Lens Spotlight
HLB M Plan Apo 5x
The HLB M Plan Apo 5x is a microscope objective designed for metallurgical applications. This test aims to evaluate how well it performs in focus stacking setups without the use of a professional microscope.
The Objective
The HLB M Plan Apo 5x was developed for metallurgical applications and is part of a parfocal objective series with varying magnification levels. All variants in this series share the same overall length (housing plus working distance) and largely identical housing diameters—even at low magnifications such as 2x, which presents a significant design challenge at the front lens element.
The advantage of parfocality becomes particularly evident when used with specialized microscopes, where the camera extension is mechanically fixed, often in combination with a permanently installed tube lens.
A long working distance is essential in metallography, as illumination often needs to be applied from the side. This clearly distinguishes such objectives from traditional microscope optics designed for laboratory use with transmitted light—where a long working distance is often unnecessary or even counterproductive.
The HLB M Plan Apo 5x also performs exceptionally well in a focus stacking setup. When combined with a suitable tube lens and a full-frame camera, the generous working distance allows for flexible lighting control and significantly simplifies object illumination.
The HLB M Plan Apo 5x is part of a parfocal objective series with a uniform housing diameter.
The Manufacturer
The HLB M Plan Apo 5x is manufactured by the Japanese company Shibuya Optical, a producer of lenses, specialized microscopes, and optical accessories for a wide range of professional fields. In Europe, the series is distributed by Stonemaster (www.stonemaster-onlineshop.eu).
The well-known objective series from Mitutoyo likely served as a model, having set benchmarks with its parfocality, long working distance, and excellent imaging quality—albeit at very high prices. The HLB series offers comparable features in many respects. Certain models, such as the HLB M Plan Apo 20x, can match Mitutoyo-level performance, though they are also priced in the upper range. Other HLB objectives, however, are considerably more affordable.
In addition, there are numerous Chinese clones that closely resemble the Mitutoyo design in appearance and are available at even lower prices—but often cannot match the optical performance.
The lens tested here was kindly provided by Rainer-Ernst-Feinwerktechnik for this review.
Technical Specifications
Magnification: 5x
Numerical Aperture: 0.13
Infinity-corrected optics (requires tube lens)
Compatible tube lens focal length: 200 mm
Thread diameter and pitch: M26 x 0.706
Weight: 170 g
Housing length: 50 mm
Housing diameter: 34 mm
Parfocal distance (housing length plus working distance): 95 mm
Focal length: 40 mm
Working distance: 45 mm
Resolution: 2.12 µm
Depth of field: 16.3 µm
Imaging Performance – 208 mm Tube Lens
The following test images illustrate the optical performance of the lens. The first shows an overview shot (full-frame sensor) using the Raynox DCR 150 tube lens, resulting in an approximate nominal magnification of 5x. The two subsequent images each show a magnified crop.
Test image at nominal magnification (DCR 150), with frame markers for the following cropped enlargements – fairly good sharpness, no visible corner darkening, free from chromatic aberrations, and minimal edge distortion.
In the central cropped enlargement, good and consistent detail sharpness, free from chromatic aberrations.
In the corner cropped enlargement, the decrease in detail sharpness is clearly noticeable, with structures appearing softer. A very slight pincushion distortion is also visible in the corners, though it would not be noticeable without upscaling.
The optical performance of the HLB M Plan Apo 5x (NA 0.13) when used with a 200 mm tube lens on a full-frame sensor leaves an overall strong impression, particularly in terms of sharpness, contrast behavior, and field uniformity—though, upon closer inspection, the typical limitations of this lens class also become apparent.
Center
In the center, the lens delivers very good resolution: the fine circuit traces of the test target are clearly separated, appear well-defined, and exhibit strong contrast. Even at high magnification, there are no visible resolution artifacts or chromatic aberrations. Microcontrast is well differentiated, and the image appears clear and balanced. The sharpness is slightly softer than that of the Mitutoyo HR 5x but noticeably superior to that of traditional macro lenses such as the Canon MP-E 65mm at 5:1.
