M9 engineering geek question

[AlanG]

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Phase detection allows the camera to determine whether the subject is behind or in front of the plane of focus; lens construction, features or thread direction have nothing to do with it.

 

Henning

 

Sure it does if the focus arrow points left for closer however turning your lens to the left sets the lens further.

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[peter55]

My Nikon D1H has this focusing feature and it works with my all mechanical AIS & AI lenses as well as any all mechanical M42 or K mount lens that I attach via the appropriate adapter. So it must be true that it is not at all lens dependent but rather a funtion of the camera only. Therefore Leica could implement this feature into a future M DRF and still retain all existing lenses.

[Guest noah_addis]

I've used lots of slr and dslr cameras with focus arrows and confirmation, but I have to say that it's nothing like the experience of shooting with a mechanical rangefinder. It doesn't show you HOW MUCH in either direction you're out of focus, and I've always ignored the lights when manually focusing an slr.

 

If Leica were to make a cheaper digital SL with an M mount and electronic RF, that would be fine, but I sincerely hope the folks at Leica don't replace the mechanical RF with an electronic one if they ever make an M9.

 

The main reason I shoot with Leica MP and M8 cameras is that I like the rangefinder focusing method. I have absolutely no desire to focus with little blinking lights.

[jrc]

I've used lots of slr and dslr cameras with focus arrows and confirmation, but I have to say that it's nothing like the experience of shooting with a mechanical rangefinder. It doesn't show you HOW MUCH in either direction you're out of focus, and I've always ignored the lights when manually focusing an slr.

 

If Leica were to make a cheaper digital SL with an M mount and electronic RF, that would be fine, but I sincerely hope the folks at Leica don't replace the mechanical RF with an electronic one if they ever make an M9.

 

The main reason I shoot with Leica MP and M8 cameras is that I like the rangefinder focusing method. I have absolutely no desire to focus with little blinking lights.

 

I agree in general, but the little blinking lights would be a huge benefit in very low light situations. On another thread somebody was talking about the need to shoot at 1250+ with a Nocti, at which point it would be pretty hard to see well enough to focus a straight rangefinder. The problem would only get worse if the M9 actually had a D3-quality chip, and people were trying to shoot at f1 at 3200 or 6400 on the street...

 

I never really bothered with the blinking lights until I got the new Zeiss manual lens, and then I began to wonder how the whole system works -- and the indicator light seems fairly accurate on my D3.

 

JC

[Bob Ross]

Okay. But is there *some* existant technology that would do it for a rangefinder? The laser thing seems problematic to me -- I have used laser rangefinders both on survey total stations and to play golf and hunt, and the quality of return depends too much on the target's surface, and the response isn't always quick. Perhaps because it would only need to work at relatively short range, it would be okay...On the other hand, the lasers I've used don't work at very close ranges...I do know that Nikon is now offering a rifle scope with a built in rangefinder good out to several hundred yards, so lasers can work in conjunction with precision optics.

 

JC

In theory, there could be an external phase detection unit where the rangefinder window is on the M8. As the lens is focused, the cam connection would tell when the lens focus distance matches the phase detection unit's distance and a signal would light up in the viewfinder. The problems to be worked out are the accuracy, parallax and the FOV of the phase detection unit vs the lens in use. It would sort of be like the old add on meters that used a 90mm field, so it would vary in its degree of "spotty-ness", depending on the lens in use. If this could be worked out, it would be the way to radically reduce the price for an economy M9, since the optical rangefinder unit has to be the most costly part of the M8.

The external phase detection units have been used on top end digicams from Nikon and Panasonic/Leica in a hybrid combination with the contrast detection off the sensor. This gave a coarse and fine AF for better response (at the time). Phase detection units have come a long way since then. Who knows.....maybe it would work for economy RF bodies.

Bob

[cbretteville]

What's a M9?

 

A camera that dos not (yet) exist.

