Introduction  Closeup Lenses  Achromats  Extension Tubes  Combining Extension Tubes and Achromats  Conclusions  Final Word  References
This page presents my practical experiences with closeup shots using closeup lenses or achromats and extension tubes with the Leica M (Typ 240) in live view mode.
See page CloseUp Options (Live View)  Part 3: Practice II for my practical experiences with extension bellows.
See also page CloseUp Options (Live View)  Part 1: Overview for an overview of the options that you have for closeup shots when using the Leica M (Type 240) in live view mode and pages CloseUp Options (Live View)  Part 4: Samples I and CloseUp Options (Live View)  Part 4: Samples II for sample closeup photos with the Leica M (Typ 240).
Note: Page CloseUp Behavior of the MMount Lenses describes the closeup characteristics of the lenses when used without any closeup options.
On page CloseUp Options (Live View)  Part 1: Overview, I mentioned that rangefinder camera are not well suited to closeup photography because of the parallax. With the Leica M (Typ 240), however, this has changed, because Leica added live view to the camera. With respect to closeup/macro photos, in live view mode the M behaves like a system camera (or like a DSLR) and can use all the techniques that these can use: closeup lenses, extension tubes, and extension bellows. On that page, I provide an overview of the options that you have for closeup shots when using the Leica M (Type 240) in live view mode. On this page and another page, I would like to present my practical experiences in this domain, which are, of course, of anecdotic nature.
Because of the length of this page, I prepared two pages for presenting sample closeup photos: CloseUp Options (Live View)  Part 4: Samples I and CloseUp Options (Live View)  Part 5: Samples II.
From dkpeterborough (lcameraforum) I adopt the way how magnification is calculated:
Below, I will use this formula for calculating the achievable magnification under various conditions.
I bought a B+W +5 closeup lens for my Leica X Vario. Therefore, it has a 43 mm filter diameter. The lens fits directly two of my lenses, the Zeiss Biogon 35mm f/2.8 and the Voigtländer Color Heliar 75mm f/2.5. I therefore tested it with these lenses.
I took quickanddirty test shots (see below) to calculate magnification for the following conditions:
The following table summarizes my results for the B+W +5 lens:
Zeiss Biogon 35mm
f/2.8 mm 
Voigtländer
Color Heliar 75mm f/2.5 
B+W +5 

Distance 
Distance 
# Lenses  Diopters  
Infinity  0.7 m (closest)  Infinity  1.0 m (closest)  
172 mm 0.21 = 1:4.8 approx. 1:5 
139 mm 0.26 = 1:3.9 approx: 1:4 
94 mm 0.38 = 1:2.6 approx. 1:2.6 
72 mm 0.5 = 1:2.0 approx. 1:2 
1  +5 
Notes: Minimum object distance taken from the test shots below; maximum object size roughly estimated; magnification ratios calculated from the exact values via inverse function
Below are test shots for illustration that I made with aperture wide open. Please note that they were only made for estimating magnification, not for demonstrating the achievable quality.
Photos: Test shots with Zeiss Biogon 35mm f/2.8 and one +5 BW lens; distance set to infinity (left) or closest distance (right)
The photos show slight to medium pincushion distortion.
Photos: Test shots with Voigtländer Color Heliar 75mm f/2.5 and one +5 BW lens; distance set to infinity (left) or closest distance (right)
The photos show slight pincushion distortion.
With one B+W +5 lens, quite remarkable magnifications can be achieved for lenses with focal lengths from 50 mm and longer. Particularly with the Voigtländer 75 mm lens magnifications in the 1:2 range are possible. The 35 mm lens covers an area of about a postcard.
The pincushion distortion seems to be lower than for the Marumi +5 achromat. Only real world tests will show, whether the resulting quality is indeed acceptable and how the lens compares with the Marumi +5 achromat (on the Leica X Vario, the achromat was slightly better).
Here, I will discuss my Marumi +5 achromats. I mentioned already that these have a filter thread of 52 mm (which is the minimum size for these achromats; Raynox offers smaller filter threads, but I learned about this too late...). Therefore, I bought a Quenox 4352 mm stepup ring for the Leica X Vario and recently also a Quenox 4652 mm stepup ring:
Photos: Marumi +5 achromats with stepup rings and at the camera
These rings can be used on my following lenses.
