[Leica] Coded or non coded lenses, that is the question ADAM!

[abridge at mac.com (Adam Bridge)]

Hi Ted,

With our M8's it's not so much of an issue because the sensor is smaller. 
The weird things happen out at the edges where the light comes in at a 
steeper angle.

When you think of a sensor on a digital camera you need to think of the 
light-sensitive part living down in a pit. Sort of like you're standing at 
the bottom of a well looking up at the sky. Light from the back of the lens 
spreads across the sensor. If you're in the middle then you get all the 
light. But out the edges the light hits the side of the pit and doesn't make 
it to the bottom.

The answer is to put a small lens (they call them "micro-lenses" at the top 
of the pit which gathers the light and directs it down to the bottom. But 
the design of that lens would have to be different for each lens you mount 
on your camera. What to do? Well, every camera has a small computer in it to 
handle taking the electronic information from each little sensor location 
and using that in some rather complex ways to organize it into a "picture" 
that makes sense. If the computer knows that you've got a 24mm f2 lens on it 
can adjust for both how the light from the lens reaches the sensor at the 
bottom of each pit AND it can even adjust for known problems in the design 
of that particular lens!

Of course with film this isn't a problem. With black and white film the 
layer of light-sensitive particles is very thin while for color the 
different layers are still very thin - no pits!

I hope this helps. I could probably do a neat little illustration if it 
would help you.

It IS very complicated. We're still at that awkward phase of technology 
where exactly how to do the engineering is being worked out in an almost 
minute by minute advance. Film, however, has been a mature technology for 
decades. Now, if you had started out in photography in the 19th century 
you'd have done much the same except you'd be worried about wet plates, or 
dry plates, or film, or different formats. That all settled down with a few 
formats and lots of well-understood chemistry to make it all happen. Just 
think about the different developers used on something like Tri-X and all 
the discussions on this list about which was best and how to get the optimum 
result.

That's happening all over again but its even more complex now. But, I think, 
it'll start to get simpler again. When my grandson (now 6 months old) is our 
age....

Happy snaps! As always I read all of your posts and am deeply grateful for 
them, even when you're feeling cantankerous. <grin>

Adam

On 2014 Apr 7, at 6:56 PM, tedgrant at shaw.ca wrote:

> I shoot with my M8 and whatever lens it maybe, my images look just super 
> fine while printing 13X19 size prints. So is there some kind of situation? 
> Lighting effect? Whatever? A situation where I can shoot a scene and see a 
> diffeence. I'll rent a coded lens or maybe someone living near by has one 
> I'll ask a loan for a few hours or so. And shoot with both non-coded and 
> coded.
> 
> Maybe that'll make me see the errors of my anti-coding rants!
> thank you.
> cheers,
> ted