M8 and Noctilux - backfocusing?

[newyorkone]

It might be my eyes since they aren't what they used to be after all this staring into computer monitors for work and recreation everyday, but...

I think I might have a calibration issue with my Leica M8 and Noct when shooting wide open at f1. The 35 cron and 90 APO ASPH seem to be spot on but of course those have wider DOF.

The M8/Noct (with 1.25x mag) combo appears to focus OK from 1-1.5 m but from there on out it appears to be backfocusing quite a bit. At around 5 m the focus point is 2-3 feet behind my intended focus point. I notice that when I bring the focus scale back a little (closer) then the image is in focus.

Is it normal for a lens to get progressively worse, backfocusing, as the object distance increases. I know that focusing precision comes into play and the further away the object is the harder it is to focus but even when the object is not to far away and I can clearly see that the RF images line up clearly, using the 1.25x mag, the resulting picture is still out of focus where I want and in focus behind it. If I defocus slightly so that I can see a slight separation of the RF images then the resulting image is in focus where I intended. Here is a sample image. I focused on the woman in white showing another women a picture on her digital camera. The woman in focus is the one holding the Whole Foods bag behind her and to the left.

ISO 320, f1

[jaapv]

It is hard to say. In situations like this it is so easy to move the camera a bit, especially with the added error introduced by focus/recompose as you obviously did here. The plane of focus seems to be somewhat in front of the lady holding the bag. I would hesitate to draw any conclusions based on this one. It would have been a nice street shot btw.

[Eoin]

Disappointing, the focus appears way off and while I have respect for Jaapv's suggestion I however feel the margin for error with focus and recompose is far less than shown here. I'm assuming this is a full image and not a crop. There seems to be quite a bit of DOF given the f/1 aperture but it seems to start well after your subject perhaps about 3 feet.

Strangely enough I was having a similar problem with a leica 1.25x and a 50 cron, everything appeared in focus in the RF but the images weren't. Removed the 1.25x and the images were spot on. Strangely I never had such a problem with the 75 cron and the 1.25x. I just put it down to my eyes playing tricks with me that day!.

I'm more concerned with the purple fringing I see in the image, I know it's common with very fast glass and high contrast subjects and I'd expect it around the white jacket but her hands are a mess, did you have a UV/CutIR on the Noctilux for this shot?.

I'm waiting for my new Noctilux and hope the focus will at least be accurate for a new lens, given the rest of my glass seems spot on except in cases of user error.

[jaapv]

One thing about the Leica Okular is that it has no diopter correction and it does change the strength of the viewfinder, I found. With the 1.25 I need +.05 correction and without it +0.75 (which does not exist). I think that is enough to throw the focussing out in critical situations, i.e. the Noctilux on the M8. One more argument for the Megaperls magnifier which has a built-in variable correction.

[erl]

Steve,

I had exactly that problem with my Noct. M8 combo. I never was conciopus of backfocus with my analog M's and the Noct, but I have heard (apochraphal?) that digital is more critical for focus than analog.

I sent my Noct back to Solms for test and correction. It now seems fine. The only problem was the $600 bill and the 4 months turnaround time. I would strongly reccommend you first do the photograph the ruler trick on a tripod before making firm decisions on the nature of the problem. Solid testing with focus being the only variable.

[billh]

I have the same problem with various lenses. my APO 75 focus is spot on, but most of the others back focus varying amounts. I hesitate to make any changes because I don’t want to mess up the focusing accuracy of the APO 75, but that is now pretty much the only lens I use on the M8, which limits its usefulness. I have heard far too many horror stories to even contemplate sending it or the lenses back to Germany, especially when there seems to be so much variability in the focus shift among the lenses (28 f2.8ASPH, 35 f1.4ASPH, Noctilux, 50 f1.4 ASPH, 75 f1.4, APO90 f2.0, APO135 f3.4). My 50 f1.4 ASPH is the worst offender, which is sad because it is such a sharp and useful lens. Someone with more common sense than me would sell the lot of them and be done with it.

