Mitutoyo 10X M Plan APO
Updated February 25th 2024
The Mitutoyo M Plan Apo 10x 0.28 (MY10x) is a Metallurgical Plan Apochromatic objective designed especially for a long working distance, high NA, and large image field for industrial applications. The MY10x is a Metallurgical Plan Apochromatic objective designed to be used without a coverslip and is part of a compensation free system, no eyepiece or tube lens aberration compensation is needed. The M Plan APOs from Mitutoyo are very well-known in the world of macro photography setting the standard for long working distance, great aberration control and good sensor coverage.
As a matter of optical design a plan apochromat with a long working distance and large field is very difficult and very expensive to achieve. A long working distance will mean higher amounts of secondary spectrum (greenish or purple fringes on sharp edges), chromatic aberration, and spherical aberration. So how did Mitutoyo do it? They designed the M Plan APOs from a clean slate using a larger and longer body with a 95mm parfocal length. This new design avoids the system constraints and limitations faced by the bigger manufacturers like Nikon and Olympus. M plan APO objectives are up to twice the length, and offer much larger working distances than standard bioscience microscope objectives.
M Plan Apo 10x design changes
Gradually Mitutoyo redesigned the M Plan APOs from an exposed front element design with a protective rubber edge to the current models that use a recessed front element design. There were also some small cosmetic changes made at the same time, as you can see below.
There are at least three models of the M Plan Apo 10x 0.28 objective on the used market. The earliest mode 378-803 has the label M Plan Apo 10x 0.28 etched and painted in red. The 378-803-2 that is very commonly seen and has an exposed rubber ring on the front of the lens and an engraved band bright yellow, the lettering are painted on. The latest 378-803-3 model M Plan Apo 10x 0.28, the model tested here, had a painted yellow band, and a recessed front element.
Early 378-803-2 and late model 378-803-3 versions
There is no information on the optical designs of the three 10x M Plan versions seen on the used market. We have tested the 378-803-2 and 378-803-3 side-by-side and the latest model seemed to be very slightly sharper and better corrected chromatically but there is no real way to know if the difference I found was copy to copy variation or due to an upgraded optical design. We always recommend buying the latest model directly in new condition from Mitutoyo or a distributor to be sure of the performance.
The 378-803 version appeared in the 1990s to about 2005. From 2006 on the 378-803-2 model appeared. The newest 378-803-3 appeared gradually from 2010 to 2012, some Mitutoyo catalogs at this time have the 10x mislabeled, others have both the -2 and the -3 models listed at the same time. The model 378-803-3 is current at the time of writing this in 2024.
Late model 378-803-3 version of the M Plan APO 10x/0.28 from Mitutoyo
MITUTOYO M PLAN APO 10x 0.28 OBJECTIVE SPECIFICATIONS
Mitutoyo Part Number: 378-803-3 (latest model)
Official name: M Plan Apo 10x 0.28 Long working distance bright field objective
Objective type: Industrial inspection systems
Len tube length: 200mm
NA and Nominal Aperture: This lens has a numerical aperture of 0.28, Nominal aperture: f/1.62, effective aperture: f/17.86
Focal length: 20mm
Parfocal length: 95mm
Working Distance: 33.5mm
Image circle: Ø 30mm
Suggested retail price in the US: $855 USD, in the EU: 825.00 € (VAT excluded)
Resolution: 1 µm
Mounting Threads: M26 x 36TPI or M26 x 0.706mm JIS B-7141-1988
Coverage: 30mm OFN (Optical Field Number), 30mm image circle Ø
Source: made in Japan
Used market prices: $200-$1500 USD, asking prices are sometimes higher than the new price.
Notes: The unit in the test was purchased in Japan straight from Mitutoyo and was hand-carried on the flight to California.
Mitutoyo Plan APO 2X, 5X, and 10X all give a constant value of 10µm on the sensor, multiplying the resolution with the magnification factor.
Late model 378-803-3 version of M Plan Apo 10x 0.28
Dimensions for the 378-803-2 left and 378-803-3 right.
378-803-3 model with a recessed front element behind the older 378-803-2 model with the exposed rubber ring at the front.
COMPARING IMAGES AT 100% VIEW
To view a larger version of any of the image below click on an image to open it in a Lightbox viewer, but the size of the image is matched to your device based on the screen size. The comparison image below are 2500 pixels across. To check the size of the image you are looking at, look up at the URL window at the top of the browser, the address should have 2500w at the end. If the image size is anything smaller you can easily change the number to 2500 manually and press enter to bring up the largest image.
