M9 engineering geek question

[adan]

Lordy - a lot of "noise" on this thread...

1. AF SLRs provide manual focus assist via the same AF sensor (NOT the image sensor) they use to find focus in Auto-focus mode. Since AF was around in film SLRs for 15 year before digital SLRs became common, obviously the image sensor is mostly irrelevant to the focusing process. Basically, the sensor can tell whether the image falling on it is fuzzy or sharp, and which way to turn the lens motor to get to "sharp".

In maual mode, instead of telling the lens which way to turn, it tells the photographer which way to turn the lens by way of the arrows.

Alan G is quite right - if you use a third party lens where the focus ring turns the opposite direction of the camera makers lenses, the arrow indication will be backwards, just as the metering arrows in an M6 classic were "backwards" for turning the shutter dial (but correct for turning the aperture ring).

To put an SLR-style focusing indicator and sensor into a rangefinder would require some way of capturing part of the incoming image light in front of the shutter and redirecting it to a focus sensor. Not unlike the gray bar that redirects metering light in the M8 - BUT random light wouldn't be enough. It has to be focused light, so needs a mirror rather than just a pale surface.

You end up having to build in the dual mirror system of an SLR (with its weight and movement before exposure)

The Contax G1/G2 cameras used a dual proxy-focus system that did not require stealing light from the lens, but DID require communication with the lens (just as the cam on the back of a Leica-M lens "communicates" between the lens and the camer RF).

The dual system used infrared laser triangulation - equivalent to shining a bright light through the eyepiece of a Leica, producing two glowing spots on the subject. Twist the lens until the two spots move together and superimpose - and that subject is sharp. (with infrared, the CAMERA can see the dots, but not people)

Laser triangulation allowed the Gs to focus on a blank wall, if needed.

They also used phase detection via two spider-eye windows above the lens mount - like most other viewfinder P&S AF cameras - switching systems as needed based on subject contrast, rough distance range, etc.

The contax systen also had a less binary readout - it DID give a rough idea of how far OOF one was, rather then just IN/OUT, by way of an LCD "bar" that changed length.

Again - this system requires some way to tell where the lens is actually focused (via cam or electronics).

Either system would require a significant amount of extra "stuff" to be crammed into an M-sized body.

In effect, the split image of a rangefinder IS a focus-assist device. Put the two images on top of one another and you're focused. A double image is like the arrows right or left - showing you're off. Up to 50mm it is just as easy and precise as Nikon's "< O >" - beyond that it DOES require good vision.

[offshore]

Originally Posted by cbretteville

A camera that dos not (yet) exist.

How do you focus a hypothetical camera? Hypothetically?

[vieri]

Originally Posted by offshore

How do you focus a hypothetical camera? Hypothetically?

I'd say very definitely hyperfocally

[AlanG]

I think what may be going on is that Panasonic and Olympus have found a way to make contrast detect AF off the sensor work reasonably quickly. I think we'll have to wait and see if this is true, but if so it seems like an elegant solution compared to the other possibilities.

I have a hard time seeing how they can expect to sell cameras in 2009 unless they focus as quickly as those from the competition. (Of course they could surprise me.)

My several year old Konica/Minolta A2 is a nice and very feature rich camera. I love a lot about the camera but unfortunately its focusing is a bit slow, and it is not great at higher ISOs. (No surprise there.) But some of the features on it would be interesting in a new camera. Here are some things I like about it:

The AF has a single and continuous mode. But what is different from SLRs is that you can use the jog buttons to position the focus point anywhere on the screen. The EVF will display its location.

In continuous mode, you can set the AF point on a subject and it will try to trak it as it moves. You can even see the AF point following the subject across the screen. Unfortunately this too is a bit slow and not that useful for fast action. But if new faster processors and better AF technology can improve this it will be amazing.

Power features. The A2 has grip sensors that can tell when you are holding the body of the camera and powers up when you touch it. There is a proximity sensor on the back of the camera so the EVF turns on automatically when your eye gets near it and back off when your eye is removed. Display can auto automatically toggle between the EVF and the LCD depending on if your eye is against the viewfinder or not.

The EVF tilts up for low shots and the camera also has a movable LCD - but it is not fully articulating and should be.

It has probably the best control layout I've seen on any camera where most everything needed while shooting can be set via control knobs and buttons without resorting to the menu.

The EVF is not as good as that of an optical viewfinder because the dynamic range of our eyes is much greater than that of the EVF. But resolution is 1 megapixel and seems quite usable. One interesting feature is it can be set to momentarily display the image right after you shoot it so you can see if you caught the right expression without removing the camera from your eye. The EVF and LCDs can work in a low light mode where the image is amplified. Manual focusing can work fairly well because the image displayed can toggle quickly between magnified mode and normal viewing. All in all an EVF opens up all kinds of possibilities and the A2 makes use of most of them as far as I can see.

