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M9 - coincidence at infinity


pack_tor

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Well, I just confirmed that my Noctilux, though it focuses perfectly close up, and infinity seems ok, doesn't do mid-distances (around 15 meters) very well, at least wide open.

 

My 50 Lux is ok, but that's perhaps because it's stopped down (1.4 vs 1.0)...

 

So taking a tip from Julian, I'll be doing the screwdriver adjustment as well as infinity and see where that gets me.

 

Thanks again Julian... I think I'll try it though, without the beer :)

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OK - so here's the thing. If you study the graphs you'll see that it's not possible for infinity to be perfect and then close focussing also be perfect. Either:

 

1) Your infinity is fractionally off

 

or

 

2) You are not allowing sufficient tolerance for the focus shift as you open the aperture. This is leading you to a false conclusion that close focus is good. (ie if you are getting perfect focus absolutely wide open on the Nocti then as you stop it down you'll see the focus point change in the DOF - Try repeating the tests at smaller apertures to get a feel for that shift and then you can evaluate where you are. Be strict with yourself in your evaluation.

 

It's a bit of a learning curve Jamie but I promise you when you come out of the tunnel at the other end you'll find your ability to focus the camera will be better. I don't know why this is but doing all that really improved my shooting.

 

PS If you do make the length adjustment don't bother to shoot a test shot until you have recorrected infinity otherwise you'll scare yourself. The infinity adjustment is THAT important!

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Julian--no worries; I've been adjusting the infinity focus on my Ms for years :) Often, that's all it takes.

 

I'm also comfortable with the Nocti's focus shift. But close focus from 1.0 to f2.0 is perfect right now.

 

The Nocti RF patch is off at infinity. The 50 Lux is apparently not, or not much. So there you go :)

 

Thanks for the encouragement though!

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Julian--

 

A couple more questions...

 

What kind of screwdriver to use for adjusting the cam screw?

 

How much force should it require? I'm assuming it's counterclockwise to loosen :) Just want to check before I go in there...

 

(I also found out that my 50 Nocti and 50 Lux will not align together at infinity: when the Nocti is on at infinity, the 50 is out. Both have been adjusted by Leica. Argggh.)

 

When the 50 aligns at infinity, all my lenses "front focus" at closer focus (I guess Wilson would call that backfocus :)) So I'd like to correct this if I can.

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For some strange reason, I bypassed sending it to Leica and decided to try it myself (probably voided my warranty in the process). I guess maybe my inability to part with the camera for weeks.

 

I get the idea now, but I think I have messed it up a bit because I don't have the right screwdriver. I can't move the cam screw too much clockwise and the more i tried, i left more marks on the screw.

 

Julian - what would you suggest at the right tool? now that I have jumped in, I intend to finish the process.

 

Thanks.

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Whoa.

 

OK.

 

First, you loosen the screw by undoing it anticlockwise.

 

Then you use the tip of the screwdriver to rotate the cam either clockwise or counterclockwise.

 

The screw is only a locking mechanism for the cam.

 

Your screwdriver wants to have a very gentle slope filed on it so that you gain perfect drive on the screw. You will not do it nicely with a screwdriver that is not ground to a slight angle as the screw will be quite tight.

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I forgot to say. Before you start take a quick photo of the position of the cam, roughly, as it is now, so that if you want to get back to starting point you can reference roughly where it is now. This sounds an odd thing to do but when you get the cam adjustment loose you may knock it a lot by accident and it's helpful to know roughly where to put it before doing some test shots.

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Jamie - force wise to unscrew it's quite tight. It's best to gradually increase the torque as you attempt to unscrew it in a very smooth action, making sure you're gripping everything tightly and that the screwdriver you are using is perfect for the job.

 

You want to loosen the screw enough to be able to rotate the cam but not enough so that the cam flops around. I did do this initially so that I could gain understanding of how it works but now we already know that there is no point in you doing it as well !

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pack_tor - just reread your post.

 

DO NOT TRY TO TURN THE SCREW FURTHER CLOCKWISE!!! That will tighten it even more and risks snapping the screw and disaster!!

 

To reiterate -

 

The screw is a locking mechanism only. ANTICLOCKWISE to undo it and then rotate the cam to adjust the focus throw! Then clockwise to tighten it back up and lock it, then reset infinity, then test shot. And repeat until happy.

 

You nearly gave me heart failure when I read that!

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Jamie - I tried that initially but wasn't lucky enough to have the screw head on the M9 in such an orientation that I could get the right angle driver in.

 

It's pretty tight and you need full control over the tool Jamie - I found that the screwdriver with a filed end was perfect and allowed me to easily do it.

 

If your screw is such that you can get the right angle in then I reckon, yes, perhaps that'd be OK.

