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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!

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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 by Julian Thompson
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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!

 

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 :

 

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

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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!

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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!

 

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.

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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 :eek:). 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

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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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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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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.

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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?

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