Very interesting answer from Leica on 35mm 1.4

[ho_co]

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That was why they cost upwards of £30,000.

Wilson--

Does that price include the tape measure?

 

--HC

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[wlaidlaw]

Wilson--

Does that price include the tape measure?

 

--HC

 

Howard,

 

I am afraid not. The special DIN compliant tape measure (also complies with European Low-Emissions directive EU24599-e/*1) is an extra £1,000. However it is also particularly good at measuring straight bananas and square potato chips.

 

Wilson

[ho_co]

Good reply! LOL!

[tashley]

Sergio--

First off, I think your English is quite good, but I do know the strain one goes through to get technical in a foreign language.

 

I agree completely with your analysis, in both your first and your second posts, and I agree with Alan's as well.

 

The reasons I approached the matter as I did were:

1) Tim's birdhouse is not in my mind a 'focus and recompose' situation;

2) You raised the geometry question quite succinctly;

3) In Tim's non-'focus-and-recompose' situation, the only place I see applicability of the focus plane vs subject plane relationship is at the sensor.

 

My math skills are quite challenged, and your post may have just completely misproved what I thought, but kindly and subtly! I will go back and evaluate my slow and tortuous grasp of the situation in the light of your immediate one.

 

Summary: As I see it, your input is directly related to why photographing a plane--say, a building wall--might show different focus at center and edge, simply because the edges are further than the center; and also to why if you focus on the end of the wall, the center is likely not to be sharp. Rotating the camera will move the new focus plane to intersect with the first plane, and will change the distance to objects in the first plane.

 

But also as I see it, in Tim's case of shooting the birdbox, the angle will have changed so little that the change in distance to the birdbox is negligible.

 

Back to you, guys! I know I may be missing something important here, and I'd love for you to point it out. After reading your second post a couple times and looking again at Alan's, I am becoming fuzzily aware that there is something that is at the moment just outside my grasp, Could I be more confused than I think?

 

 

In the matter of Tim's various lenses, both Jamie and I quoted Erwin Puts above. One of his assessments of the 35/1.4 implied that it was completely flat field. Later he compared it to the 35/2 and said the 35/2 had flatter field than the Summilux (which is to say, the Summilux' field isn't all *that* flat). And later still, he tested the Summicron (the winner against the Summilux, remember) against the Zeiss Biogon, and found that although he prefers the Leica lens overall to the ZM design, the Zeiss lens did have a flatter field than the Summicron.

 

So with the willingness of so many people to look at this issue, I think we've got the solution: The 35 Summilux is a great lens and has a very flat field for a lens of this speed, but particularly with a digital sensor (we never saw these complaints before the M8, did we?), it isn't as flat-field as we might want. The 35 Summicron is better in that regard but still not perfect. The 35 Biogon uses a far simpler design and is able to achieve the flattest field of the three, but at the expense of almost every other optical characteristic.

 

My respects to all. I hope I haven't misunderstood something, and I hope I've been helpful. I think Tim's set of 4-cornered birdhouses with the Summicron and Mark's of tea-bag packages with the Summilux support this assessment.

 

--HC

 

I agree with you exactly. My own observations are precisely this (though I don't have the biogon): the cron is less afflicted than the lux - and that was quite exactly what, several pages ago in this thread, I related the optical chappie from Solms as having said I would find.

 

It is further clear to me that Mark Norton is a great example of someone who at first could not reproduce these findings and was therefore in the 'I've got one that works' group, but that when he homed in on exactly what the issue is, he tested again and found that his lens exhbited this behaviour too. I'd place a charitable donation of moderate size on my ability to demonstrate this on any current model 35 lux or cron, ceteris (notably the RF alignment being correct) paribus. An exception may be Jamie's chrome version, which may have different manufacturing factors in play.

 

As for why so many people have not noticed it? It happens most at F2.8 and F4, not always used by any means. It is mostly visible in a fairly small area at the centre of the frame, and many of us use rules of thirds whether intentionally or not, so we tend to focus and recompose. When I trawl my wider portfolio of shots from Venice, those from the first day which are good are those with subjects on a third. Thereafter I was more circumspect with the lens, either stopping down more, pulling focus a little forward or, more usually, using something else.

