New lenses and the future of FF

[A Sfeir]

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This topic may have been discussed here, just as it may not make sense.

Judging by the size (only), I am wondering if the new wide angle lenses are not of retro-focus type so that they may allow larger angles between the light rays and the plane of the film, so that a full frame CCD or MOS may become a possibility.

[This is not a criticism of the current M8/8.2 which is a superb instrument for what I do]

[lars_bergquist]

Of course they are retrofocus designs. All Leica wide angles after the v.4 35mm Summicron have been. It has been necessary for TTL metering with 28mm lenses and shorter since the M5, in fact. And even the latest wides cover the full 35mm frame. Leica know that there are lots of film M cameras in use out there, and they are keeping their options open for a full frame or nearly full frame digital M.

 

The old man from the Age of the Zeiss Hologon

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[luigi bertolotti]

Of course they are retrofocus designs. All Leica wide angles after the v.4 35mm Summicron have been. It has been necessary for TTL metering with 28mm lenses and shorter since the M5, in fact. And even the latest wides cover the full 35mm frame. Leica know that there are lots of film M cameras in use out there, and they are keeping their options open for a full frame or nearly full frame digital M.

 

The old man from the Age of the Zeiss Hologon

 

Exactly... my Summaron 28 is still a nice lens - not retrofocus - and indeed metering on M8 isn't correct ... I suppose it would be so also on a M6 (thinking well... I never tried how my CL meters with it... there is always something new to try...)

Edited April 30, 2009 by luigi bertolotti

[tobey bilek]

My 21 2.8 pre asph and 28 2.8 V 111 from middle 1980~s are reto focus.

[Iansky]

I suspect we will have to wait a long time for a full frame M digital, Leica are going to struggle to make a full frame compatible with all the lenses that can be used on the current M8's.

 

I would have expected them to have done it from the start to maximise sales potential, we know they have the contacts and expertise (look at the S2 sensor) but as long as the majority of customers are happy with the current sensor (and I suspect they are) Leica will not rush - they cannot afford any more "White Elephants".

[lars_bergquist]

It was and is technically impossible to do it with present sensor technology. Because of the short backfocus of the M camera, corner rays hit the sensor at very acute angles. Film could handle this, but even with offset micro-lenses over the sensor, silicon can't. This is the reason why the M8 cannot use a larger sensor than 18x27mm, and it is not because Leica thought that they could get away with doing less than they could.

 

That would be pretty well the first case of Leica cutting corners ...

 

We shall assuredly have a full frame M when improved sensor technology makes this possible. When? Leica people think it will come, but Leica is taking the long view. And to paraphrase John Maynard Keynes, 'in the long view we are all dead'.

 

The old man from the Class of '36

[adan]

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Lot of confusion here. It is perfectly easy to build a Leica M rangefinder with a full-frame sensor right now, today - IF the optics of the wide-angle lenses are redesigned.

 

Go to the Leica factory floor, grab one of the last 19 f/2.8 "R" lenses (before they are all sold), take a Leica-R-to-M adapter and weld it on the back, and stick in a linkage for RF focusing.

 

Such a lens would work fine on a full-frame sensor in an M body, just as it works fine on a full-frame Canon body (better even, since there are no mirror-clearance issues)

 

The only limitation to full-frame in an M camera are the CURRENT and PAST WIDE-ANGLE lens designs. Throw them away and design new lenses, and there is no problem.

 

The issue, of course is that (a) Leica M owners who already own M wideangles would be left out in the cold, and would rebel, and ( quasi-SLR wideangle optics designed into M-mounts would generally be very large compared to traditional M-mount lenses, which again would spark a rebellion amongst those of us who value the compactness of the M cameras/lenses.

 

Looked at from another angle, it would be a mechanical, but not an optical, problem to take any full-frame DSLR, take out the mirror and prism (but leave the mirror box/lens mount as is), put a rangefinder on top, figure out a way to link the RF to the lenses - and bingo, you have a full-frame rangefinder digital camera - that will work with any lens down to 14mm from either Canon or Nikon.

 

The original post asked the question of whether Leica is moving in this direction (building more SLR-like lenses for the M), suggested by the large size of the 21/24 f/1.4 lenses. Something I wondered about myself.

 

After studying the optical diagrams and specs, I would say "mostly no". The 21/24 Summiluxes are larger mostly because of the larger f/1.4 aperture, and the amount of glass needed to bend that much light. The optical back focus is still pretty short, and thus limited for the reasons Lars describes.

 

But let's be clear on the issue - it is not the M back focus per se that limits sensor size. It is Leica's pre-digital lens designs. A full-frame digital M could arrive tomorrow - IF we accept turning all M lenses under 50mm (or maybe 35mm) into paperweights, replaced by new optics.