The best way to view the images is to right click, or two-finger press, and select Open in a New Tab or New Window from the menu. You can also right click, or two-finger press, and select Save Image As and compare the images in an image viewer.
2500 pixel IMAGE EXAMPLE
Mitutoyo 10x M Plan APO with Thorlabs ITL200 tube lens
10x test: Mitutoyo M Plan vs the competition
Left to right, Nikon LU Plan 10x, Nikon CFI Plan 10x, Mitutoyo 10x M Plan APO, Nikon 10x MM toolmakers objective.
Un-cropped 10x wafer image resized to 1500 pixels with the crop areas highlighted in blue.
TEST SET-UP
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
Tube Lens: Thorlabs ITL200, a detailed review of this lens is available here on Closeuphotography.com: https://www.closeuphotography.com/thorlabs-itl200/
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
A series of images was made with each lens in 2 micron steps and the sharpest frame was then chosen using Photoshop at 100% view. Separate images were selected for each crop area as 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 crop images shown here are single files. None of the crop images are stacked.
Center crop at 100% view
Judging by the numerical apertures the MM should be the least sharp and the LU Plan should be the sharpest but a nominal value doesn’t always translate to results, especially when it comes to Nikon overstating objective specifications in my experience.
Nikon MM 10x 0.20
The 10x MM objective’s strength is not sharpness due to the lowest NA of all the lenses here and the results illustrate that fact. Chromatic aberrations are the strongest of the four.
Nikon Plan 10x 0.25
Not bad results here but like the MM objective, the Plan 10x aperture is modest so it will not win any sharpness contests against faster lenses, it’s strength is a big image circle.
Mitutoyo M Plan Apo 10X 0.28
Best sharpness here, equal to the LU 0.30 objective but without Nikon’s purple chromatic aberrations. Check the diagonal like in the upper right corner. The Mitutoyo is free from any hint of CAs.
Nikon LU Plan 10X 0.30 BD
This lens should be the sharpest with numerical aperture of 0.30 but its not any sharper than the Mitutoyo but instead of sharpness the Nikon adds some purple fringing in the upper right corner diagonal.
Best in Center: Mitutoyo M Plan Apo 10X 0.28
Off Center crop at 100%
Nikon MM 10x 0.20
Similar results as the center. Less sharpness and more chromatic aberrations are the other 3 objectives.
Nikon Plan 10x 0.25
Same results as the center. Middle of the road sharpness with some CAs.
Mitutoyo M Plan Apo 10X 0.28
Best here again, sharpness is equal to or better than the LU 0.30 objective but without Nikon’s purple chromatic fringing.
Nikon LU Plan 10X 0.30 BD
About equal sharpness with more CAs than the Mitutoyo, see the diagonal lines at the top and bottom of the image.
Best off center: Mitutoyo M Plan Apo 10X 0.28
Corner crop at 100% view
This should be interesting, the Mitutoyo and Nikon Plan should be best since they are both well known for large image circles.
Nikon MM 10x 0.20
This is a little strange, the sharpness is actually a little better here then the center judging but the micro bars labeled 0.60, 0.70, 0.80, 0.90. Chromatic aberrations are not any worse.
Nikon Plan 10x 0.25
CAs seem less noticeable in the corner crop. Sharpness is good.
Mitutoyo M Plan Apo 10X 0.28
Best sharpness here without any CAs.
Nikon LU Plan 10X 0.30 BD
Sharpness is weaker here due to the small image circle but the CAs remain just strong as the center or maybe a little worse.
Best in the corner: Mitutoyo M Plan Apo 10X 0.28
Extreme corner crop at 100% view
The Nikon MM is not quite rated to cover an APS-C sensors 28mm diagonal, either is the Nikon LU plan with a FN of only 25. So the only real question is will the Nikon Plan or Mitutoyo be sharper in the corners.
Nikon MM 10x 0.20
The sharpness quickly dropped from the corner to extreme corner. This lens is not designed to cover the 28mm diagonal of the APS-C sensor.
Nikon Plan 10x 0.25
Sharpness is good in the extreme corner.
Mitutoyo M Plan Apo 10X 0.28
Excellent sharpness and contrast here, easily the best of the four. Best in the extreme corners.
Nikon LU Plan 10X 0.30 BD
Very poor performance in the extreme corner but to be fair the lens is not supposed to cover a sensor this large anyway.
