Leica Apo-Summicron-M 2/50 APSH

[lct]

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...I strongly doubt that Leica will come up with a successor to the regular Summicron.

Well the current model is slightly different to the previous tabbed version. I happen to have both of them and the former flares a bit more and is a bit softer at f/2. As long as there is some demand, new coatings might be applied and some novelty may be introduced in the form of a focus tab, a smaller package and/or a more efficient hood i don't know.

[Erik Gunst Lund]

Well the current model is slightly different to the previous tabbed version. I happen to have both of them and the former flares a bit more and is a bit softer at f/2. As long as there is some demand, new coatings might be applied and some novelty may be introduced in the form of a focus tab, a smaller package and/or a more efficient hood i don't know.

 

Yes and I agree these are very likely possibilities...

[IWC Doppel]

Different users have different preferences and styles of course. I have never used any of the Noctilux versions nor the Summilux 75.

I do use my Summilux 50 ASPH and the APO Summicron 75 ASPH more than my other lenses by quite a margin. I do not routinely use them wide open but the 75 just works fine for me at f/2 when I want.

Thoughtful in BW photo - Geoff Hopkinson photos at pbase.com

 

I've never experienced any imprecision nor difficulty with the focus on my 75 in the manner that I use it. I just checked and I have shot about 2,500 frames with mine. My Summilux 50 ASPH has had to be recalibrated but is now behaving impeccably again.

 

I'm bemused when I read such firm statements describing design deficiencies in the new APO 50 Summicron ASPH when it is of course still in extremely limited use and supply.

 

Peter Karbe and his team have designed a state of the art benchmark lens from what I understand. Pretty bold to suggest that he got it wrong, most especially when there cannot be more than a handful of people worldwide with significant experience with it in use.

 

Very nice shot, I didn't realise what a nice lens the 75 F2 was

[insomnia]

Very nice shot, I didn't realise what a nice lens the 75 F2 was

 

You know that Mozart and Piano joke, right?

[Erik Gunst Lund]

Yes it is hard to see probably more... 95 deg?

But definitely much less than the latest 50 Summicron

Edit Post #15 above has a nice image that shows the throw

 

I just checked my 50 Summicron latest version and it has 120 deg focus throw...

[hoppyman]

Huh!? Where has such a suggestion been made?

I was referring to your comments such as

........................................................................

The bad points of this lens are the focusing throw (which is way too short to support quick and accurate focusing) and the stupid built-in hood (which is nicely executed but way too short to be useful).

 

Optical performance, of course, is just excellent ... provided you get it focused at where you intended to.

....................................................................

In the context of your remarks about the APO Summicron 75 ASPH I can understand your preference. My experience with that one is very different.

 

For this new one I think it's premature to form any conclusions. The design team clearly disagrees with your preference though.

[Rick]

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I would like to put forth the idea that the 50mm/f1.4 Summilux is the predecessor of the 50mm APO.

 

Peter Karbe started working on the design of the 50mm Summicron APO in 1997. His design of the 50 APO Summicron was a departure from the standard Double-Gauss design utilizing 6 elements and no aspheric surfaces - utilized in the current of the day Mandler designs.

 

Karbe's new Summicron 50 APO is an eight lens system with one aspheric surface and a floating group.

 

The current 50 Summilux FLE (III) was derived from this design and was first delivered in 2003-2004. It is also an eight element, one aspherical surface, with a floating group and was the first lens to employ a FLE to improve near focus error. Its chromatic correction values were not considered by Leica to receive the APO designation. If, you look at the lens diagrams of these two lenses you will see the resemblance is close to exact.

 

Semantics aside, the current 50 Summilux came before the 50 Summicron APO and although it was a design inspired by the then current work by Peter Karbe on the 50 Summicron APO, it certainly seems like the closest candidate based on design to be the predecessor of the 50 Summicron APO.

[Michael Geschlecht]

Hello Everybody,

 

I think that the chart that lct made (Post #35 - This Thread has moved quickly in just one day.) is very nice & I'm sure it represents a lot of work on lct's part.