 

I also think that what Sergio and Alan are referring to is the 'distance from the sensor' argument, which does explain why the slightly further away edges are in better focus. I don't think (and I am with you here) that it applies to any significant degree to the bird box example but short of planting four more trees and getting a bulk deal on the boxes, I can't prove it because my trigonometry sucks!

 

A final challenge. Can anyone spot what's wrong with this image: in other words, if you had taken it yourself, would you have thought it the product of a great lens with no real issues? Would you submit this to the picture editor of a glossy travel mag for a double pages spread?

 

http://tashley1.zenfolio.com/img/p399774702.jpg

 

Thanks to all. Jamie, watch your camera bag...

 

;-)

 

Tim

[egibaud]

Tim,

 

They are very professional, I could test everything I wanted, set me up a tripod, a target for shoting and time to analyse everything on my Macbook.

 

Ask for Marcos first floor http://www.casanovafoto.com/ tell you spoke with me, Eric, French guy from Tenerife.

 

Casanova Foto

Pelai, 18

08001 Barcelona

tel:93.302.73.63

fax:93.301.60.48

 

I hope you like the place and service.

 

Eric

 

Are Casanova good? I'm going to Barcelona tomorrow!

 

Just for reference, my first two returns were 35 lux, the one I have now is a 35 cron. I also tested in-store and it seemed ok, but more rigorous tests at home disagreed.

 

Keep well

 

Tim

[marknorton]

Well, I'm wondering to what extent this renders the 35/1.4 a basket case? We take a close look at the Leica lens which might be the default choice for fast, normal in the M8 world and find it wanting in normal, not untypical use.

 

It is, admittedly, one of the oldest lenses on the block; of the current line up, only the 90/f2.8 is older since the last revision, so it seems clear 11874 is overdue for a makeover.

 

We might want Leica to do exotics like a 28/1.4, 24/2, 16 f2.8 but with lenses like the 50/1.4 and 75/2 setting the pace, there's some catch-up elsewhere to do.

[sergiolov]

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Tim wrote

>

I also think that what Sergio and Alan are referring to is the 'distance from the sensor' argument, which does explain why the slightly further away edges are in better focus. I don't think (and I am with you here) that it applies to any significant degree to the bird box example but short of planting four more trees and getting a bulk deal on the boxes, I can't prove it because my trigonometry sucks!

 

A final challenge. Can anyone spot what's wrong with this image: in other words, if you had taken it yourself, would you have thought it the product of a great lens with no real issues? Would you submit this to the picture editor of a glossy travel mag for a double pages spread?>

 

Tim, last first. It depends on the art director's preferences, that is dramatic lighting, sunset light, etc,etc. I published hundreds of double page spreads on travel magazines with a quality lower of that of your image. (they usually prefer "strong " images)

 

Returning to the bird box question, I am in no way referring to the distance from sensor argument - (if you intend it that objects on the edges are farther from the sensor-everything on the focus plane should be in focus, independently from the distance to the sensor) I don't even consider the bird box shot as a way to explain the problem of the lens, that I agree from the first moment that is real and measurable. My opinion, many time expressed, is that with the correct lens adjustement it is possible to reach a reasonable compromise.

 

My point with the bird box is that your test made rotating the camera is not significative.

To avoid any mathematical reference , I hope this little drawing is clearer than my unsuccesfull try with written concepts. (With calculations, if the bird house is at 10 meters, rotating the camera it goes out of focus plane approx. half meter)

 

There are many question mixed in this thread, and, for that of changing sharpness across the field, have you taken a look to the MTF data of the lens?

 

Me too, waiting for Barcellona's masterworks.

 

Ciao.

Sergio

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[wparsonsgisnet]

OK, guys. Here goes:

 

L-o-t-s of shots, as follows:

flash, 1/250, handheld, iso 160, 486 filter --- from the jpegs --- resized for here.

 

1. 75 'lux at 1.4 and closest focus distance

2. 75 'lux at 1.4 and 5.5 feet

3. 50 'lux asph at 1.4 and closest focus distance

4. 50 'lux asph at 1.4 and 5.5 feet

5. 35 'lux asph at 1.4 and closest focus distance

6. 35 'lux asph at 1.4 and 5.5 feet

7. 24 asph at 2.8 and closest focus distance

8. 24 asph at 2.8 and 5.5 feet.

