Leica True Sense Imaging, maker of CCD's for the M-E and M Monochrom, now ON Semiconductor

This problem can be solved, I really cannot understand why the KAF-18500 cannot be revised to use the more durable cover glass. It is the same refractive index, is as efficient absorbing IR as is the existing glass. Leica should consult with On Technology and Schott for a long-term solution. The KAF-18500 was made for Leica, was not offered as a general offering. Changing out the cover glass is not hard, and sensor manufacturers try to accommodate the customer. 20+ years ago Kodak revised a KAF-1600 for me, called them up and told them I wanted one without the IR cover glass. They called back a few weeks later, said they would do it, made a batch of 50 with clear glass covers. No delamination problems, the sensor still works.
 
I went through all of the CCD products that On Technology produces, the KAF-18500 is the only product with IR Absorbing glass used as the cover glass, all others use clear cover glass. Most cameras use IR absorbing glass that is mounted between the sensor and lens. Leica could not do this as traditional sensor stacks are too thick. Some sensors use a cover glass that is taped to the sensor, most have cover glass that is cemented to the sensor.

The thermal expansion of BG-18 is less than S8612, but I could not find the thermal expansion for the KAF-18500.

Some users maintain that the problem with the KAF-18500 is with the coatings, not the type of cover glass used. The Schott recommendation for use of S8612 glass is to cement glass that is not sensitive to humidity to it, essentially make a sandwich. Again- Leica could not do this because of the need for a thin sensor stack. The other method of sealing the S8612 glass is to use a resin coating to keep humidity out. This latter seems to be the problem for long-term durability. To me, the easiest way to bypass the problem with coatings that delaminate is to use glass that does not require the coatings in the first place. Placing a coating over glass that corrodes in the presence of a humid environment- then stating the problem is with the coating- is ignoring the deeper issues with the type of glass used.

and- we're being linked to by the German portion of the Leica forum. I ran a translator to read that "cover glass is not an issue, coatings are an issue". The statement is true, but the question should be "why are the coatings delaminating". As the glass used presently corrodes in the presence of humidity, that is my first suspect.

http://www.l-camera-forum.com/leica...9/338394-umfrage-wer-hat-seiner-m9-me-91.html
 

Duane Pandorf

Top Veteran
Location
Western NC
Hope Leica doesn't take too long to figure something out. I'm about to send my M-E for cleaning and to check to see if I have a bad column. My trouble is I will hate being without the camera. I've actually considered buying a second hand M9 or M-E to cover me during that time and then sell it when mine comes back.

I'd really love to have a MM . That way I can share batteries, etc. For some reason I'm still not interested in upgrading to the M240/M-P.
 
I understand about "upgrading" to the M240, the M9 gives me what I want in a camera. The M Monochrom- same thing.

I kept my M8, it is a late production unit that I bought used. The original sale date on it is 10/2009, receipt provided by the original owner. It's my "backup". Sensors are "rev'd" during production life, and the one in my M8 gives outstanding results using M8raw2dng.

This is ISO2500 equivalent, with the M8, using M8raw2dng+LR4.

14470625147_c35caeb74b_b.jpg
skate4_ISO2500 by fiftyonepointsix
 

uhoh7

Regular
This problem can be solved, I really cannot understand why the KAF-18500 cannot be revised to use the more durable cover glass. It is the same refractive index, is as efficient absorbing IR as is the existing glass. Leica should consult with On Technology and Schott for a long-term solution. The KAF-18500 was made for Leica, was not offered as a general offering. Changing out the cover glass is not hard, and sensor manufacturers try to accommodate the customer. 20+ years ago Kodak revised a KAF-1600 for me, called them up and told them I wanted one without the IR cover glass. They called back a few weeks later, said they would do it, made a batch of 50 with clear glass covers. No delamination problems, the sensor still works.

Ty so much for this hard information.

I wonder if we should just cut to the chase and get someone like maxmax, where they already replace cover glass/filters, in the loop and offering a replacement with the variant you specify. I've been in email contact with them in the past, and found them quite responsive. They replace 5D sensor covers all the time, for about 400USD

Not sure how to interpret"
"The cover glass does not appear to be the problem. Rather interpret the many details on the protective coating around the coverslip down. You'd have separate coverslip from the sensor unit to make it possibly at a different cover glass with appropriately resistant coating replaced. Since I immediately on Google found a page: EURECA Messtechnik Ltd. And if they can do it, then this can be a provider as well as ON Semiconductor."

from your link.
 
Okay- the cover glass is cemented into place, it can not easily be removed. Soaking the sensor in solvent is required to remove it, and that would very likely destroy the microlens array. So, the KAF-18500 must be revised to use a different cover glass. I already contacted one company for an IR conversion.