Extended Center
In the extended center—roughly the middle third between the image center and the edge—the image quality remains high. The drop in sharpness is minimal, details are still rendered precisely, and line definition remains clean. Only the finest contrast nuances begin to fade slightly, noticeable in a mild reduction of microcontrast in very small structures—though this does not amount to actual blur.
Edge Zone
In the edge zone, particularly in the corners of the sensor, a clear but not dramatic quality loss becomes evident. Sharpness visibly declines, microcontrast decreases, and finer structures begin to visually merge. However, the subject remains identifiable and geometrically accurate—there are no chromatic fringes, distortion, or astigmatism as often seen near the edges with many macro lenses. The field curvature remains relatively flat. Notably, the edge degradation occurs in a smooth and "forgiving" manner—no abrupt drop-off, but rather a gradual reduction in detail.
Overall Impression
The combination of high central detail rendering, stable performance in the extended center, and still acceptable—though reduced—sharpness in the edge zone makes the HLB Plan Apo 5x a solid choice for focus stacking on full-frame sensors, particularly for centrally positioned subjects.
In direct comparison to the Mitutoyo M Plan Apo 5x (NA 0.14), the HLB falls slightly behind optically, though not dramatically. The Mitutoyo offers more precise line definition in the center, higher microcontrast, and better differentiation of fine structures in the extended center—especially in densely branched circuit patterns. It also exhibits a more gradual sharpness falloff toward the edges, reduced field curvature, and a more uniform, well-balanced overall image.
Nevertheless, the HLB M Plan Apo 5x delivers a remarkably strong overall performance—especially considering its price point. For those seeking a 5x objective for full-frame work and factoring in the significant cost advantage over established Mitutoyo optics, this lens represents a serious and practical alternative—particularly for centrally structured image compositions.
Imaging Performance – 125 mm Tube Lens
The following test image is another overview shot, this time using the Raynox DCR 250 tube lens, which reduces the magnification to approximately 3.125x (instead of 5x). Some metallurgical microscope objectives from the mentioned HLB series tolerate this approach to a certain extent, although not all to the same degree. This test is intended to assess what qualitative compromises can be expected when using the Mitutoyo M Plan Apo 5x under these conditions.
Test image with DCR 250: This shorter tube lens focal length results in a lower magnification. In this combination (which the objective was not designed for!), a crescent-shaped darkening is visible on the left and right sides—an indication that the image circle's optically correct usable zone is already being exceeded.
In the central cropped enlargement, detail sharpness is higher in the center than in the edges or corners. This indicates that the shorter tube lens focal length causes the image to extend into the lens’s aberration-prone outer zones.
In the corner cropped enlargement, distortion and blurriness increase dramatically toward the edge, making approximately one-third of the total image area near the periphery likely unusable.
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Center
In this test shot using a tube lens with only 125 mm focal length, it becomes clear that the lens cannot reach its full potential under these conditions. The central image zone remains formally recognizable and still delivers usable structure, but even here, fine detail loss is noticeable. Microcontrast is reduced, and many of the closely spaced circuit traces in the test target begin to visually merge. As a result, the image appears somewhat soft and flat overall.
Extended Center
In the extended center, image quality continues to decline. Lines lose clarity, edge definition becomes increasingly imprecise. Early signs of field curvature and emerging astigmatism are evident, particularly where vertical and horizontal structures appear differently focused. This highlights the disadvantage of using a shorter tube lens—this objective was designed for 200 mm, and reducing to 125 mm places optical strain on the lens’s outer zones, amplifying aberrations.
Edge Zone
In the edge zone, image quality drops off significantly. Structures become indistinct, contrast plummets, fine lines appear as though softened, and in some areas, geometric structure is barely discernible. While color fringing and field curvature are not extreme, the blurriness increases to a degree that renders this zone nearly unusable for critical applications.
Overall Impression
Overall, it’s clear that the optical performance of the HLB M Plan Apo 5x deteriorates significantly when used with a 125 mm tube lens. The losses are especially severe in the extended center and edge zones. Anyone intending to use this lens on a full-frame sensor should strictly adhere to the specified 200 mm tube lens focal length—otherwise, overall image quality suffers considerably, and the strengths of the lens cannot be fully realized.
