M9 + lens max sharpness (resolution + contrast)

[k-hawinkler]

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I have read the thread: When does diffraction kick in on M8.2? http://www.l-camera-forum.com/leica-forum/leica-m8-forum/80523-when-does-diffraction-kick-m8-2-a.html

 

Assuming good lighting conditions, my impression is that the maximum sharpness, that can be obtained with an M9 and Leica lenses, depends on equipment being in optimal adjustment, focusing correctly, the size of the M9 image sensor pixels, lens imperfections, diffraction, f-stop number used, etc...

 

So, here are my questions:

 

1) Provided M9 + subject don't move, what f-number yieds the sharpest images for different Leica lenses, from 16-18-21mm to 135mm?

 

2) How much variation is there from lens to lens?

 

3) What are good (photographic effects) reasons to use even larger f-numbers?

 

The last question is intended similarly to the question about purpose of using wide open apertures. Answer, used for subject isolation and available light photography.

 

Thanks for your help.

[UliWer]

Ooops, there are so many Leica lenses which makes it almost impossible to answer all your questions.

 

I'll just try:

 

1. and 2.. With current - aspherical - lenses you may exspect their maximal sharpness, contrast and resolution at about f1:4, may be even at f 1:2.8. Though you won't see real differences in performance if you stop them further down until 1:8. Older lens designs need to be stopped down further - maybe until f1:8 to gain their maximum. The present 50luxAsph could be at it's maximum already at 1:2,8, its non-asph. precedessor certainly needed 1:5.6 or 1:8. Perhaps you find more information in the Leica Handbook of Puts/Laney, in Erwin Puts' tests on his website or in ReidReviews.

 

3. Depth of field (or is it depth of focus???). If your picture needs sharpness in a very large range you might opt to stop down to 1:16, even if you loose a little bit of resolution. Low apertures are especially helpful or even necessary if you make close-up or makro shots.

[BrianNakata]

k-hawinkler,

 

Download this and read: http://us.leica-camera.com/assets/file/download.php?filename=file_1768.pdf

 

It's slightly dated as not all the newest lenses are described, but it's probably worth a read for you.

 

I do have to say, however, that you appear to obsess over sharpness. Do you intend on always using a tripod with an M9?

 

Brian

[carlmuck]

Ooops, there are so many Leica lenses which makes it almost impossible to answer all your questions.

 

I'll just try:

 

1. and 2.. With current - aspherical - lenses you may exspect their maximal sharpness, contrast and resolution at about f1:4, may be even at f 1:2.8. Though you won't see real differences in performance if you stop them further down until 1:8. Older lens designs need to be stopped down further - maybe until f1:8 to gain their maximum. The present 50luxAsph could be at it's maximum already at 1:2,8, its non-asph. precedessor certainly needed 1:5.6 or 1:8. ....

 

 

Uli, full aperture on the fastest lenses ('lux and 'cron) is NOT the sharpest, or best contrast or best resolution. That is between f/4 and f/5.6 on all, it just physics...as well corrected as the modern lenses are, there are just too many photons bouncing around at the widest apertures to corrall them all for the best focus.

 

c.

[250swb]

Uli, full aperture on the fastest lenses ('lux and 'cron) is NOT the sharpest, or best contrast or best resolution. That is between f/4 and f/5.6 on all, it just physics...as well corrected as the modern lenses are, there are just too many photons bouncing around at the widest apertures to corrall them all for the best focus.

 

c.

 

I may be wrong but I think Uli was alluding to the traditional way to describe aperture, so f1:4 is f4, f1:2.8 is f2.8 and etc. f1.4 would therefore be f1:1.4

 

Steve

[UliWer]

I may be wrong but I think Uli was alluding to the traditional way to describe aperture, so f1:4 is f4, f1:2.8 is f2.8 and etc. f1.4 would therefore be f1:1.4

 

Steve

 

Yes, of course! Sorry for causing misunderstandings!