I've read comments on other forums stating that the coatings are the problem, that the cement used to hold the cover glass in place is the problem, etc. As an engineer- the root of the problem is that the S8612 cover glass corrodes due to humidity. The sensor stack must be thin for the Leica M-Mount lenses. The traditional method of using an AR-coated clear cover glass with the same coefficient of expansion as the sensor itself and using a separate IR absorbing filter between the sensor and the lens is not optimal. Leica/Kodak chose to go with the very efficient S8612 glass and to seal it from humidity. The seal is breaking down, and humidity is getting to the glass. To me- the easiest way to solve this problem is to use glass that is not sensitive to humidity. As an added bonus- the BG-18 has a coefficient of thermal expansion that is lower than S8612, ie closer to the sensor. I do not know the relative strength of this glass compared with S8612, another important factor.

One other thought: CCD's and sensors in general heat up as they are used. The glass will expand and contract as a result. The S8612 expands and contracts at a different rate than does the sensor. The problem of the seals breaking down "could be" related to shooting style. Someone that is shooting as fast as possible will produce larger expansion/contraction cycles than someone that uses single-mode, rarely fills the buffer.

I worked with digital imagers throughout the 1980s, switched to optical networks in the 90s. We had custom sensors built to our specs, custom glass made to our specs. In the 90s- custom components and boards to our design, "Gallium Arsenide" chips for speed, stamped "prototype". 36 years into it now. Still can't help looking at a problem like this and wanting to task engineers to trade-off between components. "My style" was to read the data sheets, pick some candidates, hand it to one of my engineers and ask if there was a reason why it could not be used, or if they could find one that was better. Sometimes, just had to tell them - "Use this one". In something like the S8612, the warning about corrosion in humid environments should have been enough reason not to use it. Always looking for Murphy's Law to get you wherever possible. The S8612 cover glass seems to be Murphy's Law at work. As best as I can tell, The KAF-18500 is the only sensor in ON's current offering that uses it.

Shimming Jupiter-3's and converting Contax mount Sonnars to Leica mount, just like knitting. This other stuff- work.
 

asiafish

All-Pro
Location
Bakersfield, CA
Real Name
Andrew
So here is the dilemma. I bought my M Monochrom used and without a warranty. I've had for more than two years now, so even if there was a warranty, it would now be expired. I live in a rather dry climate and thus far have had no issues whatsoever with my sensor, BUT, I don't want my camera to become an expensive paperweight.

Should I.....

1. Sell it now while it is still corrosion-free?
2. Just pretend the problem doesn't exist and if it manifests either pay for repair or just don't stop dow?
3. Quit worrying about nothing?

I love shooting the M Monochrom, but its hardly my only fix. I actually enjoy my M5 even more.

Advice?
 
I am keeping my M9 and M Monochrom no matter what, I trust that Leica will take care of their cameras and the photographers that use them. Raid bought his M9 used, the sensor died, and Leica replaced it free of charge well after the warranty expired. (had to add- AND keeping My M8, I hope to get 20+ years out of it like my Kodak DCS)

SO- my advice is for #2 and #3 on your list. With that stated, I would not use a wet cleaning agent on the sensor and have it professionally cleaned by Leica if using a blower is not good enough. I would also not make a habit of shooting on continuous until the buffer fills up. I've never done the latter, a hold-over from film days. "Spray and Pray" vs "Decisive Moment", now think of it in terms of sensor temperature and thermal expansion.
 

Mijo

Veteran
Location
San Francisco
I'm also considering trading in my M-E, for a 240 to avoid any future sensor issues. I prefer the CCD but I do travel to some humid environments annually as part of my job. Maybe it's paranoia on my part from reading forums but I can't help but notice there appears to be more used M9 on the market and even some used M-E. The price of used 240s are also coming down which means only my preference for the CCD is holding me back from upgrading to the 240.
 

asiafish

All-Pro
Location
Bakersfield, CA
Real Name
Andrew
Just sent my MM to Leica for sensor cleaning. Even with blank warranty card (never filled out) and no receipt they said the sensor cleaning should be under warranty anyway and they will check for corrosion and any other issues.
 
