).

Tonight I took two test shots with the 8E Clone, M9M on tripod. One at f2 and the other at f4. Close range. Target at centre of frame. Result: both shots focus spot on. f2 shot only centre portion is sharp, further away starts to get softer but the bottom right corner is sharpen up. At f4, almost the whole frame is almost evenly sharp, but that the bottom right corner spot is unusually sharper than its neighbour. (Btw these test shots are too boring to be shown here. Unless there are some technical reasons to further examine them, I shall spare everyone from them LOL).

In short, my copy has that weird sharp corner but otherwise no focus shift issue like yours.

That's what I was trying to point out in my previous two shots I posted (on the previous page with the tree directly in the middle). The extreme upper right side corner's tree leaves (and to some degree the extreme left side corner tree leaves) are very sharp (although well out of the depth of field), but adjacent tree leaves on both sides are blurred as they should be. I attribute this to some sort of field curvature. Again both images taken with the M9.

Dave (D&A)

 

[Ccoppola82]

I’ll have to test mine out with this, but so far I’ve been extremely happy with my copy. I’ve read that the 35 FLE has a sort of curvature like this as well and part of me wonders if it’s sort of purposeful. I recall a time in a drawing class where I drew in every little detail and the instructor came and said “it’s boring. Everything is too perfect, how am I supposed to know what to look at” and he was right. If everything screams at a viewer, they don’t know what to look at. The human eye has a VERY limited focal plane if you really pay attention. Even while viewing a photo, there is a point the eye focus on and the rest is peripheral blur. I have no doubt that Leica could produce a perfectly sharp, ultra flat lens...but it would also be rather boring like a sigma art series. If ultimate sharpness is the only criteria, there are lenses for that. This makes sense to me artistically speaking...but perhaps I’m just making excuses for leica 🙂

 

[Ccoppola82]

Ive been using this lens primarily on my M2 as a carry around lens to shoot whatever seems interesting to me. Some are a bit more abstract.

Tri X

[/url]Woodlawn Beach by Chris Coppola, on Flickr[/IMG]
2020-13-8.jpg by Chris Coppola, on Flickr
Caged Shadows by Chris Coppola, on Flickr
Spirit Talker by Chris Coppola, on Flickr

 

[rscheffler]

Sorry for the late response (busy at work and due to very wet weather these few days, no chance to go out to test shoot).

Tonight I took two test shots with the 8E Clone, M9M on tripod. One at f2 and the other at f4. Close range. Target at centre of frame. Result: both shots focus spot on. f2 shot only centre portion is sharp, further away starts to get softer but the bottom right corner is sharpen up. At f4, almost the whole frame is almost evenly sharp, but that the bottom right corner spot is unusually sharper than its neighbour. (Btw these test shots are too boring to be shown here. Unless there are some technical reasons to further examine them, I shall spare everyone from them LOL).

In short, my copy has that weird sharp corner but otherwise no focus shift issue like yours.

Thanks for making the test.

I think what you're seeing in the corner is due to field curvature. According to the LLL technical documentation supplied with the lens, this should be normal. From the center of the frame, field curvature should gradually bend towards the camera through the outer mid-frame, then rapidly bend away from the camera towards infinity at the extreme edges/corners.

With my copy, at f/2, it is evenly sharp across the frame - as sharp as it's going to get with a lot of spherical aberration wide open. It seems yours already has signs of field curvature at f/2 whereas with mine it is very minimal. My guess is if you're getting sharp results across most of the frame at f/4, the field curvature in your copy remains consistent in strength and it and focus shift (if any) is likely masked by depth of field, except for the extreme edges where the curvature is quite sudden. With mine, curvature becomes more severe as the lens is stopped down and focus shift away from the camera compounds this. Depth of field at f/11 is finally able to provide even across-frame sharpness.

It's just a hunch, but I my guess right now would be that optical alignment/spacing of the lens elements in my copy might be a factor and I wonder if adjusting it for consistent stopped down performance will change its wide open behavior, with which I'm currently very happy.