 

I have another set at f8 that is coming next.

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[wparsonsgisnet]

Here's a second set at f8, same deal;:

flash, 1/250, handheld, iso 160, 486 filter --- from the jpegs --- resized for here.

 

1. 75 'lux at f8 and closest focus distance

2. 75 'lux at f8 and 5.5 feet

3. 50 'lux asph at f8 and closest focus distance

4. 50 'lux asph at f8 and 5.5 feet

5. 35 'lux asph at f8 and closest focus distance

6. 35 'lux asph at f8 and 5.5 feet

7. 24 asph at f8 and closest focus distance

8. 24 asph at f8 and 5.5 feet.

 

These are somewhat sharper.

 

Typically, I would not be focusing at the closest distance, wide open. The first set shows why.

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[wparsonsgisnet]

The extra sharpness at f8 is both highly desirable and expectable.

 

I note from the first set that, although the 75 has problems with sharpness in the corners -- hey, this is 1.4 at a couple of feet! -- the 50 does pretty well at 1.4. Not too shabby.

 

What I like a lot is the second set. When I do close work, I use smaller openings. ALL of these lenses are good at the closest distance at f8.

 

I depended on the flash for the color balance. I looked at the 75 @ 1.4 in C1 and decided that the color balance was good.

 

What you see here are resized jpg's, as mentioned.

 

Hope you like the music ...

[sergiolov]

Sergio--

First off, I think your English is quite good, but I do know the strain one goes through to get technical in a foreign language.

 

I agree completely with your analysis, in both your first and your second posts, and I agree with Alan's as well.

 

The reasons I approached the matter as I did were:

1) Tim's birdhouse is not in my mind a 'focus and recompose' situation;

2) You raised the geometry question quite succinctly;

3) In Tim's non-'focus-and-recompose' situation, the only place I see applicability of the focus plane vs subject plane relationship is at the sensor.

 

My math skills are quite challenged, and your post may have just completely misproved what I thought, but kindly and subtly! I will go back and evaluate my slow and tortuous grasp of the situation in the light of your immediate one.

 

Summary: As I see it, your input is directly related to why photographing a plane--say, a building wall--might show different focus at center and edge, simply because the edges are further than the center; and also to why if you focus on the end of the wall, the center is likely not to be sharp. Rotating the camera will move the new focus plane to intersect with the first plane, and will change the distance to objects in the first plane.

 

But also as I see it, in Tim's case of shooting the birdbox, the angle will have changed so little that the change in distance to the birdbox is negligible.

 

Back to you, guys! I know I may be missing something important here, and I'd love for you to point it out. After reading your second post a couple times and looking again at Alan's, I am becoming fuzzily aware that there is something that is at the moment just outside my grasp, Could I be more confused than I think?

 

 

In the matter of Tim's various lenses, both Jamie and I quoted Erwin Puts above. One of his assessments of the 35/1.4 implied that it was completely flat field. Later he compared it to the 35/2 and said the 35/2 had flatter field than the Summilux (which is to say, the Summilux' field isn't all *that* flat). And later still, he tested the Summicron (the winner against the Summilux, remember) against the Zeiss Biogon, and found that although he prefers the Leica lens overall to the ZM design, the Zeiss lens did have a flatter field than the Summicron.

 

So with the willingness of so many people to look at this issue, I think we've got the solution: The 35 Summilux is a great lens and has a very flat field for a lens of this speed, but particularly with a digital sensor (we never saw these complaints before the M8, did we?), it isn't as flat-field as we might want. The 35 Summicron is better in that regard but still not perfect. The 35 Biogon uses a far simpler design and is able to achieve the flattest field of the three, but at the expense of almost every other optical characteristic.

 

My respects to all. I hope I haven't misunderstood something, and I hope I've been helpful. I think Tim's set of 4-cornered birdhouses with the Summicron and Mark's of tea-bag packages with the Summilux support this assessment.

 

--HC

 

Hi Howard,

rotating the camera after having focused the subject at the center is not so irrelevant. In my reply to Tim i presupposed a rotation of 17,5 deg, which causes the object to go away from the focus plane approx. half meter shooting from a distance of 10 meters. But I see now that he positioned the bird box on corners (diagonals). In this case, the real rotation is 23deg, and the shift from focus plane is nearly 1 meter. To this add 2 considerations:

The bird box is probably a 100% crop, and this reduces the usable depth of field approx.2 stops; the MTF data for this lens shows strong variations of resolution across the field, and the center is NOT the best area.

