new backfocus thread-solution

[Ben Marks]

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I know that this thread is old news. But I have to say that this forum is QUITE the resource. I was baffled by the behavior of my M8 with certain lenses . . . Now the Noctilux, 75 Summicron and 90 Summicron all focus well . . . What fun!

[alex7075]

I really want to thank you for this thread and for the solution. My M8 was front-focusing: I only have one lens for now, a 50mm 2.0. I plan to get a Noctilux so focusing is going to be quite critical. The shift in focusing increased with the increasing of the distance: 1 centimeter at minimal focusing distance (70 centimeters), up to 1,5 meter when focusing at around 10 meters, and even more when focusing at infinite.

Now the focusing point is sharp at any distance as it should be. Thanks again!

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[alex7075]

Uh oh I spoke too fast. Now the lens can't reach focus at infinity! At least it is ok at all distances up to around 50 meters. Do you have any suggestions? From what I understood, I should first set the infinity point like explained on this thread, and then correct the screw on the elbow for mid-distances? I am a bit lost, perhaps I should bring it to Leica...

[wlaidlaw]

Uh oh I spoke too fast. Now the lens can't reach focus at infinity! At least it is ok at all distances up to around 50 meters. Do you have any suggestions? From what I understood, I should first set the infinity point like explained on this thread, and then correct the screw on the elbow for mid-distances? I am a bit lost, perhaps I should bring it to Leica...

 

Alex,

 

I spoke to Leica UK about my Noctilux today. At first they said "camera". I then explained that the camera body was fine at all distances on other lenses, including the equally critical Elmarit-M 90. In fact like you, I had been playing around with the infinity cam yesterday. I found I could get the Nocti right for mid ranges but then it was out at infinity just like yours. In the 'correct for mid-distances on Nocti' cam position, the Elmarit 90 was out at all distances. I therefore reset to the original position.

 

Leica UK said if the body was OK with my Elmarit 90 at all distances and also my Elmar 50, then it had to be a maladjustment of the internal focusing cam for the moveable elements on the Nocti and it would have to go to Solms, as they are the only people who have the correct piece of equipment to do it. Annoying since it has just come back from Solms. Shades of Tim's Summilux.

 

Wilson

[barjohn]

I just got a replacement camera back from NJ last week and was very excited to have a camera back. I have since discovered that the range finder is slightly out at infinity with both of my lenses. I cannot quite get full coincidnece of the images. This leads to slight front focusing on the lenses when tested against a test chart. My question is: should I attempt this adjustment or should I send it back to NJ for a RF adjustment. The idea of spending another $85 in shipment and being without the camera for another 2+ weeks really bothers me. As it was the replacement arrived with a dirty sensor (I cleaned it). I have no idea whether it was a refurbished unit or not but I am guessing it was. I have read in another thread here where Mark said that one should not use the cam to adjust the RF. If Mark is correct then I need to call NJ. Helpful suggestions appreciated.

[wlaidlaw]

I just got a replacement camera back from NJ last week and was very excited to have a camera back. I have since discovered that the range finder is slightly out at infinity with both of my lenses. I cannot quite get full coincidnece of the images. This leads to slight front focusing on the lenses when tested against a test chart. My question is: should I attempt this adjustment or should I send it back to NJ for a RF adjustment. The idea of spending another $85 in shipment and being without the camera for another 2+ weeks really bothers me. As it was the replacement arrived with a dirty sensor (I cleaned it). I have no idea whether it was a refurbished unit or not but I am guessing it was. I have read in another thread here where Mark said that one should not use the cam to adjust the RF. If Mark is correct then I need to call NJ. Helpful suggestions appreciated.

 

John,

 

Tweaking the rangefinder infinity cam is such an easy adjustment, there is little to be lost giving it a go. As long as you are very gentle, you are not going to damage the camera. Only change by tiny amounts at a time, noting your direction of adjustment on a pad and checking infinity carefully with both lenses, after each adjustment. You can always put it back to the start position if adjusting it it does not help. As I posted above, it did not help in my case, as the infinity focus was OK to start with. I was a little bit wary at first but it is less heart-stopping than cleaning the sensor, which I hate doing.