[sdai]

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The problem would only get worse if the M9 actually had a D3-quality chip, and people were trying to shoot at f1 at 3200 or 6400 on the street...

 

If one can only get a shot at ISO3200 or 6400 with the Noctilux wide open, I'm afraid even the D3's AF sensor won't be up to its task under such lighting condition.

[jaapv]

You would have a hard time finding a street that is dark enough to need f 1.0 @ 6400 ISO. And how would you know where to point your camera, even if you could focus with blinking lights?

[jaapv]

Is Sponge Bob an Iiikia man?

 

The Scandinavian is our Danish friend Ammitsboel

And Sponge Bob is :

SpongeBob SquarePants (character) - Wikipedia, the free encyclopedia

[isaac]

Hello!

In fact, if you use a dumb adapter, the focus confirmation on a Canon EOS won't work. That's why people buy those "AF confirmation" adapters, and you can code this adapters with your specific focal length and maximum aperture to guarantee proper metering with the EOS camera.

In principle, you mix up the two systems of AF confirmation chip on Canon and Olympus.

Canon only needs (a kind of) feedback from the lens to activate the focus confirmation. And this feedback is simply the focal length and f-stop. Both values are of no significance for focus confirmation.

On the other side, Olympus 4/3 needs obviously the same two values, but both are valid (but also not significant for AF confirmation).

Sideeffects in 4/3 system are only on cameras with image stabilisation, because this feature depends on the correct value for focus length.

I have tested once my Vario Elmar (?) 75-200/4.5 and AF confirmation chip for 150mm on a E-510 and, well, it works, but I have not tested with low and very low shutter speeds at all. On my E-300, focus confirmation works very well (in the same way, the extra build in split prism focusing screen works).

Also in my 5D, AF confirmation works with almost equal accuracy with the same Vario Elmar like in the E-300.

Phase TTL autofocus is quit the same like a split prism, only the human eye is replaced by a tiny sensor.

[marknorton]

The D3 has a half-silvered mirror with a further mirror behind it which reflects the image into the floor of the camera throat where the AF sensor is located. With a manual lens, you are simply seeing the arrowheads showing the direction the AF would turn the focus ring if it were an AF lens.

 

The secondary mirror is smaller than the main mirror - that's why the D3 AF points don't make it into the frame corners, the secondary mirror could not be made big enough. When the main mirror lifts, the secondary mirror folds flat against it. A compromise though - light which goes to the AF sensor doesn't make it to the viewfinder and there's a low light limit below which AF will not work, hence the IR focus assist on the flashes.

 

One thing the D3 and the pro-lenses need is backlit controls; it can shoot in such low light that it's impossible to see the settings of things like the VR lens switches.

[marknorton]

I've used lots of slr and dslr cameras with focus arrows and confirmation, but I have to say that it's nothing like the experience of shooting with a mechanical rangefinder. It doesn't show you HOW MUCH in either direction you're out of focus, and I've always ignored the lights when manually focusing an slr.

 

If Leica were to make a cheaper digital SL with an M mount and electronic RF, that would be fine, but I sincerely hope the folks at Leica don't replace the mechanical RF with an electronic one if they ever make an M9.

 

The main reason I shoot with Leica MP and M8 cameras is that I like the rangefinder focusing method. I have absolutely no desire to focus with little blinking lights.

 

It certainly takes experience to be able to visualise the level of out of focus judged by the horizontal rangefinder shift.

 

We all agree that the rangefinder is a great way to compose and focus (otherwise, what are we doing here?) but there's no denying the M rangefinder runs out of precision when you are using a long lens, wide open and close-up. Sensing actual focus at the sensor using some sort of live view mode would really help in these focus critical situations.

[sdai]

In principle, you mix up the two systems of AF confirmation chip on Canon and Olympus.

Canon only needs (a kind of) feedback from the lens to activate the focus confirmation. And this feedback is simply the focal length and f-stop. Both values are of no significance for focus confirmation.

