diglloyd: "Leica M Typ240: Unreliable"

[lct]

Advertisement (gone after registration)

Different beasts indeed. I was tempted by the 5D3 for my R lenses but it cannot fit split image focus screens either unfortunately.

[Advertisement]

The Leica Q3 is available for pre-order at B&H Photo Video and Adorama

[StephenPatterson]

Just saw that, so apologies for the repeat. To be clear, I prefer the M240 to the 5DIII.

 

Horses for courses. The Canon is a work horse and far superior for video and fast for events, weddings, etc. The M240 is a thoroughbred (with all that implies).

[Guest malland]

Horses for courses. The Canon is a work horse and far superior for video and fast for events, weddings, etc. The M240 is a thoroughbred (with all that implies).

Stephen, am disappointed that you didn't manage to get a reference in there to the Porsche 911, but then look at this thread

 

—Mitch/Bangkok

Bangkok Obvious [WIP]

Eggleston said that he was "at war with the obvious"...

[dant]

Is it as bad as the article said with the battery? You have to unscrew the base plate? Why doesn't Leica have a trap door?

[Rick]

Is it as bad as the article said with the battery? You have to unscrew the base plate? Why doesn't Leica have a trap door?

 

Yes, you have to take the baseplate off first.

 

My suggestion to Leica is to make a new bottom that has a trap door only, not base plate.

 

Then, sell an accessory base plate for Leica traditionalist that prefer to go the extra step of taking a base plate off in order to change film, I mean memory card and battery. Leica could even sell limited edition base plates. How cool would that be?

[hamey]

Is it as bad as the article said with the battery? You have to unscrew the base plate? Why doesn't Leica have a trap door?

 

Because back in 1954 Leica's engineers were not smart enough to think of it...Lol

 

Same applies to their M FILM cameras, I suppose it's traditional.

 

Thank goodness all that changed when they devolped the Reflex system, but even thats all changed now.

Now they're trying desperately to convert that 1954 philosophy into their Digital M cameras ?????

 

 

Ken.

[NazgulKing]

Advertisement (gone after registration)

By this nonsense "definition", the Super-Elmar-M 21 mm Asph would definitely be no retrofocus lens because it has a negative front element and a negative rear element.

 

Yes, but it is enough to say it is retrofocus like since there are multiple positive elements in the rear and the design is clearly asymmetric. Even for the Zeiss Tounit 32/1.8 lens, an achromat was added on to the standard planar design probably to flatten out the field.

 

 

 

This is true for all retrofocus lenses—but also for many non-retrofocus lenses. So no, this is not "the definition."

 

As a matter of fact, the definition of a retrofocus lens is very clear and very simple. For the life of me I cannot understand why some participants in this discussion so stubbornly refuse to grasp this.

 

So what is you definition of a retrofocus lens then?

 

 

 

Flange distance has absolutely definitely totally nothing to do with all this.

Yes it does and if you ever plug and chug with a lens design software like Zemax, you will immediately see that flange distance is a design constraint and will ultimately determine how difficult it is to reduce the incidence angle of the incoming rays on the sensor. And since Leica users like to fret and complain about lenses intruding in the viewfinder, this makes the lens designers' life even more difficult because he can't simply add as many elements as he likes.

[CalArts 99]

Because back in 1954 Leica's engineers were not smart enough to think of it...Lol

 

Same applies to their M FILM cameras, I suppose it's traditional.

 

Thank goodness all that changed when they devolped the Reflex system, but even thats all changed now.

Now they're trying desperately to convert that 1954 philosophy into their Digital M cameras ?????

 

 

Ken.

 

Removing the base plate (at least beginning with the M4 quick load system) is pretty ingenious. The basket on the bottom end of the base plate pushes itself onto the tulip where the film leader is placed. Once you pop the film cassette in and feed the leader, all you have to do is stick the film leader end into the tulip and then close the base plate and you're done. It's super quick. And better than a conventional swinging rear door, imho.

[StephenPatterson]

Stephen, am disappointed that you didn't manage to get a reference in there to the Porsche 911, but then look at this thread

 

—Mitch/Bangkok

Bangkok Obvious [WIP]

Eggleston said that he was "at war with the obvious"...

 

Too funny! Thanks for the heads up Mitch, and I will try to brush up on my Chinese idioms instead...

[01af]

So what is your definition of a retrofocus lens then?

