Author Topic: Interesting interview from Leica Director (Read 527 times)

count_zero · « **on:** October 25, 2011, 11:30:47 PM »

http://www.megapixel.co.il/english/archive/23834

Quote

Q: If you look at the DXOMARK results of the M9 you can see that the ISO marks are considerably lower than other full frame cameras. Do you see this as one of the major things you would like to improve in the next M version?

A: The reason why this is lower lies in the special circumstances of the M-System. It is quite complicated, but I will try to make it short: M-lenses hit the sensor in a flat angle, therefore they are the most compact on the market and older lenses are compatible with M8 and M9. This flat angle will not allow us to use interference IR cut coating on the sensor cover glass, as this would cause uncontrollable color fringes. Instead of, we use an absorption filter, which is not sensible to different light angles, but does filter much more of the visible light as interference filters, and therefore the signal from the sensor needs to be amplified much more which results in a lower light sensitivity. Of course, having a higher sensitivity of the sensor is an issue and we put a significant amount of effort in improving this.

I wonder if the same is even more true for m43 lenses and sensor combo.

ratobuhler · « **Reply #1 on:** October 26, 2011, 07:34:14 AM »

That is a legacy lens problem. The original 4/3 format lenses had a "tele-centric" design to deal with this problem (all light bundles corresponding to an object point fall onto the sensor perpendicular). I believe that with the m4/3 lenses this is no longer as strict but they are still good enough to avoid extreme angles.

Em5 Pete · « **Reply #2 on:** October 26, 2011, 07:42:02 AM »

That is an interesting question. But, Leica had different problem than other digital camera makers.
Their past and present M lenses were not of a retro focus design, except the 24mm and under lenses. So, the they sat deeper and the light fall off (for film M 's) from the center to the corners was a bit more than a a sensor can hande properly. That is way the M8/9 have a micro lenes for each photo site, and as they move off center, they are aimed towards the center so the corners are evenly lit as the center photo sites.

M4/3 lenses are retro focus design, AFAIK, so, they are not set as far back, and, they where made to illuminate the sensor evenly from the first lens that Olympus made for the 4/3 E cameras.

But, the modern Lieca glass are still a straight forward non-retro design. And must be able to be used with film and digital M's with equally great results.

As far as I know....

Sent from my iPad

ratobuhler · « **Reply #3 on:** October 26, 2011, 08:03:45 AM »

Tele-centric is not the same as retro focus. In a pure tele-centric design the aperture stop is placed into the front focal plane (physically or optically) of the lens. This forces all central rays of the incoming light from object points to go through the front focal point. Then, by definition, the focused light bundles corresponding the these object points on the image side of the lens are parallel. Ideal for the sensor!

Retro focus design is used to make room for the mirror on a SLR on short focal length lenses. It is in effect a reversed telescope design.

Em5 Pete · « **Reply #4 on:** October 26, 2011, 08:09:56 AM »

Thanks for the correction. I figured (wrong), that m4/3 where retro design.

Sent from my iPad

Interesting interview from Leica Director