Suppositions vindicated! Blue Dot revealed. [Archive]

jaapv

10-01-2006, 02:32

The newest LFI confirms that the mysterious blue dot is indeed an external light sensor, used in optimizing CA and vignetting. As I recall, in this forum, Mark Norton, I and some other were philosophizing about this possibility.
We should be paid as advisors to the Leica design team! :D :D

The Digilux2 has an external lightbalance sensor. Such a thing could easily read ambient light levels and then the camera could calculate the f-stop through TTL. I think it very possible the M8 will have an external lightbalance sensor as well, as it works exceedingly well on the Digilux2

Last edited by jaapv : 06-07-2006 at 16:41.

rvaubel

10-01-2006, 03:20

The newest LFI confirms that the mysterious blue dot is indeed an external light sensor, used in optimizing CA and vignetting. As I recall, in this forum, Mark Norton, I and some other were philosophizing about this possibility.
We should be paid as advisors to the Leica design team! :D :D

This is fantastic news! But I have trouble believing that the news was kept under wraps for so long. I respect all the folks that had NDAs but it still surprises me that the nothing leaked out.

How can I get a copy of LFI ? How about some long "news quotes" .

Rex

Mark Norton

10-01-2006, 03:33

You can subscribe here...

www.lfi-online.com

I certainly won't take credit for thinking about using an external sensor to estimate working aperture - I was one of those who thought it was unlikely to work but Rex pointed out it will work better if it's a spot meter rather than a wide-angle incident meter.

jaapv

10-01-2006, 04:30

The question in my mind is whether they've figured out a way of sensing the working aperture...

this one started the train of thought....

rvaubel

10-01-2006, 09:52

You can subscribe here...

www.lfi-online.com (http://www.lfi-online.com)

I certainly won't take credit for thinking about using an external sensor to estimate working aperture - I was one of those who thought it was unlikely to work but Rex pointed out it will work better if it's a spot meter rather than a wide-angle incident meter.

Mark

I'm surprised no one has confirmed that the "blue dot" is, in fact, an external sensor for estimating working aperture. It seems to me that this would be vital information to invigorate the speculation about vignetting and lateral color correction.

I'd like to read the article in LFI but at 80 Euros I think I'll wait.

Does someone want to confirm the "blue dot" function?

Rex
hoping its true

jaapv

10-02-2006, 00:17

Quoted from LFI:

........by providing the M8 with an exterior light meter,comprised of a tiny sensor installed on the top, directly beside the shutter-speed dial. This sensor measures the light independently from one inside the camera. The aperture is the simply calculated by subtracting the light travelling through the lens from the exterior lighting. Only when the camera is aware of the aperture set and the lens attached can it also know how much vignetting there will be, and correct it. The correction is executed automatically, whilst lens recognition and any related corrections can also be deactivated in the menu.....

and:

....The exterior light meter is by nature not as exact as the meter located in the camera body; the lens itself might be blocking a light source, and the measuring cell is unaware of the lens's focal length. Leica claims its measuring faculty to be accurate by approximately plus/minus one stop. Any vignetting is therefore corrected with reserve......

and:

.....Those who are interested in an M8, already own a collection of lenses and can live without Exif documentation, have no need to worry.....

The article contains much, much more information plus some interesting street photography by Simon Wheatly using the M8 and is int itself a good reason to get hold of this copy of LFI.

willemvelthoven

10-02-2006, 13:13

The newest LFI confirms that the mysterious blue dot is indeed an external light sensor, used in optimizing CA and vignetting. As I recall, in this forum, Mark Norton, I and some other were philosophizing about this possibility.
We should be paid as advisors to the Leica design team! :D :D

I seem to recall that is was ME! who started the blue dot thread here with exacly this description of it's functionality.

Tadaaaa!