I took quickanddirty test shots (see below) to calculate magnification for the following conditions:
The following table summarizes my results for the Marumi +5 achromats:
Minolta MRokkor
28mm f/2.8* 
Zeiss Biogon 35mm
f/2.8 
Marumi +5 Achromat  
Distance 
Distance 
# Achrom.  Diopters  
Infinity  0.8 m (closest)  Infinity  0.7 m (closest)  
225 mm 0.16 = 1:6.3 approx. 1:6.5 
176 mm 0.2 = 1:4.9 approx: 1:5 
180 mm 0.2 = 1:5.0 approx. 1:5 
139 mm 0.26 = 1:3.9 approx. 1:4 
1  +5 
110 mm 0.325 = 1:3.1 approx. 1:3 
101 mm 0.35 = 1:2.8 approx. 1:2.8 
90 mm 0.4 = 1:2.5 approx. 1:2.5 
79 mm 0.45 = 1:2.2 approx. 1:2.2 
2  +10 
Zeiss Sonnar 50mm f/1.5 
Voigtländer
Color Heliar 75mm f/2.5 
Marumi +5 Achromat  
Distance 
Distance 
# Achrom.  Diopters  
Infinity  0.9 m (closest)  Infinity  1.0 m (closest)  
130 (132**) mm 0.275 = 1:3.6 approx. 1:3.6 
104 (103**) mm 0.344 = 1:2.9 approx: 1:3 
92 mm 0.39 = 1:2.56 approx. 1:2.5 
72 mm 0.5 = 1:2 approx. 1:2 
1  +5 
67 (68**) mm 0.534 = 1:1.87 approx. 1:2 
58 mm 0.617 = 1:1.6 approx. 1:1.6 
47 mm 0.76 = 1:1.3 approx. 1:1.25 
40 mm 0.895 = 1:1.12 approx. 1:1.1 
2  +10 
Notes: Minimum object distance taken from the test shots below; maximum object size roughly estimated; magnification ratios calculated from the exact values via inverse function
*) With additional 40.543 mm adapter ring; second series of test shots not
used for calculations.
**) Values taken from second series of test shots, not used in calculations.
Below are test shots for illustration that I made with aperture wide open. Please note that they were only made for estimating magnification, not for demonstrating the achievable quality.
Photos: Two sets of Test shots with Zeiss Biogon 21mm f/4.5 and one +5 Marumi achromat (top row) and two Marumi +5 achromats (= +10 diopters); distance set to infinity (left column) or closest distance (right column)
The photos show strong pincushion distortion, strong vignetting for two achromats, and color shading. Therefore, I did not use this lens in the calculations above. I would not use it for real closeup shots with achromats either (except for "special effects").
Photos: Two sets of test shots with Minolta MRokkor 28mm f/2.8 and one +5 Marumi achromat (top row) and two Marumi +5 achromats (= +10 diopters); distance set to infinity (left column) or closest distance (right column)
The photos show strong pincushion distortion and fairly strong vignetting in the original photos (not shown here). Not really useable for me...
Photos: Test shots with Zeiss Biogon 35mm f/2.8 and one +5 Marumi achromat (top row) and two Marumi +5 achromats (= +10 diopters); distance set to infinity (left column) or closest distance (right column)
The photos show strong pincushion distortion. I would not use this lens with achromats for closeup shots.
Photos: Two sets of test shots with Zeiss Sonnar 50mm f/1.5 and one +5 Marumi achromat (top row) and two Marumi +5 achromats (= +10 diopters); distance set to infinity (left column) or closest distance (right column)
Photo: Test shots with Zeiss Sonnar 50mm f/1.5 and two +5 Marumi achromats (= +10 diopters); distance set to closest distance, aperture set to f/5.6
The photos show strong to medium pincushion distortion. Only real world photos can show whether this can be acceptable an certain motifs. The photo taken with an aperture value of f/5.6 shows that stopping down improves image quality dramatically.
