IR coating

[davidmires]

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Would it be possible to coat the front lens element to block infrared radiation?

 

Definitely not an inexpensive or easy solution. Heck, I don't even know if it is possible...

Hopefully this suggestion won't get anyone all bent out of shape here, it's just a thought...

Existing lenses could be sent in for coating, and new lenses could be manufactured with the coating.

The coating would not affect film performance. (maybe?)

For instance 28mm Summicron IR ?

Could it be the correct way to look at the IR issue since we want to minimize the glass directly on the front of the sensor?

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[ho_co]

Would it be possible to coat the front lens element to block infrared radiation?

Possible but not practical.

 

From other posts here, it sounds as if blocking IR requires exact use of 1/4-wave increment coatings. In other words, you would need to go to a business that does very specialized coatings. That would mean very high prices, much higher than buying the filters.

 

I do not use filters on Leica lenses because the filters in some cases can cause flare etc. But I know people who use filters all the time and are happy with the results. I'd go with the filters if that's the solution to the M8 problem.

 

I don't know anything about whether having someone add an IR-blocking coating to your lens would damage it in any way; my guess is that if you went to a NASA subcontractor, there would be no detriment to its performance. But it would void Leica's warranty.

 

Still, if you're a good enough salesman, it might enhance the value of the lenses on the used market when Leica solves the problem.

 

--HC

[robertwright]

i think its just easier to put on the IR filter and be done with it. But I understand that is not a solution for users with 15mm lenses and the like. Leica should realize this also.

 

From the specs I posted in the Kodak Sensor thread it appears that the Ir absorbing glass is not quite as effective as the filter in the DMR, but the difference is a small percentage, like maybe 2 to 5 % less effective. The question seems to be, are these CCD performing in spec? Is the dark calibration working effectively or perhaps the CCD is recording heat prior to or after the exposure that is only revealing itself in areas of little exposure? Clearly they have a problem with the data reading from the CCD, that is the source of the blooming we are seeing. Pixels are leaking voltage across other pixels when they get too saturated. This is something that should not happen and indicates that the chip is not being controlled or read out properly.

 

I would imagine Leica is thinking about capturing a few cameras and sending them to be tested to see what is happening in production.

[bill vann]

very problematic

 

clean rooms

 

astronomically expensive equipment and $$$ per hour amortization

 

development of effective coating, not canned.

 

total dissambley of lens to coat the element properly

 

bill vann

[davidmires]

Thanks for the replies. I was actually looking at it as something that could be incorporated in new lenses, and perhaps added to existing lenses for those who felt they could justify the expense.

If IR filtering is a problem at the sensor, perhaps it should be addressed at the lens.

Cheers, David.

[ho_co]

... From the specs I posted in the Kodak Sensor thread it appears that the Ir absorbing glass is not quite as effective as the filter in the DMR, but the difference is a small percentage, like maybe 2 to 5 % less effective....

Robert--

Technically you're right. As I remember the numbers, DMR chip has 5% or less IR transmission, while M8 chip has 10% or less IR transmission.

 

But even though that's only 5% difference, it amounts to a doubling of IR transmission in the M8.

 

--HC

[marknorton]

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What we don't know is whether the sensor Leica actually use is the KAF10500 as specified on the Kodak web-site. It might be that Leica get a special version with a modified cover glass.