M9 - coincidence at infinity

[pack_tor]

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Hi Guys,

 

I tried to focus on a cellphone tower (a few kilometers away) on my M9/50 Lux ASPH to test for rangefinder misalignment. At infinity on the Lens, the double images are ever so slightly off. I have to work hard to see the fact - for all purposes the tower seems like a slightly fuzzy line in the focus area. At closer distances the images coincide just fine.

 

My question is, how much should I be worried about this? I'm a rangefinder newbie, so I'm not sure how much it would affect shots that are taken at about 6-25 feet away. I usually work in this range, mostly wide open at 1.4. I'm wondering this because lately the 50 Lux shots don't seem to be bitingly sharp as I'd hope @ 1.4 and I'm wondering if the rangefinder might be off.

 

Thanks!

[Julian Thompson]

It is really important. If the infinity is off then you can't truly evaluate focus elsewhere because the infinity is the 'reference' point. From this point the length of the roller cam arm itself determines how much the rangefinder patch moves as the lens rotates.

 

In my experience of 5 digital M's (2 x M8.2 and 2 x M8 and 1 x M9) I have never had a camera with a spot on infinity/roller arm length combination from the factory, and have learned how to adjust them myself rather than send them back.

 

If you don't want to touch it yourself then you'll have to bite the bullet and send it back to Leica for adjustment. Sorry its not better news!

Edited April 12, 2010 by Julian Thompson

[Jamie Roberts]

Hi Guys,

 

I tried to focus on a cellphone tower (a few kilometers away) on my M9/50 Lux ASPH to test for rangefinder misalignment. At infinity on the Lens, the double images are ever so slightly off. I have to work hard to see the fact - for all purposes the tower seems like a slightly fuzzy line in the focus area. At closer distances the images coincide just fine.

 

My question is, how much should I be worried about this? I'm a rangefinder newbie, so I'm not sure how much it would affect shots that are taken at about 6-25 feet away. I usually work in this range, mostly wide open at 1.4. I'm wondering this because lately the 50 Lux shots don't seem to be bitingly sharp as I'd hope @ 1.4 and I'm wondering if the rangefinder might be off.

 

Thanks!

 

So the 50 Lux ASPH is pretty darned bitingly sharp--even at 1.4--when focused correctly on the M9, though the DOF can be very slight!

 

Do some tests--shoot a ruler for example--and see if the lens is front or backfocusing. If it is, given what you've said, yes, I'd suspect the infinity focus is off. Get it fixed, or as Julian suggests, learn to fix it yourself. There's a wiki entry on how to do it here at the LUF.

 

As a guide--here are some quick snaps I fired off with the 50 1.4 Lux APSH at 1.4...(sorry for the dog pic, but she's the only one to hand right now!)

 

I have to say that the 50 1.4Lux APSH is the sharpest 50 lens I've ever seen wide open:

 

Two shots, resized for web:

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Now 100% crops, no sharpening (straight from C1 to PS for cropping). Focused on wings / head :

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focused, more or less, on eyes (they're kinda covered by fur )

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[pack_tor]

Hi Guys,

 

Thanks for the replies. I did a few tests - The sharpness at close distances (to about 10 ft) seems to be fine. However focusing beyond 10 ft seems hit and miss. More often than not the images are back focused.

 

Would this confirm that the rangefinder needs to be realigned?

 

Thanks!

[digitalfx]

The easiest way to confirm infinity focus is to look at the moon. It's bright enough and far enough to instantly judge if your rangefinder is off

[ArtZ]

Hi Guys,

 

I tried to focus on a cellphone tower (a few kilometers away) on my M9/50 Lux ASPH to test for rangefinder misalignment. At infinity on the Lens, the double images are ever so slightly off. I have to work hard to see the fact - for all purposes the tower seems like a slightly fuzzy line in the focus area. At closer distances the images coincide just fine.

 

My question is, how much should I be worried about this? I'm a rangefinder newbie, so I'm not sure how much it would affect shots that are taken at about 6-25 feet away. I usually work in this range, mostly wide open at 1.4. I'm wondering this because lately the 50 Lux shots don't seem to be bitingly sharp as I'd hope @ 1.4 and I'm wondering if the rangefinder might be off.