Comparison:
HLB M Plan Apo 5x – Mitutoyo M Plan Apo 5x – Canon MP-E
The direct comparison with the Mitutoyo M Plan Apo 5x shows that the HLB M Plan Apo 5x is inferior to this extremely high-end, sharp-rendering objective. However, it's important to keep in mind that the HLB’s purchase price is only about half of what one would pay for the Mitutoyo. Expecting the same level of optical performance at that price difference is simply unrealistic.
For further comparison, the Canon MP-E 65mm was also included, used at the 5x setting with an aperture of f/5.6 (while f/4 might offer a slight increase in sharpness, it also introduces early signs of chromatic aberration—hence the choice of f/5.6). Here, it becomes clear that the HLB provides significantly more sharpness and detail reproduction than a standard full-frame macro lens is capable of delivering.
Three 5x objectives in direct comparison: HLB M Plan Apo 5x on the left, Mitutoyo M Plan Apo 5x in the center, and Canon MP-E 65 at 5x and f/5.6 on the right. The HLB doesn't quite match the sharpness performance of the Mitutoyo, but it outperforms the Canon macro lens.
In the direct comparison of the three lenses—HLB Plan Apo 5x, Mitutoyo M Plan Apo 5x, and Canon MP-E 65mm at 5:1—a nuanced picture emerges, clearly showing the individual strengths and weaknesses of each.
The Mitutoyo M Plan Apo 5x (NA 0.14) delivers the overall sharpest and most precise image reproduction. Lines are cleanly separated, even the finest structures remain distinctly visible, and microcontrast is outstanding. Particularly striking is the crisp rendering of the tightly packed circuit traces in the test target, with no smearing or blooming. The image appears neutral, precise, and calm—exactly what one would expect from a high-end, well-corrected industrial objective.
The HLB Plan Apo 5x (NA 0.13) performs surprisingly well in this context. Center sharpness is high, contours are clearly defined, and contrast is solid. While the image appears slightly less finely resolved than the Mitutoyo—especially in closely spaced structures—the difference is minor and unlikely to be critical for most applications. Only in very detail-sensitive subjects or in large-format prints might the difference become more noticeable. Notably, the HLB shows no distracting color fringes or distortion. Overall, it delivers a very respectable result—especially considering its price advantage.
The Canon MP-E 65mm (at 5:1 and f/5.6) falls somewhat behind in this comparison. Although it is a capable macro lens, it becomes evident that it cannot quite match the specialized industrial optics. Center sharpness is decent, but less precisely defined. In fine structures, the image begins to soften slightly—contrast is lower, and the separation of fine lines is less distinct. Additionally, the image has a slightly warmer tone, indicating a subtly different color rendering.
In summary: The Mitutoyo remains the gold standard among the three optics, closely followed by the HLB, which positions itself as a surprisingly strong alternative. The Canon MP-E 65mm serves well as a flexible macro lens for everyday photographic use, but in direct comparison with the two infinity-corrected precision objectives, it falls short—particularly when it comes to resolving the finest detail.
Imaging Performance – 208 mm Tube Lens: Microprocessor
A tiny microprocessor designed for use in mobile phone electronics features extremely delicate structures. Measuring just 3 x 3 mm, it serves not only to demonstrate a lens’s sharpness and detail resolution but also its color reproduction.
The test with the microprocessor confirms the results: relatively good sharpness performance combined with accurate color reproduction.
The test image shown here—a magnified crop of a smartphone microprocessor (3 × 3 mm)—provides a highly precise impression of this lens’s optical performance in the critical image area.
At first glance, the high image sharpness is striking, characterized by the clean rendering of extremely fine structures. The typical complex trace patterns of the microprocessor are clearly delineated throughout, with no visible smearing or structural degradation. The bright, block-like areas along the right edge, composed of metallic contact surfaces, are rendered with strong contrast and well-separated boundary lines, indicating solid microcontrast control and effective correction of spherical aberrations.
Color fringing is virtually nonexistent—neither along high-contrast edges nor in densely patterned zones with frequent line transitions. This suggests excellent chromatic correction, both axially and laterally. The overall color rendering is neutral—the metallic hues of the processor appear accurate, without discoloration or any visible color cast.
