The Schneider Makro Symmar 5.6/120 and Componon 2.8/28 lens in a stacked configuration mounted inside Thorlabs SM2/52mm tubes on a Sony A6300 body.
This is one of my favorite pairs of lenses for stacking. The performance from these two lenses when coupled properly is really excellent. I’m not exaggerating, this pair is sharper and more consistent than the Mitutoyo 5x M Plan APO pushed down to 4.3x, you can see the results of the test below. The best part is that both lenses are easy to find on both new and used markets unlike other high performance lens pairs.
Schneider Makro-Symmar 5.6/120 + Componon 2.8/28 Lens Pair
Front lens: Schneider Kreuznach 2.8/28 Componon lens reverse mounted
Rear lens: Schneider Makro-Symmar 5.6/120 line scan lens normally mounted focused at infinity
Magnification: 4.3x
Stacked lens nominal aperture: f/3.1
Stacked lens effective aperture: f/12.0-13.3
Using a typical 100/4 bellows or enlarger lens focused with extension to reach 4.3x would give you an effective aperture of f21.2 that is if the lens is sharp wide-open, most are best half to one stop closed down.
Why STACKed LENSES?
Stacking lenses, also called coupling lenses, is a technique to increase magnification where you mount a longer focal length lens on the camera and a second shorter focal length in reverse and face-to-face on the rear lens which is set to infinity focus. Together the combination has the potential to resolve more than either of the lenses setup for close-focus with extension.
A f2.8 lens focused at 3x magnification by extension would have an effective aperture of f/11 using the simple formula, effective aperture = nominal aperture * ( Magnification + 1 ). With the same lens setup in a stacked configuration the effective aperture would be only f/8.4 using the formula effective aperture = nominal aperture * Magnification.
Mounting the stack
In the image above the Componon 2.8/28 is reversed and mounted on the rear lens in the stack, a Schneider Makro-Symmar 120 that is mounted out of sight inside the SM2-52mm extension tube and focused on infinity. The Componon lens is reversed in the above image with the lens hood mounted on the rear of the lens.
The Schneider Makro-Symmar 120 is mounted inside a SM2-52mm extension tube using a V38 to 42mm x 1.0mm adapter attached to a Thorlabs SM2 to 42mm to 1.0mm adapter. Another 42mm x 1.0mm adapter goes on the front of the 2.8/28 and that mounts to the Thorlabs SM2 to 42mm to 1.0mm adapter and the lens also mounts inside the 52mm extension tube directly in front of the Makro-Symmar lens.
The advantages of mounting both lenses inside a SM2-52mm tubes is that each lens can be positioned exactly as needed either touching or leaving room for a threaded iris or aperture disk. It’s possible to leave the front barrel and aperture protruding from the tube to allow easy access to change apertures.
4.3x Test: the Componon 2.8/28 vs Mitutoyo 5x M Plan APO
The Componon 2.8/28 is excellent at 3.2x but over 4x is going to be very difficult since this is where microscope objectives almost always have a sharpness advantage due to a larger effective apertures. The Mitutoyo 5x M Plan APO was chosen for this test since its one of the most popular and best performing objectives at this magnification beating almost all comparable objectives. FYI Nikon and Olympus objective’s are designed to cover a smaller field than the Mitutoyos as a matter of fact with a much smaller FN or field number and most don’t even cover the manufacturers specifications for the lens. So comparing the Schneider Makro-Symmar 5.6/120 + Componon 2.8/28 lens to a Nikon or Olympus 5x objective would be a waste of time in my experience since the sharpness consistency from center to corner is pretty weak even on a small APS-C sensor like the sensor in the Sony A6300.
Componon 2.8/28
Front lens: Schneider Kreuznach 2.8/28 Componon lens reverse mounted
Rear lens: Schneider Makro-Symmar 5.6/120 line scan lens normally mounted focused at infinity
Stacked lens nominal aperture: f/3.1
Stacked lens effective aperture: f/13.33
Mitutoyo 5x/0.14 M Plan APO
Objective: Mitutoyo 5x M Plan APO
Tube lens: Thorlabs ITL200 reversed and on short focus for 4.3x
Stacked lens nominal aperture: f/3.57
Stacked lens effective aperture: f/15.35
Camera: Sony α6300, model # ILCE-6300, also known as: A6300
Sensor size: APS-C 23.5 × 15.6 mm. 28.21 mm diagonal. 3.92 micron sensor pitch
Flash: Godox TT350s wireless flash x 2 with one Godox X1s 2.4G wireless flash transmitter
Vertical stand: Nikon MM-11 with a Nikon focus block
For this test a stack of images was made with 2 micron steps, and was repeated for each aperture. The sharpest frame was then chosen using Photoshop at 100% actual pixel view. Separate images were selected for center, edge, and corner if needed. Each image was processed in PS CC with identical settings with all noise reduction and lens correction turned off, all settings were zeroed out (true zero) and the same settings were used for all of the images. All of the images shown here are single files.
