50Noct, luxasph, Zeiss character and focus

[Ben Marks]

Interesting. I was able to adjust my M8 so that it works with one set of lenses well at all apertures and distances. They include:

28/2.8
35/2
50/1 (wide open)
50/1.4 Asph
50/2
50/2 Planar
75/1.4
90 tele-elmarit

So: pretty good working kit.

The following lenses just won't play nice:

C/V 28/1.9
50/2 Hexanon
90 Apo Asph
135/2.8 (w/goggles)

These tend to focus behind the indicated area. I will send them off to be tweaked to the extent possible at some point when I can bear to be parted from the camera. Interestingly, I just got a new (to me) M5 and all of the above lenses focus perfectly on it. I can only assume that tolerances for film are looser than the tolerances for digital.

Ben Marks

[sean_reid]

Originally Posted by Jamie Roberts

Jack, I so agree on the framelines. Though the 75 is great, I'm surprised at how much using it is coloured by the weirdness in the framelines there. I don't have this issue with other lenses, just the 75.

So hopefully the M9 will rectify this

I'd like to see the 75 mm frame lines set at 1 - 1.5 meters, by default or as an a la carte option.

Cheers,

Sean

[carstenw]

I double, triple and quadruple that, for all my focal lengths. Although I often shoot near the near limit, I would *much* prefer a compromise which makes it more accurate overall, rather than more accurate only at the near limit.

[Eoin]

Originally Posted by michaelstokes

Eoin, what method/process did you use to check the focus?? I have a 35mm and 50mm Lux that I would like to check.

Very simple, take the very best and most complex lens Leica make, 50 Summilux Asph, mount it on the camera and go out side and shoot for 5 minutes. Look in disbelief at the LCD screen, scratch your head in wonder, shoot for a further 5 minutes taking duplicate pictures of eveything at varying apertures and distances first picture perfectly alligned in the VF and the next turning the focus ring 2-3mm back to closer focus. Go back inside and view on screen. Result.... every image taken with perfect allignment looks like I shot it through a milk bottle and every one I tweeked the focus ring looks like it came from a €2500 lens. Put your head in your hands in disbelief and wonder if your going to be loosing your camera for a further 6 weeks or more over the christmas period while these people have to redo the job they should have checked before the lens left the factory. I'm as sick as a parrott over this at the moment, please forgive my sarcasm.

No real test needed,

[carstenw]

Here is a portrait to give you some patience to wait it out:

L1030014.jpg

[pelikan1931]

... and here is another one

[Eoin]

Carsten, I don't know which is more scary....my back focus or your subject.

[carstenw]

Eoin, this lens is a dream. Hang in there. With the announcement of the FF M9, it will be the best lens ever made.

[Dan States]

Originally Posted by Jamie Roberts

Yes, so if they're all actually front-focussing wide open close up it sounds to me like the RF needs a tiny tweak (again, the Nocti should be bang on at f1.0, if a little soft).

All warnings here apply: YMMV etc... I'd let DAG in the US or Kindermann in Canada have a look and let them fix it.

I have to say that having all my M lenses act predictably means I have better low-light fast focus than any AF system I've ever tried.

Jamie, wide aperture front focusing (focus point is closer to the camera than intended) is typical of the lenses mentioned above. (Minus the 50 ASPH which I have not owned) All the lenses will shift focus outward as they are stopped down.

The Noctilux and the Sonnar are two of the most dramatic examples of focus shift. The Sonnar will shift the focal plane dramatically between f1.5 and 2.8. For me it made the lens too unpredictable for true wide aperture use.

The Noctilux will focus shift just like the Sonnar, but not nearly as much. If you are making enlargements from film it's unlikely you will ever notice this tendancy. On digital the ability to create huge magnifications combined with the 1.33 crop factor means the old Noct will not compare well with standard speed lenses.

All the threads recently about self adjusting your RF have muddied the waters for many users. Folks, there is NO WAY to eliminate focus shift. It is apparent in BOTH SLR and RF systems and is part of the trade offs in using high speed lenses. Adjusting your lens to focus perfectly at full aperture will only mean back focus at smaller apertures.

If you can't stand this tendancy I suggest lenses like the Summicron or Planar 50's. Their plane of focus is dead solid at all apertures.

Some other focus shifting lenses I have owned:

Voigtlander Ultron 28, Nikon 17-35, Nikon 35F1.4, Contax Sonnar f2 and my Summicron R, first version.

Best wishes
Dan

[DaveB]

Originally Posted by carstenw

With the announcement of the FF M9, it will be the best lens ever made.

Now stop that!

[tom0511]

Originally Posted by Dan States

Jamie, wide aperture front focusing (focus point is closer to the camera than intended) is typical of the lenses mentioned above. (Minus the 50 ASPH which I have not owned) All the lenses will shift focus outward as they are stopped down.