Complications, complications of the digital age.....

Sergio

[bsmith]

I shot my 35 lux at 1.4 , 2, 2.8, 4.0, 5.6 on a tripod w/ self timer, from 5 feet and 15 feet . Set up staggered boxes with type. The focus NEVER changed on the box I focused on. The DOF did increase as f stops increased, but the front box I focused on, ALWAYS remained tact sharp. I have a black ASPH 35mm 1.4 uncoded

[marknorton]

Sergio, I agree the MTFs are interesting.

 

The MTFs when the lenses are wide open exhibit the expected image fall off towards the edge but stop down and you get this wild roller coaster for fine detail, just look at the 35/1.4 at f2.8 and the Nocti at f2.8. Then compare that with the 28/2 and 75/2. Even the 50/1.4 exhibits it to some degree.

 

It does seem that Leica's more recent lens designs tame these wild variations in micro-contrast but making a short focal length lens faster than f2 is clearly a challenge.

 

Seems clear to me now. You buy the 35/1.4 for the speed but the 28/2 is likely a better all-round lens.

[wparsonsgisnet]

Here is an example of the 35 'lux asph at about 3 feet, taken this afternoon:

iso 160, 1/750, f8, 486 filter, processed with Tuned2 profile.

I have chosen to have the highlights blown out in this particular pic.

 

I woudl say that the left side of the picture is about 1 foot behind the focus, which was at the right-hand juncture of the red and green foil.

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[sergiolov]

Should anyone be interested, I put on my website a resolution chart test of my cron 35 asph showing that it stays perfectly in focus from F2 to F8 on the complete field, that corners are less sharp full open but get better stopping down, and that center resolution of the lens outresolves the sensor from F2 to F8. ISO 320, IR filter, fluorescent light.

Focused on center cross. Each image is jpg from dng, full resolution.

 

This is the link:

 

SUMMICRON 35 ASPH FOCUS SHIFT TEST

 

 

Sergio

[rosuna]

Hope you like the music ...

 

You like Bach music... a lot of Leonhard and Gould discs. I love this music too. For many years, I was a maniatic and compulsive buyer and collector of classical recordings. I would recommend Ivo Pogorelich's recordings of the English Suites (Deutsche Grammophon).

[wparsonsgisnet]

You like Bach music... a lot of Leonhard and Gould discs. I love this music too. For many years, I was a maniatic and compulsive buyer and collector of classical recordings. I would recommend Ivo Pogorelich's recordings of the English Suites (Deutsche Grammophon).

 

Thanks for the suggestion, Rubén. I'll look for Pogorelich's E. Suites.

[ho_co]

Hi Howard,

rotating the camera after having focused the subject at the center is not so irrelevant. In my reply to Tim i presupposed a rotation of 17,5 deg, which causes the object to go away from the focus plane approx. half meter shooting from a distance of 10 meters. But I see now that he positioned the bird box on corners (diagonals). In this case, the real rotation is 23deg, and the shift from focus plane is nearly 1 meter. To this add 2 considerations:

The bird box is probably a 100% crop, and this reduces the usable depth of field approx.2 stops; the MTF data for this lens shows strong variations of resolution across the field, and the center is NOT the best area.

Complications, complications of the digital age.....

Sergio--

Once again, I agree with you. Your diagram also makes your point clearly. I approve also the recomputation of angle based on using the corners instead of the edges of the frame. Your points are all valid, and I hadn't thought to diagram them as you did. You bring a rigor to the matter that I hadn't even thought to do.

 

And I think I finally grasp what you have been trying so diligently to show me (): Even though the camera is still 10m from the birdhouse, because its focal plane is rotated, the focus plane in object space is also shifted. (Gee, this is hard to express even though I think I know English pretty well!--I mean, of course, the American version of the language.)

 

I believe my calculations done at the sensor (hopefully accurate) show about the same as yours, even though I went at the matter from a different point of view. And I believe that I've shown that the focus shift here would be pretty much within the depth of field of the lens, as your diagram also implies. All this is interesting and useful background to Tim's problem.

