Which 50mm?
Summicron-M (“type 5”)
C Sonnar (focus optimized for f/2.8)
Classic Heliar f/2
Classic Heliar f/3.5
I decided to compare my four 50mm lenses. I wanted to become more familiar with their individual characteristics. I have read about how a lens draws, and about the "glow" of some lenses. Of course, I also expected to see some of that Leica magic from my Leica Summicron.
I decided that I would not mark a lens down for focus shift or curvature of field because I can learn to compensate for those if I really like the way the lens draws. I would evaluate each lens based upon the realism and clarity of whatever part of the image was in best focus. I checked the images from each lens at f/1.5 (C Sonnar), f/2.0 and f/2.8 ( C- Sonnar, Summicron, f2.0 Classic Heliar), f/4.0 and f/5.6 and f/8.0 (C Sonnar, Summicron, both Classic Heliars).
I set up my tripod about 2 meters from a flower arrangement on my front porch that has indirect northern light. I focused each lens on the same middle flower as carefully as I could with a 1.25 magnifier. The size of the flower arrangement gave enough object field for some part to be in crisp focus. I kept the exposure constant by varying shutter speed as I ran through each lens's range of apertures.
I examined the images from the RAW files for overall impression and at 100% for details.
For each aperture range, the lens producing my favorite image was given a score of 4; next best, a score of 3; so on down to 1. If a lens did not produce any image at a given aperture it was given a score of zero. Spreadsheets and totals and over-all rankings ensued.
Because my first results surprised me, I repeated this test three more times. One of the four repetitions was indoors, photographing the field of clutter on my work-table at about a 2 meter distance. All of my repetitions produced the same rankings.
I think other people would rank these lenses differently. My approach in these comparisons was entirely subjective. Publishing my number scores for these lenses would be useless and potentially contentious.
My conclusions:
1. Focus is much more critical than lens selection. Apparently it is easy to mis-focus any of these lenses within an inch or so at a 2 meter object distance. At apertures of f/2.8 and wider the exact focus point affects an image more than any other factor. Each lens produces an excellent image of something, but not always what I tried to focus on with the rangefinder. Among my four repetitions there were no consistent mis-focus results (other than the well-known front focus of the C Sonnar) from which I could suspect serious mis-calibration of my equipment.
2. These are four excellent lenses. None of them disappoint in any way. The differences are extremely slight. My preference goes to an ability to give a 3-D impression in the image. This seems to have something to do with the transitions of resolution and contrast from in-focus to out-of-focus.
3. When I can use it, the f/3.5 Classic Heliar is the winner. This has prompted me to order that rare 27mm IR blocking filter for it.
4. The f/2.0 Classic Heliar draws nearly identically and gives more aperture range.
5. It is not wise for me to use f/1.5 on my M8.2 because the depth of field is so shallow that accurate focus is almost by chance. For low light, I stick to f/2 and slightly higher ISO. I find that f/2.8 does a beautiful job of isolating subjects for my purposes. So f/1.5, for me, is very rare, special purpose and used with plenty of focus bracketing.
50mm Photography 2013:
As a result of these tests, the 50mm Summicron has spent most of 2013 in its case on my shelf. I have no intention of abandoning it. The Summicron is a spectacularly fine lens. I merely wanted to become more familiar with my other lenses. I have primarily used the C Sonnar and f/2 Classic Heliar for my 50mm shots, which are my most numerous. I like the handling of both the C Sonnar and the f/2 Classic Heliar. Both of them focus easily with a nice “feel.” Both of these lenses have produced bad images when I goof, excellent images when I do things right, and great images occasionally (because I am not a great photographer). Neither lens has produced an image which prompted me to think, “I wish had used the Summicron on this shot.”
Summicron-M (“type 5”)
C Sonnar (focus optimized for f/2.8)
Classic Heliar f/2
Classic Heliar f/3.5
I decided to compare my four 50mm lenses. I wanted to become more familiar with their individual characteristics. I have read about how a lens draws, and about the "glow" of some lenses. Of course, I also expected to see some of that Leica magic from my Leica Summicron.
I decided that I would not mark a lens down for focus shift or curvature of field because I can learn to compensate for those if I really like the way the lens draws. I would evaluate each lens based upon the realism and clarity of whatever part of the image was in best focus. I checked the images from each lens at f/1.5 (C Sonnar), f/2.0 and f/2.8 ( C- Sonnar, Summicron, f2.0 Classic Heliar), f/4.0 and f/5.6 and f/8.0 (C Sonnar, Summicron, both Classic Heliars).
I set up my tripod about 2 meters from a flower arrangement on my front porch that has indirect northern light. I focused each lens on the same middle flower as carefully as I could with a 1.25 magnifier. The size of the flower arrangement gave enough object field for some part to be in crisp focus. I kept the exposure constant by varying shutter speed as I ran through each lens's range of apertures.
I examined the images from the RAW files for overall impression and at 100% for details.
For each aperture range, the lens producing my favorite image was given a score of 4; next best, a score of 3; so on down to 1. If a lens did not produce any image at a given aperture it was given a score of zero. Spreadsheets and totals and over-all rankings ensued.
Because my first results surprised me, I repeated this test three more times. One of the four repetitions was indoors, photographing the field of clutter on my work-table at about a 2 meter distance. All of my repetitions produced the same rankings.
I think other people would rank these lenses differently. My approach in these comparisons was entirely subjective. Publishing my number scores for these lenses would be useless and potentially contentious.
My conclusions:
1. Focus is much more critical than lens selection. Apparently it is easy to mis-focus any of these lenses within an inch or so at a 2 meter object distance. At apertures of f/2.8 and wider the exact focus point affects an image more than any other factor. Each lens produces an excellent image of something, but not always what I tried to focus on with the rangefinder. Among my four repetitions there were no consistent mis-focus results (other than the well-known front focus of the C Sonnar) from which I could suspect serious mis-calibration of my equipment.
2. These are four excellent lenses. None of them disappoint in any way. The differences are extremely slight. My preference goes to an ability to give a 3-D impression in the image. This seems to have something to do with the transitions of resolution and contrast from in-focus to out-of-focus.
3. When I can use it, the f/3.5 Classic Heliar is the winner. This has prompted me to order that rare 27mm IR blocking filter for it.
4. The f/2.0 Classic Heliar draws nearly identically and gives more aperture range.
5. It is not wise for me to use f/1.5 on my M8.2 because the depth of field is so shallow that accurate focus is almost by chance. For low light, I stick to f/2 and slightly higher ISO. I find that f/2.8 does a beautiful job of isolating subjects for my purposes. So f/1.5, for me, is very rare, special purpose and used with plenty of focus bracketing.
50mm Photography 2013:
As a result of these tests, the 50mm Summicron has spent most of 2013 in its case on my shelf. I have no intention of abandoning it. The Summicron is a spectacularly fine lens. I merely wanted to become more familiar with my other lenses. I have primarily used the C Sonnar and f/2 Classic Heliar for my 50mm shots, which are my most numerous. I like the handling of both the C Sonnar and the f/2 Classic Heliar. Both of them focus easily with a nice “feel.” Both of these lenses have produced bad images when I goof, excellent images when I do things right, and great images occasionally (because I am not a great photographer). Neither lens has produced an image which prompted me to think, “I wish had used the Summicron on this shot.”
