[Leica] 6bit coding

[Frank.Dernie at btinternet.com (Frank Dernie)]

sorry, badly written, should read "needs to get greater" then it is obvious, 
I hope.
FD

On 26 Nov, 2010, at 05:33, Frank Filippone wrote:

> I agree, however DOF of a 21mm covers up inaccuracy in focusing.....which 
> is
> essentially what a too thick or too thin mount would do to/for you.....
> 
> I do not understand why " mount precision gets greater with wide angle
> lenses, not less, since a given axial error is a bigger proportion of the
> focus travel."
> 
> Can you explain to me ?  
> 
> Frank Filippone
> Red735i at earthlink.net
> 
> 
> -----Original Message-----
> From: lug-bounces+red735i=earthlink.net at leica-users.org
> [mailto:lug-bounces+red735i=earthlink.net at leica-users.org] On Behalf Of
> Frank Dernie
> Sent: Thursday, November 25, 2010 12:18 PM
> To: Leica Users Group
> Subject: Re: [Leica] 6bit coding
> 
> Hi Frank,
> it is not the depth of field which is important for the focussing register,
> but the focussing travel. The importance of mount precision gets greater
> with wide angle lenses, not less, since a given axial error is a bigger
> proportion of the focus travel.
> I am sure someone on the list has the data but IIRC the axial focus travel
> for a given change in distance is proportional to the focal length, so a
> 21mm is about 2.5 times -more- sensitive to an axial error than a 50mm 
> lens.
> cheers,
> FD
> 
> On 25 Nov, 2010, at 18:35, Frank Filippone wrote:
> 
>> It made no difference to my 21.... but then again, my DOF is a "bit" 
>> more relaxed.....
> 
> 
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