 

Wilson

[alex7075]

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Wilson, I thank you for your answer.

Since the 50 summicron is the only lens I have for now, I couldn't know if it was the lens or the M8. But reading your post made me understand that it's probably the lens. I will reset the rangefinder to the initial position, and see with my Leica dealer if something can be done on the lens.

Thanks again!

[barjohn]

Wilson,

 

Thanks for the feedback. I will give it a try and try and mark where I am starting from so I can go back if need be.

[mb1pb]

This procedure seems to be relatively straightforward. I was out by an inch or two at close focus but have now got it down to about half an inch. Infinity seems to be OK. I guess I'll use the camera as it is and see if I can live with it. I'm thinking that user error is probably as great as half an inch anyway.

 

PB

[ggriswold]

Came across this problem and made a test jig with multiple cards in a 18" board-- cards are increasingly high-- shoot it straight on. I got the 1 meter (or slightly less) where I want it and the focus seems to track to infinity. Leica M6, .72 with 90mm f2 Summicron. The camera did not show the focus error until I got the 90 and used it to isolate objects in a close-up and everything was in focus BEHIND the subject... ouch.

 

George Griswold

New Orleans, LA

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[Jamie Roberts]

George--surely your findings mean your 90mm lens needs adjustment.

[ggriswold]

The center target with the arrows was my focus point-- my adjustment got me to where I wanted it--- focused dead on according to the viewfinder. This is a shot after my adjustment. It was 2-3 cards behind that when I started.

[JHAG]

Now I discovered the same problem.

Noctilux is focussing well.

Summilux 50 and

Summilux 35 are slightly frontfocussing.

On this picture, shot at 1.4 on tripod, I focussed on the "V" of LEAVITT (frontpage),

and focus is slightly on the "A".

Should I try a cam adjustment or is there a risk to misalign the body for the two other

lenses ?

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[wlaidlaw]

Now I discovered the same problem.

Noctilux is focussing well.

Summilux 50 and

Summilux 35 are slightly frontfocussing.

On this picture, shot at 1.4 on tripod, I focussed on the "V" of LEAVITT (frontpage),

and focus is slightly on the "A".

Should I try a cam adjustment or is there a risk to misalign the body for the two other

lenses ?

 

I would not worry about this amount of front focus. In fact that is how I have my 35 ASPH Lux set up. Even a very good 35 Lux like mine is going to aperture shift a bit and if you have a small amount of front focus to start off with, the focus point will stay nearer the ideal (1/3 behind; 2/3 in front) than if you start off with the f1.4 focus point 100% correct. The 50 ASPH Lux also aperture shifts a little bit, if less on average than the 35 ASPH Lux, so again it is not a problem, as long as the centre point remains well within the focus zone. I would do some aperture shift tests with particularly your 35 Lux and see how it works out. 35 ASPH Luxes vary hugely with some e.g. my chrome one, having next to no shift but others will shift right out of the focus zone (trip to Solms/DAG/Malcolm Taylor required). If you use the Nikon D70 focus chart, you will get a more stochastic result than using a book. Nikon D70 Focus Chart

 

Wilson

[JHAG]

I would not worry about this amount of front focus. In fact that is how I have my 35 ASPH Lux set up. Even a very good 35 Lux like mine is going to aperture shift a bit and if you have a small amount of front focus to start off with, the focus point will stay nearer the ideal (1/3 behind; 2/3 in front) than if you start off with the f1.4 focus point 100% correct. The 50 ASPH Lux also aperture shifts a little bit, if less on average than the 35 ASPH Lux, so again it is not a problem, as long as the centre point remains well within the focus zone. I would do some aperture shift tests with particularly your 35 Lux and see how it works out. 35 ASPH Luxes vary hugely with some e.g. my chrome one, having next to no shift but others will shift right out of the focus zone (trip to Solms/DAG/Malcolm Taylor required). If you use the Nikon D70 focus chart, you will get a more stochastic result than using a book. Nikon D70 Focus Chart

 

Wilson

 

 

Thanks Wilson,

 

In fact (my mistake), it's with the Noctilux that the problem is more sensible.