 

Thank you lct.

 

The only thing is I don't understand it.

 

For me a chart comparing something is more understandable if all things in it compare the same thing. For example: "closest focussing distance" is not a standard "thing" for all lenses. Not even for all lenses of the same focal length.

 

Also, I can't figure out where the reference point for "infinity" is on the circle.

 

If it is not too much bother could lct or someone else revise the chart with infinity at the top showing on the circle the number of degrees of rotation necessay to focus the lenses to a standardized distance of one (1) meter.

 

For example: With the 35mm F2.8 Summaron (M3 version) mentioned that would be a rotation of 90 degrees.

 

Also: How much does the difference in eye relief digital/film matter in terms of focussing accuracy film/digital? Especially when coupled with an approximately 6% (.68/.72) reduction in image magnification. Is this combination of different eye relief & reduced magnification that quantatative change which becomes qualatative? The straws that broke the camel's back?

 

I ask these questions because no one I know complains about focussing a 135mm lens WITHOUT goggles on a .91X, M3. That might be why Leitz cut the focus throw almost in half when the Tele-Elmar replaced the second 135mm Elmar in 1965. With the earlier lens focussing was even easier & this ease in focus might contribute to the 1960 vintage Elmar's reputation of being sharp as a tack.

 

I wonder how much sharper a Tele-Elmar would be if it had the focussing throw of a 135mm Elmar?

 

Best Regards,

 

Michael

[lct]

I'm sure you can make a better chart. Show me your skills my friend.

[lct]

...With the 35mm F2.8 Summaron (M3 version) mentioned that would be a rotation of 90 degrees...

Much more than this with mine.

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[Michael Geschlecht]

Hello lct,

 

Thank you for writing.

 

Unlike most people here: I have limited ability with a computer. I am self taught & even with the help of people on this Forum & elsewhere: Basically I can just write.

 

As to re-doing the chart: I asked that the degree of rotation be shown to focus at one (1) meter.

 

With infinity marked on the diagram.

 

For the M3 version of the 35mm Summaron that is 90 degrees.

 

Even though the lens can focus somewhat closer.

 

For me the number of degrees of rotation to get to the same distance is more useful than measuring to a minimum distance that varies.

 

Best Regards,

 

Michael

[lct]

Hi Michael. My skills are not much better than yours i'm afraid so the best i can do is to refrain from asking royalties to those who would wish to improve my chart.

[pgk]

To increase focusing precision control I am sure that it is possible to find a 'focus lever' which can be fitted to M lenses. Whilst lct's 'chart' does show differences in focus throw, I still remain skeptical that there is sufficient variation to cause real world problems on a 50/2 M lens.

[wizard]

Well the current model is slightly different to the previous tabbed version. I happen to have both of them and the former flares a bit more and is a bit softer at f/2. As long as there is some demand, new coatings might be applied and some novelty may be introduced in the form of a focus tab, a smaller package and/or a more efficient hood i don't know.

 

Lct, I fully agree with what you say, but I believe changes of this type would not be enough to speak of a new version of that lens. Mind you, there seems to be consensus in the Leica world that the still current optical computation of the regular Summicron 50 is called version IV, and that version IV includes the earlier tabbed/separate lenshood version as well as the current non-tabbed, built-in lenshood version.

 

 

...Also, I can't figure out where the reference point for "infinity" is on the circle....

 

Michael, lct took the minimum focusing distance position of each lens as the reference point, so his representation gives an information on the absolute amount of focus throw. With just a few exceptions, the minimum focusing distance of the specified lenses are the same, namely 0.7m, so the results give a good indication for comparison. Scientifically, you are correct in that you would have to compare the focus throw of each lens concerned starting at e.g. infinity (or, alternatively, at any given distance setting, e.g. 1m) and measuring up to a predetermined setting, say, 1m (or measure up from there to infinity).

