Noctilux myths

[TJV]

I think there are three reasons:

- film vs. sensor flatness: film will bend inwards the film gate slightly. Which might cause a film-adjusted lens with very shallow DOF to back-focus on a digital camera, I guess. Obviously more in the center of FOV.

- it is much, much easier with a digital camera to test a lens. And, the Noctilux has become much more popular with the M8. I think some of the issues discovered today with the M8 existed in the past but remained undiscovered.

- with the crop factor, the DOF decreases. That is, you are effectively dealing with 65/f1.0 and 100/f1.4 lenses on the M8 when considering Noctilux and 75 Summilux. Harder to focus on M8. I would guess that many Nocti and 75 Summilux film users used .85 or .91 viewfinders, before the M8 hit the market.

I don't think film thickness is important.

Best,

Roland.

I see you bet me too the post! Slightly different points but you've touched upon my idea of the crop factor. I guess it's a bit like the DOF markings of lenses - they aren't accurate with 35mm film to the extent they were with 8x10" plates because you're enlarging and therefore emphasing any otherwize negligible focus errors whey you take the 35mm neg to the equivelent 8x10" size. Don't think I'm making myself clear, hope I'm understood?

 

[peter_n]

I would guess that many Nocti and 75 Summilux film users used .85 or .91 viewfinders, before the M8 hit the market.

I use a 0.85x M with a 1.25x magnifier with my Noctilux. That gives me an effective 1.0x camera. I need it especially with close-ups.

 

[Finder]

You can say that and you will be wrong SA has more than one consequence.

Due to spherical surface of the lens, the point of best focus is different with full opening and with peripherial areas closed out. Check out e.g. this article.

OK, I went to a book, and focus does shift.

 

[MikeL]

I think some folks expectations for a sharp photo at 100% on a screen monitor when shooting it at f1.0 are a bit high. The noct is all about vignette anyways, so who cares about a little backfocus?

Worst myth
It gets softer when stopped down. I know where a big part of this myth comes from, but it hasn't been my experience. Maybe my expectations for 35mm are lower and it's real and all, but I just don't see it. I don't pixel peep either, since most of my photos suck at both 4x6 and 8x10.
f4 or f5.6

 

[varjag]

Finder, sorry - I made a typo when linking, fixed that now.

Anyway, for me the issue is more of a book theory than practical problem. Maybe because I don't really shoot all that much wide open at closest focus distance.

 

[john_s]

If you think that Erwin Puts is capable of measuring a lens, and if you think that he wouldn't reveal a defect unless it were true, then look at his article on the Noctilux in which he lists a resolution decline at f2 compared to the resolution at f1.

Even if your Noctilux is "sharp enough" around f2 or f2.8, all of your depth of field is behind the focused distance. This is very often not a bad thing, but you need to be aware of what it's doing.

 

[Finder]

Finder, sorry - I made a typo when linking, fixed that now.

Anyway, for me the issue is more of a book theory than practical problem. Maybe because I don't really shoot all that much wide open at closest focus distance.

Ditto. I don't think a Leitz lens would be so bad the SA was cause such a large shift where it would be noticable. I have use a few soft-focus lenses and never noticed a focus shift.

 

[Gabriel M.A.]

Hello all,
still waiting on my Noctilux and have been reading some people complaining (on stupid digi pixel obsessed forums) about back focus issues.

Don't get me started.

I don't have a Noctilux, but I do have the Canon 50mm f/1.2 LTM, and I can focus my subjects precisely with my M8. I have heard of other people having issues with the same lens when it comes to focusing.

So a slightly miscalibrated lens and/or rangefinder (i.e. the one in the M8) can add up and contribute to misfocusing with a particular lens.

 

[TJV]

Out of interest, I've got a 60mm slim B+W filter to put of front of my Nocti when it arrives. Had a thought that when mounted it may not let the hood be extended. Does anyone know if this is the case? Also, would a slim filter introduce any (more) vignetting? Was thinking this could be another quirk of such an extreme lens design.

 

[Freakscene]

would you have 'front' focus then? because the buttons are more in focus than the face?

I have here what's called 'movement'. On a tripod with all my Ms my Nocti is spot on at F1. The issue here is that at 1m and wide open depth of field is shallow enough that if you have to focus and recompose, what you focused on originally may not be in focus anymore due to the camera movement. If it really needs to be sharp, the best way, hand held, to keep everything sharp is to compose in a way that puts the point you are focusing on under the RF patch in the VF. This is 1/30 @ f1 at EI 1600 btw.

Marty

 

[furcafe]

No, the filter itself will not produce any additional vignetting.

Also, would a slim filter introduce any (more) vignetting? Was thinking this could be another quirk of such an extreme lens design.

 

[furcafe]

Per Puts's article, the focus shift is real but doesn't occur when shooting @ f/1, & a sizeable # of Noctilux users tend to use their lenses wide-open & will never notice it (this is the opposite of the new Zeiss 50/1.5 Sonnar ZM, @ least the initial version, which was not optimized for shooting wide-open). I haven't kept up type of focus shift the folks on the "Leica forum" (& I don't know which Leica forum we're talking about), but it shouldn't be confused w/misfocusing that's caused by improperly calibrated lenses & bodies, which is a potential problem w/all M bodies, but is much more easily discovered w/the M8.