I'll check with the chart.

Hellstan

 

P.S. By the way, someone on this forum stated tweaking with the cam of the M8 would void the warranty.

Any information about that ? Prior to do anything, I would like to be clear.

[wlaidlaw]

Thanks Wilson,

 

In fact (my mistake), it's with the Noctilux that the problem is more sensible.

I'll check with the chart.

Hellstan

 

P.S. By the way, someone on this forum stated tweaking with the cam of the M8 would void the warranty.

Any information about that ? Prior to do anything, I would like to be clear.

 

Hellstan,

 

If tweaking the infinity cam voids the warranty, then I would guess 50%+ of this forum would have voided warranties. I looked very carefully when I first tweaked mine and there was no evidence of marker paint. Also look at Mark Norton's "anatomy of an M8" and there is no evidence there. Maybe tweaking the mid range elbow cam is different and is much more difficult - ditto the vertical alignment behind the red dot. My front cam is very easily moved and I have to "tune" mine about once every two to three months as it drifts off a tiny bit. I wait for a clear night and use the planet Jupiter as my infinity object. I tune with the 135 Tele-elmar and cross check with the 50 Summilux. Chimping plus zoom is really good enough to check that the lens focus coincides with RF infinity.

 

Wilson

[JHAG]

Alright.

I just tried it.

Now it seems focussing full open

and very slightly backfocussing at 5.6.

I'll check it further.

[rafael_macia]

Thank you for all these solutions but it would be really better to have some pictures to illustrate all these adjustments... I'm afraid to make a big mistake

 

Also a suggestion on how to make the test.

I put my M8 on a tripod and angled it downwards about 45 degrees, aiming it at a yardstick ruler.

The nice thing about using a yardstick is you can really see exactly; point of focus, focus drift, and back focus.

 

I put an extra mark alongside an inch,, to make my point of focus, easier to focus on, .... and after a beer or two ... easier to remember which inch is the focus inch ..

With the lens wide open, I had tried to do front /near focus first, then check infinity second, but that was not 100%. The watertower two blocks away and a star, are two different positions. (The star is a perfect infinity target, as it shows itself really well on a rangefinder patch when it's in focus.)

 

Once I had infinity, the near focus, seemed fine.

 

About the 2mm Allen adjustment;

Make the tiniest of movements with the allen tool. It is a delicate tool to insert. Mark on a sheet of paper the direction you are turning the adjustment. Rather than thinking "right or left" (adjustment direction), which became confusing, facing the camera for the adjustment, and then behind the camera for the visual check.

I would adjust the camera from the SAME side of the tripod, each time and make tiny adjustments in tiny increments "to me" or "away from me" with the allen .... until you land on infinity.

It took me awhile

 

good luck

 

Rafael

 

ps.

These kind of problems with lenses,especially the very fast Leica lenses, are rampant with the M8.

Leica as a company is really getting a black eye because of service issues. Just recently it has become a priority to remedy the repair situation, and the quality control issues.

[fotografr]

P.S. By the way, someone on this forum stated tweaking with the cam of the M8 would void the warranty.

Any information about that ? Prior to do anything, I would like to be clear.

 

I don't think there is any way Leica techs would be able to tell. The adjustment is very easy so the liklihood of leaving wrench marks on the nut are extremely low.

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[wlaidlaw]

A Leica dealer I was talking to, did not know about the cam tweak. When I showed him how easy it was he was a bit cross that Leica had not told him, as he reckoned he could have avoided a number of his customers having to have their cameras returned to base for RF adjustment. It is certainly a lot easier and less heart stopping than doing a wet sensor clean.

 

Wilson