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Julian

 

This is an excellent post and I believe that small calibration errors are often overlooked when testing at close distances . At mid distances these become clear misses.

 

I would tell you that I have three sources of intelligence on calibration of the leica M rangefinder and none of them put any emphasis on checking infinity .

 

1. In NJ the primary test is at about 10M . The body is placed on a large heavy looking fixture and the target is a backlit piece of test equipment hung on a wall about 10 m away. Thats the primary test. A wall chart is used at about 2M and this is a handheld test. Finally the distance test is a few shots of a nearby building that is clearly not at infinity. I stood there and watched the process and discussed the details with the technician. A reference 50mm and 90mm lenses were used . The process was similar to tuning a violin.

 

2. Having had the infinity focus issue in a big way with a 135apo ...I went thru this with DAG. It took 3 tries to get the 135apo to focus at infinity. When we discussed the testing DAG indicated that he has found that if it focuses accurately up close ..it will hold up thru infinity. He does not have a good infinity test available. I had to send him a file of images of mailboxes at 100ft spacing.

 

3. If you look at the video of those that went to the factory to see the M9 being produced you can see the Lens Align rulers at different distances ..all seem to be at close or medium range.

 

I think your logic is sound but this isn t how the professionals appear to be calibrating the M rangefinder.

 

It is an ongoing challenge and small variances in bodies and lens can easily create misconceptions about ones equipment. Lens you think are spot on may be slightly off and the body is off to zero out the variance.

 

And again I am not challenging your POV but just pointing out what I learned talking with Leica and DAG. I am sure I have much to learn. I do completely agree that when the system is on.. it is superbly accurate .

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Jamie - I tried that initially but wasn't lucky enough to have the screw head on the M9 in such an orientation that I could get the right angle driver in.

 

It's pretty tight and you need full control over the tool Jamie - I found that the screwdriver with a filed end was perfect and allowed me to easily do it.

 

If your screw is such that you can get the right angle in then I reckon, yes, perhaps that'd be OK.

 

Thanks Julian!

 

@ Roger, it is sometimes more of an art, especially with a lot of lenses in play. As I said, I can't get both my Noctilux (new) and my Summilux ASPH 50 to align with the RF at infinity.

 

When I took my M8 and all my lenses into Kindermann, we used a building that was over a kilometer away for infinity. That seemed to work. I'm currently using a tower that's 5K away on the horizon, and that's also ok.

 

The compromise between the Nocti and Lux seems ok for infinity; 1m / ,8 M is now out, ever so slightly, on both lenses, but both are better at 20m again. This can drive you crazy :)

 

I'm off to look for the right screwdriver :)

Edited by Jamie Roberts
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Yes, the key is that the lens threads are a fixed pitch, so if the close focus is perfect then infinity should be perfect too.

 

And vice versa.

 

So you can start at either end, therefore, yes.

 

If your infinity is out when your close focus is good your arm length is not perfect.

 

and flipped:

 

If your close focus is out when your infinity is good your arm length is not perfect.

 

It's a good point to make - it doesn't matter really which adjustment you do first but I just find it easier to start with the infinity.

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Brett - :D - 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? :D

 

Julian - absolutely not !! I've been adjusting my M8 in this manner from the start for specific lenses. Unfortunately it's not in my interests to try and promote this process but you have managed to express it extremely well.

 

Just to say though that adjusting the hex is easy enough but unlocking and retightening the screw head is tricky and entirely at your own risk. You can damage the head or the mechanism.

 

The best way I can describe the process is it's like trying to lower those horizontal blinds to the window sill with two strings and making them hit the deck perfectly level. Sometimes it takes 7 or 8 adjustments to match everything up.

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... it's not possible for infinity to be perfect and then close focussing also be perfect....

 

Doesn't Leica say the rangefinders are adjusted for three distances? That would imply that a lens could be in focus at infinity and close up, but out at mid-distances, wouldn't it?

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{snipped}

I'm off to look for the right screwdriver :)

 

Well, that was frustrating :)

 

I can't even find a screwdriver that will fit into the slot properly. I found a miniature ratchet I thought would be perfect (right angle and everything) but even it's too large and won't gain any purchase on the screw.

 

So I don't think I've managed to do anything but reset my infinity focus and scratch the screw badly enough to void the warranty :)

 

I just wish Leica would find a way to let us do this ourselves. Or recommend tools, or something.

 

Julian, if you have a picture of the screwdriver you used, that would help us tool-challenged folks.

 

Ah well. Slight front-focus (back focus for Wilson) at extremely close distances isn't, on balance, totally horrible. I just don't want to have to worry about it when I'm on a job, of course.

 

@ Howard, certainly at Kindermann Gerry used to check 1M, 10M and infinity. But of course infinity was outside the building :)

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