 

In their Leica Pocketbook (7th Edition,2001) Laney and Puts give the following dates of optimal apertures for the current lenses which were already on the market at this time:

 

28 Summicron: 3,5

35 Summicron: 2.8 - 4

35 Summilux: 2 - 2.8

50 Summicron: 4

90 Apo Summicron: 2.8

135 Apo Telyt: 4.

[wparsonsgisnet]

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Diffraction kicks in about f8. You can see it on the viewing screen after this. Do a search; there's a long thread about it. Look for the "f8 last stop for gas" thread.

 

For sharpness and all-around usefulness, I use the 35 'lux-a. Great sharpness -- everywhere. It's on my M9 most of the time.

[carlmuck]

I may be wrong but I think Uli was alluding to the traditional way to describe aperture, so f1:4 is f4, f1:2.8 is f2.8 and etc. f1.4 would therefore be f1:1.4

 

Steve

 

Uli, sorry, I saw the colons and read a period...

 

c.

[george_b]

In addition, are the depth of field (dof) marking on the lenses as 'generous' on the M9 compared with an M6 (film camera)? Or is the dof smaller? With an M6 I often set at say f8 and put the infinity focus at the f8 mark to get maximun dof. Does this vary with different lenses?

[UliWer]

If you follow the link in the original posting to the other thread you'll find some very interesting explanations by Lars Bergquist about the DOF-markings on the lenses.

[stunsworth]

In addition, are the depth of field (dof) marking on the lenses as 'generous' on the M9 compared with an M6 (film camera)?

 

The DOF markings were overgenerous with a film M, and even more so with a digital M - I have an M8, not an M9.

[jaapv]

The DOF markings are based on the thick film of the 1930-ies and an enlargement to 6x9 cm. Since then things have changed a bit... With an 18x24 cm print and a sensor camera I would advise to go two stops down in the DOF markings on the M9 and about the same, maybe 1/2 a stop less, on the M8. On film you might get away with a correction of just one stop. This is not exact science, but based on the perception of the viewer and the requirements in sharpness of the subject matter, not to mention the judgment of the photographer. The reason the markings were not changed over time is said to be that lens manufacturers feared that the popular perception would be that lenses would "have lost quality" as soon as the public would see the new scale. It seems to me that this is an apocryphal reason. The real reason, I think, is that it is just a standard and users must use the DOF scale as suits them best, so it is most practical not to change.

[yanidel]

Maybe a naive question, but why then Leica designed asph lenses that are at their optimum around F2.8-4.0 ? The DOF on the M9 when shooting subjects at 3-5 meters becomes shallow that it would warrant shooting more in the F5.6-F8.0 to take less risk on focused plane. Same issue with landscapes if you want to include a foreground F2.8-F4 will get you more out of focus area than F8.

So did Leica design the Asph lenses with mostly low light capability in mind ?

[k-hawinkler]

Many thanks for the excellent feedback and references. Aside from the feedback, I found these references easily accessible and most useful for the purposes of my questions. Thanks for the pointers.

 

F8: last stop for gas

Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks

Erwin Puts, TAO of LEICA

Leica M-Lenses, Their soul and secrets by Erwin Puts

 

Please, let me summarize my current understanding of the issue as follows. Provided M9 and lens are in perfect adjustment, the following 3 things have an influence on the maximal sharpness, contrast and resolution that can be obtained, namely:

 

• sensor properties, especially pixel pitch of 6.8 micron, lack of AA filter,...

• the optical system, i.e. the lens with its built-in imperfections and

• diffraction.

 

As has been pointed out, optical performance of Leica lenses typically improves from small to mid range f-numbers and is actually of such high optical quality that for f-numbers just larger than 8 the deteriorating effects of diffraction are noticeable. So, what I had in mind is a table, similar to the one UliWer started, that lists the optimal apertures for different Leica lenses. I'll add some lenses of potential interest to me to his list. I'll list the optimal apertures for some of the lenses as given in the last reference above and in the Tao of Leica.

