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CCD Sensor - New Leica Information about the State of Development


Leon_B.

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ONSEMI.COM, manufacturer of the KAF-18500 used in the M9, M Monochrom, and M-E, now has a new part number available for the KAF-18500 showing it available with BG55 glass. The S8612 version is also still shown.

 

New Part Number from ONSEMI, kaf-18500-fxa-jh-aa-bg55

 

The BG55 Data Sheet:

 

http://www.schott.com/advanced_optics/english/download/schott-bandpass-bg55-dec-2014-en.pdf

 

S8612 cover glass that caused the problems:

 

http://www.howardglass.com/pdf/s_8612_datasheet.pdf

 

Schott also revised the S8612 data sheet recently, 2014 version shows "1 warning" for humidity instead of 2 as in the 2009 data sheet.

 

Will be interesting to see how the new sensor being installed by Leica was revised.

Edited by fiftyonepointsix
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It might be coincidence that the new part number for the KAF-18500 shows up, but the change in the naming also indicates that a different pigment is used in the RGB mosaic filter, "Pigment RGB Bayer, GEN 2".

 

At least it shows that On Semi can change the pigment and IR cover glass within months. This new part number did not show up before.

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Would that be related to the different transmission spectrum of the cover glass?

That would be a valid reason for changing the pigment, especially in the Red region. The Red layer of the M8 absorbed much more light compared with the M9. The M8 IR cover glass "needed the assistance".

 

Neither of my cameras shows problems in the cover glass, the S8612 is very efficient for absorbing IR and passing visible. There are many 10+ year old cameras using the FillFactory 14-MPixel full-frame sensor with S8612 glass that do not have problems. It is nice to know "Leica has my Back" if a problem develops in the future with the M9 or M Monochrom.

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http://www.schott.com/advanced_optics/english/download/schott-optical-filters-2015-catalog-complete-en.pdf

 

Page 24 of the 2015 Schott catalog shows BG55 glass in a group that is "single-umbrella, virtually no long-term change" even without a protective coating. I believe BG55 with a protective coating would solve the problems of the S8612 glass. BG55 is in the same group as BG18, BG55 was recently reintroduced in 2011. Think of this change as an "in-service revision to correct issues of certain operating environments" rather than an "upgrade".

 

As usual, "just could be a coincidence", like a rangefinder camera in focus.

Edited by fiftyonepointsix
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In the data sheet linked above, the S8612 glass has but one umbrella, too. I can see no hint in the data sheets that one glass has fewer problems than the other. However, it's not really necessary that I do because I am not involved in any way in the production or repair of  cameras.

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So does this mean Leica plan to continue producing the M-E, or is this just to cover repairs of existing units?  

 

I don't think they've made the M-E for quite a while.  More likely they have a lot of M9 spares and those are whatever M-E cameras have been made since 2012.

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In the data sheet linked above, the S8612 glass has but one umbrella, too. I can see no hint in the data sheets that one glass has fewer problems than the other. However, it's not really necessary that I do because I am not involved in any way in the production or repair of  cameras.

That's the interesting part- in the past (2009 edition) , the S8612 Data Sheet showed 2 warning signs for humidity= meaning "Group 3" for humidity related damage. The latest version (Dec 2014) shows 1 umbrella, meaning "Group 2".

 

2009 Catalog:

 

http://pdf.directindustry.com/pdf/schott-glas/glass-filter-catalogue/22716-169342.html

 

In the 2015 Catalog the BG55 glass is in "Group 2" for humidity resistance and S8612 is in "Group 3". 

 

Group 2 (BG55 is a member) : "there is virtually no long-term change when used and stored in moderate climates or in closed work and store rooms (constant temperature below 35°C, relative humidity less than 80%). A desiccant should be used if the possibility of wetting exists. For use and storage in open air and tropical climates, it is advisable to apply a protective coating"

 

Group 3 (S8612 is a member) : "a change in the glass surface is possible after a few months of normal storage. For this reason, applying a protective coating or lamination is recommended for durable optical filter glass from Group 1"

 

Link Repeated for the 2015 catalog, source of the above quotes is numbered page 24:

 

http://www.schott.com/advanced_optics/english/download/schott-optical-filters-2015-catalog-complete-en.pdf

 

Manufacturers often "change specs without notice" and the change takes a while to propagate through all of the literature. I've had to resolve problems with equipment by finding old copies of a spec sheet to explain a problem. Like "1988 Spec" vs "1993 spec" a decade later. Either the BG55 glass, or an improved formulation of the S8612 that moves it into the "One Umbrella Group", will solve the problems of using a "Group 3" glass.

Edited by fiftyonepointsix
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I have inquired with Schott as to which S8612 data sheet is correct, the Dec 2014 S8612 datasheet or the 2009 datasheet and 2015 glass catalog. The catalog and Dec 2014 datasheet contradict each other. Either the glass has been changed and the catalog not updated, or the Dec 2014 datasheet is in error. Being able to reformulate the S8612 glass for better corrosion resistance would be optimal, but it would be a new type and should have been given a replacement part number- like S8612A.  Some life testing would be required before releasing.

Edited by fiftyonepointsix
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