Will 35mm Lux Asph backfocus on M9 ?

[yanidel]

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I have no knowledge on technical stuff so glad to hear from any of the experts in that domain. Given the following facts :

- most 35mm Lux Asph will back (front) focus at some aperture on the M8 (mine does F2-F4)

- I read that it also did on FF film but was less visible.

 

So will it also back-focus on the M9 or does full frame or the new body change anything to that technically ?

 

(still trying to resist the temptation ...)

[rosuna]

I have no knowledge on technical stuff so glad to hear from any of the experts in that domain. Given the following facts :

- most 35mm Lux Asph will back (front) focus at some aperture on the M8 (mine does F2-F4)

- I read that it also did on FF film but was less visible.

 

So will it also back-focus on the M9 or does full frame or the new body change anything to that technically ?

 

(still trying to resist the temptation ...)

 

I don't know. I doubt it. I am tired of the focus problems with the M8, and with the 35mm Summilux in particular.

[jaapv]

No- not really. The changes in DOF will be so marginal and dependent on variations in distance and crop that I don't think you will notice much difference. The problem is that film has a more mild sharp-unsharp gradient than a sensor, which makes misfocus less noticable.

[luigi bertolotti]

I have no knowledge on technical stuff so glad to hear from any of the experts in that domain. Given the following facts :

- most 35mm Lux Asph will back (front) focus at some aperture on the M8 (mine does F2-F4)

- I read that it also did on FF film but was less visible.

 

So will it also back-focus on the M9 or does full frame or the new body change anything to that technically ?

 

(still trying to resist the temptation ...)

Not at all, I think: a bigger sensor makes more critical some lenses' specs for it uses a bigger part of the circle "covered" by the lens (distortion, vignetting...) : nothing related to the problem of backfocus in itself (i.e., movement of the focus plane varying the aperture).

[jaapv]

Yes, Luigi, but focus shift is caused by spherical aberration, which gets worse towards the outside of the image circle. Larger sensor = more focus shift. Larger sensor= more shallow DOF=focus shift more visible. If anything, it should be worse. But as I said, the difference is probably marginal.

[noah_addis]

A larger sensor will also mean less enlargement is needed for a given print size. So that complicates the issue slightly.

 

I did a more careful test of my 35 'Lux the other day. I had it 6-bit coded and adjusted when I got my M8 (though they didn't have my camera so it wasn't adjusted specifically for any one body).

 

With my M8 and M8.2 (loaner), it performed the same. At F/1.4 it was VERY slightly frontfocused. It was as is my focus point was sharp but the very tiny DOF at F/1.4 was all in front of the point.

 

At F/2-F/4 it was the same thing only backwards. My focus point was definitely sharp but most of the DOF was behind the focus point. By 5.6 the lens is starting to have enough DOF so that the results seem normal--focus point is sharp and there is a tad less DOF in front of the focus point than behind.

 

I'm not saying it's a perfect lens, but I've always loved the look of the 35 'Lux ASPH on film. And on the M8 it also seems to retain that look.

 

I think a lot of people get caught up in obsessing over their files at 200% in photoshop. On my sample at least any focus shift is small enough not to worry about. It's much more likely that if a frame is so out of focus it's not usable it's more likely my fault than the fault of the lens.

 

I've been very happy with 12x18in prints from the 35 'Lux and the M8, and I expect it to be one of my most-used lenses on the M9.

 

I assume if there were a new 35 'Lux being introduced soon it would have a featured spot in the brochure among the newer lenses. Personally, if it performs on the M9 as it does on the M8, I have no desire for a newer model.

[dpattinson]

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A larger sensor will also mean less enlargement is needed for a given print size. So that complicates the issue slightly.

 

I did a more careful test of my 35 'Lux the other day. I had it 6-bit coded and adjusted when I got my M8 (though they didn't have my camera so it wasn't adjusted specifically for any one body).

 

With my M8 and M8.2 (loaner), it performed the same. At F/1.4 it was VERY slightly frontfocused. It was as is my focus point was sharp but the very tiny DOF at F/1.4 was all in front of the point.

 

At F/2-F/4 it was the same thing only backwards. My focus point was definitely sharp but most of the DOF was behind the focus point. By 5.6 the lens is starting to have enough DOF so that the results seem normal--focus point is sharp and there is a tad less DOF in front of the focus point than behind.

