Archived posting to the Leica Users Group, 2005/01/13

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Subject: [Leica] Zeiss Ikon Focus Shift
From: s.jessurun95 at (animal)
Date: Thu Jan 13 16:44:45 2005
References: <BAY101-F27F519BC134B3746BDA8ADAB890@phx.gbl>

apple,s and pears
Erwin is talking about line paires per mm on the negative not the lenses 
aerial(is that english?)performance as such .Have no time to look it up but 
what aperture would one need for 400 lppmm ? surely larger then the Zeiss 
proposed lenses or no?
Also a bit OT but what,s the purpose of close focusing withe very wide angle 
lenses ?Can you show me one pleasing picture utilising that capability?
Just asking
am a total amateur and suck big time at photography
simon jessurun
the netherlands

> On Monday, Richard wrote:
>>"Well, since I am one of the people that calls it "smelling of marketing 
>>hype," let me reiterate why I thought so:
> - stress on high resolution when most experts say what are they smoking?"
> Richard, I assume that you are referring to the 400 lp/mm claim. I don't 
> know who the so-called "experts" are. The only one I read who wrote about 
> it at any length was Erwin Puts & he did so in rather scathing terms. It's 
> interesting that Kornelius Fleischer, who did the testing for Zeiss that 
> resulted in the high resolution claim, responded to Erwin on a public 
> forum ( If you didn't see it, you can find it under the topic 
> "Can ZM lens really resolve 400lpm???", posted by Arthur Yeo on October 
> 24. Fleischer's post is fairly lengthy & was posted on October 29; if you 
> scroll down, you will find it. Read it & see what you think about who is 
> smoking what. The url is: 
>>"- stress on high RF baselength when only one lens (85/2) would benefit."
> Richard, I dispute the claim that only one lens will benefit. Is this 
> criticism saying that it's not a good thing to have a more precise 
> rangefinder & that all lenses won't benefit from focusing with it? First, 
> a longer bae line will minimize the effect of the range of tolerances - 
> whatever that range is. Second, a longer base line will also focus more 
> effectively with all lenses when they are shooting close up - & especially 
> close up & wide open. Have you noticed that the CV Bessa R2, for example, 
> is rangeinder coupled only to 0.9 meter (35")? The ZI is rangefinder 
> coupled to 0.3 meters (12"). Huge benefit for all the ZI lenses! Finally, 
> the ZI isn't restricted to its own lenses. It's an M-mount camera that can 
> use any M-mount lens; it will handle all of those super fast Leica & CV 
> lenses & will focus them beautifully.
>>" Also again, doesn't the RF mechanism need to be of higher quality for 
>>the focusing accuracy to show there?"
> Since none of us have any idea what the quality is, we have no idea 
> whether it needs to be of "higher quality." Some of us have impressions 
> from photo shows, but none of us have inspected the RF mechanism to see 
> how well built it is. Hopefully it is of high quality & hopefully Zeiss 
> has spec'd it for tight tolerances. But even it it of exactly the same 
> quality as other Cosina-built RF mechanisms, its length alone will make it 
> a more effective instrument. For example, if Cosina builds in a tolerance 
> of +/- 1 mm, this will represent a potential error of +/- 1.3% or a total 
> error range of 2.7% on the ZI. On the Bessa cameras, the same 1 mm 
> tolerance = +/- 2.7%, or an error range of 5.3%. In other words, the same 
> tolerance will have double the effect on the shorter base line because it 
> is half as long.
>>"- stress on focus shift without showing its benefits"
> Simply put, I think that this whole focus shift issue was just 
> techno-speak for saying "We made these lenses as sharp as modern lenses 
> can possibly be made." Poor choice of marketing strategy to get overly 
> technical, perhaps, but not really a knock on the product nor should it 
> diminish expectations to the point where we say "It's all just hype & 
> nothing more." Yes, there's been hype, but I think that there is substance 
> behind it. The Zeiss reputation alone should suggest that.
> Thanks for your reply.
> Cheers,
> Bill
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In reply to: Message from billgem at (Bill Marshall) ([Leica] Zeiss Ikon Focus Shift)