The Noctilux and the Sonnar are two of the most dramatic examples of focus shift. The Sonnar will shift the focal plane dramatically between f1.5 and 2.8. For me it made the lens too unpredictable for true wide aperture use.

The Noctilux will focus shift just like the Sonnar, but not nearly as much. If you are making enlargements from film it's unlikely you will ever notice this tendancy. On digital the ability to create huge magnifications combined with the 1.33 crop factor means the old Noct will not compare well with standard speed lenses.

All the threads recently about self adjusting your RF have muddied the waters for many users. Folks, there is NO WAY to eliminate focus shift. It is apparent in BOTH SLR and RF systems and is part of the trade offs in using high speed lenses. Adjusting your lens to focus perfectly at full aperture will only mean back focus at smaller apertures.

If you can't stand this tendancy I suggest lenses like the Summicron or Planar 50's. Their plane of focus is dead solid at all apertures.

Some other focus shifting lenses I have owned:

Voigtlander Ultron 28, Nikon 17-35, Nikon 35F1.4, Contax Sonnar f2 and my Summicron R, first version.

Best wishes
Dan

Dan ,
I think its clear the focus shift is something which can not be prevented by adjusting/calibrating a lens or a rangefinder.
Its just important to know about it and to have the lens and rangefinder calibrated, that it works/focuses at the wanted f-stop. In case of Noctilux and Sonnar it would be for most people wide open (I guess).
As far as I understand the 50asph does not suffer from focus-shift-so I hope that at least that lens would be usable at all f-stops once its calibrated/my M8 is calibrated.
If this is the case we could use the "focus-shift-lenses" just for wide open photography (or correct manually still wantig to shoot further closed down) and use lenses like the 50/1.4asph for all other f-stops.
Nowpeople could say does it make sense to keep a Noctilux just for the few wide open images? I would say it depends on your personal needs.
But having a Noctilux which focuses fione at f2.8 and not at f1.0-1.4 doesnt make much sense for me.
Cheers, Tom

[pklein]

Do different samples of the same lens model vary in how much focus shift they have? Has anybody tested this systematically?

We have some anectodal evidence that it does vary from lens to lens, but since different people are doing the observing, we have no way of knowing how accurate their focusing technique is, etc.

And does focus shift vary with distance? In other words, is it possible for a lens to focus shift at 1 meter distance, but not significantly at 3 or 4 meters?

All my lenses of f/2 and faster that I've tried on the M8 have a detectable focus shift, at least in the close-up range where I can get useful data focusing on a tape measure. The good news is that it doesn't seem to matter most of the time. And lenses can be adjusted to be correct where you use them the most.

For example, if I'm using my 35/1.4 ASPH at middle apertures, I'll just focus on the closest thing I want in focus, and all's well. It's optimized for wide open, and that's as it should be, because I use it wide open a lot.

On the other hand, when I sent my 35/2 Summicron v. IV to DAG for a CLA, I asked him to optimize it at f/4 and wider, because that's where I use it most of the time. It front focuses a bit at f/2. At f/2.8, the RF focus point is at the rear of the actual zone of focus. From f/4 on, it's spot on. So, if I take a picture of a person at f/2, I focus on an ear lobe or earring instead of their eye.

A tip: If you want to see the a realistic appraisal of focus shifts, depth of field, image noise and a lot of other stuff, don't look at the image at 1:1. It's like putting your nose on an Impressionist painting. You see a level of detail that the eye is going to blend in normal viewing. I've found that viewing at 2:1 on the screen is about right for judging an image that you'll print at between 8x10 and11x14 inches.

--Peter

[wattsy]

Originally Posted by Eoin

Put your head in your hands in disbelief and wonder if your going to be loosing your camera for a further 6 weeks or more over the christmas period while these people have to redo the job they should have checked before the lens left the factory

I understand the frustration - it took Solms two attempts to get my 50 ASPH right.

[usefeet]

Having read about focussing problems on the forum in recent times, and with suggestions about adjusting the camera body rather than the lens,
I had some tests done on my gear (locally) using a collimator (a precision laser measuring instrument), and found that in every case it was the lens that was out of adjustment, at least in my case.

The worst out-of-adjustment lenses were the most recent types, ..my 50 Summilux ASPH and the 75 Summicron ASPH.
(Not sure what this points to with Quality Control.)

[wattsy]

Originally Posted by usefeet

(Not sure what this points to with Quality Control.)

At least we now have a name we can point the finger at. According to Jörg Konrad: "My colleagues and I are there to ensure that no Leica product leaves the factory anything short of the standard that customers have come to expect from Leica."

[tom0511]

Originally Posted by wattsy

At least we now have a name we can point the finger at. According to Jörg Konrad: "My colleagues and I are there to ensure that no Leica product leaves the factory anything short of the standard that customers have come to expect from Leica."

I thought the same thing when reading the article.
On of my M8s is on the way to Leica together with 4 lenses now. I am excited how they will come back- I still have hope