Photos: Test shots with Voigtländer Color Heliar 75mm f/2.5 and one +5 Marumi achromat (top row) and two Marumi +5 achromats (= +10 diopters); distance set to infinity (left column) or closest distance (right column)
The photos show strong to medium pincushion distortion. One Marumi achromat provides acceptable quality.
With one or two Marumi +5 achromats, quite remarkable magnifications can be achieved for lenses with focal lengths from 50 mm and longer. Particularly with the Voigtländer 75 mm lens, magnifications in the 1:2 range are possible, and one can even come close to 1:1 with two +5 achromats and this lens. Wide lenses not only show much lower magnifications, they also show strong vignetting, particularly when two achromats are being used. Other achromats may lead to better results, but the low magnification rules out wide angle lenses, anyway.
The strong pincushion distortion exhibited by all lenses is annoying. It seems to be a little bit lower, when distance is set to the closest possible value. Only real world tests will show, whether the resulting quality is indeed acceptable for certain motifs. I did some preliminary tests with small flowers and found these to be acceptable (I did that before these tests and thus, did not know of the distortions).
I ordered a Quenox Extension Tube for Leica M (replaces the "extinct" Leica OUFRO) to get a smaller focusing distance for my Mmount lenses, particularly, for the Zeiss Sonnar 50mm f/1.5 lens.
Photos: Quenox Extension Tube for Leica M  alone and attached to the camera (bottom row; with Zeiss Sonnar 50mm f/1.5 to the right)
I find the Quenox Extension Tube for Leica M a bit disappointing. It looks a bit roughly made and does not work as smoothly as expected. It is not "a joy to use"  at least, not for me. Maybe, some practice with it will help...
I took quickanddirty test shots to calculate magnification for the following conditions:
*) I performed two tests with the Zeiss Sonnar lens: a first preliminary test, and then a second test with many lenses, in which it was also included. Both tests lead to the same results.
The following table summarizes my results for the Quenox Extension Tube:
Lens > 
Zeiss Biogon 21mm
f/4.5 
Leica ElmaritM
21mm f/2.8 

Distance > 
Infinity  0.8 m (closest)  Infinity  0.7 m (closest) 
Quenox Extension Tube for Leica M 
76 mm > 0.47 = 1:2.1 approx. 1:2.1 
70 mm > 0.51 = 1:1.96 approx: 1:2 
80 mm > 0.45 = 1:2.3 approx. 1:2.3 
72 mm > 0.50 = 1:2.0 approx: 1:2 
Lens > 
Leica ElmarM
24mm f/3.8 
Voigtländer
SnapshotSkopar 25mm f/4 

Distance > 
Infinity  0.8 m (closest)  Infinity  0.7 m (closest) 
Quenox Extension Tube for Leica M 
85 mm > 0.42 = 1:2.4 approx. 1:2.4 
77 mm > 0.47 = 1:2.15 approx: 1:2.2 
89 mm > 0.4 = 1:2.5 approx. 1:2.5 
82 mm > 0.44 = 1:2.3 approx: 1:2.3 
Lens > 
Minolta MRokkor
28mm f/2.8 
Zeiss Biogon 35mm
f/2.8 

Distance > 
Infinity  0.8 m (closest)  Infinity  0.7 m (closest) 
Quenox Extension Tube for Leica M 
103 mm > 0.35 = 1:2.9 approx. 1:3 
93 mm > 0.385 = 1:2.6 approx.1:2.5 
125 mm > 0.29 = 1:3.5 approx. 1:3.5 
101 mm > 0.35 = 1:2.8 approx: 1:3 
Lens > 
Zeiss Sonnar 50mm
f/1.5 
Voigtländer
Color Heliar 75mm f/2.5 

Distance > 
Infinity  0.9 m (closest)  Infinity  1.0 m (closest) 
Quenox Extension Tube for Leica M 
180 mm > 0.2 = 1:5 approx. 1:5* 
137 mm > 0.26 = 1:3.8 approx: 1:4* 
263 mm > 0.14 = 1:7.3 approx. 1:7 
158 mm > 0.23 = 1:4.4 approx: 1:4.5 
Lens > 
Leitz ElmarC
90mm f/4 
Leitz TeleElmar
135mm f/4 

Distance > 
Infinity  1.0 m (closest)  Infinity  1.5 m (closest) 
Quenox Extension Tube for Leica M 
303 mm > 0.12 = 1:8.5 approx. 1:8.5 
154 mm > 0.23 = 1:4.3 approx: 1:4.5 
482 mm > 0.07 = 1:13.5 approx. 1:13.5 
183 mm > 0.20 = 1:5.1 approx: 1:5 
Notes: Minimum object distance taken from the test shots below; maximum object size roughly estimated; magnification ratios calculated from the exact values via inverse function
*) I performed two tests with the Zeiss Sonnar lens: a first preliminary test, and then a second test with many lenses, where it was also included. Both tests led to the same results.
