Archived posting to the Leica Users Group, 2009/12/19

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Subject: [Leica] M9 Internal IR-Cut filter make the camera fragile to use?
From: steve.barbour at gmail.com (Steve Barbour)
Date: Sat, 19 Dec 2009 10:51:36 -0800
References: <8c8849060912180102j3e923072n699bfa64072e7442@mail.gmail.com> <4563F7F7-54B0-434F-BE00-17FFAC3C1E15@ameritech.net> <36172e5a0912181442w147b5244rbc2debf41f2c6dc1@mail.gmail.com> <634544D3-95D0-4A72-AF0F-91C2B8AB76EE@ameritech.net> <36172e5a0912181950h5e8faea5i4555f72307297462@mail.gmail.com> <C1A2D335-E6C1-4323-8E12-BBF3997AD506@btinternet.com> <3751BA58-50B2-426A-ADA8-14407A2A47C0@gmail.com> <09741AA2-4785-452C-A775-9CBEB6D937CD@btinternet.com>

On Dec 19, 2009, at 9:17 AM, Frank Dernie wrote:

> Hi Steve,
> the limiting factor in whether a lens "matches" the M9 offset microlenses 
> and IR filter is the position of its exit pupil which, if I understand 
> correctly, is a virtual point from which the image can be considered to be 
> projected onto the sensor. It has been argued, strongly by Olympus in 
> early digital days, that only lenses designed specially for digital, with 
> exit pupil at infinity, were suited to digital sensors. Long lenses 
> approximate to this anyway and clearly this is an exaggeration since it 
> seems any wide angle lens designed for a reflex camera has a sufficiently 
> distant exit pupil by the time it has been designed to miss the mirror. WA 
> lenses for rangefinder cameras have their exit pupil much closer to the 
> sensor, because they can, and for film this was no problem, coming up with 
> a compromise which suits the M9 to the Leica lenses is what the offset 
> microlenses etc are all about. I am sure the design of the M9 and its 
> software are a good match for the 21mm f2.8 asph.
>  The 21mm f4.5 Zeiss lens OTOH is almost symmetrical, was designed for 
> film without taking these precautions and has very low distortion as a 
> result, but making it unsuited to the digital sensor.
> I am sure Leica lenses work fine with the M9, with the exception of those 
> published in their literature.
> Making the offset more would start to make the M9 unsuited to the longer 
> lenses...
> Some of the Zeiss and Voigtlander Leica mount lenses are unsuited to the 
> M9 but at the beginning Zeiss did not say so. AFAIK nor did Voigtlander.


very interesting and totally clear Frank, even to me...thank you,  Steve
> cheers,
> Frank
> On 19 Dec, 2009, at 16:51, Steve Barbour wrote:
> 
>> 
>> On Dec 19, 2009, at 2:46 AM, Frank Dernie wrote:
>> 
>>> My WATE works fine on the M9. I always assume a lens with an exit pupil 
>>> extremely close to the sensor will be too extreme to be compensated, so 
>>> the 15mm CV almost certainly won't work, though I took a few shots with 
>>> my 12mm and it seems not bad, I preferred uncorrected. Depending on the 
>>> subject the shortcomings may not be noticed at all. It was pretty 
>>> obvious that the Zeiss 21mm f4.5 would be unsuitable for digital
>> 
>> I'm sorry Frank, I don't follow... why is that and does it apply to the 
>> Leica 21/2.8 Elmarit ASPH on the M9....?
>> 
>> Does that apply to use with the appropriate external viewfinder?  
>> 
>> 
>> 
>> thanks, Steve
> 
> 
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In reply to: Message from jsjgroups at gmail.com (Jerry Justianto) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)
Message from dstella1 at ameritech.net (Dante Stella) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)
Message from dstella1 at ameritech.net (Dante Stella) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)
Message from Frank.Dernie at btinternet.com (Frank Dernie) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)
Message from steve.barbour at gmail.com (Steve Barbour) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)
Message from Frank.Dernie at btinternet.com (Frank Dernie) ([Leica] M9 Internal IR-Cut filter make the camera fragile to use?)