Solms has spoken:

[LCT]

Ah yes! I forgot the goggles, you're right Ben.
Then i would not be surprised if the VF mag were at least .78x and the finder window somewhat larger to fit 21mm (28mm FoV) frame.
Best,
LCT

 

[Bob Parsons]

I don't think we need to be scientists to understand that all existing Leica lenses were designed to focus on the same plane, the same distance from the body flange. So they will all focus on the same plane, the same distance from the body flange in the M8. Just as any lens that could focus on a Nikon F or Canon EOS body focuses on the plane of their digital sensors.

And even if for the sake of argument we suspend common knowledge and sense and allow that the 135 APO doesn't focus on the M8 plane, it would be a simple matter to have the rangefinder cam adjusted so that it does. That would mean it wouldn't focus correctly on a film body, but nonetheless it would be usable on the M8.

I suspect the real reason for Leica saying the 135 is not compatible is due to the offset microlenses in the sensor corners. Those most certainly have been optimised for what will be the most popular wide angles and would probably give corner darkening with long focal lengths.

Bob.

 

[Ben Z]

The light rays coming in from a 135/2.8 @ f/4-22 would be the same as a 135/4 @ f/4-22 and that lens is on the codable list. I'm as certain as I can be that the issue is related to focusing accuracy, which would indicate that the M8 will have an effective baselength shorter than the 0.72 M finder.

 

[Trius]

I suspect the real reason for Leica saying the 135 is not compatible is due to the offset microlenses in the sensor corners. Those most certainly have been optimised for what will be the most popular wide angles and would probably give corner darkening with long focal lengths.

Bob.

The whole idea of microlenses, as I understand it, is to compensate for non-telecentric designs, especially with WAs. So, without being an optical engineer, I doubt this is the reason. Even if falloff for this lens were the case, encoding the lens could provide the information necessary to compensate in the firmware.

 

[rxmd]

The light rays coming in from a 135/2.8 @ f/4-22 would be the same as a 135/4 @ f/4-22 and that lens is on the codable list. I'm as certain as I can be that the issue is related to focusing accuracy,

This makes no sense. The 2.8/135, which is in, requires even more focusing accuracy than the 3.4/135, which is out. The reason must have something to do either with the optical characteristics of the Telyt's construction or with the lens coding system.

(Edit: I forgot that the 2.8/135 has googles. So the accuracy argument does make sense. But then again, in 2006 who would use a 180 mm FOV lens on a rangefinder at all?)

I'm interested in the specifics of the coding system because that will be interesting when adapting screw mount lenses to the M8. The system apparently supports lenses with at least eight focal lengths (135, 90, 75, 50, 35, 28, 24, 21), possibly some more (a 15 or 17, maybe), and five different opening apertures (1, 1.4, 2, 2.8, 4, note that only full apertures are supported). Not every single of these combinations makes sense, of course. It could also be that the system has extra provisions for encoding some optical parameters such as vignetting. There have to be some extra codepoints for the M macro adapter and coding the Tri-Elmar(s), too - it would be possible to have the a future Tri-Elmar announce itself differently at different focal lengths, but with the old one I don't think this would be possible. Just assigning every lens an individual codepoint would be possible, too, but that way they would have wasted 45 of their precious 64 codepoints already without presenting any new lenses at all! Maybe they simply couldn't fit the Telyt or its 3.4 opening aperture in there?

But that's a lot of speculation, of course.

Philipp

 

[Ben Z]

in 2006 who would use a 180 mm FOV lens on a rangefinder at all?

I'm not sure what the year has to do with it but 180mm has always been and continues to be a very useful and popular focal length. I have cropped hundreds of 135mm shots to approximately the 180-200 fov.

 

[Bob Parsons]

The whole idea of microlenses, as I understand it, is to compensate for non-telecentric designs, especially with WAs. So, without being an optical engineer, I doubt this is the reason. Even if falloff for this lens were the case, encoding the lens could provide the information necessary to compensate in the firmware.

As I understand, microlenses can give an overall sensitivity increase including avoiding some of the light loss due to high angles of light incidence in the corners. Further improvements in the corners are possible by offsetting the corner microlenses as is done on the DMR sensor. However the offset is only optimum for a particular angle of incidence. The angle depends on where the lens exit pupil is placed in relation to the sensor, which in turn depends on the lens design.

If the offsets are optimised for wide angle RF lenses which tend to be symmetrical designs with the exit pupil near the film plane then it's possible performance would not be good with a more telecentric design such as a 135mm.

The light rays coming in from a 135/2.8 @ f/4-22 would be the same as a 135/4 @ f/4-22 and that lens is on the codable list. I'm as certain as I can be that the issue is related to focusing accuracy, which would indicate that the M8 will have an effective baselength shorter than the 0.72 M finder.