Note: The data also apply to the no longer available Leica OUFRO / Leitz 16469Y, which the Quenox Extension Tube replaces.
Below are test shots for illustration that I made with aperture wide open (except for the ElmaritM and ElmarM). Please note that they were only made for estimating magnification, not for demonstrating the achievable quality.
Photos: Test shots with Zeiss Biogon 21mm f/4.5 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Photos: Test shots with Leica ElmaritM 21mm f/2.8 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Photos: Test shots with Leica ElmarM 24mm f/3.8 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Photos: Test shots with Voigtländer Snapshot Skopar 25mm f/4 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Photos: Test shots with Minolta MRokkor 28mm f/2.8 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Photos: Test shots with Zeiss Biogon 35mm f/2.8 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Photos: Test shots with Zeiss Sonnar 50mm f/1.5 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right); first test in top row, second test in bottom row
I performed two tests with the Zeiss Sonnar lens: a first preliminary test (photos in top row), and then a second test with many lenses, where it was also included (photos in bottom row). Both tests led to the same results.
Photos: Test shots with Voigtländer Color Heliar 75mm f/2.5 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Photos: Test shots with Leitz ElmarC 90mm f/4 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
Note: The Leitz TeleElmarit 90mm f/2.8 should deliver similar results (not tested yet)
Photos: Test shots with Leitz TeleElmar 135mm f/4 and Quenox Extension Tube for Leica M; distance set to infinity (left) or closest distance (right)
The test demonstrates for the Quenox Extension Tube: the shorter the focal length, the greater the magnification, both when distance is set to infinity, as well as to the shortest possible value (where magnification is larger).
The three telephoto lenses (75 mm, 90 mm, 135 mm) should be used together with the extension tube only when distance is set to the closest value. Then all of them capture more or less an object of the size of a postcard (or a little bit more...). This may suffice, for example, for larger flowers.
The standard lens (50 mm) is in the "middle of nowhere", and delivers fuzzy (or hazy) images wide open. But this should improve when the lens is stopped down. Magnification is lower with the extension tube than for the Marumi +5 achromat, but distortion is also lower.
The two medium wide lenses (28 mm and 35 mm) achieve more magnification than the longer lenses, with an edge for the shorter Minolta lens. Maximum object width is in the range of about 10 cm for them. Still not earthshaking, but useful for flowers.
The wide lenses (25 mm, 24 mm, and 21 mm) finally come close to the "1:2 realm," but you have also to get fairly close to the object. I am not sure whether this is practical in real photo practice...
I did not test my widest lens (15 mm) because you have to get very close to the object with it. I prefer lenses where you can stay farther away from objects so that they are less disturbed.
While there is a slight light loss involved in using this extension tube, distortion is much lower than for the Marumi achromats. Thus, the extension tube should be preferred if magnification needs are not too high.
It should also be noted that the extension tube works with any lens, you need not worry about the filter thread (my Leitz ElmarC 90mm f/4 has a nonstandard filter thread) and filter diameter.
Of course, the idea to combine achromats with extensions came up. Admittedly, I did not expect these combinations to do miracles...