Still, I wonder wether I would have ever thought about it without seeing the blue dot FIRST. So i'm probably not worthy to serve on the Leica design team.

willemvelthoven

10-02-2006, 13:30

The newest LFI confirms that the mysterious blue dot is indeed an external light sensor, used in optimizing CA and vignetting. As I recall, in this forum, Mark Norton, I and some other were philosophizing about this possibility.
We should be paid as advisors to the Leica design team! :D :D

Actually, i did serve as a full professor at the Berlin University for the Arts. That's where Achim Heine, the industrial designer on the M8 is teaching too. But he never lold me a anything. He's very discreet.:bang:

jaapv

10-02-2006, 15:51

I seem to recall that is was ME! who started the blue dot thread here with exacly this description of it's functionality.

Tadaaaa!

Still, I wonder wether I would have ever thought about it without seeing the blue dot FIRST. So i'm probably not worthy to serve on the Leica design team.

We started this discussion in July 6th, long before the blue dot was known.Benz and I postulated the system then. Search function would have revealed that. I didn't want to steal your thunder when you reinvented it here on September 9th...;):p

Nemo

10-02-2006, 23:43

In passing, have you noticed a change in the type of paper used by LFI?
The paper was gross and matte, and this new paper is thinner and and a bit glossy...

:confused:

jaapv

10-02-2006, 23:52

I think the print quality of the photographs is not what it used to be either.

Ben Z

10-03-2006, 21:53

ghost

10-03-2006, 22:28

m-ttl, that's what the guy said in one video. i don't get how they'd think amateurs would want that over a completely beeyooteefulll objet d'art.

jaapv

10-04-2006, 00:41

Directly from a friend who just returned from Photokina, according to Ralph Hagenauer, Leica product manager, anad Christian Erhard from Leica USA, the "Blue Dot" measures the pre-flash for what is being referred to as "M-TTL Flash". They said it has absolutely no other function whatsoever. Sorry to disappoint the Trekkies :D

Interesting- LFI is a semi-official Leica publication and says exactly the opposite in great length....:rolleyes: I tend to believe that over a spokesman told a friend who told me.;) But time will tell... They'll have to do something if they want to compensate aperture-influenced vignetting.

Mark Norton

10-04-2006, 00:41

Mark

I'm surprised no one has confirmed that the "blue dot" is, in fact, an external sensor for estimating working aperture. It seems to me that this would be vital information to invigorate the speculation about vignetting and lateral color correction.

I'd like to read the article in LFI but at 80 Euros I think I'll wait.

Does someone want to confirm the "blue dot" function?

Rex
hoping its true

Rex, that 80 euros is for a year's subscription, not a single copy!

Mark Norton

10-04-2006, 00:44

Directly from a friend who just returned from Photokina, according to Ralph Hagenauer, Leica product manager, anad Christian Erhard from Leica USA, the "Blue Dot" measures the pre-flash for what is being referred to as "M-TTL Flash". They said it has absolutely no other function whatsoever. Sorry to disappoint the Trekkies :D

Have to say I got exactly the same response when I asked at Photokina. OTOH, Andy Piper saw an EXIF file header from an un-coded lens on an M8 with an aperture approximation in it, so it must have figured it out somehow.

rvaubel

10-04-2006, 20:28

Have to say I got exactly the same response when I asked at Photokina. OTOH, Andy Piper saw an EXIF file header from an un-coded lens on an M8 with an aperture approximation in it, so it must have figured it out somehow.

OK. What's the Blue Dot do? Is it an external meter used for determining taking aperture? I thought this was settled.

Rex

jaapv

10-04-2006, 23:46

Once the camera is in user hands, the matter is simply settled. Just put your finger over the dot when shooting and see what the exif does. Otoh it seems pretty silly for Leica to put a light sensor on the camera and use it for E-TTL (sorry - M-TTL) flash measuring only, not using it for any other possibilty for which it is obviously suited. Time will tell.

ulrik

10-05-2006, 10:08

TTL Through The Lens - if blue dot measures flash, i wonder why it's refered to as M-TTL?

jlw

10-05-2006, 10:30

TTL Through The Lens - if blue dot measures flash, i wonder why it's refered to as M-TTL?