The positions of the exit pupils for the two 135 lenses could be different due to their optical design. So one may give acceptable corner performance with offset microlenses and not the other.

We'll have to wait and see if the answers will come from the horse's mouth.

Bob.

 

[rxmd]

I'm not sure what the year has to do with it but 180mm has always been and continues to be a very useful and popular focal length.

Well, not with rangefinder lens makers. Has any new >135 mm rangefinder lens been developed ever since SLRs came about?

I have cropped hundreds of 135mm shots to approximately the 180-200 fov.

Cropping is an entirely different story. You still use a 135 mm lens for framing. Using a >135 mm lens with a rangefinder is awkward, lenses are big, focusing is potentially inaccurate, framing is difficult and parallax is a problem. I think we can all agree on this. Given the development of SLRs over the last fifty years or so rangefinders really have very few advantages..

Philipp

 

[Grober]

" The 3.4 apo 135 cannot be used at all as the focal point is not on the sensor."

What about the older but still great Tele-Elmar 135/4 lens?

I have re-read both tables on Leica's recent 6-bit lens coding memo and don't find this good lens mentioned on either the "current" or "discontinued" tables. Did Solms just forget about this optic?

 

[Ben Z]

The positions of the exit pupils for the two 135 lenses could be different due to their optical design. So one may give acceptable corner performance with offset microlenses and not the other.

We'll have to wait and see if the answers will come from the horse's mouth.

Bob.

Yep, so far it's all been speculation that might as well have come from the other end of the horse However the exit pupil of any of the >35mm lenses is quite far forward. The rear elements themselves are all rececessed up into the mounts.

Cropping is an entirely different story. You still use a 135 mm lens for framing. Using a >135 mm lens with a rangefinder is awkward, lenses are big, focusing is potentially inaccurate, framing is difficult and parallax is a problem

But cropping is exactly what will happen when a 135 is used on an M8. It'll be the same size lens as it always was, focus as it always did. Just the subject inclusion within the frames will be smaller. The frame itself could be bigger, depending on the finder magnification.

What about the older but still great Tele-Elmar 135/4 lens?

That's the one I have, mine's the 39mm version with the removable lens head. I've already used it on my 20D (via OTZFO short focusing mount + 14167 V-R adaptor + R-EOS adaptor) and it's great (by definition the exit pupil must be the same distance from the sensor as it is from film and would be on an M8). The 20D has a 1.6 vs 1.33 crop, but no offset microlenses. If I can find someone with a 1D-II or a 5D I'm going to see how it works. I think the only reason Leica isn't considering the 135 as viable on the M8 is because they must have lowered the finder magnification so the effective base is the same or less than a 0.58 M body, probably to give more eye relief. No other explanation makes sense.

 

[LCT]

Due to the reduction of the circle of confusion (0.03/1.33=0.023mm) a 135mm lens would need a 60mm RF effective base length (EBL) to be focused accurately at f/4.
Assuming that the RF of the digital M will have the same mechanical base length as that of classic M camera, such an EBL would need at least a .87x finder magnification.
Best,
LCT

 

[Ben Z]

Or a .72 and the 1.25 magnifier (0.9x).

 

[LCT]

Yes but .72 wouldn't be enough to focus a 'cron 90 or a 'lux 75 at full aperture and we can assume that Leica will not ask us to use the magnifier for those lenses IMHO.
Best,
LCT

 

[a.black]

Is it possible to have two magnifications in one viewfinder that could be switched according to the type of lenses one wants to use. One that works with WA and one for the longer end.

Having no idea about the technical side of rangefinders, I think I remember somebody saying that the magnification can be changed by just exchanging one lens in the VF.

 

[LCT]

Is it possible to have two magnifications in one viewfinder that could be switched according to the type of lenses one wants to use. One that works with WA and one for the longer end....

I don't know but it would be a great idea if the magnifications could switch automatically when changing lenses.
But how to do this for zebra and non-zebra lenses?
Best,
LCT

 

[Mark Norton]

This is a hobby horse of mine because I'd like to see the viewfinder handle the full range of lenses from 21 - 90 mm without recourse to aux finders, magnifiers and especially the need to choose the magnification when you buy the camera. They're all fudges to some degree to improve on the basic design.

A dual range viewfinder would go a long way to improving the usability of the viewfinder. The thread about new lenses on this forum has the brain numbing detail.

I don't think you'd need to switch finder magnifications automatically, it would be fine to simply select "wide" and "normal" as you wish.

 

[LCT]

...I don't think you'd need to switch finder magnifications automatically, it would be fine to simply select "wide" and "normal" as you wish...

Medium frames (28, 35, 50) would remain visible with both magnifications i guess.
Great idea, Mark.
Best,
LCT