 

Thanks!

 

Remember infinity is different for every focal lengh.

 

As the rule of thumb you can add a zero to your focal distance in mm and read it as meters.

 

For a 28mm lens, infinity is a 280 meters

For a 35mm lens, infinity is a 350 meters

For a 50mm lens, infinity is a 500 meters

For a 90mm lens, infinity is a 900 meters

...

 

Test with differents lenses before you send the camera. It could be also just the lens or both.

 

Cheers.

[cbretteville]

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This can also be the fault of the focusing cam it self. I've had this issue with two lenses lenses that showed this symptom when they came back from coding by CS in Solms (one of the lenses had to go back twice ). In all the cases the lens was focusing properly at infinity, but the RF patch was off by a fraction. Not a problem with the RF it self as with all my other lenses this wasn't a problem. Solms fixed it for both of them, finally, but the wait was a real PITA, especially for the 50 'Cron that had to go back twice.

Carl

[Julian Thompson]

Have a look at this graph - it may help you to visualise it.

 

The dotted line is the actual lens focus as you rotate the barrel. It should be straight but I did it without a ruler!

 

I have then drawn a red line on to show what is happening in your case. The infinity point is wrong and therefore at bigger distances you are getting bad focus but then as you get closer the fact that your cam arm is too short allows the rangefinder window to 'catch up' with the real focus and give the mistaken impression that all is well.

 

If you did really drill down on this and do some more careful testing you would see that it is misbehaving in a predictable way.

 

I will take you through those steps in the next posts...

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[Julian Thompson]

So if you then take your allen key and turn the hex bolt anticlockwise you will get this:

 

Now your infinity will be perfect but you'll now have the close focus off because the 'slope' of the graph has not altered because you have not changed the actual gearing of the mechanism yet...

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[Julian Thompson]

...And now loosen the slot head screw on the main arm cam and turn the cam fractionally anticlockwise to shorten the arm down and increase the amount of available focus throw in the rangefinder window.

 

Now you will get this:

 

(Actually you won't - quite - the infinity will have gone out again a touch since the start point of the roller at infinity is changed because you have shortened the arm a touch - so you will need to wind the infinity back a fraction)

 

Hopefully this gives a good idea of the procedure in a visual format - if you have front focus you obviously reverse the direction of the adjustments!

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[bybrett]

Hi Julian I'm loving it! Can you do one for depth of field too?

[Jamie Roberts]

Thanks Julian!

 

I've adjusted the infinity focus and it seems that's all it took for my M9 to be in focus across the range.

 

Are you saying you always have to loosen the arm as well? (and truthfully, where do you do that, exactly?)

[adli]

The problem is when you start adjusting your camera and it turns out it was not the camera but the lens which was the problem. All your other lenses will then be out of focus.....

[Jamie Roberts]

The problem is when you start adjusting your camera and it turns out it was not the camera but the lens which was the problem. All your other lenses will then be out of focus.....

 

Yes, that can be true, but I've had my lenses on the M8 and M6 and they're all pretty good (they've all been checked by Leica or Kindermann Canada, in other words). So when my 35, 50 and 75 lux are all front focused, and only on the M9, and I can't consistently achieve infinity, I know it's not the lenses.

[Julian Thompson]

Brett - - you have to place that manually and stop up and down in your testing but knowing how good your eye is you'd have no trouble making sure you were setting it in the right place. Then again I should imagine you have your own personal team of gnomes from Solms following you around with a shiny Leica support van, re-setting your bodies like a tennis pro has rackets tensioned ? No?

 

 

 

I know this is not for everyone and that's not what I'm saying - my aim in posting is to share the work I have done and the successes I have had with my own adjustments.

 

It is very nice to know how to tweak one's own camera very quickly if necessary. It is nice to remove the 'aura' from the rangefinder mechanism in one's own mind and kind of feel at one with it. That's all.

 

 

So

 

Jamie - this is the explanation I posted a little while back along with a couple of pics for you to look at. As adil says you need to take a sample of shots from every lens (and body if possible) you have to make sure you're calibrating it right.