 

[raid]

It may be best to just use the lens and enjoy it.

 

[Ccoppola82]

It may be best to just use the lens and enjoy it.

Yes. +1. Totally agree

 

[xmas_one]

Good stuff Chris, I really like that first shot of the beach!

 

[D&A]

Thanks for making the test.

I think what you're seeing in the corner is due to field curvature. According to the LLL technical documentation supplied with the lens, this should be normal. From the center of the frame, field curvature should gradually bend towards the camera through the outer mid-frame, then rapidly bend away from the camera towards infinity at the extreme edges/corners.

With my copy, at f/2, it is evenly sharp across the frame - as sharp as it's going to get with a lot of spherical aberration wide open. It seems yours already has signs of field curvature at f/2 whereas with mine it is very minimal. My guess is if you're getting sharp results across most of the frame at f/4, the field curvature in your copy remains consistent in strength and it and focus shift (if any) is likely masked by depth of field, except for the extreme edges where the curvature is quite sudden. With mine, curvature becomes more severe as the lens is stopped down and focus shift away from the camera compounds this. Depth of field at f/11 is finally able to provide even across-frame sharpness.

It's just a hunch, but I my guess right now would be that optical alignment/spacing of the lens elements in my copy might be a factor and I wonder if adjusting it for consistent stopped down performance will change its wide open behavior, with which I'm currently very happy.

You're most welcomed. I've often encountered gradual field curvature in lenses (funny how must have been 35mm focal length lenses)...but never the extreme corner "U-turn" as you described. That's something new to me and interesting and would account for what I previously described in the far extreme right and left hand top corners of the two recent images I posted.

Interestingly I did not see it at the two bottom corners and that perplexes me as to why not?

Again either a change was made to the replica lens as was suggested by the forum member a few pages ago who also received the latest replica with evenly spaced f-stops on the aperture ring.....or alternatively you received a lens that is not performing the way all replica lenses are intended to. I honestly don't agree with the suggestion to just use it (the way it is). if it is mal-adjusted or defective, that would be like someone suggesting a person should live with a newly purchased defective car or TV that doesn't operate the way all other models of that car or TV operate.

Again, alternatively your lens may be absolutely perfect if they did institute optical changes as was suggested and the only way that will be determined is either word of such changes from LLL directly or from those that received a recent evenly spaced f-stop version and tested theirs. Since lenses are still being sent out, I'm sure before long, you'll have more info.

Dave (D&A)

 

[D&A]

Here is a shot I took recently with the 35mm LLL replica lens on the M9.

Titled: "The Pearly Gates"?

Dave (D&A)

 

[yossi]

Thanks for making the test.

I think what you're seeing in the corner is due to field curvature. According to the LLL technical documentation supplied with the lens, this should be normal. From the center of the frame, field curvature should gradually bend towards the camera through the outer mid-frame, then rapidly bend away from the camera towards infinity at the extreme edges/corners.

With my copy, at f/2, it is evenly sharp across the frame - as sharp as it's going to get with a lot of spherical aberration wide open. It seems yours already has signs of field curvature at f/2 whereas with mine it is very minimal. My guess is if you're getting sharp results across most of the frame at f/4, the field curvature in your copy remains consistent in strength and it and focus shift (if any) is likely masked by depth of field, except for the extreme edges where the curvature is quite sudden. With mine, curvature becomes more severe as the lens is stopped down and focus shift away from the camera compounds this. Depth of field at f/11 is finally able to provide even across-frame sharpness.

It's just a hunch, but I my guess right now would be that optical alignment/spacing of the lens elements in my copy might be a factor and I wonder if adjusting it for consistent stopped down performance will change its wide open behavior, with which I'm currently very happy.

Thanks for the analysis. It does make sense.

While I don't think the curvy field thingy is a feature, this lens is still good for making nice images as evident from the many samples shown here. Exact clone of the 8E Summicron it is not though.