If you think that Erwin Puts is capable of measuring a lens, and if you think that he wouldn't reveal a defect unless it were true, then look at his article on the Noctilux in which he lists a resolution decline at f2 compared to the resolution at f1.

Even if your Noctilux is "sharp enough" around f2 or f2.8, all of your depth of field is behind the focused distance. This is very often not a bad thing, but you need to be aware of what it's doing.

 

[Nemo]

If you think that Erwin Puts is capable of measuring a lens, and if you think that he wouldn't reveal a defect unless it were true, then look at his article on the Noctilux in which he lists a resolution decline at f2 compared to the resolution at f1.

That is due to focus shift, caused by spherical aberration. Erwin Puts then makes new calculations correcting focus, and he gets a new table of resolutions. He is very careful in testing lenses, and his comments are accurate and insightful.

 

[john_s]

......... Erwin Puts then makes new calculations correcting focus, and he gets a new table of resolutions...........

Right. But the rangefinder user who takes pictures is not in a position to take advantage of the new table of resolutions. The ideal would be a mount that altered focus distance as aperture was altered, but that would be difficult to realise. A real nightmare for the designers no doubt.

The Noctilux is great at f1! Leave it at that.

 

[iridium7777]

thanks for the answer, kinda what i figured that unless you're focusing on infinity you don't have much room for mistakes.

would you have 'front' focus then? because the buttons are more in focus than the face?

I have here what's called 'movement'. On a tripod with all my Ms my Nocti is spot on at F1. The issue here is that at 1m and wide open depth of field is shallow enough that if you have to focus and recompose, what you focused on originally may not be in focus anymore due to the camera movement. If it really needs to be sharp, the best way, hand held, to keep everything sharp is to compose in a way that puts the point you are focusing on under the RF patch in the VF. This is 1/30 @ f1 at EI 1600 btw.

Marty

 

[x-ray]

For what I know, german lenses are designed to be sharp from the start while japanese lenses ( Nikkors for a fact) are sharpest stopped down.

Back then, those differences we're what defined Japanese VS. German lenses. Today I guess things changed.

I've never heard this and never observed this in 40 years and shooting a hundred + lenses in critical work. I've never seen any lens, Leica or nikon that doesn't improve one or two stops down. The reason is the spherical surfaces can't be ground as precisely at the edges particularly in larger lenses. Stopping it down uses the center and more precisely ground part of the lens. The Germans have no magic in optical design and construction.

 

[Ororaro]

I've never heard this and never observed this in 40 years and shooting a hundred + lenses in critical work. I've never seen any lens, Leica or nikon that doesn't improve one or two stops down. The reason is the spherical surfaces can't be ground as precisely at the edges particularly in larger lenses. Stopping it down uses the center and more precisely ground part of the lens. The Germans have no magic in optical design and construction.

Of course I've never seen a lens that's sharpest wide open and declines as the f stops are closed down! I'm not that much of a Clown altough I don't have problems with being one when I deserve it!

I was talking about the older lenses up to the 90's or so. Apparently, the german engineered lenses we're aiming for sharpness and high contrast right from the start while Japanese lenses we're going for another philosophy, less contrasty.

All the old charts tend towards this. But I am not saying I am right or wrong. As a matter of fact, I love the Summilux 35 pre-asph and I'm crazy for the summarit 5cm, Both lenses that contradict whhat I'm saying above.

 

[Finder]

I was talking about the older lenses up to the 90's or so. Apparently, the german engineered lenses we're aiming for sharpness and high contrast right from the start while Japanese lenses we're going for another philosophy, less contrasty.

The argument is that Germans optimized their lenses for contrast (acutance) and the Japanese for resolving power. You can optimize a lenses for one or the other, but not both at the same time. This "fact" I usually heard from owners of German optics. You may find this is an urban myth. I have not found any such difference between the place of origin for optics.

BTW, I heard the same thing as you and also in the past tense. Except I first heard it in the early 1980's.

 

[furcafe]

I think you guys both have it sort of backwards. I believe the conventional wisdom was that in the 1st years after WWII, when technology only permitted lenses to be optimized for either high resolution *or* high contrast but not both, Leitz & other German companies tended to engineer their lenses for more resolution/microcontrast, whereas Nikon, following the precedent set by the German Zeiss Corp. before WWII, &, later, other Japanese companies generally optimized their lenses for higher overall contrast/accutance for more "snap." Nowadays, it's possible to have both, so there's been a convergence of optical philosophies, probably since the 1970s.

The argument is that Germans optimized their lenses for contrast (acutance) and the Japanese for resolving power. You can optimize a lenses for one or the other, but not both at the same time. This "fact" I usually heard from owners of German optics. You may find this is an urban myth. I have not found any such difference between the place of origin for optics.

BTW, I heard the same thing as you and also in the past tense. Except I first heard it in the early 1980's.

 

[Finder]

Nowadays, it's possible to have both, so there's been a convergence of optical philosophies, probably since the 1970s.

You still have an acutance/resolution problem and designers have to figure out where to fall between the two - but it has little to do with the photographer as most people can never tell and MTF analysis brings manufacturers closer together at where the optimum point is. Today there are simply better tools to make better lenses. I doubt there were never optical "philosophies." Lens manufacturers have always tried to make the best lenses possible within the limitations given them.