 

16-18-21 Tri-Elmar-M ASPH: 8

21 Elmarit-M: 5.6

21 Elmarit-M ASPH: 4-5.6

21 Summilux-M ASPH: 4

24 Elmarit-M ASPH: 4

24 Summilux-M ASPH: 4-11

28 Elmarit-M: 4

28 Elmarit-M ASPH: 5.6

28 Summicron: 3,5

28 Sumicron-M ASPH: 4

35 Summicron: 2.8 - 4

35 Summicron-M: 8

35 Summicron-M ASPH:

35 Summilux: 2 - 2.8

35 Summilux-M: 8

35 Summilux-M aspherical

35 Summilux-M ASPH: 4

50 Summicron-M: 4

50 Summilux-M: 8

50 Summilux-M ASPH: 1.4-8

50 Noctilux: 5.6-8

50 Noctilux-M: 4-5.6

50 Noctilux-M ASPH: 1.4-8

28-35-50 Tri Elmar-m ASPH: 5.6

75 APO Summicron-M ASPH: 2-8

75 Summilux-M: 2-8

90 Tele-Elmarit-M: 5.6-8

90 Elmarit-M: 5.6

90 Summicron-M: 5.6

90 APO Summicron-M ASPH:: 2.8

135 Tele-Elmar:

135 Tele-Elmar-M: 5.6

135 Elmar-M:

135 Elmarit-M: 5.6

135 Apo Telyt-M: 4.

 

This table is incomplete and no doubt has some errors in it. It also would benefit from a source quotation for each data point. Nevertheless, I am certainly impressed that optimal performance is typically reached at fairly low f-numbers and that only DOF considerations would one lead to use smaller apertures.

 

Being new to rangefinders and Leica this has been an interesting exercise. I am mostly interested in available light and hand-held photography and use occasionally a tripod for landscapes. However, I would like to make photographic choices based on hard information and not misunderstandings or worse.

 

Thanks again for all the feedback and please correct any mistakes I made or misunderstandings I have.

[jaapv]

Maybe a naive question, but why then Leica designed asph lenses that are at their optimum around F2.8-4.0 ? The DOF on the M9 when shooting subjects at 3-5 meters becomes shallow that it would warrant shooting more in the F5.6-F8.0 to take less risk on focused plane. Same issue with landscapes if you want to include a foreground F2.8-F4 will get you more out of focus area than F8.

So did Leica design the Asph lenses with mostly low light capability in mind ?

It is not a design choice, it is physics. Leica optimizes the maximum aperture to enable users to shoot wide open, but the deterioration of the image at smaller apertures is determined by diffraction, brought on by the small diameter of the diaphragm, which no designer can change.

[yanidel]

It is not a design choice, it is physics. Leica optimizes the maximum aperture to enable users to shoot wide open, but the deterioration of the image at smaller apertures is determined by diffraction, brought on by the small diameter of the diaphragm, which no designer can change.

ok thanks, so it basically means that performance at F8.0 remains similar between asph and pre-asph lenses because of physics limitations and that large improvements were only possible at larger apertures in the asph range ?

[jaapv]

Yes- but because the performance wide open has improved, sometimes dramatically, the relative difference at 8.0 or smaller has become more noticable

[yanidel]

Another point, maybe a bit academical, but always thought you get better in practice when you understand the theory behin.

In a link provided on top, it is said that markings on the lenses are not accurate, that one should adjust by two stops on the M8/M9. To illustrate, if I want a plane in focus to infinty with a subject a 5 meters, the marking of the 35mm Lux Asph tell me that I need to stop down to F8. Add two stops to that, and I would really need F16 where diffraction would kick in significantly and result in loss of sharpness and contrast.

So in conclusion, if you shoot mainly 35mm in mid ranges (3-7 meters) and want extensive DOF, you will not be able to use the Asph lenses at their very best. Yet for wide open shooter (like me), it is a dream

[jaapv]

That is right, I usually try to shoot at 5.6 max, unless, of course, I want deep DOF. That is what makes the loss of 1/8000th so annoying. It was a great feature.

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[ChrisC]

..... makes the loss of 1/8000th so annoying. It was a great feature.

 

Really? That particular M8 'free lunch' came at the expense of a more stressed and suspect shutter than the M8.2 shutter, and noticeably more noise. For me, saddling M8s with that shutter was one of Leica's dafter moves. There again; I'd gladly take 1/2000 top speed if accompanied by whisper quietness.

 

.............. Chris