Edited May 1, 2009 by adan

[dcuthbert]

One thing i'd like to see adopted is the ability to manually override the lens detection.

 

We all know that hand coding lenses is rather tedious, especially since the algorithm used isn't rocket science. What would be pretty impressive is a firmware option that allows the user to specify what lens is attached, regardless of the make/model.

 

If FF is the end goal, the firmware needs to reflect the fact that there are other lenses available for the M platform and work with those lenses.

[adan]

"my Summaron 28 is still a nice lens - not retrofocus... I never tried how my CL meters with it"

 

!!!!!!!!!!!!!

 

An experiment I would not attempt - it will snap off the the little arm that carries the metering cell - which is the REAL reason why Leica redesigned their 21 and 28 lenses starting with the 28 f/2.8 v.2 to be retrofocus. To avoid wrecking M5's and CLs

 

!!!

[blakley]

But let's be clear on the issue - it is not the M back focus per se that limits sensor size. It is Leica's pre-digital lens designs. A full-frame digital M could arrive tomorrow - IF we accept turning all M lenses under 50mm (or maybe 35mm) into paperweights, replaced by new optics.

 

I'm not convinced this accurately characterizes the situation. If you start with the assumption that today's 50mm and above lenses will still be used, you must retain today's film-to-flange distance. On full-frame, Leica's existing 50mm and probably 75mm lenses will exhibit the same angle-of-incidence issues you see with today's wideangles on the M8, because they (like the wideangles) have not been designed to be telecentric.

 

Furthermore it's not clear to me that telecentric redesigns of the Leica wideangles are possible while retaining both today's film-to-flange distance and today's lensmount diameter; even if these redesigns are possible they may produce lenses so big they block rangefinder windows positioned where today's windows are. If this is the case we'd need a bigger camera with a new rangefinder design - probably with a lot better parallax correction.

 

I'm not an expert in any of this, but I'd love to hear from someone who designs lenses for a living what the constraints and possbilities are.

[A Sfeir]

...

 

The original post asked the question of whether Leica is moving in this direction (building more SLR-like lenses for the M), suggested by the large size of the 21/24 f/1.4 lenses. Something I wondered about myself.

 

After studying the optical diagrams and specs, I would say "mostly no". The 21/24 Summiluxes are larger mostly because of the larger f/1.4 aperture, and the amount of glass needed to bend that much light. The optical back focus is still pretty short, and thus limited for the reasons Lars describes.

 

But let's be clear on the issue - it is not the M back focus per se that limits sensor size. It is Leica's pre-digital lens designs. A full-frame digital M could arrive tomorrow - IF we accept turning all M lenses under 50mm (or maybe 35mm) into paperweights, replaced by new optics.

 

This is precisely what I meant when I started this post. Thanks for clarifying, and if the choice is between large size FF and compact M8/8.2 I opt for the latter.

[georg]

"it is not the M back focus per se that limits sensor size. It is Leica's pre-digital lens designs"

 

Wideangles with the performance/size of the M-lenses aren't possible with strong retrofocus. So you compromise the quality of the lenses OR you design better sensors. The best digital-lenses (Rodenstock HR / Schneider Digitar) right now are also no (or only weak) retrofocus-designs. They work extremely well with sensors without microlenses, but you loose about one stop sensitivity - no option for the M9. But the new generation of microlenses was just introduced with the new DALSA-sensors, I think we're closer to a fullframe-M9 than ever before.

[adan]

blakley: Nikon and Canon both provide 50mm lenses that are NOT retrofocus. They are plain old double-gauss symmetrical lenses just like the 50 'cron. The only difference is that they build more of the physical backfocus into the camera, and less into the lens mount. But the optics are basically the same - and they work fine on D700s and 5Ds.

 

Just for comparison, here's an x-section of a Nikkor 50, with the rear element actually BEHIND the lens flanget:

http://www.photoreview.com.au/reviews/cameraaccessories/Nikkor50mm_lens-diagram.jpg

 

Here's a x-section of the Leica 50 (you'll have to download the technical data pdf and scroll to page 2) with the glass ~12mm in FRONT of the lens flange.

Leica Camera AG - Photography - LEICA SUMMICRON-M 50 mm f/2

 

Nikon puts more metal behind the glass as part of the camera - Leica puts more metal (1.2cm) behind the glass as part of the lens barrel, but the net result is the glass is the same distance (within a mm or so) from the image plane either way.

 

I don't know - maybe Nikon is smarter than Leica when it comes to lens design (ya think?). Personally I think that if Nikon's 50mm lenses work with full-frame digital, Leica's will do just fine.