 

I'm not saying it's a perfect lens, but I've always loved the look of the 35 'Lux ASPH on film. And on the M8 it also seems to retain that look.

 

I think a lot of people get caught up in obsessing over their files at 200% in photoshop. On my sample at least any focus shift is small enough not to worry about. It's much more likely that if a frame is so out of focus it's not usable it's more likely my fault than the fault of the lens.

 

I've been very happy with 12x18in prints from the 35 'Lux and the M8, and I expect it to be one of my most-used lenses on the M9.

 

I assume if there were a new 35 'Lux being introduced soon it would have a featured spot in the brochure among the newer lenses. Personally, if it performs on the M9 as it does on the M8, I have no desire for a newer model.

 

Mine behaves pretty much the same as yours Noah, very slight front at 1.4 and very slight back after that - not enough to trouble me.

[yanidel]

A larger sensor will also mean less enlargement is needed for a given print size. So that complicates the issue slightly.

 

I did a more careful test of my 35 'Lux the other day. I had it 6-bit coded and adjusted when I got my M8 (though they didn't have my camera so it wasn't adjusted specifically for any one body).

 

With my M8 and M8.2 (loaner), it performed the same. At F/1.4 it was VERY slightly frontfocused. It was as is my focus point was sharp but the very tiny DOF at F/1.4 was all in front of the point.

 

At F/2-F/4 it was the same thing only backwards. My focus point was definitely sharp but most of the DOF was behind the focus point. By 5.6 the lens is starting to have enough DOF so that the results seem normal--focus point is sharp and there is a tad less DOF in front of the focus point than behind.

 

I'm not saying it's a perfect lens, but I've always loved the look of the 35 'Lux ASPH on film. And on the M8 it also seems to retain that look.

 

I think a lot of people get caught up in obsessing over their files at 200% in photoshop. On my sample at least any focus shift is small enough not to worry about. It's much more likely that if a frame is so out of focus it's not usable it's more likely my fault than the fault of the lens.

 

I've been very happy with 12x18in prints from the 35 'Lux and the M8, and I expect it to be one of my most-used lenses on the M9.

 

I assume if there were a new 35 'Lux being introduced soon it would have a featured spot in the brochure among the newer lenses. Personally, if it performs on the M9 as it does on the M8, I have no desire for a newer model.

Good points, mine is spot on at F1.4 but I suspect my rangefinder is slightly off as when I used the 35 Lux Asph a lot on the M8, I never noticed any problem. Yet lately, a lot of shots at mid distance at F2.8 do show significant lack of sharpness.

If I acquire the M9, I intend to use the 35 Lux Asph as my main lens too. If the shift impacts pictures minimally, that is fine but it would be too bad to make such an investment without taking full advantage of the full format sensor potential.

[UliWer]

I think that each individual 35mm Summilux reacts differently, though there are many individual sources who confirm that this lens suffers from focus shift. That's my experience as well and it has been the same when I already used it on 35mm film (though I didn't know the meaning of "focus shift" then...)

 

This may not be a very big problem. On the other hand I ask myself why I bought this lens and no other: wasn't it the promise of getting images of superb sharpness on all stops from wide opened down? Without this exspectation I could have put up with a pre-aspherical Summilux or even with a wonderful 2.8/35 Summaron. When I tested the Summaron and the Summilux both at f/2.8 side by side and the Summaron - on which I spent 1/5 of the Summilux' price - produced the sharper results I felt some disappointment.

 

Each time I manage to compensate for the focus shift and get the results spot on, the Summilux asph will of course not be bettered, but unfortunately this is not each time I use it.

[SJP]

As far as I can figure out, any focus shift will be more apparant on the M9 as the enhanced sensor size gives a shallower depth of field for the same lens (focal length) & aperture. So I think at f/2 - f/4 things will become even more critical.

[rosuna]

As far as I can figure out, any focus shift will be more apparant on the M9 as the enhanced sensor size gives a shallower depth of field for the same lens (focal length) & aperture. So I think at f/2 - f/4 things will become even more critical.

 

The 35mm Summilux is one of the more expensive lenses in Leica's portfolio, and focus shift make it very difficult to use. You cannot be sure about focus at short distances from f/1.4 to f/4. The performance of the lens is in other respects very good, but Leica should redesign this lens in order to give priority to spherical aberration. Even more, Leica should stop the production of this lens, until a new design is ready. It is vey uncomfortable to use.

