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IR filters and the LFI article


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LFI 5/2007 just reached these shores, and there is a follow-up article on IR filters. The intro is still rather Panglossian, but for the first time says that the idea of a dichroic filter over the sensor itself was rejected by the development team because of a fear of internal reflections "for some wavelengths" and a reluctance to deal with correcting for red vignetting with the wide angle lenses. (Which of course was eventually required, and delivered fairly successfully in firmware 1.102 for use with external filters.)

 

The article is still a little confused about the behavior of an interference filter. It calls the possibility of color shifts when light passes through such a filter at an angle an "unanswered question," and says that the glass of the filter viewed at an angle "reflects an increasing amount of cold bluish green towards the periphery." The color shift (reflecting visible red at angles of 30 degrees and more) is known. After all, that's why the development group didn't want to use an interference filter at the sensor. And the cold blue green is the color that a white material under the filter takes on in transmission (as illustrated in the article) not the color that is reflected. So what they call "cyan vignetting" is really red vignetting, or as Sean Reid likes to call it, "cyan drift." In the caption of one figure, they also observe that the vignetting correction in the "ON+UV/IR" mode is weaker than in the "ON" state, as has been noticed here.

 

There are hints of the causes of the delays in delivering the larger filters (E55, E60 and E67). Problems with a supplier and the discovery that early units of these filters needed a different specification are suggested. A few weeks ago, several posters reported receiving E55 filters -- have these been recalled, as the article suggests? Why the E39, E43 and E49 filters which have been available for some time are not affected is not explained, so I presume these come from a different supplier.

 

One conclusion: It seems that the Leica filters needed for the JM 49mm filter holder to use with the CV15 are available, but there may still be delays in getting the 55mm filter that is needed for the CV12 and the Elmarit 21 and 24's.

 

Anybody spot additional points that I left out?

 

scott

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Scott,

Thanks for posting the summary. Still waiting for my copy to arrive.

 

You mention a 49mm filter for JM's filter holder/hood for the CV15. In his own thread he mentions it using 39mm filters. Did I miss something along the way?

 

- C

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Guest guy_mancuso

Carl he uses the 39mm filter for the CV 15mm but the WATE takes a 49mm.

 

 

As far as filters leica mentioned to me that there is a extra layer of coating on the 55mm , 60mm, and 67mm filters. This was partly the reason they are coming last plus these filters apparently are hard to make with up to 30 coatings. Also there not made by leica but a vendor to leica specs. i would like to read what LFI has to say about the filters though, look forward to the article

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from a fairly reliable Leica dealer is that Heliopan is now making the Leica IR/cut filters

I hope they will one day get around to making a drop in filter for my 560 f5.6 Telyt ...it takes a Serie VII as a drop in which is 50 mm across

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Guest guy_mancuso

Arthur that is not correct per say and it may depend on the size. The 55 and 60mm are not heliopan that i know for sure

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Scott,

Thanks for posting the summary. Still waiting for my copy to arrive.

 

You mention a 49mm filter for JM's filter holder/hood for the CV15. In his own thread he mentions it using 39mm filters. Did I miss something along the way?

 

- C

 

No, I got the WATE's filter (done about a month ago) and the CV15 filter (in progress) mixed up in my mind.

 

scott

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I believe many have returned their 43mm filters as the threads were cut .06 mm too large diameter. They just about fit some of the older Leica lenses, if you are prepared to be brutal but they are not standard international 43mm thread size (42.77mm). Jessica told me at the beginning of last week that the 60mm filters had arrived in Germany and were in the process of being sent out by the dispatching agency. Mine has not arrived yet in France.

 

Wilson

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A few weeks ago, several posters reported receiving E55 filters -- have these been recalled

 

Scott,

 

I received my free 55mm filter just over a week ago and have had no recall on it.

 

Regards

Eric

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from a fairly reliable Leica dealer is that Heliopan is now making the Leica IR/cut filters

I hope they will one day get around to making a drop in filter for my 560 f5.6 Telyt ...it takes a Serie VII as a drop in which is 50 mm across

 

Foto Huppert delivered a B&W series VII within three weeks after ordering. They are in the catalog, but delivered to order.

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Guest sirvine
I believe many have returned their 43mm filters as the threads were cut .06 mm too large diameter. They just about fit some of the older Leica lenses, if you are prepared to be brutal but they are not standard international 43mm thread size (42.77mm). Jessica told me at the beginning of last week that the 60mm filters had arrived in Germany and were in the process of being sent out by the dispatching agency. Mine has not arrived yet in France.

 

Wilson

 

That's the first I've heard of that. I thought it was my lens (only have a single 43mm lens).

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That's the first I've heard of that. I thought it was my lens (only have a single 43mm lens).

 

Sol,

 

Apparently they are all wrong so far. The correct industry standard thread diameter for a 43mm filter is 42.77 - 42.78mm. Both my B+W and a Schneider filter are this. The 43mm sent to me had a diameter of 42.83mm. I tried another in a shop in Nice and it was 42.84mm. My local Leica dealer in the UK said he had had the same problem and sent them back.

 

Wilson

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  • 1 month later...

Just to bring this up to date. I picked up an E43 UV/IR filter today (13417) it is a perfect fit for my 50/1.4 summilux 2308*** circa 1968. I had a UVa on it previously the "thin" version which was made to allow the reversible lens hood to fit (12586). The new filter is much deeper than the E39 and E46 filters I have having a "groove" behind the grips which allows the hood to fit on securely both in use and reversed for carrying. The B+W does not have this.

 

This also links to this thread on the specific issue of summilux fit filters.http://www.l-camera-forum.com/leica-forum/digital-forum/16230-486-ir-cut-filter-43mm.html#post175385

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Just to bring this up to date. I picked up an E43 UV/IR filter today (13417) it is a perfect fit for my 50/1.4 summilux 2308*** circa 1968. I had a UVa on it previously the "thin" version which was made to allow the reversible lens hood to fit (12586). The new filter is much deeper than the E39 and E46 filters I have having a "groove" behind the grips which allows the hood to fit on securely both in use and reversed for carrying. The B+W does not have this.

 

This also links to this thread on the specific issue of summilux fit filters.http://www.l-camera-forum.com/leica-forum/digital-forum/16230-486-ir-cut-filter-43mm.html#post175385

 

I think we have all come to the conclusion that the e43 Leica filters are 0.5mm thread pitch against the industry standard for this size, which is 0.75mm pitch. This would not have been a problem if Leica had let us know this. Most manufacturers change from 0.5 pitch to 0.75 pitch at 39.5mm filter thread diameter or else clearly state the thread pitch. It all comes down to poor communication, the source of much of the world's ills.

 

Wilson

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Regarding Heliopan as filter source, I received my freebie E60 UV-IR-Cut filters from Leica a couple months ago with a Customs Declaration specifying that they were a product of Japan. Isn't Heliopan generally German?

 

--HC

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