 

You've raised the question of my choice of circle of confusion. I think the CoC I used is acceptable for a 100% enlargement, but I didn't look deeply into this assumption because CoC is dependent on so many factors; if you want to choose a smaller one, I have no objection. You are correct that it is an important aspect of the computation.

 

I don't agree that the 35/2's MTF charts show poor definition in the center of the image. Although someone could make that argument for the 35/1.4, I think trying to read one datum out of an MTF curve is a futile task.

 

You are absolutely correct that these are "complications of the digital age": We now have the ability to do our own lens tests on our computer screens just seconds after taking pictures. But you know what, guys? These are the same lenses that were among the best of the world 5 years ago, and they still are.

 

We've got a completely flat sensor now, which puts different demands on lenses from film.

 

We have a smaller effective field of view because of the crop factor, and that also puts new demands on the lenses. (Yes, we're using only the central part of the light cone, but we are also blowing up more.)

 

 

So here's where we stand in my opinion:

 

Tim discovered that his 35/1.4 had more curvature of field than he liked. The 35/2 is better, but he would like better yet.

 

Okay. Now we all know that. So let's leave it. As Mark says, the 35 Summilux is now an 'older' design. But as Mark also said in his teabag shots, it's still pretty impressive.

 

This has been a wonderful exercise in discovery. We've brought the theoretical to bear (MTF graphs), we've approached it mathematically (geometric diagrams), and we've approached it photographically. It has been fun, and we have all seen that Tim is right.

 

That doesn't change the fact that these lenses are the best on the market. If they're not better by a great enough margin, buy the competition--because in one way or another, it truly is competitive.

 

Guys (and Cyndi and Karen et al)--

The great advantage of Leica has always been that you don't have to shop around for 'which one of these is better.'

 

In the Leica line the rule still holds: Choose the lens for its speed and field of view. They are all compromises, but the compromises Leica makes all produce lenses that generate that 'Leica look.'

 

So I agree with Lars--we can keep learning about these lenses, and we will. But the best way to do that is to take them to Barcelona and take pictures.

 

With deep respect to all for the rigor and passion evinced here,

--Howard

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Hallo,

Look here: Interesting Leica gear

[ho_co]

Personally, I think we've done about all we can on this matter.

 

Nonetheless, I would make the following request:

 

Let's make a single type of test that is comparable to Tim's. The reason is that with older Leica lenses you could clearly see center/field/edge changes with prints up to 16 x 20, for example. All of today's lenses are superb compared to what used to be the case. Since Tim illustrated his problem in one way, all the other tests should be performed in the same way simply for clarity.

 

Check out his birdhouse photos. If Tim was at 10 feet, find an object at 10 feet for your test. (Something as detailed as Mark's teabox would be perfect.) Use the rangefinder to focus on it. WITH THE CAMERA ON A TRIPOD, change the pointing of the camera to put the same object into each of the four corners in turn.

 

Post the result.

 

The kind of tests Sergio and Bill have done prove that these lenses are excellent, but they DO NOT TEST Tim's contention. Their images show that there's very little difference over the lens's field of view; but the eye is misled by seeing a gradual deterioration as one moves outward over the frame. Not all record labels are equally clearly printed. Choose a single object and put it at the five locations mentioned.

 

Please, just try it. (I know it's easy for me to say when it's 75 F in Houston; but wait for a comfortable day and then try it.)

 

Please don't take offence. I'm not saying, "You did it wrong." All the tests you've done are good and illustrate the quality of the lenses. But they do not duplicate Tim's circumstances. As Sergio has clearly pointed out, turning the camera makes a difference. And that is what Tim did.

 

Just a request with the idea of putting the wrap on the matter.

 

 

Respectfully,

--HC

[rosuna]

I have the 35mm lens and I will test it.

I expect to get similar results to those of Bill. If that is not the case, I will be worried.

The sharpness plane moves, but the DoF keeps the subject in focus. That's what I expect to see. Of course, the DoF is a conventional parameter.

The 35mm Summilux ASPH from 1994 has some curvature of field, but it cannot be so severe. This lens is a wideangle superluminous lens, and that is a challenger for the designer. I like the classic look and fingerprint of this lens.