Archived posting to the Leica Users Group, 2007/09/02

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Subject: [Leica] Re: do it yourself back-focus adjustment..."
From: len-1 at comcast.net (Leonard Taupier)
Date: Sun Sep 2 06:59:46 2007
References: <98A0D67D-CE25-48F3-84D2-A34BBA5BEC1C@mac.com> <002001c7ec8b$e5295910$6400a8c0@corp.nortel.com> <5DDF2A59-8784-410E-9C7C-C56C8073DAB1@mac.com> <001701c7eced$f924a0c0$6401a8c0@asus930> <A5BF3089-C334-4065-87FF-7BA589E05B00@comcast.net> <000c01c7ed29$5f48d840$6401a8c0@asus930> <48026A05-8FFE-42A3-9697-785138C240E9@comcast.net> <82c9dd70709020643g66aee8d9h97d0dfac3f48eec4@mail.gmail.com>

Eric,

I agree with you to a point. I adjusted my M8 5 months ago and  
haven't looked back. For me it was make the Noctilux work or get rid  
of it. Then the new prices of the Noctilux almost doubled and I knew  
I had to make it work. I have been very happy with my M8 and lens  
system ever since and don't even think about it any more until a  
thread starts up on the LUG.

I will have that cocktail though.

Regards,
Len


On Sep 2, 2007, at 9:43 AM, Eric Korenman wrote:

> I obsessed about this for a few weeks (esp with my noctilux)
> Then I let it go..
> Certainly your camera should be in proper alignment, but to chase  
> after each
> lens' focus shift will make you insane!
>
> I am learning to compensate (again, esp with my noctilux) for wide  
> open near
> focus.
>
> The issue is focus shifts that none of us noticed prior to the  
> advent of
> super thin image sensor surfaces.
>
> take pictrues
> have a cocktail
>
> Eric
>
>
> On 9/2/07, Leonard Taupier <len-1@comcast.net> wrote:
>>
>> Hi Hoppy,
>>
>> It is a global focus error on the Noctilux, 75 Summilux, and the
>> 90AA. In the case of the Noctilux there is also a focus shift at f2.0
>> and f2.8. Without the adjustment it takes an f5.6 setting for the DOF
>> to bring it in focus. That is because the DOF increases quicker
>> behind the target then in front. The other lenses don't appear to
>> have the focus shift problem when stopping down.
>>
>> Cheers,
>> Len
>>
>>
>> On Sep 2, 2007, at 2:20 AM, G Hopkinson wrote:
>>
>>> Len, understood. You are describing a focus shift as you stop down
>>> slightly, rather than a global  focus error requiring individual
>>> lens adjustment. Focus presumably correct wide open, shifts as you
>>> stop down owing to residual aberration. Error not apparent as you
>>> get to smaller apertures with greater DOF. Evidently your method
>>> works for you guys and that's what is important. Worth reading the
>>> article in the August LFI on the subject, if you get a chance.
>>> Thanks for the information.
>>> Cheers
>>> Hoppy
>>>
>>> -----Original Message-----
>>> Subject: Re: [Leica] Re: do it yourself back-focus adjustment..."
>>>
>>> Hoppy,
>>>
>>> The adjustment is the infinity adjustment cam just inside the camera
>>> mount. The close focus adjustment is actually behind the Red leica
>>> dot on the front of the camera. It's not a case of just adjusting  
>>> DOF
>>> to be favoring in front or in the rear of the focus point. In the
>>> case of the Noctilux and the 75mm Summilux, from wide open to a stop
>>> or two closed all the photos are just plain out of focus. Between
>>> about 5 to 10 feet from the target, the only thing in focus was
>>> behind the target. I own 19 M lenses that I can use on my M8 and 5
>>> LTM lenses I use with adapters. After my adjustment every lens
>>> focuses perfectly on the M8 except the 135mm at infinity. So I am  
>>> not
>>> matching 1 lens to 1 body. I don't think the 24 lenses needed
>>> adjustment and the M8 didn't. BTW leica does not recommend using a
>>> 135mm on the M8.
>>>
>>> Len
>>>
>>>
>>> On Sep 1, 2007, at 7:15 PM, G Hopkinson wrote:
>>>
>>>> Guys can someone be explicit there regarding what you are
>>>> correcting? Focus wide open at practical infinity or a close
>>>> position?
>>>> Focus at a particular f stop?  Someone said that they are adjusting
>>>> so that there is more apparent DOF in front than usual. Since
>>>> the acceptably sharp zone will always be deeper behind, I read this
>>>> as actually moving the sharpest point forward.
>>>> There is a difference between a global back focus (lens adjustment
>>>> error) and a focus shift visible near wide open as you stop down.
>>>>
>>>> I can certainly understand that you may end up with an adjustment
>>>> that works in practice for your own circumstance (lens and use),
>>>> I'm just really interested as it seems to me that you are
>>>> introducing new errors, especially with other lenses for example.
>>>> It may
>>>> be that DOF masks the error with other lenses. Just guessing, I
>>>> imagine that Leica is checking/adjusting the individual lens focus
>>>> mechanism, which is not the same as adjusting the camera body
>>>> roller arm naturally.
>>>>
>>>> The inquiring Hoppy wants to know.
>>>>
>>>> -----Original Message-----
>>>> Subject: [Leica] Re: do it yourself back-focus adjustment..."
>>>>
>>>> Vick,
>>>>
>>>> The original idea to do this came from the Leica Forum.  Look there
>>>> if you want to find a more rigorous approach to the problem.
>>>>
>>>> Bob
>>>>
>>>> On Sep 1, 2007, at 4:33 AM, Vick Ko wrote:
>>>>
>>>>> Okay, now I understand.
>>>>>
>>>>> You are adjusting the RF arm.  I anticipate that it only takes a
>>>>> very very
>>>>> small amount of adjustment.  If the adjustment is large, then you
>>>>> will end
>>>>> up affecting the infinity alignment of the RF image.
>>>>>
>>>>> Congratulations on discovering this method.
>>>>>
>>>>> regards
>>>>> Vick
>>>>>
>>>>> -----Original Message-----
>>>>> From: Robert Rose [mailto:robert.rose@mac.com]
>>>>> Sent: Saturday, September 01, 2007 2:33 AM
>>>>> To: Leica Users Group
>>>>> Cc: vick.ko@sympatico.ca; Leonard J Kapner
>>>>> Subject: do it yourself back-focus adjustment..."
>>>>>
>>>>> Vick,
>>>>>
>>>>> We had a thread on this around March or so.  I had posted some
>>>>> samples and
>>>>> how to do it at:
>>>>>
>>>>> http://gallery.leica-users.org/v/rjrose/focus/
>>>>>
>>>>> Bob Rose
>>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Leica Users Group.
>>>> See http://leica-users.org/mailman/listinfo/lug for more  
>>>> information
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Leica Users Group.
>>>> See http://leica-users.org/mailman/listinfo/lug for more  
>>>> information
>>>
>>>
>>> _______________________________________________
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>>>
>>>
>>>
>>> _______________________________________________
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>>> See http://leica-users.org/mailman/listinfo/lug for more information
>>
>>
>> _______________________________________________
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>>
>
> _______________________________________________
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Replies: Reply from faneuil at gmail.com (Eric Korenman) ([Leica] Re: do it yourself back-focus adjustment...")
In reply to: Message from robert.rose at mac.com (Robert Rose) ([Leica] do it yourself back-focus adjustment...")
Message from vick.ko at sympatico.ca (Vick Ko) ([Leica] RE: do it yourself back-focus adjustment...")
Message from robert.rose at mac.com (Robert Rose) ([Leica] Re: do it yourself back-focus adjustment...")
Message from hoppyman at bigpond.net.au (G Hopkinson) ([Leica] Re: do it yourself back-focus adjustment...")
Message from len-1 at comcast.net (Leonard Taupier) ([Leica] Re: do it yourself back-focus adjustment...")
Message from hoppyman at bigpond.net.au (G Hopkinson) ([Leica] Re: do it yourself back-focus adjustment...")
Message from len-1 at comcast.net (Leonard Taupier) ([Leica] Re: do it yourself back-focus adjustment...")
Message from faneuil at gmail.com (Eric Korenman) ([Leica] Re: do it yourself back-focus adjustment...")