Photos: The "extreme" case  Quenox Extension Tube for Leica M plus two Marumi +5 achromats (and a 4652 stepup ring) (click photos for larger versions)
So I did some quickanddirty tests with the Zeiss 50mm f/1.5 lens, the Quenox Extension Tube for Leica M, plus one or two Marumi +5 achromats (and a 4652 stepup ring) (see photos above). Later, I repeated the test with the 50 mm, added first the 75 mm Voigtländer lens, and finally the 28 mm Minolta and 35 mm Zeiss lenses to the test. Below, I try to collect these tests into one table.
I took quickanddirty test shots to calculate magnification for the following conditions:
*) I did a first test with the Zeiss Sonnar 50mm f/1.5 alone. The results are shown below, but are nearly identical to the second test, which included more lenses.
The following table summarizes my results from the first test (it includes the Zeiss results without Quenox extension tube from above) and compares the data with the condition without Quenox Extension Tube:
Quenox Extension Tube for Leica M 
No Quenox Extension Tube for Leica M 

Zeiss Sonnar 50mm f/1.5 
Zeiss Sonnar 50mm f/1.5 
Marumi +5 Achromat  
Distance 
Distance 
# Achrom.  Diopters  
Infinity  0.9 m (closest)  Infinity  0.9 m (closest)  
180 mm 0.2 = 1:5 approx. 1:5* 
137 mm 0.26 = 1:3.8 approx: 1:4* 
  592 x 395 mm 1:16.5 541 mm 1:15.1** 
0  0 
72 mm 0.5 = 1:2 approx. 1:2 
63 mm 0.568 = 1:1.76 approx: 1:1.75 
130 mm 0.275 = 1:3.6 approx. 1:3.6 
104 mm 0.344 = 1:2.9 approx: 1:3 
1  +5 
46 mm 0.778 = 1:1.28 approx. 1:1.3 
42 mm 0.85 = 1:1.17 approx: 1:1.2 
67 mm 0.534 = 1:1.87 approx. 1:2 
58 mm 
2  +10 
*) From test shots with Quenox Extension Tube alone above
**) From calculations and real word test photos (see page CloseUp
Behavior of the MMount Lenses)
The following table summarizes my results from the second test:
Minolta MRokkor
28mm f/2.8 
Zeiss Biogon 35mm f/2.8 
Marumi +5 Achromat  
Distance 
Distance 
# Achrom.  Diopters  
Infinity  0.8 m (closest)  Infinity  0.7 m (closest)  
103 mm 0.35 = 1:2.9 approx. 1:3* 
93 mm 0.385 = 1:2.6 approx: 1:2.5* 
125 mm 0.29 = 1:3.5 approx. 1:3.5* 
101 mm 0.35 = 1:2.8 approx: 1:3* 
0  0 
103 mm 0.35 = 1:2.9 approx. 1:3 
94 mm 0.38 = 1:2.6 approx: 1:2.5 
122 mm 0.29 = 1:3.5 approx. 1:3.5 
102 mm 0.35 = 1:2.85 approx: 1:3 
0  0 
71 mm 0.50 = 1:2 approx. 1:2 
66 mm 0.54 = 1:1.8 approx. 1:1.8 
72 mm 0.5 = 1:2.0 approx. 1:2 
64 mm 0.56 = 1:1.8 approx. 1:1.8 
1  +5 
57 mm 0.63 = 1:1.6 approx. 1:1.6 
54 mm 0.66 = 1:1.51 approx: 1:1.5 
52 mm 0.69 = 1:1.45 approx. 1:1 .5 
48 mm 0.75 = 1:1.34 approx: 1:1.3 
2  +10 
Zeiss Sonnar 50mm
f/1.5 
Voigtländer
Color Heliar 75mm f/2.5 
Marumi +5 Achromat  
Distance 
Distance 
# Achrom.  Diopters  
Infinity  0.9 m (closest)  Infinity  1.0 m (closest)  
180 mm 0.2 = 1:5 approx. 1:5* 
137 mm 0.26 = 1:3.8 approx: 1:4* 
263 mm 0.14 = 1:7.3 approx. 1:7* 
158 mm 0.23 = 1:4.4 approx: 1:4.5* 
0  0 
181 mm 0.2 = 1:5.1 approx. 1:5 
137 mm 0.26 = 1:3.8 approx: 1:4 
263 mm 0.14 = 1:7.3 approx. 1:7 
159 mm 0.23 = 1:4.4 approx: 1:4.5 
0  0 
72 mm 0.5 = 1:2 approx. 1:2 
62 mm 0.58 = 1:1.7 approx. 1:1.7 
64 mm 0.56 = 1:79 approx. 1:1.8 
54 mm 0.66 = 1:1.5 approx. 1:1.5 
1  +5 
46 mm 0.778 = 1:1.28 approx. 1:1.3 
42 mm 0.85 = 1:1.17 approx: 1:1.2 
37 mm 0.97 = 1:1.0 approx. 1:1 
33 mm 1.08 = 1:0.92 approx: 1:0.9 
2  +10 
*) From test shots with Quenox Extension Tube alone above
Notes: Minimum object distance taken from the test shots below; maximum object size roughly estimated; magnification ratios calculated from the exact values via inverse function
Below are several series of test shots for illustration that I made with aperture wide open. Please note that they were only made for estimating magnification, not for demonstrating the achievable quality.