It's time to shop testing and enjoy shooting 🙂

 

[D&A]

yossie, There's no question the replica is wonderful and is a close facsimile of the 8 element cron. I think that's obvious to most. I think the question we've been recently discussing is simply what appears to be a sample of the replica that's different than all others previously shown and/or described by their owners. Namely that rscheffler's replica behaves differently and not always in a desirable way. The question is if a optical change has been made to recently produced lenses (like those with even spacing of f-stops) or is his lens an anomaly. I think its reasonable to look into that.

Dave (D&A)

 

[aizan]

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 🙂

That's a textbook example of field curvature. The plane of focus curves away from you and makes more distant objects in the corners sharp. A lot of fast wides do that, especially old ones.

I checked the Leica Lens Compendium, but Puts doesn't say anything about field curvature on the 8-element:

The 8-element design has relatively large front and rear elements, presumably to reduce vignetting. In fact, at full aperture vignetting is 2.5 stops and at aperture 2.8 is 2 stops, about the same as the Summaron. At full aperture overall contrast is low and coarse detail is rendered with soft edges over most of the picture area. Fine detail is visible on axis (image height 6mm), but becomes blurred when extending to the corners. At 1:2.8 contrast improves markedly and now centre quality is better than that of the Summaron. At 1:4, we note a small improvement in the field and at 1:5.6 fine detail is defined crisply till the corners, which stay very soft. On axis very fine detail has good edge sharpness, but the contrast is lower. There is a pronounced tendency to flare at wider apertures over the whole picture area, due to the presence of coma. Close up performance is fair and one needs to stop down for good imagery.

The lens is very compact and the balance between size and image quality is evident.

Distortion is negligible.

https://collectiblend.com/Library/Leica_Lens_Compendium_Chapter6.php

Try shooting these kinds of shots at f/8 and f/11!

 

[D&A]

That's a textbook example of field curvature. The plane of focus curves away from you and makes more distant objects in the corners sharp. A lot of fast wides do that, especially old ones.

I checked the Leica Lens Compendium, but Puts doesn't say anything about field curvature on the 8-element:


https://collectiblend.com/Library/Leica_Lens_Compendium_Chapter6.php

Try shooting these kinds of shots at f/8 and f/11!

That's interesting but I believe you described field curvature backwards. Examples of field curvature (especially as the camera to subject distances grow larger)…..is where the central part of an image shot is sharp but if you look at the sides and corners of that image, they are soft. That's the same thing described in your quote above and if you read Chapter 3 of the Putts writings you quoted, he says the same thing. The field curvature doesn't bow away or outward at the edges and corners but inward towards the camera, like a bowl. In some worse case scenario's, even at f8/11, the corners at infinity still don't sharpen with field curvature in the way I (or Putts) described. A prime example of this is the Pentax FA 645 35mm f3.5. Having tested more than 9 samples, they all exhibited this trait and the corners never ever sharpened up, even at f16. Field curvature gets more pronounced as the camera to subject distance becomes greater. A few years ago, Pentax reworked the internal optics of this lens slightly and this lens became essentially flat field with edge to edge sharpness almost from wide open till stopped down.

Dave (D&A)

 

[aizan]

Roger Cicala explains it really well on his blog:

https://www.lensrentals.com/blog/2014/09/field-curvature-and-stopping-down/

Let’s say the object I focus on is a perfectly straight barbed wire fence at right angles to my camera. Let’s pretend there’s a row of rocks a few yards in front of the fence and some trees a few yards behind. If the plane-of-focus of the lens is perfectly flat, then the entire fence is in focus from one side of the image to the other, with the rocks and trees just a bit softer.

If the field curves, however, at some distance from the center the rocks (or the trees) may be in better focus than the fence. If the curvature is complex (so-called mustache curvature) the fence is sharpest in the center, but as we move away from the center to the edge of the image the rocks get sharper, then the fence comes back in focus, and finally the trees are the sharpest. Or some similar variation on the theme.

What we’re seeing in the replica and probably the original is a case of wavy field curvature.