This has been repeated so many times now. Do I really have to repeat it once again?

 

A lens is retrofocus when the backfocus distance is longer than the focal length. Another way of saying the same thing is this: A lens is retrofocus when the rear principal plane—which is also known as second or image-side principal plane—is located outside the lens, behind the rear element.

 

So, lenses can be divided into three groups by the positions of their rear principal planes: telephoto, regular, and retrofocus. In a telephoto lens, the rear principal plane is located outside the lens, before the front element. In a regular lens, the rear principal plane is located inside the lens, somewhere between the first and the last glass element. In a retrofocus lens, the rear principal plane is located outside the lens again, behind the rear element.

 

And by the way—this is not my definition. It's the definition.

 

 

Flange distance has absolutely definitely totally nothing to do with all this.

Yes it does ...

No, it does not.

 

 

... and if you ever plug and chug with a lens design software like Zemax, you will immediately see that flange distance is a design constraint ...

Uh oh ... do you actually know what "flange distance" is in the first place? The diameter of the lens mount's throat is a design constraint. Flange distance is not.

[bill]

Because back in 1954 Leica's engineers were not smart enough to think of it...Lol

 

Same applies to their M FILM cameras, I suppose it's traditional.

 

Thank goodness all that changed when they devolped the Reflex system, but even thats all changed now.

Now they're trying desperately to convert that 1954 philosophy into their Digital M cameras ?????

 

 

Ken.

 

It was originally marketed as providing greater structural rigidity than a hinged back.

 

Regards,

 

Bill

 

Sent from another Galaxy

[mjh]

Yes it does and if you ever plug and chug with a lens design software like Zemax, you will immediately see that flange distance is a design constraint and will ultimately determine how difficult it is to reduce the incidence angle of the incoming rays on the sensor.

Neither of which is true. The flange distance is not a design constraint: You can always adapt a lens designed for a longer flange distance to a camera with a shorter flange distance. You could also design a lens with its rear elements protruding into the body (for example, Canon have done this with some lenses for their APS-C DSLRs) to overcome the limits of a longer flange distance. Furthermore, the flange distance has no bearing on the incident angles; the relevant parameter is the distance between exit pupil and sensor. Lenses for EVIL systems are often near telecentric (i.e. the distance between exit pupil and sensor is fairly large); still all those systems have a short flange distance, even shorter than that of the M system.

 

But as 01af has said, the throat diameter is a design constraint: Near telecentric lenses need large rear elements which is why all the newer systems have fairly wide throat diameters (twice the diameter of the image circle would be an ideal size).

[dant]

It was originally marketed as providing greater structural rigidity than a hinged back.

 

Regards,

 

Bill

 

Sent from another Galaxy

 

I saw a photo of an MM bottom plate. If the M is like that it is OK. From the article quoted it sounded like one needed to remove little screws to get at the battery.

[NazgulKing]

Neither of which is true. The flange distance is not a design constraint: You can always adapt a lens designed for a longer flange distance to a camera with a shorter flange distance. You could also design a lens with its rear elements protruding into the body (for example, Canon have done this with some lenses for their APS-C DSLRs) to overcome the limits of a longer flange distance. Furthermore, the flange distance has no bearing on the incident angles; the relevant parameter is the distance between exit pupil and sensor. Lenses for EVIL systems are often near telecentric (i.e. the distance between exit pupil and sensor is fairly large); still all those systems have a short flange distance, even shorter than that of the M system.

 

No the flange distance is a design constraint because you set a minimum to the back focal length and the radii of the curvature of the lenses must be computed as such that the rays of light are focused onto the image sensor. Anything that requires computation will impose a constraint because you obviously cannot have too extreme radii of curvature or you introduce distortion, and so either you split up the said lenses or use high index glass and then deal with chromatic aberration etc. Yes you can have the rear elements protruding into the body, but you obviously cannot go past the mirror.

 

But as 01af has said, the throat diameter is a design constraint: Near telecentric lenses need large rear elements which is why all the newer systems have fairly wide throat diameters (twice the diameter of the image circle would be an ideal size).

 

Why on earth would near telecentric systems have large rear elements larger than the sensor at all when the rays of light arriving near the edges wouldn't even be focused onto the sensor? And even if they did, the rays would be fairly oblique which defeats the entire purpose? Take a look at Fig. 4 on this Opto Engineering telecentric lenses tutorial. That's a proper telecentric lens, where the rear image is about the same size as the diameter of the lens. Why would a near telecentric lens have rear elements much larger than the intended image circle? Won't that be a sheer case of over engineering and thus not cost effective? The most recent 35mm digital camera system which is the Sony NEX has a throat diameter that is barely larger than the sensor.

