[Leica] I have come to this conclusion

[afirkin at afirkin.com (Alastair Firkin)]

Well, what I did was shoot a flat cream blind:

1. lens recog off
2. lens recog on (even if the lens was not coded)
3. lens recog on and UV/IR 

At 50mm and above the images were pretty close with no colour vignetting
At 35mm there was some early cyan colour vignetting
wider than that, it become progressively worse so that at 16mm with the 
UV/IR FILTER it was quite alarming with the uv/ir off

Now in practice, I have been less than stringent. I used my 35 asph last 
week with UV/IR filter and did not really notice any problem. There was no 
doubt that turning on the lens detection and UV/IR did make a difference 
even with the 35 and 50 even without coding. With the 21 even if the UV/IR 
filter detection is on, the effect of the IR filter is quite noticable, I 
presume that the correction is being done for a longer focal length lens, so 
the corners cyan out. 

--- frank.dernie@btinternet.com wrote:

From: FRANK DERNIE <frank.dernie@btinternet.com>
To: Leica Users Group <lug@leica-users.org>
Subject: Re: [Leica] I have come to this conclusion
Date: Fri, 22 Aug 2008 12:07:29 +0100 (BST)

Hi Alastair,
I am intrigued by your conclusions - because mine
differed!
I always use a filter now and the only lenses I have
coded are 28mm and WATE. I find the colours too
inaccurate outdoors without a filter, very noticeable
on grass and other greenery, as well as synthetics.
I haven't found any real problem with filter on my
uncoded lenses so far, are you having "colour
vignetting"?
cheers,
Frank

--- Alastair Firkin <afirkin@afirkin.com> wrote:

> I am home with the flu and my new M8, so its time
> for some playing around. 
> 
> 1. if you have a UV/IR filter on the lens, make sure
> you have the Lens detection/UV/IR "on". This applies
> to all lenses 50mm and greater. The 35 is touch and
> go
> 
> 2. if you are using a wide angle, and it is uncoded,
> do not use the UV/IR filter. This probably includes
> the 35mm. It is counter productive to put the filter
> on a wide uncoded lens, and you are probably better
> off to use black/purple shift to correct any black
> clothing in the image (given that you don't mind
> purples going black)
> 
> 3. do not use the wide TE with the lens detection
> off unless you remove the IR filter. 
> 
> 4. the 21 asph can be used without an external
> viewfinder (as reported by Gene) as long as you
> don't wear glasses, the FOV will equate almost
> exactly to everything you can see in the viewfinder
> outside the frames: in some ways its more accurate
> than using the frames, which have such a huge
> latitude that I find them annoying. 
> 
> 5. the 21 asph is a great lens, and I really should
> have it coded :-( Leica should really have allowed
> us to choose the lens from the menu rather than
> force coding: but I suspect this is where they are
> just collecting a bit of "cream". Also, the TE
> brings up the appropriate focal length when coded:
> why could not the TEW. 
> 
> Oh well
> 
> Cheers
> 
> Alastair
> 
> _______________________________________________
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> more information
> 


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