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An Electronic Range Finder in an M


jto555

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Now this could be interesting!!! An Electronic Range Finder in an M:

 

http://leicarumors.com/2015/10/14/leicas-patents-for-optoelectronic-rangefinder.aspx/#more-37877

 

 

 

This could be the killer feature in the next M and I really want it! We might be even able to micro-adjust the focus of each of our lenses to correct front/back focus. 

 

 

John

 

 

 

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Then again LR site has been conspicuously quiet about the 20th October and possible rumoured SL. So them saying anything at this stage about the optoelectro rangefinder would make it a less likely candidate for the 20th? ... we love rumours :-)

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[...] We might be even able to micro-adjust the focus of each of our lenses to correct front/back focus. 

 

I am not sure that is possible for those who use traditional M lenses.

 

For using existing M lenses, the device still uses the roller-lever in the body. The distance is sensed using phase-detection from the two RF lenses, then it uses a lookup table to establish focus (plus firmware when interpolation is required).  This suggests that the RF becomes a focus-confirmation method determined by the user. In other words, to the photographer little has changed.

 

We still need the same properly manufactured focus components in the lens and adjustable body cam. Whether we can tune the RF by changing the table values is unknown, but IMHO unlikely due to the risk of operator error. A possible work-around is to allow the user to calibrate and the correction to the focal-length is stored in a location other than the standard lookup table. Reversion and re-correction would then be possible.

 

The invention benefits Leica in that the rangefinder is not necessarily calibrated in-body; it is manufactured as a separate unit which is much more cost-effective.

 

The patent language offers an optional method, probably not for our M lenses which correlates measurements against the sensor image, but that seems to be intended for a different lens system.

 

I am certainly willing to be corrected. Input is welcome.

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The patent filing appears to rely on focus evaluation using optical sensors which are outside the lens, so the issues of focus coupling and restricted range of applicable focal lengths would presumably still plague this type of rangefinder implementation.

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I am not sure that is possible for those who use traditional M lenses.

 

For using existing M lenses, the device still uses the roller-lever in the body. The distance is sensed using phase-detection from the two RF lenses, then it uses a lookup table to establish focus (plus firmware when interpolation is required).  This suggests that the RF becomes a focus-confirmation method determined by the user. In other words, to the photographer little has changed.

 

We still need the same properly manufactured focus components in the lens and adjustable body cam. Whether we can tune the RF by changing the table values is unknown, but IMHO unlikely due to the risk of operator error. A possible work-around is to allow the user to calibrate and the correction to the focal-length is stored in a location other than the standard lookup table. Reversion and re-correction would then be possible.

 

For an electronic Rangefinder the roller-lever would be connected to electronics rather than mechanics. This means together with the lens identification in the barcode reader, the camera's CPU can micro-adjust based on user stored values on a per-lens basis. This is very possible.

It is also a major advantage, user calibration rather than expensive in factory calibration becomes possible.

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For an electronic Rangefinder the roller-lever would be connected to electronics rather than mechanics. This means together with the lens identification in the barcode reader, the camera's CPU can micro-adjust based on user stored values on a per-lens basis. This is very possible.

It is also a major advantage, user calibration rather than expensive in factory calibration becomes possible.

That presumes the lens is made to drive the roller perfectly. It is still all mechanical up to the roller & lever.
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That presumes the lens is made to drive the roller perfectly. It is still all mechanical up to the roller & lever.

 

No it doesn't, rather what will happen with an electric Rangefinder is any adjustments will be possible in software. That is to say, software will be able to adjust for mechanical misalignment. This is how DSLR calibration works, calibration of focus depends on the mechanical alignment of the AF sensors and the mirror box, but software adjustments are able to make up for mechanical calibration issues because the data will go through the camera's CPU before it gets to the lens AF motor. I would note focus accuracy and calibration is a major issue with Phase AF in DSLRs, probably more than it is for Rangefinders. See this link:

http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-1-center-point-single-shot-accuracy

 

 

Likewise, with an electric Rangefinder the data will go through the CPU before it gets to an EVF focus patch. I am presuming it will feature an EVF overlay in an OVF.

Hence, this makes for far cheaper calibration. And calibration that can be performed by the user.

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Here is the point:

An electronic rangefinder is likely to be an EVF focus patch overlay in an OVF. This means that the focus measurements from the mechanical lens will first go through the CPU before getting to the viewfinder, making software focus calibration possible.

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Okay, but my earlier post posited that with traditional M lenses the outcome is still focus confirmation which is no better than current Leica RF technology. If the lens mechanics are off then the electronic RF will be off as well.

 

I am aware that I might be missing a serious point, and look forward to correction.

 

Thank you.

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Any time you are processing data through a CPU rather than a direct mechanical connection, you can modify the data. For example if the electronic rangefinder is back focusing by -3, the CPU can simply add a value of +3 to the lens position.

And such can be an option the user can change via camera menus, see the example below on a Canon DSLR. I'd love this functionality in a Leica rangefinder:

 

http://www.cameralabs.com/reviews/Canon_EOS_7D/images/menus/Capture-10032.jpg

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Okay, but my earlier post posited that with traditional M lenses the outcome is still focus confirmation which is no better than current Leica RF technology. If the lens mechanics are off then the electronic RF will be off as well.

I think the point is that the number of mechanical elements involved is much reduced, and so are the sources of error. Having said that Leica has spent a lot of effort in increasing focusing accuracy by tightening tolerances for the M (Typ 240) so they may not see a need to switch to an electronic rangefinder.

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I think the point is that the number of mechanical elements involved is much reduced, and so are the sources of error. Having said that Leica has spent a lot of effort in increasing focusing accuracy by tightening tolerances for the M (Typ 240) so they may not see a need to switch to an electronic rangefinder.

 

The assumption of course is that the lenses are perfectly adjusted?

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The assumption of course is that the lenses are perfectly adjusted?

Adjustment is a different matter but while there is the possibility of self-calibrating an electronic rangefinder, whether it would actually be practical isn’t entirely clear just yet.

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Any self calibration would have to include the lens ...

 

I think the proponents of this electro-optical rangefinder are forgetting that what takes the picture is the setting on the lens in relation to the sensor.  The rangefinder is irrelevant to this process, save for assisting the photographer to set the focus. Adding electronics to the rangefinder mechanism is still doing nothing to increase the accurate of the primary process of setting the lens relative to the sensor.

 

I would have thought any real improvement in focusing rangefinder cameras will be in reading the image off the sensor - we still seem to be a way off from that.  While Leica has this patent, I'd have thought it is a dead end - the optical viewfinder remains the best bet, without adding electronics to it.  The M(240) is pretty much state of the art, and messing with that isn't the future - what we have is as good as it gets.

 

An improved EVF, with more accurate focus peaking or whatever comes next, will be the future; and I doubt it will surpass the rangefinder in the core range of 28-90mm.  Outside that range, it has a way to go to beat the SLR, but that is another story, I guess ...

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