Leica Elmar-M 3.8/24mm ASPH., part 2 (December 19, 2008)
Introduction
The analysis of the wide-angle lenses requires a film-loading M-camera. That is for the moment the only way to test the capabilities of the lens at its full angle of view. The published MTF graphs and additional info do help in getting insight into the inherent performance of the lens. You need some experience to relate the performance parameters to actual imagery. There is also the danger that too much attention is given to small differences in the published data. For a given lens the contrast at 40 lp/mm could be 45% and for another lens it could be 53%. The difference in measured value is hardly visible in practical use.
For the current tests I employed ISO100 BW films from Ilford and Kodak (Delta100 and T-Max100), developed in CG-512. This developer gives excellent sharpness and very fie grain. The negatives need to be scanned with my Nikon Coolscan 5000 and the Nikon is notorious for exaggerating the grain clumps in the negative. The finer the grain, the better the quality of the scan.
24 is 24?
The angle of view of the Elmarit is visibly wider than that of the Elmar 24mm. The magnification of the Elmar is somewhat greater as will be visible in the comparison pictures below. Strictly speaking, the Elmar is closer to 25mm and if you would be very rigorous, a direct comparison has to be done with some reservation.
Below left the edge of the Elmar, right of the Elmarit.
Vignetting
Both lenses have the same amount of light fall off: close to two stops in the extreme corners. This does seem to be a large amount. Remember, if you will, the fact that a negative is developed to a CI value of 0.55 or 0.65 for most enlargers. A full stop difference in the scene is rendered on the negative with a 50% difference in density, or effectively one stop. Depending on the brightness distribution of the scene, the fall off in density is more or less visible. Film is in this respect more accommodating than the solid state sensor. The visibility of vignetting depends in addition on the over- or underexposure of the scene. The distance of the camera to the scene is another factor. The closer you are, the more visible the fall off.
Based on the graphs, the Elmarit at 2.8 is almost as good as the Elmar at 3.8, but at 5.6 both are equal. In practical use, I could not detect occurrences of vignetting that became bothersome. In most pictures made wide open, the vignetting is negligible.
Definition
This is the main characteristic of a photographic lens. According to the MTF graphs, we may expect that the edge and corner performance of the Elmarit is slightly less good than the Elmar. Do we recognize it in actual photographs?
I took pictures of a building that exhibits the range of textures from very fine to major outlines. Really fine detail can be seen in the textural details of the stones of the wall.
The Elmarit 24mm hardly improves on stopping down in definition when we look at the large central portion of the negative. Photographs taken at 2.8, 4, 5.6 and 8 show a visible improvement in contrast of very small details. At normal enlargements up to A4 this difference might not be discernable. Left: Elmarit at 2.8, right Elmarit at 5.6
At the extreme corners we do indeed see a quite visible softness wide open, compared with the same picture at 1:5.6. Note that fine detail is still resolved at 1: 2.8, but contrast is quite low. At 1:5.6 very fine detail becomes visible, that is absent at full aperture.
Elmarit at 2.8 below
Elmarit at 5.6 below
The Elmar 24mm offers identical quality in the central portion of the negative. At 1:3.8 the picture is not different from the Elmarit picture at 1:4.
At the extreme corners the Elmar wide open (1:3.8) is as good as at 1:5.6 (bar a faint increase in contrast and crispness).
Elmar at 3.8 below
Elmar at 5.6 below
The claim that the Elmar presents a very homogeneous quality over the whole negative area and t all apertures has been borne out.
A comparison of the performance of the Elmarit and Elmar at 1:4 and at the edge of the negative shows a very small difference in better crispness and contrast for the Elmar, but not very impressive. But there is a small improvement!
Flare
A comparison at 1:4 for both lenses shows that flare is well suppressed. There are no secondary reflections to speak of and subject detail is preserved even in areas of a strong light source. In the shadow areas the Elmarit has a small edge where contrast is concerned. Given the large front lens the propensity to flare is very low.
Below: Elmarit at 1:4
Below Elmar at 1:4
Bo-ke(h)
A dangerous subject! There are so many variables to take account of (distance of main subject to background, distance of camera to subject, aperture used, type and direction of light and so on). In the pictures used here, I have looked at the unsharpness representation of branches of trees and foliage. Both lenses (at 1:4) show almost identical qualities here. The background is smoothly unsharp und does not show any harsh or double outlines.
Below: Elmar at 1:4
Below Elmarit at 1:4
Conclusion
The Elmar-M 1:3.8/24mm ASPH. represents outstanding value for money and shows a very high level of performance. There is hardly a discipline where the Elmar does not bring top results. The size is extremely comfortable for snapshot use. The demanding and discerning user gets all the performance that can be required for exhibition type pictures of a very high calibre.
The Elmarit-M 1:2.8/24mm ASPH. does deliver the same high quality and offers a full stop advantage in speed. The size is comparatively speaking quite large, and at the edges of the frame the performance is slightly lower than that offered by the Elmar at comparable apertures.
The wide angle of view of a 24mm lens needs mental adjustments by the user to find and exploit pleasing compositions. At closer ranges and stopped down to get sufficient depth of field the Elmar is a very fine lens for powerful snapshots of live events.
The Elmarit can impress with a mechanical quality of the highest order, especially in the silver chrome version. The Elmar has been manufactured with the new Leica standards and equipment. This topic will be discussed after the evaluation of the other new M lenses.