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Mitutoyo’s M Plan APO objective line-up is well-known in the macro photography world for setting the standard of excellence for sharpness, chromatic correction and long working distance. So how did Mitutoyo achieve this balance? They designed the objectives larger and longer with a 95mm parfocal length avoiding outdated and restrictive designs used by the competition. Mitutoyo makes a wide range of different objectives for different applications and wavelengths of light, UV, NUV, Visible & NIR, but the two most popular types for photography are the M Plan APO, or the metallurgical plan apochromatic, and BD Plan APO, or Bright/Dark Field plan apochromatic (the BD Plan and M Plan versions have identical optical designs).

The article on this page has everything I know about this objective, all the specifications, lots of general info, my set-ups, the price I paid, and images from some of the tests that I have run. This page is not set-up to get you to click affiliate links to generate money by telling you how great this lens performs, this is not a fan page, this product was not given to me, I was not paid to write this, nor did the manufacturer or distributor loan me this lens for this review.

7.5X M PLAN SPECIFICATIONS

Mitutoyo Part Number: M Plan Apo 7.5x : 378-807-3, BD Plan Apo 7.5x : 378-830-7

Official name: M Plan Apo 7.5X/0.21 Long working distance objective

Objective type: Industrial inspection systems

NA and Nominal Aperture: This lens has a numerical aperture of 0.21, nominal aperture is f/2.2 and an effective aperture of f/18.75 at 7.5x.

Focal length: 26.67 mm

Parfocal length: 95mm (Nikon objectives are designed with 65mm and 75mm, Qioptiq uses a 125mm parfocal length)

Working Distance: 35mm

Long Working Distance: with 35mm of working distance you will have enough room to set up lighting without much hassle.

APO Correction: An apochromatic or APO objective is corrected for chromatic aberration at the red, blue, and yellow wavelengths. This really adds to the subjective perception of sharpness. An APO objective should have correction of both types of chromatic aberrations or CAs, lateral CAs, or color fringing, and longitudinal CAs, or LoCAs, also called Bokeh CAs.

Resolution: the resolving power of this objective is rated at 2 µm (micron) which gives you a value of 10µm on the sensor so should make it a good choice for sensors in the 4-5 µm (micron) range like the Nikon D810 at 4.88 µm pixel size. The Mitutoyo Plan APO 2X, 5X, 10X all give a constant value of 10µm in the sensor multiplying the resolution with the magnification factor.

Image Quality: the Mitutoyo 5X has the IQ that these objectives are known for, sharp and without CAs (chromatic aberration). The IQ of these lenses are usually used as a reference for a lot of macro photographers.

Mounting Threads: M26 x 36TPI or M26 x 0.706mm

Coverage: Mitutoyo quotes a 30mm diameter image circle. This lens will cover a full frame DSLR sensor, but the corner performance is much better with a cropped frame or APS-C sensor body.

Infinity-corrected: to use a Mitutoyo Plan APO infinity corrected objective for photography, a secondary 200mm (or tube) lens is required for installation.

For a microscope objective, the Mitutoyo Plan APOs are massive, but they were designed this way for a reason. When Mitutoyo set out to design these lenses they wanted the best combination of working distance and optical performance so they went with a new approach by making the objectives larger and longer with a longer parfocal length, this brought the designs goals within reach.

7.5x M PLAN IMAGE EXAMPLEs

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SETTING UP THE M PLAN APO FOR PHOTOGRAPHY

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THE BOTTOM LINE

You really can't go wrong with any of the Mitutoyo M Plans and the 7.5x M Plan APO is one of the best in the series for photography. I can easily recommend this objective, although it can be a little harder to find than 5x M Plan APO, so expect the cost to be a little higher. Before you buy one, be sure to take a look at the warning below about buying used objectives.

Unlike a lot of high-performance objectives, see the test of the Nikon Plan APO 4x here: https://www.closeuphotography.com/4x-test-part-two-high-end-objectives, the Mitutoyo M Plan APO series really works well for photography.

7.5x M PLAN Ratings

What I Really Like About This Objective

-Large image circle for good coverage
-Consistent performance over the entire image circle
-Designed to be used without a cover-slip
-Flat field
-Long working distance
-Chromatic aberrations are corrected in the objective (other brands utilize a combination of corrections in both the tube lens and objective)

What I Don't Like

-The 7.5x is one of the more expensive M Plan objectives
-This objective can be a little harder to find than some of the other M Plans.

PRICE AND AVAILABILITY

The Mitutoyo M Plans and BD Plans are all Plano Apochromats and this level of correction is typically very expensive, but thanks to the high volume production, Mitutoyo is able to keep the cost down. These objectives are widely used in manufacturing and research around the world so there is always good stock on the used market which keeps the prices reasonable.

Prices on the secondary markets are excellent for most common M Plans, used prices in 2017-2018 are from $250 and up for a BD Plan APO 5x in decent shape, with an average starting around $400. The 7.5x M Plans are a bit more expensive at around $1300 retail new in-the-box and about $1100 sold as new on ebay, and about $600-750 used.

You will come across SL Mitutoyo objectives on the used market but these have a lower NAs than the normal M Plan and BD Plans so I would avoid them. There are also HR (high resolution) versions from Mitutoyo but they are very expensive, about 6 times the price of the standard units.

What You Need to Know Before You Buy a Mitutoyo Objective

Objectives are finely tunes optics that have been optimized at the factory and are fragile enough that the performance can suffer due to damage from a single drop. The best place to buy a Mitutoyo is from an online store in the US with return privileges, just watch for re-stock fees. If you try Ebay make sure that you only buy from a seller that offers returns with good feedback and is from the US.

Lately Ebay has been flooded with re-sellers from China that are running Ebay ads with the very same objectives, without physically owning the objectives, and marking the prices up 100% and more. Buying from China is a huge risk, its not worth it, believe me, after 2 bad experiences, I won't risk buying 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. In camparison, Chinese sellers use old recycled bubble wrap and old re-used boxes and do not give any consideration to the fact that they are shipping fragile expensive items.

For more on this subject, see: "Have I ruined my mitutoyo 10/0.28?" : http://www.photomacrography.net/forum/viewtopic.php?t=20548
and, My new Mitutoyo 10X is very good! : http://www.photomacrography.net/forum/viewtopic.php?t=20594

The Competition

For photography I am not aware of any other objectives that can compare with the same magnification as the M Plan 7.5x. The only objective close the M Plan 7.5x is the Qioptiq LD APO 8X/ 0.32. This is not really a fair comparison since the Mag.x is prohibitively expensive, at $16,000, and has specs that but it in a different class than the Mitutoyo, with sub-micro resolution (vs. 2 microns). The Mag.x has a numerical aperture or NA of 0.32, thats a nominal aperture of f/1.4 and the effective aperture is f/12.5 at 8x. For comparison the Mitutoyo M Plan 7.5x 0.21 has a the nominal aperture is f/2.1 and an effective aperture of f/17.86 at 7.5x. For more info: https://www.closeuphotography.com/qioptiq-magx-8x-objective/

7.5x OBJECTIVE Dimensions

Identification of the properties of an objectives is easy because most parameters are inscribed or printed on the outer housing (or barrel) of the objective.