The A2 is not perfect but an interchangeable lens version of it that focuses quickly and shoots images that are at least equivalent to that of the best current 4/3rds models would be an extremely appealing camera to me. Are you listening Leica? Hopefully it won't even need a shutter so it will be quiet and vibration free. The A2 is stabilized and smooth. I just played around with it and shot this image (full and cropped) at 1 sec ISO400 28mm equivalent. Noisy but reasonably sharp.

[offshore]

Originally Posted by vieri

I'd say very definitely hyperfocally

Hypofocally? Or is this all hype?

[Scott Root]

Why doesn't Leica introduce autofocus M lenses with an autofocus M9 that is compatible with manual focus M lenses? Who would be opposed with this scenario as long as the rangefinder system remained mechanical. I do not see any reason why this couldn't be engineered as described and it would up their sales for new lenses without upsetting the diehard manual focus afficiendos.

[jaapv]

Originally Posted by Scott Root

Why doesn't Leica introduce autofocus M lenses with an autofocus M9 that is compatible with manual focus M lenses? Who would be opposed with this scenario as long as the rangefinder system remained mechanical. I do not see any reason why this couldn't be engineered as described and it would up their sales for new lenses without upsetting the diehard manual focus afficiendos.

It would produce a centrifugal effect on the customers. Some would go high-end P&S, others small DSLR. It may well be impossible to fit all the gear into the M form and size too, especially the lenses.

[vieri]

Originally Posted by offshore

Hypofocally? Or is this all hype?

Let's settle for Hippo-focally, a testimony to the speed of the new system

[adan]

Originally Posted by Scott Root

Why doesn't Leica introduce autofocus M lenses with an autofocus M9 that is compatible with manual focus M lenses? Who would be opposed with this scenario as long as the rangefinder system remained mechanical. I do not see any reason why this couldn't be engineered as described and it would up their sales for new lenses without upsetting the diehard manual focus afficiendos.

You have some engineering drawings to show us? Or Leica?

Seriously.

Mark Norton dissected an M8 - you can use those photos, stored somewhere here on the forum, to establish where and how much empty space is available in the M8 body for an AF system.

Google "Contax G" and you can likely find some 3d drawings showing how much volume a G-type AF system takes up. Or if you prefer the SLR-style system I mentioned above, there are cutaways on the web of those, as well.

In the end you will either have a plan for a very nice M autofocus system - or you will "see" a whole host of reasons why it can't "be engineered as described," far better than our words can do it (since you will have done the intellectual work for yourself).

[SJP]

Autofocus makes no sense on a M rangefinder.

The camera cannot connect to the lenses, the lenses have no way to connect to the camera. Moreover an autofocus lens needs space to drive the machinery which is exactly opposite to why we all love M camera's & lenses they are (incredibly) compact.

If the M9 has autofocus it is not a Leica M & I do not want to have it.

Focus assist for those that want perfection without suffering may be feasible via an electronic evaluation of the RF focussing patch. That would not interfere with the M camera basic priciples - there is no junk in between the ouside world and the sensor except a shutter and the Leica glass. Same as before. Probably this is possible by meauring the intensity of the highest wavenumbers and finding the maximum to optimise the focus. However the main PITA is that the camera has no way to know whether the operator is focussing 'in' or 'out' + the image itself is not 100% stable due to camera movement. This is not easy to solve.

[sdai]

Originally Posted by SJP

Autofocus makes no sense on a M rangefinder.

Exactly.

Anyone who has played with a Contax G1/G2 or Konica Hexar AF - although they're all very nice cameras - should know they're totally different beasts from the M series.

[AlanG]

Originally Posted by SJP

Autofocus makes no sense on a M rangefinder.

The camera cannot connect to the lenses, the lenses have no way to connect to the camera. Moreover an autofocus lens needs space to drive the machinery which is exactly opposite to why we all love M camera's & lenses they are (incredibly) compact...

I looked up the sizes and weight of the Contax AF lenses for the G and G2 to the equivalent Leica lenses and they are very comparable. So it should be possible for Leica to make AF lenses without increasing the size and weight, especially if they are designed for a 1.3x or 4/3rds sensor. (In which case they could be even smaller.)

I agree that auto-focus probably makes no sense on an M rangefinder, but how about a different smaller camera that perhaps meets the traditional role of a Leica (small, light, fast, quiet) in a new package that fully takes advantage of modern technology? (Stabilized sensor, some kind of electronic focusing - manual or AF, live view, etc.)

By the way, in the A2 picture I posted above, I may have not made it clear that it was shot hand held at 1 second. I had about a 50% success rate at 1 second. Since I don't believe I am capable of holding a camera that steady, I feel the IS and lack of a shutter made a big difference as long as I didn't shake more than the IS could compensate for. It will be hard for me to overlook these kinds of features in future cameras.