$600 and four months away is nothing short of obscene.

[frank_dernie]

I have just finished "playing" with my M8 checking the close focus point (at about 5 feet) of some of my lenses. I marked an A4 letter with a 1mm diameter circle which I focused on, took photographs and measured where the plane of focus was by seeing where the text was clearest on the letter. I checked with and without the 1.25 magnifier and tried both several shots without and with re-focussing each one to check my own consistency. The results were surprising.
21 f2.8 asph focused about 300mm behind the point of rangefinder coincidence.
24 f2.8 asph was spot on
28 f2.8 type 4 focused about 120mm behind the point of rangefinder coincidence.
a 28mm f2.8 prototype I had on my collectors shelf was spot on and clearly better than my 28 f2.8 production lens, perhaps this design did not go into production because of manufacturing cost rather than lacking performance.
50 f2 current model was spot on.
50 f1.4 always focused about 30mm behind the point of rangefinder coincidence, varying ny 10mm or so with re-focussing so my repeatability was not too bad.
50 f1 focused about 140 to 200 mm behind the point of rangefinder coincidence depending on aperture and my repeatability and whether I was using the 1.25 magnifier. The biggest effect was aperture not my repeatability.
75 f1.4 focused about 70mm behind the point of rangefinder coincidence wide open and about 130 mm behind at f4.
75mm f2.5 Voigtlander was spot on.
a 1957 90mm f4 screw mount on Leica adaptor - spot on.
135 f2.8 with eyes was spot on.
135 f4 focused about 120mm behind the point of rangefinder coincidence.
This got me interested so I dragged out my old f1.2 Noctilux and it back focused about 50mm

[newyorkone]

Thanks for all the responses. Very helpful!

I did a little more testing and it appears that from about 2 m and out, the M8/Noct combo backfocuses consistently and gets progessively worse the further out you go until of course infinity focus comes more and more into play. The worse seems to be at a distance of about 5 m. Or perhaps this is just the distance where a lot of my images fall under which is not surprising for street shooting.

The image above is a crop. The women in white was in the center and the camera/lens was level (not tilting up or down). I cropped it so that you can see the women behind that is more in focus more clearly.

From 2 m, if I make sure to use the focus point right when the images appear to line up or even ever so slightly before that (note: in other words focusing slightly closer). This becomes progressively more and more necessary from 2-5 m. To the point that at 5 m it is necessary to compensate in the RF and make the image noticeably not line up (again always moving from near to far - if I make the image not line up from the other direction, far to near, then the image is even more out of focus). This coincides with the fact that the lens is backfocusing since I need to compensate by focusing slightly closer.

I guess now that I know I can compensate but this is quite annoying. I'm afraid to adjust anything since that might throw off other lenses and I really can't do without the camera for 4 months. Oh well...

[newyorkone]

Originally Posted by Eoin

I'm more concerned with the purple fringing I see in the image, I know it's common with very fast glass and high contrast subjects and I'd expect it around the white jacket but her hands are a mess, did you have a UV/CutIR on the Noctilux for this shot?.

Not using any filters since I haven't received mine yet. The purple fringing is pretty bad with the Noctilux. Not so obvious with my other two lenses, 35 cron ASPH and 90 cron ASPH. CA correction in LR barely tones it down - not enough at all.

Does anybody have an idea as to how to post process the "purple bleeding?" Thanks.

[robsteve]

Steve:

The Noctilux is a lens that they can adjust in New Jersey. You should call them and see what they can do for you.

If NJ is too busy, Kindermann Canada, the Leica service agent in Canada has done a few Noctiluxes lately and are very familiar with them, after all, they were made in Canada.

[carstenw]

Steve, Lighroom and CS2 are some of the worst programs to correct purple fringes, unfortunately (I am a Lightroom user). Try using C1LE when you have bad purple fringing.

