Tim Ashley M(240) Review

[jaapv]

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[marknorton]

We always knew that the M8 and M9 were difficult to focus because the sensor thickness was rather greater that the emulsion thickness of film. Decrease the thickness of the sensor and there is greater tolerance of where the sensor sits in the focus sweet spot created by the lens and you have a more tolerant focussing mechanism.

 

Similarly, as you stop down the lens, the sweet spot deepens (and may move) and it's easier to keep the sensor inside it.

 

There may be also be engineering changes which improve the accuracy - it was always said the need to mount the lens further forward made replicating the precise focus roller position/rangefinder distance relationship difficult, witness the profiled cam in the M8 and M9 which translates the angular position of the roller arm shaft into the swing action position of the rangefinder telescope.

 

Only Leica know how close these cameras ever came to achieving the desired relationship. It's possible, with a new design, that Leica have been able to do a better job this time around.

[k-hawinkler]

We always knew that the M8 and M9 were difficult to focus because the sensor thickness was rather greater that the emulsion thickness of film. Decrease the thickness of the sensor and there is greater tolerance of where the sensor sits in the focus sweet spot created by the lens and you have a more tolerant focussing mechanism.

 

Similarly, as you stop down the lens, the sweet spot deepens (and may move) and it's easier to keep the sensor inside it.

 

There may be also be engineering changes which improve the accuracy - it was always said the need to mount the lens further forward made replicating the precise focus roller position/rangefinder distance relationship difficult, witness the profiled cam in the M8 and M9 which translates the angular position of the roller arm shaft into the swing action position of the rangefinder telescope.

 

Only Leica know how close these cameras ever came to achieving the desired relationship. It's possible, with a new design, that Leica have been able to do a better job this time around.

 

 

Hi Mark,

 

Could you please elaborate on this?

Thickness? Register distance?

Thanks.

[UliWer]

Dishwasher History.......

 

Well, at least I learned from this thread, that William Howard Livens' dishwater idea is almost ten years younger than a similar funny idea for a little camera with 35mm format - though Livens idea was no commercial success.

[120]

...As for what this can mean for focussing the new M, I will be covering that in an upcoming piece but in short, with this lens, focussing wide open and then stopping down before shooting seems to give better results. To say more would be to write a great deal and to pre-empt the upcoming piece....

 

... I will give examples when I publish the piece but this lens has a complex MTF that results in complex and 'tricky' behaviour of its field of focus as you stop down. I think the M's RF handles this better...

 

The rangefinder is only coupled to one thing. Before you write a second review about the improvements of the new rangefinder you should confirm there really is such a thing. A recent thread showed the visible bits are of the same old (60 yrs.?) rangefinder. Someone has also given a reasoned test above to show the rangefinder is independent of the aperture setting.

 

What is special about the MTF or focus shift of this 35 lens?

[120]

...I checked with head of Leica tech. support in my country...M has same mechanical rangefinder as in M9, etc.

[macjonny1]

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...I checked with head of Leica tech. support in my country...M has same mechanical rangefinder as in M9, etc.

 

I suspect it's a case of "my brand new shiny camera seems to work better than my 3 year old M9 that I've banged around for years."

[Wilier]

I suspect it's a case of "my brand new shiny camera seems to work better than my 3 year old M9 that I've banged around for years."

 

And the comparison is more difficult since you have sold your M9 two years ago.

[UliWer]

At least it works. Doesn't matter why.

[mjh]

The wells are shallower and microlenses are more cucumbershaped rather than spherical. I do think it will enhance edge and corner sharpness at higher incidence angles over the M9. And that helps with wideangle lenses. And speculatively the elongated microlenses may give more leeway in focussing because they do give a certain physical thickness to the layer. Michael?