Although the image represents only a central and slightly right-shifted portion of the sensor, there are no signs of field curvature, astigmatism, or loss of sharpness—the flatness of the optical field appears to be very well maintained in the central and mid-frame areas.
Overall, the HLB Plan Apo 5x delivers an impressive optical performance in this capture. The combination of very good resolution, high contrast fidelity, clean color correction, and a largely uniform image impression makes this lens a powerful tool for microscopically precise applications around 5:1 magnification—especially for flat subjects like electronic components or fine mechanical surfaces. While the rendering may not appear quite as “smooth” or clinical as that of the finest Mitutoyo optics, what is shown here is remarkably strong considering its price class.
Stray light hood
While working with the microprocessor, a very weak color contrast was noticed. Attempts to enhance contrast proved successful with the use of a lens hood made from one-sided black, light-blocking cardboard (black side facing inward; lining it with black felt would have been even better). The left image was taken without this lens hood, while the right image was captured under otherwise identical conditions but with the hood, which extended 25 mm beyond the front of the lens body—leaving approximately 20 mm of free working distance. While this won't benefit every lens or lighting setup, it’s definitely worth trying.
Contrast enhancement through the use of a lens hood – worth trying with many lenses under a variety of lighting conditions.
The difference between the two images is clear and speaks for itself: using a simple, homemade lens hood resulted in noticeably better contrast and definition in the microprocessor image. The right image (with hood) reveals finer structures more clearly, blacks appear deeper, and the bright circuit traces more luminous—all without any post-processing.
Left image (without lens hood)
The entire image appears slightly hazy. The microprocessor seems covered by a diffuse veil, and contrast between dark and bright areas is reduced. In regions with high structural density (e.g., center or right half), fine details blend together more, visibly diminishing microcontrast performance. This is likely caused by indirect stray light from the LED sources or diffuser, which is scattered inside the optical system or reflected onto the front lens.
Right image (with lens hood)
Here, the subject shows a significantly better tonal range. The background appears darker, and the circuit paths stand out more clearly. Microcontrast—that is, the subtle tonal transitions between adjacent structures—is improved, enhancing depth and dimensionality. Even small structures in darker regions are more distinctly rendered. The image appears overall “cleaner” and more refined, as disruptive light reflections have likely been effectively blocked.
Overall Impression
These images offer compelling evidence of how effective a lens hood can be—even in reflected-light setups with LED illumination. The issue seems to stem not from direct stray light, but from internal reflections, such as those off the inner walls of the lens barrel or from scattered light within the tube optics. In shorter lenses, these reflections are more likely to bounce back onto the front element or sensor. A longer, matte-finished hood can interrupt these internal light paths.
A simple cardboard cylinder with a black inner lining measurably improves image quality with the HLB Plan Apo 5x—particularly in terms of contrast and microcontrast. The result is so striking that this approach is strongly recommended for all reflected-light applications, especially when working with shiny objects, intense lighting, or where fine microcontrast analysis is required. While it may not improve every lens, it’s a worthwhile experiment for boosting image contrast.
Resolution Test
The Zeiss Resolution Test 300 allows the resolution of a microscope objective to be read as a numerical value. While this reading involves some degree of interpretation and is not perfectly exact (see details here), it does provide a useful general impression of fine detail rendering and image definition.
The resolution value, shown here in the two right-hand fields, was measured at the center of the lens at 360 line pairs per millimeter (lp/mm).
Conclusion
The HLB Plan Apo 5x leaves an overall strong impression, though one that should be viewed with nuance—especially in light of its price.
Mechanically, the lens is solidly built, featuring the compact, parfocal design typical of industrial objectives. The long working distance is a clear advantage for lighting and handling during focus stacking. Its compatibility with a 200 mm tube lens is practical and allows for easy integration into existing setups.
Image quality at the center is excellent. Fine structures are rendered clearly and with strong contrast; lines are well separated, and microcontrast is high. Even in direct comparison with significantly more expensive lenses—such as the Canon MP-E 65mm or the Mitutoyo M Plan Apo 5x—the HLB holds up impressively. The difference compared to the Mitutoyo reference optic is measurable but small—and negligible for many real-world applications.
