Archived posting to the Leica Users Group, 2007/09/30

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Subject: [Leica] Lens reflections from IR cut filter - Mui Wo Ferry Pier
From: len-1 at comcast.net (Leonard Taupier)
Date: Sun Sep 30 05:26:26 2007
References: <200709300013.l8U0CFOD051278@server1.waverley.reid.org> <A36DDC81-0FF4-47EB-9084-503C0F75B2B0@netvigator.com>

Hi Howard,

I'm so glad to hear you're finally getting your M8 back again. The  
ordeal is nearly over.

I don't think the reflection is caused by the UV/IR filter. The  
artifact is too well defined and happens to be near the reversed and  
overlaid position of the true illuminated sign. Is the photo cropped  
at all? If I were a betting man I would say the reflection is caused  
by some sort of sensor bleed over, overload condition. This is a  
guess of course and you may want to try and duplicate the phenomena  
with and without a filter.

While it is true that lenses over 35mm don't need to be coded, they  
do need the UV/IR filter. The coding will correct for vignetting and  
cyan creep in the more affected wide angle lenses. However it will  
remove the unwanted IR purple cast with all lenses including normal  
and telephoto. The filters are required for all lenses, especially if  
you are shooting in color.

Best Regards,
Len




On Sep 29, 2007, at 9:55 PM, Howard Cummer wrote:

> Hello Luggers,
> Well my replacement M8 is in Hong Kong with Fedex, according to the  
> tracking, but didn't get delivered on Saturday. Monday is a holiday  
> (China's National Day) so I expect the camera will arrive on my  
> doorstep on Tuesday. In the meantime, Schmidt has given me a loaner  
> M8 and so I have been out on the streets again. Here is a picture  
> of the Mui Wo ferry Pier, where the ferries come in from Hong Kong  
> Island, taken with my newly coded 50mm Summilux Asph, wearing an IR  
> cut filter. I know that conventional wisdom is that lenses longer  
> than 35mm don't need to be coded, nor are IR cut filters really  
> required, but I have decided to code and filter equip all my lenses  
> - so that I don't have to think about switching lens detection on  
> and off for Coding and IR filters. Besides I like to know the focal  
> length in the EXIF data. One problem, however, with using IR Cut  
> filters unnecessarily is unwanted reflections. Please see the  
> attached photo of the Mui Wo ferry pier.
>
> http://gallery.leica-users.org/v/Howard+Cummer/Hong+Kong+Pix/ 
> MuiWoFerryTerminalBWw.jpg.html
>
> http://tinyurl.com/29vhzk
>
> Cheers
> Howard
> (Hot but Happy in Honkers and waiting for Santa to come on Tuesday)
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information


Replies: Reply from len-1 at comcast.net (Leonard Taupier) ([Leica] Lens reflections from IR cut filter - Verified)
In reply to: Message from cummer at netvigator.com (Howard Cummer) ([Leica] Lens reflections from IR cut filter - Mui Wo Ferry Pier)