 

The throat diameter is a constraint, but it isn't such a big constraint that is insurmountable. Long flange distances dictated by the physical structure of SLRs and movie cameras dating back from the 3 color Technicolor movie camera is a more difficult constraint since that demanded a long back focal length and thus led to the development of retrofocus lenses in the first place!

[brill64]

According to what I've heard from several dealers and Leica users there is almost zero interest in the X Vario and it isn't moving (selling) at all...

 

I am certain that most Leica users aren't really too interested in the X Vario. There are probably exceptions: 1. Gear heads that just wants to test everything and then later re-sell it. 2. People with too much money to waste, and 3. People that are obsessed with brands, and which prioritze owning a certain brand above all.

 

The thing is utterly overpriced for what it is. Even most typical Leica evangelists agrees to that.

 

I think you are speaking only for yourself.

[NazgulKing]

This has been repeated so many times now. Do I really have to repeat it once again?

 

A lens is retrofocus when the backfocus distance is longer than the focal length. Another way of saying the same thing is this: A lens is retrofocus when the rear principal plane—which is also known as second or image-side principal plane—is located outside the lens, behind the rear element.

 

So, lenses can be divided into three groups by the positions of their rear principal planes: telephoto, regular, and retrofocus. In a telephoto lens, the rear principal plane is located outside the lens, before the front element. In a regular lens, the rear principal plane is located inside the lens, somewhere between the first and the last glass element. In a retrofocus lens, the rear principal plane is located outside the lens again, behind the rear element.

 

And by the way—this is not my definition. It's the definition.

 

When lens designers talk about a design, they talk about the arrangement, the formulas relating the arrangement, and the properties derived from such an arrangement. What you say is correct, but by no means does it invalidate what I said that the fundamental design form of a retrofocus lens is a negative element in front and a positive element at the back. If I wanted to be even more precise, I could go cite the equations required to relate both lenses. And if you really want to, go check page 396, eqn 14.1 and 14.2 of Modern Lens Design by Warren Smith. And obviously such a two-lens system is too bloody simple for any high MTF-resolution imaging use so the two lenses will obviously be split into multiple lenses to correct for any aberrations.

 

And by the way, to be more precise, a "general" lens is a symmetric convex lens. Meniscus lens have their cardinal points outside the lens depending on the relative curvature of the two surfaces.

[pico]

Why on earth would near telecentric systems have large rear elements larger than the sensor at all when the rays of light arriving near the edges wouldn't even be focused onto the sensor? And even if they did, the rays would be fairly oblique which defeats the entire purpose?

 

I realize that you carefully wrote near telecentric, however for our purposes (full-frame 35mm format, typical real-world color, our wide focus ranges), existing so-called consumer telecentric lenses should be called not-even-nearly telecentric.

[ALD]

If anybody is unhappy with their new M240 judging it to be "unreliable" let me please, please, pretty please, save you from your anguish. I will buy it from you.

[Advertisement]

Hallo,

Look here: Leica M

[Guest tanks]

Something could be considered "unreliable", but still be tolerable. We deal with that almost every day, and lower our expectations for non-mission critical items.

 

I find that to be the case for those that find their M to be "unreliable", but still keep it.

[01af]

No, the flange distance is a design constraint because you set a minimum to the back focal length ...

No, you don't. So it isn't.

 

 

Yes, you can have the rear elements protruding into the body, but you obviously cannot go past the mirror.

Which mirror?

 

If you had a mirror flapping behind the lens then this would lead to a minimum backfocus distance—which of course would be a design constraint indeed.

 

 

Why on earth would near-telecentric systems have large rear elements larger than the sensor ...?

It doesn't. But there's more to a lens than just the glass, so for a small-format system, twice the sensor diagonal is a good size for the bayonet. Look at the µ4/3 lens mount, or that of the Nikon 1 system.

 

 

Long flange distances dictated by the physical structure of SLRs and movie cameras dating back from the three-color Technicolor movie camera is a more difficult constraint since that demanded a long back focal length and thus led to the development of retrofocus lenses in the first place!

Ah, it becomes clearer now. You're confusing flange distance and backfocus distance.