Actually physical thickness isn’t beneficial in itself. A thicker emulsion limits maximum sharpness whereas a thin emulsion increases maximum sharpness – but to realise that maximum, focusing must be spot on. If your focusing is slightly off, the image won’t be maximally sharp with a thin emulsion, but then it wouldn’t be much sharper had you used a thicker emulsion. The advantage of film isn’t so much that the emulsion is thicker but that there are several (three or more) layers at different depths: The focusing mechanism is geared toward obtaining maximum sharpness at the depth of the middle, green-sensitive layer, and when there is a slight front or back focus, you still get a sharp image in the red- or blue-sensitive layer. Now if you compose an image from one sharp layer and two slightly unsharpness ones, the result is still sharper than the result obtained with a single layer of a thickness corresponding to the thickness of the three layers combined. None of the common sensor types, not even Foveon’s X3 sensor, shares this property of a multi-layer emulsion.

[sblitz]

Interesting. This layer design begs the question, where is the focus set for bw film? For a sensor?

[k-hawinkler]

Right. I am curious about the definition of the register distance with respect to B&W and color film and a digital sensor. What is the actual thickness of these layers? For a digital sensor what layers/parts are relevant?

[marknorton]

So, think of depth of field. Set the lens to a specific focussing distance and objects at that distance will be in focus at the focal plane behind the lens which for Leica is 27.8mm behind the front surface of the lens mount.

 

Depth of field means that objects in front and behind will also appear more or less in focus - depending on how closely you look - and their own optimum focus will be in front or behind the focal plane. Closer objects will be optimally in focus behind the focal plane, objects further away will be optimally in focus in front of the focal plane.

 

There is then a zone - which varies by lens focal length, focussing distance and lens aperture - where if you position the sensor, you will get a sharp image. Increasing the focal length, reducing the focussing distance and opening the lens all contribute to reducing the depth of the zone and focussing becomes more critical.

 

For a given zone depth, you have greater latitude if the distance over which you require good focus is as small as possible. Film emulsion is thinner that the depth of the light collecting wells in sensors which is why the M8/M9 stretched the capabilities of the rangefinder - placement of the sensor became ever more critical. In the new M, the sensor is shallower which provides more latitude and it's that which I think leads to the perception (real in my experience) that the rangefinder is more accurate.

 

YMM (of course) V.

[jaapv]

Hmm...I wonder how important the well depth is, as the microlenses focus the light, presumably in one plane.

[gpwhite]

It is intriguing to read the array of comments that contest whether an RF improvement exists with the M240 and projecting why photogs like me would imagine it exists after comparing my prints from M240 images to M9 images.

 

No need to grind further on how M240 users have reached favorable conclusions... the best advice is to pick your most difficult lens or two and go shoot with an M240 when first given the opportunity. The VF difference should be immediately noticeable and your image results should speak for themselves, at least in terms of decent sized prints or large monitor viewing.

 

Personally, I like Jaap's explanations for what I have observed.

 

Leica marketing information has always been entertaining, IMHO, but not really meaningful. I love the one when Leica says that the Noctilux is so fantastic because it can render nuances in color tones beyond what the human visual system can perceive... I am not sure I get the value in that claim, but you hear it all the time

 

Peter

[dwbell]

This is interesting to read. Thanks Mark for the explanations. If true, it would appear to be an advantage of the new sensor that wasn't entirely expected, but never the less very welcome.

[k-hawinkler]

If true this explanation doesn't seem to involve the rangefinder for increased focus accuracy.

[marknorton]

Hmm...I wonder how important the well depth is, as the microlenses focus the light, presumably in one plane.

 

I take your point, but an out of focus image projected by the lens onto the top of the microlenses is not suddenly going to come in to focus. The detail is lost by the initial lack of focus.

 

I think deciding where, exactly, the effective focal plane is must be quite a challenge and I believe that they changed their minds from the earliest M8's. Both of my M8U's, originally very early cameras, came back with the focussing transformed after upgrade.

 

There is someting about the M rangefinder which makes it easier to use; I don't have my M back yet and I am leaving on a trip so it will be a while before I find out, but I wonder whether the rangefinder patch is brighter or something like that.

