Lens performance diagrams

[Susie]

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Hi All,

 

I have recently got a copy of Dennis Laney's book on Leica Lens Practice.  In it are some interesting Leitz produced 'box' diagrams showing lens performance data.  Does anyone know if diagrams of more lenses were made available, and if so, where?

 

Thanks,

 

Susie

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[a.noctilux]

Hello Susie,

 

If you mean "Edge Spread Width" in the Part II of his book, I have never seen elsewhere something like that.

In pages 136-137, the "boxes" are very interesting when comparing 50mm Summar with Summicron.

In a glance, we can see the sharpness or lack of across the image field.

 

The prefered graphs by now are those MTF published by lens manufacturers, like this link for Summicron-M 2/50:

http://www.summilux.net/m_system/images/Summicron50.pdf

 

At summilux.net site, you could find datas for other Leica lenses.

 

Regards,

 

Arnaud

[Susie]

I agree Arnauld, but I was most interested to see that at full aperture, in the centre of the field, the Summar came out sharper than the Summicron, hence my interest in seeing other diagrams, particularly of older lenses.

 

As Laney states, for the lay person, these 'box' diagrams are much easier to read than MTF graphs

 

Susie

[a.noctilux]

Yes, we can see that the very old Summar is sharper in centre than the Summicron, at full aperture.

With those boxes, I can understand the Summar's rendering that I prefer with my LTM's Leica.

Sharpness is not all that I need in a picture.

Characters count a lot but need to be know how to use those "flaws".

 

Really easy to read as Laney wrote.

[Michael Geschlecht]

Hello Susie,

 

Another interesting pair to compare are the 100mm F4 Elmar & the 100mm F2.8 Elmarit.

 

In the center, at some apertures, the 100mm F4 Elmar is sharper.

 

Probably because Tessar derived designs (!00mm F4) tend to be at their best in the central 1/3d or so of their image angle while Double Gauss designs (100mm F2.8) tend to be more evenly corrected over their entire image field. This is is 1 of the reasons Double Gauss designs are often chosen when designing lenses with wider angles of coverage.

 

Best Regards,

 

Michael

[otho]

[...] As Laney states, for the lay person, these 'box' diagrams are much easier to read than MTF graphs [...]

 

Many MTF's published E. Puts in Leica Compendium, even for some very old lenses, e.g,. Elmax 50mm f/3.5, period: 1920-1921 (Ed. 2011, p. 448).