 

What feedback are you talking about? it's a AF enabling pin at 9:45 direction inside the mount, if you break it or not trigger it, none of your lens will work at all.

 

Encoding the lens adapter with focal length and max. confirmation is to give you other metering modes besides center weighted.

[AlanG]

Well Panasonic and Olympus just introduced a "Micro 4/3rds" format that uses live view with AF (no SLR mirror.) No details of the focusing method have been released. This system has the prospect for small cameras and lenses.

 

Since they've reduced the flange to sensor disntance from 40mm to 20mm, I wonder what all of the earlier talk about needing "telecentric" lenses was all about.

 

Olympus / Panasonic announce Micro Four Thirds: Digital Photography Review

[fotografr]

I agree in general, but the little blinking lights would be a huge benefit in very low light situations. On another thread somebody was talking about the need to shoot at 1250+ with a Nocti, at which point it would be pretty hard to see well enough to focus a straight rangefinder. The problem would only get worse if the M9 actually had a D3-quality chip, and people were trying to shoot at f1 at 3200 or 6400 on the street...

JC

 

It would seem to me that if it's too dark to focus with a rangefinder, it's also too dark to be able to compose an image or even see what's in the frame.

[AlanG]

It would seem to me that if it's too dark to focus with a rangefinder, it's also too dark to be able to compose an image or even see what's in the frame.

 

 

My old Konica Minolta A2 has image amplification onto the EVF for use in low light. Sony made models that had "Night Shot and Night Framing IR modes for "no light" framing and shooting." The camera painted the scene with IR illumination.

[jrc]

It would seem to me that if it's too dark to focus with a rangefinder, it's also too dark to be able to compose an image or even see what's in the frame.

 

I find that's not true, often enough. You can be shooting in interesting low light, with some parts, like faces, illuminated, while most edges go dark with shadow. (It's like when you see a painting by Rembrandt, where the round parts of the faces and the eyes are sharp, but the back edges fade into obscurity; it's what you see sitting late at night in a bar.) The problem is finding something to split the image across, and then seeing it come sharp; you also have the problem that it usually takes too long to focus, because you can't see well enough; and the further problem that while some people may be able to use the distance scale to focus, that can be tough with the Noctilux and other very fast lenses, because the focusing needs to be so precise.

 

I've been fooling around with the Zeiss 25 manual lens on my D3, and here is another curiosity for Leica users...or maybe not, depending on your level of curiosity. The distance around the focus ring from infinity to 2 meters is a little less than a centimeter. From 2 meters, there are markers for 1 meter, .06, .05, 0.35, 0.3,0.25, 0.22, 0.20.19, 0.18, and 0.17 meters. The twist or throw of the focus ring must be around 350 degrees.

 

JC

[Bob Ross]

Well Panasonic and Olympus just introduced a "Micro 4/3rds" format that uses live view with AF (no SLR mirror.) No details of the focusing method have been released. This system has the prospect for small cameras and lenses.

 

Since they've reduced the flange to sensor disntance from 40mm to 20mm, I wonder what all of the earlier talk about needing "telecentric" lenses was all about.

 

Olympus / Panasonic announce Micro Four Thirds: Digital Photography Review

It is either telecentric for the lenses or off-set microlenses for the sensors, but we have to keep those light rays going into the photo buckets and not bouncing all over the place...

Bob

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Hallo,

Look here: Leica M

[ammitsboel]

No. He means Sponge Bob. He is a Scandinavian himself....

I had a laugh there myself...

I just opened my M8 and found the QC sticker, mine is QC'ed by John Wayne, anybody else?

 

I hope that the M9 will include Auto QC.

[mjh]

Okay. But is there *some* existant technology that would do it for a rangefinder?

A contrast-based AF as employed in compact digicams would work, provided the sensor supported live view. But while phase-detection could tell you whether you have focused correctly or not – and in the latter case, whether optimum focus is in front of or behind (and how far away, approximately), a contrast-based AF basically just tells whether it’s getting better or worse.