Photos: Test shots with Minolta MRokkor 28mm f/2.8, Quenox Extension Tube for Leica M, without achromat (top row), one +5 Marumi achromat (middle row), and two Marumi +5 achromats (= +10 diopters; bottom row); distance set to infinity (left column) or closest distance (right column)
Photos: Test shots with Zeiss Biogon 35mm f/2.8, Quenox Extension Tube for Leica M, without achromat (top row), one +5 Marumi achromat (middle row), and two Marumi +5 achromats (= +10 diopters; bottom row); distance set to infinity (left column) or closest distance (right column)
Photos: Test shots with Zeiss Sonnar 50mm f/1.5, Quenox Extension Tube for Leica M, and one +5 Marumi achromat (top row) and two Marumi +5 achromats (= +10 diopters; bottom row); distance set to infinity (left column) or closest distance (right column)
Photos: Test shots with Zeiss Sonnar 50mm f/1.5, Quenox Extension Tube for Leica M, without achromat (top row), one +5 Marumi achromat (middle row), and two Marumi +5 achromats (= +10 diopters; bottom row); distance set to infinity (left column) or closest distance (right column)
Photos: Test shot with Zeiss Sonnar 50mm f/1.5, Quenox Extension Tube for Leica M, and two +5 Marumi achromats (= +10 diopters); distance set to closest distance, aperture set to f/5.6
Photos: Test shots with Voigtländer Color Heliar 75mm f/2.5, Quenox Extension Tube for Leica M, without achromat (top row), one +5 Marumi achromat (middle row), and two Marumi +5 achromats (= +10 diopters; bottom row); distance set to infinity (left column) or closest distance (right column)
Photos: Test shot with Voigtländer Color Heliar 75mm f/2.5, Quenox Extension Tube for Leica M, and two +5 Marumi achromats (= +10 diopters); distance set to closest distance, aperture set to f/5.6
The photos seem to show a little less distortion when the extension tube is included in a setup with one or two achromats, but this may well be an artifact. Magnification is boosted when one achromat is used, but less so with two achromats.
The best combination seems to be to combine one Marumi +5 achromat with the Quenox Extension Tube. Interestingly, all tested lenses behave very similarly under this condition; only the Voigtländer lens has a slight edge. Real life tests should reveal, which combination delivers the better image quality. Magnification is in the region of 1:2 here. If you use two achromats with this lens, you come even into the 1:1 realm...
But again, maybe that all these combinations are unusable from an image quality point of view in the end... Real life tests are needed to explore this question.
Test shots taken with an aperture value of f/5.6 show that image quality improves when the lenses are stopped down. This is also important when using these combinations for reallife closeup shots.