 

[D&A]

Roger Cicala explains it really well on his blog:

https://www.lensrentals.com/blog/2014/09/field-curvature-and-stopping-down/



What we’re seeing in the replica and probably the original is a case of wavy field curvature.

I can't say I saw evidence of wavy field curvature in the original 8 Element when I owned it and except for the very corners being sharp when they are out of the depth of field in the replica, I don't see evidence of wavy curvature in my replica. The old Af Nikon 18mm f 2.8 lens had wavy (mustache) curvature in abundance and I could probably find an old image demonstrating it and was exactly as Roger Cicala explained. Now the most recent samples of the replica may be different and have wany field curvature as shown some posts above by a fellow RRF member who just received his lens and that indeed may have wavy field curvature but I don't see it in the classical sense in the original replica lenses released (except for those extreme corners I just mentioned and showed in my two posted images a page or two ago). That though is not wavy field curvature. Again I may be mistaken and would have to reexamine some of my in-depth test shots. I appreciate the in-depth conversation.

Dave (D&A)

 

[rscheffler]

yossie, There's no question the replica is wonderful and is a close facsimile of the 8 element cron. I think that's obvious to most. I think the question we've been recently discussing is simply what appears to be a sample of the replica that's different than all others previously shown and/or described by their owners. Namely that rscheffler's replica behaves differently and not always in a desirable way. The question is if a optical change has been made to recently produced lenses (like those with even spacing of f-stops) or is his lens an anomaly. I think its reasonable to look into that.

Dave (D&A)

Thank you for understanding my intention!

While it's easy to say 'just use it and enjoy it' when one's own copy lives up to one's expectations, it would be the first time in ~30+ years I've owned a lens that becomes soft at f/4-5.6 in only the center of the frame, which effectively makes it unusable (without resorting to live view) other than near wide open or stopped down to f/11.

Interestingly though, if I only had a mirrorless camera and received this copy, I'd be wondering why it was only sharp in the center until f/11...

Regarding field curvature, here is what is published by LLL - a scan of the information included with the lens.

The first image is as published, which represents half of the image circle diameter.

The second image I've taken the graph and flipped it sideways, copied it, flipped the copied layer and then put them side by side to illustrate what field curvature should be like across the full image circle.

You can see that the wavy field curvature means that with ideal focus at the center, the plane of focus would move to front focus in the mid zone area and then curves at the edges to fairly strong back focus. By placing the plane of focus to intersect the subject plane a bit outside of dead center, with sufficient depth of field, there will be good across-frame sharpness. I believe that is how my copy is RF calibrated. But my copy's wavy field curvature undulates to such an extent that depth of field doesn't fully cover it until f/11. My copy changes from fairly flat field curvature wide open to very wavy by f/4.

The third photo is what I posted before - the Find Edges version of a test photo to show the shape of field curvature at f/4 from my copy. It sure looks stronger than the field curvature published by LLL.

 

[rscheffler]

Here are the MTF curves published by LLL:

 

[rscheffler]

The field curvature doesn't bow away or outward at the edges and corners but inward towards the camera, like a bowl.

I've seen field curvature both ways, where it bends towards infinity at the edges or towards the camera (normally one direction for a given lens).

My copy of the replica does both. It bends towards the camera in the mid-field if the center of the image is properly focused, and away towards infinity at the edges. 🙂

 

[dourbalistar]

Roger Cicala explains it really well on his blog:

https://www.lensrentals.com/blog/2014/09/field-curvature-and-stopping-down/

What we’re seeing in the replica and probably the original is a case of wavy field curvature.

Since aizan cites Roger Cicala and the Lens Rentals Blog, here's another post that shows that double field curvatures is not uncommon with M-mount 35mm lenses, even lenses made by Leica:
https://www.lensrentals.com/blog/2014/08/some-m-mount-field-curvatures/

Take a look at the curvature for the Voigtlander 35/1.4! 😱 Seems they took the M in M-mount literally and applied it to their field curvature as well. 😉