In the extended image field, sharpness remains good. Structures remain distinguishable, although with a slight drop in contrast and the beginning of some softening. Field curvature is moderate, and overall image sharpness is more consistent than that of many older finite-conjugate objectives or zoom solutions. Compared to the Canon MP-E, the HLB appears less punchy but offers finer rendering of detail.
One area of weakness becomes evident here: sharpness visibly drops toward the edges. Depending on the subject and use case, this may be a drawback—especially with evenly structured objects across the full sensor area. However, the edge softness is not extreme, but rather moderate—comparable to the behavior of many competing objectives. There are no significant issues with color fringing, astigmatism, or severe distortion. For centrally or symmetrically composed subjects, this falloff is quite tolerable. Only when using a reduced tube lens focal length does the quality drop become substantial enough to be problematic.
In terms of price-performance, the HLB scores particularly well. It delivers optical performance that comes close to Mitutoyo quality in many scenarios—at a fraction of the cost. For serious macro photographers who want high optical quality without breaking the bank, the HLB Plan Apo 5x is a very appealing alternative. It is usable on full-frame sensors, though not at maximum quality across the entire image area. On smaller sensors (APS-C, MFT), edge softness is likely to be negligible.
The HLB Plan Apo 5x is a capable industrial lens with excellent center resolution, usable field uniformity, and acceptable edge performance. It presents itself as a cost-effective, serious alternative to the renowned Mitutoyo optics—particularly where budget, space constraints, or emphasis on central image detail are key factors. Those who demand absolute edge-to-edge sharpness will opt for the Mitutoyo. Those seeking 90% of the performance for 50% of the cost will find the HLB an excellent choice.
Advantages
Extremely long working distance, higher image sharpness and detail accuracy than many macro lenses, parfocality within the lens series allowing for easy lens changes, and a significant price advantage compared to the Mitutoyo reference lens (approximately 50% less).
Disadvantages
Unusual thread size requiring a special adapter (e.g., www.stonemaster-onlineshop.de); significant loss of image quality when using a shorter tube lens focal length (DCR 250).
Daniel Knop, www.daniel@knop.de">www.daniel@knop.de, www.danielknop.eu
Testbild mit DCR 250: Im Zentrum ist die Bildschärfe bei dieser Kombination nur moderat und deutlich geringer als bei der Nominalvergrößerung, und außerhalb des Bildzentrums lässt sie gewaltig nach. Hier zeigt sich auch eine leichte kissenförmige Verzerrung. Die Abdunklung des Rand- und Eckenbereichs ist deutlicher als bei Verwendung der DCR 150.
Das Bildzentrum hat noch gewisse Schärfe, aber feinste Details werden in Kombination mit der DCR 250 nicht mehr wiedergegeben.
Die Randzone weist starke kissenförmige Verzerrung und intolerable Unschärfe auf, die zur Ecke hin extrem wird (hier links oben). Im Vollformat ist diese Kombination aus Objektiv und Tubuslinse schlicht unbrauchbar.
Der direkte Vergleich mit dem Canon-Lupenobjektiv MP-E 65 mm bei Stellung 3,5x zeigt, dass das HLB Planapo 3,5x diesem sehr scharf abbildenden Makrospezialisten deutlich unterlegen ist. Das Canon bringt mehr Schärfe (Bild oben rechts), und der Schärfeabfall zum Bildrand und vor allem zu den Ecken hin ist beim Canon deutlich schwächer als beim HLB. Allerdings muss hier auch berücksichtigt werden, dass das HLB Planapo 3,5x neu weniger als die Hälfte dessen kostet, was für ein Canon MP-E 65 mm zu veranschlagen ist.
Vergleich HLB M Plan 3,5x – Canon MP-E 65 mm
HLB Planapo 3,5x (links) im Vergleich mit dem Canon MP-E 65 mm bei Stellung 3,5 (rechts), oben jeweils das rechte obere Viertel des Originalbilds, aufgenommen mit Vollformatsensor (Focus Stack), unten jeweils ein Sechzehntel des Originalbilds, entsprechend hochskaliert.
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