[Jamie Roberts]

Mine has never exhibited any significant focus shift that make it difficult to use close up or wide open. The focus point is always in focus with this lens.

 

But I do think that unlike, say, a 28 Elmarit, it's one of the lenses that shows any mis-calibration of the system.

[yanidel]

This may not be a very big problem. On the other hand I ask myself why I bought this lens and no other: wasn't it the promise of getting images of superb sharpness on all stops from wide opened down? Without this exspectation I could have put up with a pre-aspherical Summilux or even with a wonderful 2.8/35 Summaron. When I tested the Summaron and the Summilux both at f/2.8 side by side and the Summaron - on which I spent 1/5 of the Summilux' price - produced the sharper results I felt some disappointment.

I think you uncovered the underlying point being this thread. As some might recall this thread, I have been trying to reduce my kit to one lens :

http://www.l-camera-forum.com/leica-forum/leica-m8-forum/91585-anyone-went-24-35-kit-28mm.html

Well, after two months shooting with the 28mm Summicron, it is not the solution for me. I think the 28mm framelines and FOV are the best but both the 24mm Elmarit and 35mm Lux are better lenses for my photography as there is two kinds of shots I particularly like :

- #1 close action where sharpness is not critical. I try to depict a mood more than details. Often shot between F1.4 and F4.

- #2 urban scenes where humans are a small part of the pictures. Here I want maximum sharpness. A bit like a XVIth century Dutch painting, all details are important to the interpretation of the picture. I don't post many of these on my blog (details require bigger files) but I like to contemplate the prints for long moments.

On the M8, the 35mm Lux Asph is great for #1, the 24mm Elmarit blows both the Cron and the Lux for #2. I never print smaller than A3 by the way and will start with A3+ soon (once I can get my hand over a satin one).

On the M9, the 24mm Elmarit becomes a 24mm which is now way too wide. The 35mm Lux becomes the standard lens as 35mm is my favorite FOV (I will drop the 50mm FOV so no subsitute lens would be needed on the M9). The signature of the 35mm Lux Asph wide open will probably be amazing on the M9 but I would also love that it comes close to the 24mm Elmarit in terms of sharpness when stopped down for pictures of style #2. With that focus shift issue, I was wondering if this would be possible or whether I would still need two lenses for the different style of pictures.

[Jamie Roberts]

{snipped}The signature of the 35mm Lux Asph wide open will probably be amazing on the M9 but I would also love that it comes close to the 24mm Elmarit in terms of sharpness when stopped down for pictures of style #2. With that focus shift issue, I was wondering if this would be possible or whether I would still need two lenses for the different style of pictures.

 

You'll have to wait and see, I guess, how your Lux works on the m9, but IMO the 35 Lux ASPH gives nothing to the 24 Elmarit ASPH in terms of sharpness. If it's in focus, that is But when it is, it's extremely sharp and contrasty (and I noticed that the majority of the shots in the "m9 brochure" that's on the 'net were taken with the 35 Lux ASPH).

[UliWer]

The 35mm Summilux is one of the more expensive lenses in Leica's portfolio, and focus shift make it very difficult to use. You cannot be sure about focus at short distances from f/1.4 to f/4. The performance of the lens is in other respects very good, but Leica should redesign this lens in order to give priority to spherical aberration. Even more, Leica should stop the production of this lens, until a new design is ready. It is vey uncomfortable to use.

 

I do not agree that it is uncomfortable to use, but it may be hit and miss more often than you wish.

 

That's the reason I was almost sure that we would see a new version of this magnificent lens at the upcoming "big day". Besides the last version of the 50 Summicron it is the lens with the longest production times of all present Leica lenses. So to exspect a new 35mm Summilux seemed to me much more probable than any M9.

 

When i now look at some leaked brochures I don't find any hint about a new version, but only data which are identical to the old one.

 

So may be Leica missed the date to announce a lens which surely will see much more of the future than any camera body they might announce. A 35mm M-Summilux with all the qualities of the current one but none of it's issues would certainly belong to a very very small and elitist group of world's ever best lenses. I am still sure they won't miss this aim even if they missed the date.

 

By the way: wasn't there talking about 9 new products? When I look at the S2+lenses, the M9 and some X1 i can count only up to seven.

