new backfocus thread-solution

[bradreiman]

Ok-ive been suffering with a bad "backfocus" problem for months. I was scared to adjust myself based on some posts here. Finally yesterday got fed up and took out the 2 mil allen key. Focus to infinity-adjust a bit. Focus to near limit-adjust a bit. Rinse and repeat (3 times). Focus is now spot on. Really easy adjustment. I adjusted with the noctilux so any error would be magnified well. I feel much better now-about the m8, about life in general....b

[carstenw]

How did you adjust it? The near limit adjustment is meant to be behind the red Leica dot...

[rondeb]

Mine is boxed up for NJ as I type for adjustment. I also would love to do this myself, but I didn't find the previous thread to helpful. Can you help me out a bit? Pics or the adjustment parts would be helpful as well.
Great to hear of your success.

Best,
Ron

[bradreiman]

carsten-i guess i didn't need to adjust the near limit. I just rolled the hex nut in the cam arm back and forth and within minutes near and far limit were spot on. even my 135 2.8 is working now (I thought that lens was out of whack-still is vertically)....b

[bradreiman]

....i suspect the near limit is usually correct and the far limit is what goes out as it has contact with the real world...b

[bradreiman]

ron-there is a 2mil allen key adjustment in the center of the "roller cam" in the lens mount. i just set the lens to infinity-look at a vertical on the horizon-take lens off and turn the allen key a bit-lens back on to check infinity-rinse and repeat-then fine tun a bit at near and mid focus...b

[gesper]

Can someone take a picture so we can have a better idea what this means?

[jcbjr]

Originally Posted by bradreiman

ron-there is a 2mil allen key adjustment in the center of the "roller cam" in the lens mount. i just set the lens to infinity-look at a vertical on the horizon-take lens off and turn the allen key a bit-lens back on to check infinity-rinse and repeat-then fine tun a bit at near and mid focus...b

interesting test, bradley, and thanks for sharing with us. one thing i don't understand, however, is why you need to readjust at different focus points. i thought the cam always sprung back to same position when a lens is removed, no matter what the focus. as such, the adjustment will impact all focus distances the same, or am i missing something?

john

[jcbjr]

well, i was a bit skeptical it would work, but just tried it and it worked perfectly. just as bradley suggested, use a 2mm allen wrench. remove lens, insert short end of wrench into round silver cam at top of camera body opening. with camera laying flat on surface facing you, long end of wrench pointing straight out from camera body, gently place finger behind cam to hold it in place (it's spring loaded). for back-focus, gently rotate wrench to the right (away from m8 logo), just a few degrees. i think mine required about two or three degrees. voila! perfect focus using nocti @ f1.0, short and medium distance (couldn't do infinity as it's night here). good work, bradley! saves a trip to nj or possible solms!

john

[robsteve]

Originally Posted by carstenw

How did you adjust it? The near limit adjustment is meant to be behind the red Leica dot...

Carsten:

The vertical alignment of the rangefinder is behind the Red dot.

The near focus limit is at the fulcrum of the arm that the focus roller is on. I just looked at my M7 and it doesn't look like anything you want to play around with as it is in quite close quarters.

Brad is correct, the near is seldom off. If you get the infinity right it will usually cure focus problems.

Robert

[bradreiman]

Originally Posted by jcbjr

interesting test, bradley, and thanks for sharing with us. one thing i don't understand, however, is why you need to readjust at different focus points. i thought the cam always sprung back to same position when a lens is removed, no matter what the focus. as such, the adjustment will impact all focus distances the same, or am i missing something?

john

Hi John-I really only did middle to check. Near and max distances seem to do the trick and what a piece of cake to do. I've been out with the noctilux all day since I can finally use it.

[ho_co]

Originally Posted by bradreiman

I've been out with the noctilux all day since I can finally use it.

Drat, Brad!

I was biding my time waiting for you to get so frustrated with the lens that you'd accept an offer of $1000.

Seriously, glad you got it going!

--HC

[carstenw]

What does fulcrum mean in this context: shoulder or elbow (given that the arm has two links)?

Mine needs a near-focus adjustment badly. I have adjusted the infinity which is bang on, but near focus is off by several centimeters at short distances. It is also slightly vertically out. My camera is the one which Leica forgot to adjust, and two times at that.

[pascal_meheut]

Same experience as Bradley Reiman, same results. Focusing precision with the 75mm af f/2 and short distance is incredible.

[tom0511]

Originally Posted by carstenw

What does fulcrum mean in this context: shoulder or elbow (given that the arm has two links)?

Mine needs a near-focus adjustment badly. I have adjusted the infinity which is bang on, but near focus is off by several centimeters at short distances. It is also slightly vertically out. My camera is the one which Leica forgot to adjust, and two times at that.

Carsten,
in my case its more aproblem of lenses and not the camera.
Some lensesspot on (at short and long distance (i.e. 75/1.4, 90/2.8,35/!.4), others are off at short distance (Noctilux, 50/1.4asph, 135/3.4)
I will send those lenses in to Leica.
I also will send samples images and a letter with the lenses to clearly describe the problem.
I once sent my 35/1.4 to Leica for focus adjustment and now its spot on.
cheers,Tom

[robsteve]

Originally Posted by carstenw

What does fulcrum mean in this context: shoulder or elbow (given that the arm has two links)?

Mine needs a near-focus adjustment badly. I have adjusted the infinity which is bang on, but near focus is off by several centimeters at short distances. It is also slightly vertically out. My camera is the one which Leica forgot to adjust, and two times at that.

Carsten:

The adjustment is at the pivot point of the arm, where it attaches to the rangefinder. You loosen the screw and move an eccentric. I wouldn't play with it as it may not be easy to set up. Leica uses a jig for these settings.

Robert

[fredbonhomme]

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

[johnkuo]

Thanks for the tip. I just tried this and there is definitely improvement. Although now I discovered that my 28mm front focuses...

[pascal_meheut]

Here are the pictures. You just put your 2mm Allen wrench where the red arrow is, as shown in the 2nd picture and your turn slowly, 1/10th of a turn or less being careful not using excessive force and just rotating, not pressing in any direction.

If you do not have an infinite point to adjust, you can try by shooting some books on a shelf, each at a difference distance. After adjusting, you mount a long lens wide-open, you focus precisely and you check on the screen where your focus point is.
Once you are in focus, check that you are in the DOF range, not at the end of it.

You can also use a special target. See http://www.leica-camera-user.com/dig...cus#post131553

[fredbonhomme]

Merci Pascal