 

You will need a 2.5mm allen key and a small screwdriver which you should grind a very slight angle on so that as you fit the screwdriver into the head on the focus throw pivot (A) on the diagram it allows a nice flat drive.

 

A) is the focus throw adjustment. If you look at the pic you can see that the screw retains an eccentric cam. If you loosen the screw you can rotate the cam (as denoted by the pink and blue arrows) freely. As you do so, the length of the arm itself changes.

 

By moving the cam counter-clockwise (as in pink arrow) you INCREASE the total available focus throw.

 

By moving the cam clockwise (as in blue arrow) you DECREASE the total available focus throw.

 

is the infinity adjustment as we know.

 

If you rotate the 2.5mm hex key counter clockwise (as in green arrow) you move the point at which the rangefinder 'sees' infinity further away - and this 'references everything forward of that.

 

If you rotate the 2.5mm hex key clockwise (as in yellow arrow) you move the point at which the rangefinder 'sees' infinity closer to you - and this 'references everything forward of that.

 

Right - so they are the two adjustments you have available to you. From my playing about the best way to set it up is this.

 

1) Infinity is very important. Step 1 is to look at something with lots of contrast a long way off (a star does seem to work very well but today I've been using a clock tower in the far distance and that's fine too) and then adjust the roller ( so that this perfectly coincides. Don't accept the nonesense I was spouting before about it not mattering. It really matters that you can 100% converge the object at infinity.

 

2) Now, take a photo at a big aperture of something close to you - like 0.8 meters or similar. I found text to be excellent. Note whether you now have front focus or back focus. If you have front focus (like I did - big time!) then your focus throw is too short; ie your arm is too long, so when the lens rotates you're not pushing the rangefinder enough. So you need to shorten the arm by loosening (A) and twisting the cam slightly anti-clockwise. (If you have backfocus then it's obviously the inverse and you need to go clockwise to lengthen the arm and reduce your focus throw).

 

3) Now, recheck infinity. It will now be wrong, because you have now moved the arm and so the roller wheel has also moved. But this is not a problem - just recorrect infinity as in 1) above to compensate for the altered focus throw.

 

4) Repeat step 2. You will see that the focus point has altered. Whether it has moved too little or too much will calibrate your hand/eye as to how much you need to make the adjustments but in general I made positive, but not excessive tweaks each time.

 

5) When you are happy with the infinity and close settings you want to shoot some images off that are at various distances just to make sure that everything is right. On my setup which consists of all current model lenses (not sure if this is relevent) I did not have to compensate with any kind of compromise here. When my infinity setting is right and the focus throw is perfect the transgression from near to far is linear and my lenses are sharp right the way through the range. I suppose that if this were not the case or if your lenses varied then you'd need to get them recalibrated, or maybe accept a compromise setting.

 

Hope that's helpful.

 

Have fun

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Hallo,

Look here: Leica M

[Jamie Roberts]

Julian--

 

That's totally brilliant! I don't know how I missed this before. If you're ever near Toronto, the beer's on me

 

Thanks again!

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Hallo,

Look here: Leica M

[Julian Thompson]

No worries! Have fun and make small changes. You'll soon get a 'feel' for it !

[Baptiste]

It will be short, and I have not read all what has been written earlier...: I can report that my confid as well shows a slight decrease of sharpening at infinity with the Lux 50. To my eyes, it is not very obvious, but while wide open, and focused at a decent distance, the focused details seem definitely razor sharp, the pics taken with a closed diaph, focused at infinity could, to my eyes, be even more sharp.

 

My question is: is it not simply that the Lux 50 is optimized in a short range, wide open use, while some other 50mm are more optimized for other uses?

[Jamie Roberts]

{snipped}

My question is: is it not simply that the Lux 50 is optimized in a short range, wide open use, while some other 50mm are more optimized for other uses?

 

I don't think so, no, but only Leica knows for sure

[pack_tor]

Wow, this is a thread to bookmark! Thanks a lot guys - I'm sure I'll try this on my own once the M9 is off warranty, but I'm feeling a bit uneasy to try right now. Thanks for all the sketches - the procedure is very clear.