[jplomley]

This issue is not isolated to the 35 lux Asph. I am just now starting to use the 35 Cron Asph on my M8s. I had bought this lens for my M7 and there is was married for a long long time. Had no problems whatsoever and it is a brilliant performer on film. This weekend I decided to do a bit of shooting with it on the M8s and noticed that the intended focus point was sharp enough, but all the DOF was behind the plane of focus. I corroborated this on a focus chart, and even at f/8 there is no DOF in front of the plane of focus. Nonetheless, the focus point is sharp at all apertures. It is the oddest behavior I have ever seen. My 21/24/28/75 all perform flawlessly, so I'm quite surprised at the 35 Cron Asph. My concern now is that if i have it adjusted, will it be off on my M7 and M9 (will sell one of my M8s to help fund the M9). Sure wish Leica had put a calibration feature in the M9 to circumvent these annoying issues.

[nugat]

As far as I can figure out, any focus shift will be more apparant on the M9 as the enhanced sensor size gives a shallower depth of field for the same lens (focal length) & aperture. So I think at f/2 - f/4 things will become even more critical.

 

You surely mean the opposite: bigger sensor DEEPER DOF for same f-length/aperture?

 

eg FF 35mm/f1.4 at 5m DOF 1.77m (coc 0.03mm)

and M8 35mm/f1.4 at 5m DOF 1.34m (coc 0.023mm)

 

so focus shift LESS apparent on M9

[jaapv]

No - Stephen is keeping the magnification of the subject a constant - In that case the DOF is deeper on the smaller sensor. But the subject distance changes.

[nugat]

No - Stephen is keeping the magnification of the subject a constant - In that case the DOF is deeper on the smaller sensor. But the subject distance changes.

 

What do you mean he is trying to "keep the magnification of the subject constant"?

The magnification (let's assume you mean the size of the image on the sensor) is constant, when it's the same lens focused at the same distance.

Say it's a full shot of a friend standing: his image on the M8 sensor has the feet touching the bottom of the picture and top of his head touches the upper frame of the picture. Now you put the same lens on M9 without moving. The sensor is bigger so the friend's image now gains "air" below and above and occupies 18/24=75% of the picture height (M8 sensor is 27x18mm, M9 36x24). If what you want to do is increase the size of the friend's image so he again is 100% of the sensor's height, you INCREASE magnification. You do it here by walking towards the subject (although the real meaning of magnification would call for a change of the lens)

You should not compare DOF when walking in and out and changing focussing distances for the same lens put on different sensors-too many variables. What's the point?

DOF will depend now on CoC (which is 0.023mm for M8 and 0.030mm for M9) AND the focussing distance (given constant aperture).

The 35mm/1.4 summilux comes from the full frame world. It's image circle is for the 36x24 frame. It's shortcomings might show on the smaller sensor but are not so obvious on the full frme one, IMHO.

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[henning]

Since, for the most part, this will be analyzed by pixel peeping, and the pixel density is the same between the M8 and M9, the backfocus will be identical.

 

If the images are enlarged to the same size and the picture is taken at the same distance, the focus error will not be as obvious from the M9 file because the imaged items will be smaller (wider FOV).

 

I really can't believe this talk about things like the lens being 'unuseable' or incapable of delivering sharp images stopped down. What a load of rubbish. For the first, user error is very often; indeed most often the cause of technically lower quality shots. For the second, the 35 lux ASPH is capable of higher resolution than the M9 sensor is capable of recording, and at stopped down apertures like f/5.6 and f/8 focus shift is not an issue.

 

Going to a pre-asph Lux might give you photos where you can't see focus shift, but you also can't see the point of focus wide open. That lens had severe focus shift, and the Summaron also had focus shift. You're not going to get technically better photos by going to 1950's designs.

 

I have and/or have used all of Leica's ASPH M lenses, and while the 24 is indeed excellent, in practice the 28 Summicron or indeed 35 Lux are generally the equal of the 24. I got rid of the 24 because it didn't suit me, but the 35 Lux' focal length, speed and size do suit me so I use it a lot. So does the Noctilux, which has bigger issues. To suggest Leica should stop selling the 35 Lux because it has a small amount of focus shift is ludicrous.

 

Maybe I'll go out and take some pictures (hint, hint).