Lens 
Quenox
Extension
Tube for
Leica M


No Quenox
Extension Tube for Leica M

Marumi +5 

Distance 
Distance 
Achromats 

Infinity  0.8 m (closest)  Infinity  0.8 m (closest)  #  Diopters  
Minolta MRokkor 28mm
f/2.8 
103 mm 0.35 = 1:2.9 approx. 1:3* 
94 mm 0.38 = 1:2.6 approx: 1:2.5* 
  951 x 634 1:26.4* 829 mm > 1:23.2** 
0  0  
71 mm 0.50 = 1:2 approx. 1:2 
66 mm 0.54 = 1:1.8 approx. 1:1.8 
225 mm 0.16 = 1:6.3 approx. 1:6.5 
176 mm 0.2 = 1:4.9 approx: 1:5 
1  +5  
57 mm 0.63 = 1:1.6 approx. 1:1.6 
54 mm 0.66 = 1:1.51 approx: 1:1.5 
110 mm 0.325 = 1:3.1 approx. 1:3 
101 mm 0.35 = 1:2.8 approx. 1:2.8 
2  +10  
Zeiss Biogon 35mm f/2.8 
Infinity  0.7 m (closest)  Infinity  0.7 m (closest)  #  Diopters  
122 mm 0.29 = 1:3.5 approx. 1:3.5* 
102 mm 0.35 = 1:2.85 approx: 1:3* 
  652 x 434 1:18* 587 mm > 1:16.4** 
0  0  
72 mm 0.5 = 1:2.0 approx. 1:2 
64 mm 0.56 = 1:1.8 approx. 1:1.8 
180 mm 0.2 = 1:5.0 approx. 1:5 
139 mm 0.26 = 1:3.9 approx. 1:4 
1  +5  
52 mm 0.69 = 1:1.45 approx. 1:1.5 
48 mm 0.75 = 1:1.34 approx: 1:1.3 
90 mm 0.4 = 1:2.5 approx. 1:2.5 
79 mm 0.45 = 1:2.2 approx. 1:2.2 
2  +10  
Zeiss Sonnar 50mm f/1.5 
Infinity  0.9 m (closest)  Infinity  0.9 m (closest)  #  Diopters  
181 mm 0.2 = 1:5 approx. 1:5* 
137 mm 0.26 = 1:3.8 approx: 1:4* 
  592 x 395 1:16.5* 541 mm > 1:15.1** 
0  0  
72 mm 0.5 = 1:2 approx. 1:2 
63 mm 0.568 = 1:1.76 approx: 1:1.75 
130 mm 0.275 = 1:3.6 approx. 1:3.6 
104 mm 0.344 = 1:2.9 approx: 1:3 
1  +5  
46 mm 0.778 = 1:1.28 approx. 1:1.3 
42 mm 0.85 = 1:1.17 approx: 1:1.2 
67 mm 0.534 = 1:1.87 approx. 1:1.9 
58 mm 0.617 = 1:1.6 approx. 1:1.6 
2  +10  
Voigtländer Color
Heliar 75mm f/2.5 
Infinity  1.0 m (closest)  Infinity  1.0 m (closest)  #  Diopters  
263 mm 0.14 = 1:7.3 approx. 1:7* 
159 mm 0.23 = 1:4.4 approx: 1:4.5* 
  444 x 296 1:12* 391 mm > 1:10.9** 
0  0  
64 mm 0.56 = 1:1.79 approx. 1:1.8 
54 mm 0.66 = 1:1.5 approx. 1:1.5 
92 mm 0.39 = 1:2.56 approx. 1:2.5 
72 mm 0.5 = 1:2 approx. 1:2 
1  +5  
37 mm 0.97 = 1:1.0 approx. 1:1 
33 mm 1.08 = 1:0.92 approx: 1:0.9 
47 mm 0.76 = 1:1.3 approx. 1:1.25 
40 mm 0.895 = 1:1.12 approx. 1:1.1 
2  +10 
Table: Overview of achievable magnifications for the lenses that are most relevant for closeup photography with tools (lenses, tubes)
*) Very similar results were obtained in a test where only the Quenox Extension
Tube was regarded
*) Calculated for 35.8 mm according
to a simple formula based on of angle of view (technical data) and shortest
distance (technical data);
**) Adapted
to the Leica M's sensor width of 35.8 mm (instead of 36 mm), object widths
taken from test photos (see page CloseUp Behavior
of the MMount Lenses)
Lens

Quenox Extension
Tube for Leica M 
No Quenox Extension
Tube for Leica M 
Marumi +5 

Distance 
Distance 
Achromats 

Infinity  0.8 m (closest)  Infinity  0.8 m (closest)  #  Diopters  
Minolta MRokkor 28mm f/2.8 
103 mm approx. 1:3 
94 mm approx: 1:2.6 
    0  0  
71 mm approx. 1:2 
66 mm approx. 1:1.8 
    1  +5  
Zeiss Biogon 35mm f/2.8 
Infinity  0.7 m (closest)  Infinity  0.7 m (closest)  #  Diopters  
122 mm approx. 1:3.5 
102 mm approx: 1:3* 
    0  0  
72 mm approx. 1:2 
64 mm approx. 1:1.8 
180 mm approx. 1:5 
139 mm approx. 1:4 
1  +5  
Zeiss Sonnar 50mm f/1.5 
Infinity  0.9 m (closest)  Infinity  0.9 m (closest)  #  Diopters  
181 mm approx. 1:5 
137 mm approx: 1:4 
    0  0  