[newyorkone]

Thanks Carsten. You gave me a reason to install C1LE which I hadn't gotten around to doing yet.


Update regarding the backfocusing...I spoke to Tony at popflash and he said that they also had a backfocusing issue with his M8/Noct and it turned out to be the camera.

[ns_ng]

Hi,

I had similar focusing problems with my M8 with the 35, 1.4 Asph, Noctilux and the 90 AA. When shooting at around 3 m. at max. apertures, the images were out of focus even though the RF appeared fine. I decided to focus using my M3 and then transferred the lens to the M8. Yes, I could see the double image in the M8 viewfinder. However, the images taken with this setting were in focus.

I contacted the Leica agent and he confirmed my findings. It appears some M8s have this focusing error. Due to this issue, my M8 was sent back to Solms for RF adjustment.

N.S.

[newyorkone]

Originally Posted by ns_ng

Hi,

I had similar focusing problems with my M8 with the 35, 1.4 Asph, Noctilux and the 90 AA. When shooting at around 3 m. at max. apertures, the images were out of focus even though the RF appeared fine. I decided to focus using my M3 and then transferred the lens to the M8. Yes, I could see the double image in the M8 viewfinder. However, the images taken with this setting were in focus.

I contacted the Leica agent and he confirmed my findings. It appears some M8s have this focusing error. Due to this issue, my M8 was sent back to Solms for RF adjustment.

N.S.

Where are you located and what was the turn around time?

[charlesphoto99]

Good idea N.S.

The mid range focus being off has to do with the near/far adjustment of the rangefinder arm. I think this adjustment was off in a lot of M8's leaving the factory for some reason. I won't even go into this here as it's been done to death in other threads. So either get out the hex key and jewelers screwdriver or send it off to Solms esp if all or most of your lenses are suffering. Once one gets most of their lenses to focus right then one may find a lens or two that doesn't and then it's those that have to be adjusted.

Good luck!

[thpeters]

The mid range focus being off has to do with the near/far adjustment of the rangefinder arm. I think this adjustment was off in a lot of M8's leaving the factory for some reason.
Charles Peterson
--------------------------------------------------------------------------
M8, came back April 9, after R/F adjusting, Apo 90 mm is correct, tested on camera, (see pictures in Photoforum Nature)Noctilux came back, not tested on the camera?????????????? still backfocus.

The picture taken today with the Noctilux, focuspoint was the summicron lens 35 mm.
Eposure time 1/1500-F8

Today I have send the lens back to the dealer.

Theo

[rjrose]

The same thing happened with my M8 and Noctilux. I took a hex wrench, and using the technique discussed in other threads, and the following photos, seem to have fixed the problem:

http://gallery.leica-users.org/v/rjrose/focus/

If you have to turn the focus toward infinity to get the image in focus, try turning the wrench away from the red dot. Limit turns to about 1 to 2 degrees at a time.

Regards,
Bob Rose

[thpeters]

Originally Posted by rjrose

The same thing happened with my M8 and Noctilux. I took a hex wrench, and using the technique discussed in other threads, and the following photos, seem to have fixed the problem:

Focus Adjustment on M8

If you have to turn the focus toward infinity to get the image in focus, try turning the wrench away from the red dot. Limit turns to about 1 to 2 degrees at a time.

Regards,
Bob Rose

In your words, it means, I have to used every time a hex wrench to get the focus right, when I change lenses?

I dont think so.

Theo

[billh]

I have exactly this problem Theo, and it makes me crazy. Worse, it varies with different lenses. I wonder if Leica could add something to the next camera like Canon did here (scroll down to focus test) with their 1D3?

http://eng.mobile01.com/newsdetail.php?id=3263

[ns_ng]

Originally Posted by newyorkone

Where are you located and what was the turn around time?

Hi,

I am located in Singapore. No news as to when my M8 will be back from Solms. But the Leica agent is willing to lend me a demo M8 when needed.

N.S.