The technical datasheet for the CMOSIS sensor used in the M Type 240 is not available, and I do not know what type of IR absorbing glass was used in the stack. The Fillfactory CMOS sensor used in the Kodak DCS SLR/n and SLR/c used S8612 glass, same as in the KAF-18500. Engineers from Fillfactory founded CMOSIS. I'd like to know what glass was used, although my mind is made up to stick with the CCD sensors. They produce the look that I want.
 

asiafish

All-Pro
Location
Bakersfield, CA
Real Name
Andrew
The technical datasheet for the CMOSIS sensor used in the M Type 240 is not available, and I do not know what type of IR absorbing glass was used in the stack. The Fillfactory CMOS sensor used in the Kodak DCS SLR/n and SLR/c used S8612 glass, same as in the KAF-18500. Engineers from Fillfactory founded CMOSIS. I'd like to know what glass was used, although my mind is made up to stick with the CCD sensors. They produce the look that I want.

I think many of us here love the CCD look.
 

uhoh7

Regular
I am keeping my M9 and M Monochrom no matter what, I trust that Leica will take care of their cameras and the photographers that use them. Raid bought his M9 used, the sensor died, and Leica replaced it free of charge well after the warranty expired. (had to add- AND keeping My M8, I hope to get 20+ years out of it like my Kodak DCS)

SO- my advice is for #2 and #3 on your list. With that stated, I would not use a wet cleaning agent on the sensor and have it professionally cleaned by Leica if using a blower is not good enough. I would also not make a habit of shooting on continuous until the buffer fills up. I've never done the latter, a hold-over from film days. "Spray and Pray" vs "Decisive Moment", now think of it in terms of sensor temperature and thermal expansion.

Thanks so much for taking the time to explain much of this to us, Brian. For many years I've been a fan of your knitting, and now am even more a fan of your "work" LOL

1) you mention the micro-lens array would be destroyed by any attempt to change the cement or sensor stack. How does maxmax and other shops avoid this working on Canon 5ds and Sony A7s?

2) I was just about to wet clean my M9 sensor (new last december) for the first time with isopropyl per Lecia instructions which have been widely posted now. How would this make delamination/white spots more likely?
 

asiafish

All-Pro
Location
Bakersfield, CA
Real Name
Andrew
Thanks so much for taking the time to explain much of this to us, Brian. For many years I've been a fan of your knitting, and now am even more a fan of your "work" LOL

1) you mention the micro-lens array would be destroyed by any attempt to change the cement or sensor stack. How does maxmax and other shops avoid this working on Canon 5ds and Sony A7s?

2) I was just about to wet clean my M9 sensor (new last december) for the first time with isopropyl per Lecia instructions which have been widely posted now. How would this make delamination/white spots more likely?

Another fan of Brian's knitting here.
 
Thanks so much for taking the time to explain much of this to us, Brian. For many years I've been a fan of your knitting, and now am even more a fan of your "work" LOL

1) you mention the micro-lens array would be destroyed by any attempt to change the cement or sensor stack. How does maxmax and other shops avoid this working on Canon 5ds and Sony A7s?

2) I was just about to wet clean my M9 sensor (new last december) for the first time with isopropyl per Lecia instructions which have been widely posted now. How would this make delamination/white spots more likely?

for 2- I would take Leica up on their offer of free cleaning. Note that On Semiconductor advises to use Ethanol. My experience with Lab grade Isopropyl was in preparing optical fiber for fusion splicing. After using a Fiber Stripper, Takes the remnants of the coating right off, gets down to the glass.

1) there is a user on DPREVIEW that got the glass off the SLR/n sensor,

http://www.dpreview.com/forums/thread/3200898

http://www.dpreview.com/forums/post/52096442

http://www.dpreview.com/forums/thread/3280380

Wow. The company that i contacted for IR conversions stated they do not work on Leica, I have a full-spectrum EP2 from them. Some manufacturers tape the cover glass on, others use the IR glass separate from the sensor. I'm not sure of the Canon stack- do you have a link?

edit- Lensrentals.com has a series about filter stacks in Digital cameras

http://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses

The above link shows the IR filter from the Canon and a u43 camera. I'm thinking the filters are not cemented to the sensor as the main cover glass. This makes it much easier to convert a camera for IR work and Full-Spectrum. The glass comes out, and you put clear glass into it's place. Kodak cemented the IR cover glass onto the KAF-1600, which is why a special run needed to be made to get a full-spectrum CCD.
 

Duane Pandorf

Top Veteran
Location
Western NC
Just in case anyone forgets why we bought these cameras in the first place,

http://www.lensrentals.com/rent/leica/cameras/leica-m-monochrom

Roger Cicala captures it well.

I did not need to read this one Brian! I've been having a debate in my mind about could this one camera work for me. Could I do without color if I had to sell my M-E to pay for it. But my mind keeps saying no. You need to have a color option.

Then you link to Roger's experience with the camera. I have read some of Roger's other reviews but somehow I've missed this one. It did not help with the arguments that keep going thru my head.

And now we have this "sensor" issue......
 

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