Along w/ compensating for other abberations a designer will reduce the maximum F stop (resolution) of a lens to the point where the resultant increasing contrast combined w/ the remaining resolution produces the best balance of image.

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"After 1960 new glasses with high refractive indices became available. The classical glass catalogue was filled with what we now call the “old glass types”, essentially developed by Ernst Abbe. As these glasses had low refractive indices, one had to bend the lens elements quite strongly to get the type of correction needed. But such curved glass is sensitive to manufacturing tolerances and one could not accomplish all. So the search for new glasses started with the additions of rare earth elements."

The RAS is rugged, safe and reliable. With no moving parts, it is virtually maintenance free, and should offer years of trouble free operation.

A lens w/ a larger F stop will resolve more information than the same lens w/ a smaller F stop all else being equal. A lens w/ a smaller F stop will exhibit a higher degree of contrast than the same lens w/ a larger F stop all else being equal.

Leica glass lab which was closed round 1995, developed special glasses that made possible the 1.0 Noct and 75 1.4. The Leica rep showed me a 1" cube of that stuff that was a reject. It weighed like it was solid lead.

We sell a wide range of heating elements to fit our reflectors including a variety ceramic, quartz, quartz halogen and quartz tungsten emitters. Visit our heating elements page to view more.

The RAS is rugged, safe and reliable. With no moving parts, it is virtually maintenance free, and should offer years of trouble free operation.

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"After 1960 new glasses with high refractive indices became available. The classical glass catalogue was filled with what we now call the “old glass types”, essentially developed by Ernst Abbe. As these glasses had low refractive indices, one had to bend the lens elements quite strongly to get the type of correction needed. But such curved glass is sensitive to manufacturing tolerances and one could not accomplish all. So the search for new glasses started with the additions of rare earth elements."

The RAS is rugged, safe and reliable. With no moving parts, it is virtually maintenance free, and should offer years of trouble free operation.

According to Erwin Puts it is incorrect to assume contrast and resolution are opposing parameters. In general the lens with more resolution will exhibit more contrast.

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This polished aluminized steel reflector features a highly reflective casing, to maximize heat output. The units can be mounted individually or side-by-side to form IR panels.

At a distance of 10 meter a resolution test chart was mounted on a wall and the image produced by the Summilux was photographed with a Leitz Photar 12.5/2.4 at f/2.4 with a bellows extension of 220 mm. This creates an enlargement of the image plane of the Summilux of 17 times in the final image of the capturing camera.

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Erwin Puts has written a great deal of detailed information on this topic. Suffice it to say that there is more to it than meets the eye, and that Leitz has made very crafty decisions in lens design over the decades, favoring simpler designs with higher-index glasses that have fewer elements and elements with gentler curves.

The RAS is rugged, safe and reliable. With no moving parts, it is virtually maintenance free, and should offer years of trouble free operation.

The RAS is rugged, safe and reliable. With no moving parts, it is virtually maintenance free, and should offer years of trouble free operation.

I don't mean to quibble, but the color of the target might be diminishing the potential resolution due to its long wave.

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This polished aluminized steel reflector features a highly reflective casing, to maximize heat output. The units can be mounted individually or side-by-side to form IR panels.

This polished aluminized steel reflector features a highly reflective casing, to maximize heat output. The units can be mounted individually or side-by-side to form IR panels.

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Michael, you are equating F-stop with resolution: the larger the opening, the higher the resolution, you state. That is true if the lens is diffraction limited at its widest aperture. For a perfect lens, the physics of the opening determines the resolution because of the, not the optics. But if the lens is perfect, there are no other aberrations and therefore contrast is also high.

Early on, design compromises were necessary that could be simplistically reduced to 'contrast vs resolution' (more elements reduced contrast but allowed more corrections), but it is more complex than that. Even with the latest glasses and anti-reflection coatings, compromises still are necessary, but they are very much less crude.

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IRRepeater

In principle you are right that long wavelengths reduce resolution. Thanks. But this was illuminated by a halogen lamp with lots of medium wavelength in it and the diffraction limit at f/1.4 is 1065 linepairs per mm (Rayleigh criterium) for green. The statement from my measurement is that the Summilux 50/1.4 asph resolves at least 500 linepairs per mm and that is still valid.

This polished aluminized steel reflector features a highly reflective casing, to maximize heat output. The units can be mounted individually or side-by-side to form IR panels.

In the real world contrast and resolution are not necessarily coupled. "contrast" refers to high modulation at the medium and lower frequencies, while "resolution" is to have at least some modulation at the very high spatial frequencies.

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The RAS is rugged, safe and reliable. With no moving parts, it is virtually maintenance free, and should offer years of trouble free operation.

This polished aluminized steel reflector features a highly reflective casing, to maximize heat output. The units can be mounted individually or side-by-side to form IR panels.

IR reflectordot

Early on, design compromises were necessary that could be simplistically reduced to 'contrast vs resolution' (more elements reduced contrast but allowed more corrections), but it is more complex than that. Even with the latest glasses and anti-reflection coatings, compromises still are necessary, but they are very much less crude.

Although this study has little relevance for photography with an M9, it does show that a very contrasty Leica lens like the Summilux 50/1.4 asph can have very high resolution, even at its full opening.

I've shot targets with my Summilux as well for a review, but I can say quite safely just by taking pictures with it - it's an amazing lens regardless of adjectives. It's sharp, contrasty, has a high resolution, etc. They're all in there.

Our heat reflectors are designed to cater to a wide range of Ceramic and Quartz infrared emitters. This aluminumized steel (or stainless steel by special request) heat reflector features a highly reflective casing to maximize heat output. The units can be mounted individually or side-by-side to form IR panels. The RAS can efficiently heat a defined area within a large space or can totally heat either large or small areas alike.

Below the result: The Summilux reaches a resolution of at least 500 linepairs per mm. at f/1.4, which is 6.5 times more than the M9 sensor can resolve.

This polished aluminized steel reflector features a highly reflective casing, to maximize heat output. The units can be mounted individually or side-by-side to form IR panels.

One could wonder if (modern) Leica lenses would be optimized for contrast, if that would compromise resolution. To show that a good lens can satisfy both, the following experiment has been done with a Summilux 50/1.4 ASPH at f/1.4. The lens was mounted on an M6 of which the backdoor was opened and the shutter fixed to open.

According to Leslie Stroebel (View Camera Technique, Focal Press, page 116, figure 5-40), they are not necessarily couple, see here. A, B and C are different lenses with different design.

I was already wondering what ‘contrast versus resolution’ was supposed to mean, given that the resolution of a lens is commonly measured and expressed as the contrast delivered at certain spatial frequencies. So what you really referred to was ‘contrast at low and medium spatial frequencies versus contrast at high spatial frequencies’. And yes, quite obviously you can have both.

Erwin Puts has written a great deal of detailed information on this topic. Suffice it to say that there is more to it than meets the eye, and that Leitz has made very crafty decisions in lens design over the decades, favoring simpler designs with higher-index glasses that have fewer elements and elements with gentler curves.