Archived posting to the Leica Users Group, 2000/05/18

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: [Leica] Noctilux viewfinder blocking
From: John Collier <>
Date: Thu, 18 May 2000 17:10:14 -0600

According to my readings (Puts ­site below­ and Osterloh) an SLR with a
split image focusing screen has an effective base of about 10mm with a 50/2
lens (Osterloh) while the 0.72 Ms have a base of 49.8mm. Alas I do not know
how to calculate the improvement in focusing accuracy if one uses using a
f1.0 lens. Perhaps some optical mathematician can helps us out? The 0.72
finder is more than capable of focusing the Nocti accurately; after all, it
is only in the last few years that a high-mag finder has been available

John Collier

> From: "Takeshi Hashimoto" <>
> On Thu, 18 May 2000 16:00:21   Peterson Arthur G NSSC wrote:
>> I don't know, and so can only presume John is right, that the "M rangefinder
>> is more accurate than a SLR at 50mm."  But my question is this: given the
>> fact that with an SLR one is actually looking through the lens at (almost
>> always) full aperture, does it not then stand to reason that an SLR would be
>> able to focus any lens, of whatever focal length and whatever maximum
>> aperture, with sufficient accuracy for that particular lens?  I'm not being
>> argumentative, just asking what seems like a reasonable question.
> But the accuracy of the M system is fixed by the width of the two viewfinder
> ports. As the lens gets faster/longer, it (the margin of error) becomes too
> great to focus within the DOF of the lens. In other words, with an f/1.0 lens,
> the SLR is probably a little better.