Final results
Even new at full retail price this objective is an excellent value and is highly recommended. The lasted model, as tested here, seems to be slightly better than the more common older models.
What We Like
-Full frame coverage
-Consistent performance across the frame
-No cover-slip needed
-Flat field
-Long working distance
-APO correction
What I Do Not Like
The polished chrome finish attracts finger prints
10x M Plan Tube Lens Test
For this test I tried my standard 200mm tube lens, the Thorlabs ITL200, in a few different configurations. Detailed ITL-200 lens set-up information is available here on Closeuphotography.com: https://www.closeuphotography.com/thorlabs-itl200/
To see how far I could push down the 10x M Plan I tried the Makro-Symmar and Raynox 125 to push the 10x M Plan down the magnification to around 6x. I also attempted to push the magnification down further to 5x with a 100mm tube but the image quality was not acceptable.
Thorlabs ITL200 Tube Lens
Setup: Thorlabs ITL200, normal mount, beyond infinity (short) focus
Image quality: Poor results, heavy field curvature, CAs in the corners with some corner softness.
Setup: Thorlabs ITL200, reverse mount, beyond infinity (short) focus
Image quality: Poor results, lots of field curvature, less CAs than normal mount.
Setup: Thorlabs ITL200, normal mount, infinity focus
Image quality: Poor results, sharp center but field curvature, soft corners, CAs.
Setup: Thorlabs ITL200, reverse mount, infinity focus
Image quality: Excellent results from center to corner with zero CAs and mild field curvature.
Best image quality: Thorlabs ITL200, reverse mount, infinity focus
In testing tube lenses for this test with the 10x Mitutoyo the set-up on the right side labeled “Recommended Set-up For Best Image Quality” produced the best results.
Pushing the 10x M Plan down to 6x
With infinity-corrected objectives you can change the tube lens focal length to create different magnification ratios at the camera sensor, without compromising the color correction. To calculate the system magnification for different tube lens and objective combinations, you can use this simple formula; Effective magnification = Marked magnification x the new tube lens focal length / the system tube lens focal length.
Mitutoyo 10x M Plan APO pushed down to 6x with Raynox 125mm 43mm mount tube lens
6x results
Schneider 120mm f5.6 Makro-Symmar Tube Lens
Setup: Schneider 120mm f5.6 Makro-Symmar, normal mount, infinity focus
Image quality: Poor results, soft corners, heavy corner shading.
Setup: Schneider 120mm f5.6 Makro-Symmar, reverse mount, infinity focus
Image quality: Poor results, softer corners and heavier shading than normal mount.
Raynox 125mm FL 43mm mount Tube Lens
Setup: Raynox 125mm FL 43mm mount, normal mount, infinity focus
Image quality: Good with field curvature and some corner softness.
Setup: Raynox 125mm FL 43mm mount, reverse mount, infinity focus
Image quality: Excellent results from center to corner and mild field curvature and very mild CAs.Th
Best results at 6x: The Raynox 125mm reverse mounted at infinity focus made a pretty impressive image at 6x but there was a slight drop in corner sharpness so if corners are something important I wouldn’t recommend pushing the 10x M Plan past 6x unless of course corners are not important
PRICE AND AVAILABILITY
Use a lot of caution when buying a used Mitutoyo objective. These are precision instruments and can be easily damaged by the shock. In fact the objective cases are even labeled with a warning. We recommending buying a Mitutoyo M Plan APO new, if you have to buy used always make sure you have return privileges, just watch for re-stock fees. EBay has been flooded with re-sellers from China and they are a huge risk, its not worth it, believe me, after 2 bad experiences I would not buy a Mitutoyo from China again. On the other hand I have had nothing but very good experiences buying from South Korea and Japan. If there was an international contest for excellence in packing lenses, South Korea gets the gold medal. Chinese sellers use old bubble wrap and used boxes and do not give any consideration to the fact that they are shipping fragile items.
LINKS FOR MORE INFO:
Edmunds Optics: https://www.edmundoptics.com/microscopy/infinity-corrected-objectives/Mitutoyo-Infinity-Corrected-Long-Working-Distance-Objectives/
Mitutoyo Objective PDF: https://www.mitutoyo.com/webfoo/wp-content/uploads/E14020.pdf
Mitutoyo objectives at Thorlabs: https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=9922
Mitutoyo Objectives at the Mitutoyo EU shop: https://shop.mitutoyo.eu/web/