[Leica] Zeiss Ikon Focus Shift

[billgem at hotmail.com (Bill Marshall)]

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 
(photo.net). 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: www.photo.net/bboard/q-and-a-fetch-msg?msg_id=009t9L

>"- 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