72 mm approx. 1:2 
63 mm approx: 1:1.75 
130 mm approx. 1:3.6 
104 mm approx: 1:3 
1  +5  
46 mm approx. 1:1.3 
42 mm approx: 1:1.2 
67 mm approx. 1:2 
58 mm approx. 1:1.6 
2  +10  
Voigtländer Color
Heliar 75mm f/2.5 
Infinity  1.0 m (closest)  Infinity  1.0 m (closest)  #  Diopters  
64 mm approx. 1:1.8 
54 mm approx. 1:1.5 
92 mm approx. 1:2.5 
72 mm approx. 1:2 
1  +5  
37 mm approx. 1:1 
33 mm approx: 1:0.9 
47 mm approx. 1:1.25 
40 mm approx. 1:1.1 
2  +10 
Table: Overview of achievable magnifications for the lenses that are most useful for closeup photography with tools (lenses, tubes)
In terms of lenses and options, we get the following useful combinations:
Other combinations deliver too low magnifications or too strong distortions.
As a rule of thumb, put the Quenox Extension Tube for Leica M in your camera bag and one or two +5 achromats/closeup lenses. And use them only in combination with the lenses listed above (or lenses of corresponding focal lenghts).
Another rule of thumb is that two +5 achromats/lenses should only be used for focal lengths of 50 mm and longer. Better achromats may also be used in combination with shorter focal lengths, but I cannot comment on this.
Closeup lenses and achromats are most effective from a focal length of 50 mm on and longer  without doing miracles, however. But in comparison with the closeup behavior of the "pure" lenses, the boost is nevertheless remarkable. Regrettably, the samples show strong to medium pincushion distortion, which decreases somewhat with increasing focal length. Pincushion distortion increases when lenses are stacked. Better achromats such as the Leica Elpros may cause a lot lower pincushion distortion, but I cannot comment on this, since I do not own an Elpro and cannot verify this.
The Quenox Extension Tube, on the other hand, is the more effective, the shorter the focal length is. Used alone, it is again interesting from a focal length of 50 mm on and shorter. However, when the lens is too wide, you have to get very close to the object, and the perspective may also not be optimal. Distortion seems to be much lower when using extension tubes than for closeup lenses.
Lenses and the Quenox Extension Tube can be combined, but I would not stack lenses in this case. Using the tube and one +5 lens let's you enter the 1:2 realm with a 50 mm lens. Distortion might be a little bit lower when a lens is combined with an extension tube.
Thus far, the results that I have got are not very encouraging with respect to image quality. But stopping the lens down improves vignetting behavior and overall image quality (albeit not distortions), as a few test shots indicate.
I found an interesting difference between closeup lenses and extension tubes (and bellows):
Another interesting difference between closeup lenses and extension tubes that I found is:
And another difference was already known to me:
It should also be noted that the extension tube works with any lens, you need not worry about the filter thread (my Leitz ElmarC 90mm f/4 has a nonstandard filter thread) and filter diameter.
*) Leitz delivered high quality achromats (the Elpro series), and I did not find any reports on strong distortions.
The "practice" section continues with page CloseUp Options (Live View)  Part 3: Practice II, which discusses my practical experiences with extension bellows.