 

Andy

[lct]

To increase focusing precision control I am sure that it is possible to find a 'focus lever' which can be fitted to M lenses. Whilst lct's 'chart' does show differences in focus throw, I still remain skeptical that there is sufficient variation to cause real world problems on a 50/2 M lens.

90° sounds very small though. I asked if the 50/2 apo's focus throw is the same as that of the Summarit 35/2.5 but i haven't got any answer so far. I would guess that it is not significantly smaller than that of the tabbed 50/2 v4 (pic) but i may be wrong.

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[Michael Geschlecht]

Hello Paul, et al,

 

Let me try to give an example with lct's chart to explain why relative ease of focus is somewhat unclear:

 

The 35mm Summaron (M3) rotates substantially further on the chart than the 35mm Summilux.

 

But: The 35mm Summaron (M3) is rotating to focus to 65 centimeters while the 35mm Summilux is rotating to focus to 100 centimeters.

 

I know the 35mm Summaron rotates 90 degrees to go from infinity to 100 centimeters.

 

The minimum focus of a 35mm Summilux is 100 centimeters.

 

It appears from the chart that the 35mm Summilux has a LONGER focus throw TO GET TO TO THE SAME GIVEN POINT of one (1) meter.

 

But: We don;t know that for sure because:

 

There is no standardized infinity point shown.

 

There is no standard distance (ie: one (1) meter) that all lenses of all focal lengths are focussed to.

 

Separate thought:

 

Focussing tabs or knurled scallops (dependent on lens ) are a good idea. A nice example of useful knurled scallops is the second mechanical variety of the rigid bayonet mount 50mm Summicron (Not DR).

 

Best Regards,

 

Michael

[pgk]

When all is said and done with an M lens, the angular rotation of the focusing control has to equate to a movement in the focus cam. So a shorter throw lens presumably requires a steeper angled focus cam to translate the rotation into movement of the RF roller.

 

My assumption (ok assumptions can be dangerous things I know) is that Leica have sufficient experience in building lens cams, to determine the viable accuracy of the focus ring rotation to cam movement transfer to ensure that accurate focus can be achieved by the camera user.

 

As I've commented earlier, discrepancies in eyesight, judgement, subject contrast/viability, and more come into play, but I doubt very much if the design of any Leica M lens is such that its accuracy is not within the tolerance Leica consider to be acceptable (I've not come across any data which defines this, has anyone else?).

 

There are of course exceptions - 135/2.8 and 75/1.4 are probably on the edge of modern high MPixel bodies, and I'm sure that this has been discussed here in the past.

[Erik Gunst Lund]

The diameter of the focus ring also has an rather large impact on this.

[lct]

...I know the 35mm Summaron rotates 90 degrees to go from infinity to 100 centimeters.

The minimum focus of a 35mm Summilux is 100 centimeters.

It appears from the chart that the 35mm Summilux has a LONGER focus throw TO GET TO TO THE SAME GIVEN POINT of one (1) meter...

Michael, my graph shows only the (approximate) focus throws between the actual minimum focus distances and the actual infinity markings of the lenses, that's all. Now among the lenses i've listed, there are only two with a 1m minimum focus distance. One has a short focus throw (35/1.4 v3) and the other a very long one (50/2.8 v1). BTW the 35/1.4 v3 has not a longer but a (slightly) shorter focus throw than the 35/2.8 to go from 1m to infinity.

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Hallo,

Look here: Leica M

[hhanebeck]

Michael, my graph shows only the (approximate) focus throws between the actual minimum focus distances and the actual infinity markings of the lenses, that's all. Now among the lenses i've listed, there are only two with a 1m minimum focus distance. One has a short focus throw (35/1.4 v3) and the other a very long one (50/2.8 v1). BTW the 35/1.4 v3 has not a longer but a (slightly) shorter focus throw than the 35/2.8 to go from 1m to infinity.

 

Hi lct,

 

Thanks a lot for the interesting chart! I have borrowed it from you to take a look at some of the current lenses in comparison to the 50 APO. Measurements may be slightly off since I have done it all by hand.

 

Cheers, Chris

 

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