Might be for measuring a pre-flash to set the initial power level, a system used on many DSLRs.

I still think it must also measure ambient light, though -- there's got to be an external sensor somewhere if they're putting f/stop data in the EXIF headers.

Oh, well, first one on the group to receive an M8 can fill us all in!

Ben Z

10-07-2006, 19:58

I don't understand how an "approximation" of the f-stop in use can do any kind of meaningful calculation for any type of exposure, and an "approximation" is all that an external sensor can provide, because of parallax. It is the same situation with an external meter like the MR-4 or an auto flash. It reads a fixed angle and not necessarily that which the lens "sees". If this is Leica's idea of a workaround for the inability of the lens to transmit aperture data to the camera, I sincerely hope it is like the lens coding and doesn't affect the RAW files, only for the JPEG users, or at least that it can be disabled.

Mark Norton

10-07-2006, 22:06

I'm still not convinced that this is what the blue dot is for...

rvaubel

10-07-2006, 22:37

I sure hope the blue dot is an external sensor. If it could help JPEG users with vignetting and lateral color correction, it would help make the M8 more saleable. For myself, as a raw user, I wouldn't want it screwing around with the RAW data. However, it would be nice to have the data in the EXIF file.

As for it only being approximate, so what? The corrective algorithms are just approximates themselves.

The real reason that I hope the blue dot is an external sensor is because I think it would be cool. It wouldn't do me much good, but getting the approximate F# in the EXIF file would save me time when posting pictures and I have to quess or remember. DSLR users don't have to do that!!

Rex

Ben Z

10-09-2006, 05:23

As for it only being approximate, so what? The corrective algorithms are just approximates themselves.

Just my opinion but an external sensor with the potential to see something several stops different from what the lens sees is in another world compared to the sort of approximation you might find with an algorithm. I've used handheld or clip-on meters, and auto flashes for many years and they can be "fooled" much easier and much greater than eg. matrix metering.

rvaubel

10-09-2006, 21:13

Just my opinion but an external sensor with the potential to see something several stops different from what the lens sees is in another world compared to the sort of approximation you might find with an algorithm. I've used handheld or clip-on meters, and auto flashes for many years and they can be "fooled" much easier and much greater than eg. matrix metering.

Ben

The external meter is claimed to be accurate to +/- 1 stop, not "several stops". As for matrix metering being more accurate, the M8 doesn't have it and I'm glad. I can never tell what my 20D is "thinking" when its in matrix mode, so I set it for spot or center weighted. I'll bet a lot of us on this forum avoid matrix mode (if even available) except for action shooting. I don't like to let the meter rule the camera. I frequently apply exposure compensation to override the meters recommendation.

Rex

Ben Z

10-10-2006, 06:03

Ben

The external meter is claimed to be accurate to +/- 1 stop, not "several stops". As for matrix metering being more accurate, the M8 doesn't have it and I'm glad. I can never tell what my 20D is "thinking" when its in matrix mode, so I set it for spot or center weighted. I'll bet a lot of us on this forum avoid matrix mode (if even available) except for action shooting. I don't like to let the meter rule the camera. I frequently apply exposure compensation to override the meters recommendation.

Rex

Mention of matrix metering was just an example, I don't use it either, preferring as many do, to use spot or partial metering and my brain to adjust the reading for differences in tonality of the subject and/or contrast range of film or sensor. Matrix metering however, is much more consistently accurate than spotmetering in the hands of someone unfamiliar with metering and exposure theory.

As to the external sensor being "claimed" to be accurate to +/- 1 stop I'm sure it is so in the best-case. However, given the invariability of parallax between the "dot" and the lens, the invariability of the fov of the sensor, and the variability of lens focal length and variability of arrangement of light sources within the respective views of sensor and lens, I can't see how anyone could claim the potential isn't there for a difference of more than one stop.