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Crop areas outlined in white.
100% VIEW Center CROPS
The differences are very small. In some areas the Componon is sharper and in some the Mitutoyo has an advantage. Its the same case with CAs, some areas the M Plan is better, some areas its not.
100% VIEW Below Center CROPS
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The Componon seems to have slightly better sharpness but the Mituyoto has slightly better CA control. The performance from both lenses where is great.
100% VIEW Edge CROPS
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Now there is a large difference in IQ at the edge. The Componon is much sharper with better contrast, the Mitutoyo is softer but has less red fringing. For both of these lenses a specific frame was selected for the edge crops and processed identically and at the same time.
100% VIEW CORNER CROPS
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At the corner, the Componon has quite an advantage over the Mitutoyo in sharpness, resolution and CA control, see the arrow at the far upper left corner, the Componon is CA free. Also make sure to compare the lower left corners of each crop image above if you have any doubts about the differences.
4.3X TEST RESULTS
The Componon 2.8/28 and Mitutoyo M Plan are in the same price range new and used and both have similar performance here around 4x. The Mitutoyo would probable beat the Componon at 5x and higher but the Componon has an iris and is much larger and more flexible range from 1/20 to 4x. Both are excellent I could easily recommend either one.
V38 MOUNTINg ADAPTERS
Out of all the V38 adapters I have tried the Schneider adapters are very high quality but unfortunately there is a problem and I have now sold almost every Schneider adapter that I own. Almost all Schneider V-mount adapters fail to clear the rear lens cell of the Makro-Symmar (and Mejiro lenses) so I no longer recommend them due to clearance issues with their own lenses. The no-name Chinese made V38 adapters on Ebay are knock-offs of the Schneider units so of course they also have clearance problems with some lenses like the Makro-symmars and Macro-Varons.
Now I only recommend RafCamera V-Mount adapters made with my specifications that will clear the rear lens cell on the Makro-Symmar 5.6/120 lens and others see: https://www.rafcamera.com/
STACKING PROS AND CONS
The good
Better sharpness and resolution compared to same lens using extension only
Inexpensive since you can most likely use a pair of lenses that you already own
Easy to use since the magnification is set
Normal focus non-specialized lenses work well
The Bad
High performance lens pairs can be hard to find
The performance is so good it can make you want to forget about extension only setups
Each lens pair combination has a limited magnification range
LENS STACKING NOTES
Mount the front lens as close to the rear lens as possible.
Control the aperture of a coupled lens pair with the front lens iris but some pairs work better with a aperture disk placed between the lenses so its best to try both methods.
Stopping down the front lens slightly seems to improve image quality slightly with most lens pairs.
Optimally both lenses are set to infinity focus although setting the rear lens set to closer focus can work well.
Even though both lenses in a stacked setup are focused at infinity lenses optimized for close up distances seem to work as well or better than normal focus lenses.
For best results the front lens should be set to infinity focus rather than close focus.
To avoid corner shading rear lenses 80mm or longer work best.
Short focal length lenses from 24-50mm work best as front lenses.
Large aperture rear lens are said to minimize vignetting with some combinations but I find that f5.6 or slower lenses seem to work fine.
Vignetting can sometimes be partially eliminated by adding an extension tube or by setting a closer focus setting to the rear lens.
If a stacked lens pair will vignettes try to move the front lens closer to the front of the rear lens, sometimes you will have to set the front lens inside the hood or shroud of rear lens.
LINKS FOR MORE INFORMATION
Full Componon 2.8/28 lens test here on Closeuphotography.com:
https://www.closeuphotography.com/schneider-kreuznach-28mm-f2-8-componon-lens/
More information on the 5.6/120 Makro-Symmar:
https://www.closeuphotography.com/schneider-makro-symmar-sr-120/
The HM 5.6/120 Makro-Symmar version:
https://www.closeuphotography.com/schneider-makro-symmar-120mm/