[offshore]

Originally Posted by vieri

Let's settle for Hippo-focally, a testimony to the speed of the new system

Agreed!

[SJP]

What would be an exiting concept from my POV is a digital equivalent to an Olympus XA (made by Leica obviously )

To recall the XA's salient features:
35 mm film
rangefinder (much shorter base than M's so not very accurate)
35 mm 'reversed retrofocus' lens (35mm f/2.8 Zuiko - excellent IQ, high contrast) - reversed retrofocus is newspeak for telephoto i.e. it has a 35 mm tele lens
electronic shutter release button (avoides shake altogether with some practice)
fits in shirt pocket

If Leica made something like this with a approx. 10 MP FF sensor that would be brilliant, AF optional. With a fixed focal length the sensor & vignetting correction could be made 'dedicated' avoiding some of the M8 complications.

See Olympus XA for more info.

[vikasmg]

Originally Posted by offshore

What's a M9?

Just an error. He meant an M10, which is the generation after next of the Leica M series. That will be the last of the line of this type. After that the sensor will be replaced by one of those virtual eye balls sensors I heard about in the news today. With a flexible sensor simulating a natural retina.

[diogenis]

Originally Posted by george

But Leica Camera Company could incorporate a laser rangefinder - made by another Leica company (now unrelated except for name) and couple this to the rangefider cam. It seems easy. (?) And logical. (!) And could do away with all that complex prism setup.

Is it safe to point to ones eyes to focus, using lasers?
Do you really want your models to go blind, and you pay for suits ?

[jaapv]

Originally Posted by AlanG

I looked up the sizes and weight of the Contax AF lenses for the G and G2 to the equivalent Leica lenses and they are very comparable. So it should be possible for Leica to make AF lenses without increasing the size and weight, especially if they are designed for a 1.3x or 4/3rds sensor. (In which case they could be even smaller.)

Did you also compare the weight of the optical cell? Or the weightof the mount without AF gear? Of course one can make engineering and optical compromises to keep weight and size down - but it will show up somewhere else - for instance durability, stability or optical quality.

[dpstjp]

Originally Posted by adan

To put an SLR-style focusing indicator and sensor into a rangefinder would require some way of capturing part of the incoming image light in front of the shutter and redirecting it to a focus sensor. Not unlike the gray bar that redirects metering light in the M8 - BUT random light wouldn't be enough. It has to be focused light, so needs a mirror rather than just a pale surface.

You end up having to build in the dual mirror system of an SLR (with its weight and movement before exposure).

So, we either need a Visoflex IV, or at the very least a new electronic autofocus viewfinder for the Visoflex III. Sensibly priced, of course...

The benefit of the latter approach would be backward compatability for Visoflex II owners and film Leica RFs.

dpstjp

[AlanG]

Originally Posted by jaapv

Did you also compare the weight of the optical cell? Or the weightof the mount without AF gear? Of course one can make engineering and optical compromises to keep weight and size down - but it will show up somewhere else - for instance durability, stability or optical quality.

No I did not compare the weight of the optical cell. As there is no documentation on that. As for durability, weight does not necessarily translate into durability, stability or optical quality. I think we'd really be getting off-track if we try to say this method or that method of making a lens is better, or more durable, or whatever... In Formula One cars, they've gotten rid of a lot of the metal for carbon fibre and other composites. The same with aircraft. Things change...

In any case, weight wasn't part of the original question, size was. But when you consider that a AF lenses can be made without a heavy threaded brass focusing system, AF lenses may be lighter.

The question I responded too was, "Moreover an autofocus lens needs space to drive the machinery which is exactly opposite to why we all love M camera's & lenses they are (incredibly) compact..." I was taking exception to this statement as the Contax lenses demonstrate, AF lenses can be made that are as compact as Leica's current offering.

So with Leica's expertise in lens making, it should be possible for them to produce compact AF lenses should they wish too. (Especially for the smaller 1.3x or 4/3rds format.) Do you disagree with this?

Leica can continue to make the same M type of focusing system and manual focusing lenses for the next 10, 20, 50, 100 years. And maybe there will be a market for it and maybe not. But this doesn't preclude them from considering other designs for other products. I don't belive I could take a handheld photo with an M camera at 1 second and expect it to be reasonably sharp. So stabilizing the sensor is a good idea and won't affect the traditional M design. And if they added live view, it could be linked to focus confrmation lights that could easily be incorporated into the current M viewfinder. (Retaining the rangefinder also.)

[jaapv]

Originally Posted by AlanG

So with Leica's expertise in lens making, it should be no problem for them to produce compact AF lenses should they wish too. (Especially for the smaller 1.3x or 4/3rds format.) Do you disagree with this?

What is wrong with the Digilux 3 lenses then?