 

Certainly, when I compared rangefinder focussing and then switched across the Live View, the focussing was spot on - in a thread of a couple of months ago, I wondered how people would feel about the RF being out of step with Live View which, given my experience of the M8 and M9, seemed inevitable. Somehow, it appears not to be the case. Which is good news.

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Hallo,

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[tashley]

The rangefinder is only coupled to one thing. Before you write a second review about the improvements of the new rangefinder you should confirm there really is such a thing. A recent thread showed the visible bits are of the same old (60 yrs.?) rangefinder. Someone has also given a reasoned test above to show the rangefinder is independent of the aperture setting.

 

What is special about the MTF or focus shift of this 35 lens?

 

I have carefully stated that I do not believe that the aperture setting is in any way involved. It never has been. We all know that.

 

As for what the rangefinder is coupled to, again, please show me where I have stated or implied that it is coupled to anything other than the lens's focus distance via a cam. Clearly it is not connected to anything else.

 

Regarding writing 'a second review about the improvements to the RF' I have no such plan, and am sorry to disappoint you . In fact, I haven't written a first review 'about it' either. I mentioned it in the context of a much broader review. The comment I made in that review sums up my opinion, and I feel perfectly entitled to share that opinion. I did not claim to have verified it with Leica and I have given a clear possible reason as to why any company might not want to trumpet, or even admit to, a component upgrade. The head of Leica tech support in your country, wherever that is, may be right or he may be saying what you claim he said for a variety of other reasons I can imagine. Time will tell. I still think I am right, and have made it very clear that this is a very strong opinion not a fact. But as per the 'visible bits' well, maybe they didn't change the way those bits look. It's hardly evidence one way or the other.

 

Like all the opinions in my reviews, it comes from a certain amount of experience and, more importantly, is completely free of charge - so if it is of no value to you, I hereby offer you a full refund However, there do seem to be other people with M240 cameras who are noting the same thing. Do you have one? In fact the point with which these other voices seem to agree with me on is not merely that their shots seem better focussed (that in itself could have something to do with the sensor, as other here are speculating) but that it it more consistently accurate across different lenses and from near to far. This is absolutely not in comparison to a knocked-about three year old M9 that I sold months ago, by the way, it is in comparison to several digital Ms I have owned over the past six years, whether when they were brand new, just back from Solms for repair, or whatever.

 

Regarding the 35 FLE: the charts are freely available online, do please look them up. The lens has a curious field curvature pattern. It's predecessor had quite pronounced focus shift, mostly but not entirely cured in the FLE. This was something I first raised on this forum in 2007 (I see that with 43 posts and having joined last year you will not have joined in the fun on that question at the time) and which Leica themselves then confirmed. It is widely felt that the new version was designed to meet the needs of digital M users who were not satisfied with the previous version for this reason.

[jaapv]

When you go to pixel level or beyond on your screen, you'll notice that the focal plane is not a plane, but has a certain thickness, so the zone of sensor sharpness is visible. Undoubtedly due to the physical size of the pixels. I call that the "native DOF" of the sensor (no idea if this term is acceptable;)) Can you see a difference in the "nDOF" of the M9 and the M?

I take your point, but an out of focus image projected by the lens onto the top of the microlenses is not suddenly going to come in to focus. The detail is lost by the initial lack of focus.

 

I think deciding where, exactly, the effective focal plane is must be quite a challenge and I believe that they changed their minds from the earliest M8's. Both of my M8U's, originally very early cameras, came back with the focussing transformed after upgrade.

 

There is someting about the M rangefinder which makes it easier to use; I don't have my M back yet and I am leaving on a trip so it will be a while before I find out, but I wonder whether the rangefinder patch is brighter or something like that.

 

Certainly, when I compared rangefinder focussing and then switched across the Live View, the focussing was spot on - in a thread of a couple of months ago, I wondered how people would feel about the RF being out of step with Live View which, given my experience of the M8 and M9, seemed inevitable. Somehow, it appears not to be the case. Which is good news.