 

BTW - I see no telecentricity/angle-of-incidence issues with my current Leica wideangles on the M8. (cyan drift without coding, yes - but that's a completely unrelated issue). What did you have in mind?

 

Basic question: Is it possible to mount a Nikkor 20mm lens on a Leica M (keeping the Leica-Ms flange-to-film distance)? Answer: yes! Here it is, right at the top of the page: Adapters:* SLR to RF

 

You have to make the LENS longer, by putting an adapter on the back - but the camera is not modified in any way. The camera flange is still where it always was. The lens mount is no wider than it ever was.

 

Is that Nikkor 20mm compatible with a full-frame digital sensor? Ask any Nikon D700 or D3 user - the answer is also yes. (One may be able to quibble about whether it is perfectly telecentric all the way to the corners - but heck, it wasn't perfect all the way to the corners on film, and still earned me back 30 times its value over the years I used one).

 

Let's do this - give Leica a budget to license lens designs from Nikon. 20mm f/2.8, 24 f/2.8, 24 f/2 (the old manual lens) 28 f/2.8, 28 f/2. Except for the 20mm (62mm filters), those are all 52mm-filter lenses - smaller diameter than the current 21/24 Leica Elmarit-ASPHs (55mm).

 

Rebuild the back of the lens barrels to add 14mm or so to equal the Cameraquest adapter - only built-in. Add an RF cam to the back of the Nikkor optics so they will RF-focus.

 

Now you have a lens that (a) fits the regulation M flange-to-sensor distance, ( fits the regulation M mount "mouth" diameter, © is proven to work on a full-frame sensor, optically (in any D3/D700), (d) may block the viewfinder a bit (irrelevant for the 20/24 - irrelevant for the 28 in terms of whether it will produce an image on the sensor, and likely no more than the 24 f/1.4 does already on an M8), (e) is not going to block the RF window, since the lenses are smaller diameter (and only slightly longer than) Leicas current 21/24 f/2.8s. For that matter the 20 f/2.8, in total, is smaller than Leica's 75 or new Nocti - and they don't block the RF window (we hope!).

 

There are practical examples of optical designs that work with full-frame digital and could be adapted to the existing M-mount specs. In the face of practical realities, theory ("I'd love to hear from someone who designs lenses for a living what the constraints and possbilities are") becomes irrelevant.

 

Just as, once humans walked on the moon, it became irrelevant whether it was theoretically possible or not.

Edited May 1, 2009 by adan

[adan]

georg: I know what you mean, but OTOH, Leica's retrofocus 21s (pre-ASPH and ASPH) are rated by many as better than the non-retrofocus Super-Angulons of the 60's. Although that may depend on personal taste as to which is more important: resolution or contrast or distortion.

 

Lens design moves on - as does sensor design and microlens design.

 

As the happy owner of pre-ASPH 21 and 28 Elmarits and a 35 'cron, I am certainly in favor of a full-frame digital M - eventually - that will be able to use them. And that's the challenge. Accomodating the legacy lens designs.

[bill]

I have a full-frame M, with a sparkly clean new sensor for every shot. I'm pleased that leica continue to make lenses that fit my sensor; anything less would be an unacceptable compromise.

 

Regards,

 

Bill

[jaapv]

I just tried to load a similar memory card in the card reader. I had to pull it out of its cylinder, but still there was no data transfer...:confused:

[luigi bertolotti]

"my Summaron 28 is still a nice lens - not retrofocus... I never tried how my CL meters with it"

 

!!!!!!!!!!!!!

 

An experiment I would not attempt - it will snap off the the little arm that carries the metering cell - which is the REAL reason why Leica redesigned their 21 and 28 lenses starting with the 28 f/2.8 v.2 to be retrofocus. To avoid wrecking M5's and CLs

 

!!!

 

Sure it's like that for the Summaron 28 ? It's so slightly protruding at the back end... well, I'll try today with the proper cares...

[andybarton]

I just tried to load a similar memory card in the card reader. I had to pull it out of its cylinder, but still there was no data transfer...:confused:

 

I have one of those fancy Nikon data readers. While it's a bit slow, it does produce very nice 125MB files from the data storage device.

[Guest Xing]

Ah yes, nothing so aesthetically pleasing as 125MB rendering of compressed dMax and digitized film grain as only a desktop scanner can provide

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Hallo,

Look here: Leica M

[andybarton]

Your views on scanning are well known, and your sarcastic tone really isn't necessary.

 

Not everyone has the benefit of (or the time to devote to) a wet darkroom. Not everyone thinks that the M8.x is the best thing since sliced bread. Not everyone can afford an Imacon.

 

Get over it.

 

(Apologies to the thread for having wandered off topic)