Mejiro Genossen FL1030 Float Lens
The MEJIRO GENOSSEN FL1030 2.5/95 (FL1030) is a unique high-resolution variable-magnification float lens with a fast f/2.5 aperture. The large maximum aperture is required for the high resolving power of 100 lp/mm from 1-3x, remember the wider aperture = higher potential resolution. The FL1030 is designed to work with Teledyne DALSA 16K camera sensor that use a sensor 16,000 pixels wide that is 62mm diagonally with a 3.5 μm pixel pitch. These 16K cameras are used in industrial inspection to find flaws in the production of semiconductors, FPDs (flat panel displays), and PCBs (printed circuit boards). The high-resolving power and large image circle is a perfect match for modern digital medium format cameras and the 3.76 μm pixel pitch used in the Sony A7R4 body used in this test.
Mejiro Genossen FL1030 2.5/95 Float Lens
ABOUT THIS TEST
Mejiro Genossen was extremely helpful in making this FL1030 unit available for testing with accessories and technical support as needed without any strings attached. Thank you Mejiro Genossen!
To give you an idea of what it costs to test a lens like this one, even with a free loan, there are costs involved. Importing this lens from Japan via DHL Express, cost over $300 USD one way with a 50% corporate discount. Fedex Express service was right about $1000 USD one way! (price gouging from Fedex).
RAF camera made the V65 to M72 thread adapter adapter for this test (in record breaking time) for right under $100 USD including USPS Express shipping from Belarus (Express Mail cost more than the adapter). Mejiro only makes V65 rigid tubes specifically for Dalsa line scan cameras that have a very shallow FFD (flange focal distance) that will not work properly on E-mount bodies if you want the full 1-3x magnification range.
This test and all the content on my site is completely independent and free from industry influence and run for free in my spare time. Almost all photography sites today exist to generate profit selling you the products they are featuring by using affiliate links to generate a commission. I do not making any income selling you any products, I do not show ads, use any affiliate links or track your web history. The goal of this site is give people the information they need to buy the right equipment.
KEY FEATURES
Fast f/2.5 maximum aperture
Wide 3x magnification range!
Large 62mm image circle
Excellent resolving power and contrast over the entire image circle
Chromatic aberrations are effectively controlled by a floating element group
Designed to cover 3.5 μm pixel size sensors
V65 V-mount
Flat image field with zero corner shading
Lockable aperture and float rings with large lock knurled knobs
Aperture and float rings are both geared so they can set by external power drives
Very solid all metal construction
Lens azimuth mark
FL1030 PROS AND CONS
What I really like:
Excellent chromatic aberration correction
Extra large image circle
Consistent edge to edge image quality
Locking aperture and float rings
All lettering and numbering on this lens is engraved (no Rayfact decals!)
What I could do without:
Non standard size V-mount
Extremely rare to non-existent availability on the used market
FL1030 Image Quality
Test Setup
Camera: Sony α7R IV, Sony Alpha ILCE-A7R IV (A7R4)
Sensor size: Full Frame. 35.7mm x 23.8mm. 42.9 mm diagonal. 3.76 micron sensor pitch
Flash: Godox TT350s wireless flash x 2 with one Godox X1s 2.4G wireless flash transmitter
A stack of images was made at each magnification on a Nikon MM-11 with a Nikon focus block. The sharpest image was chosen at Photoshop at 100% view. The single RAW file was processed in PS CC 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 test image crops are taken from single images. All test image crops are taken from single images that have been processed identically, with similar sharpening, unless noted.
1x Test Results
Mejiro Genossen FL1030 2.5/95 Float Lens
Magnification: 1x
Sharpest aperture: f/3.8
Note: for best results I recommend the use of a front lens shroud (small diameter hood) for better contrast control.
Click on any image to open a larger version or right (two finger click on Mac) to open in a new tab or to save to compare the images with another app.
Fantastic image quality at 1x and perfectly consistent across the A7R4 sensor.
2x Test Results
Mejiro Genossen FL1030 2.5/95 Float Lens
Magnification: 2x
Sharpest aperture: f/3.0
Note: for best results I recommend the use of a front lens shroud for better contrast control.
Click on any image to open a larger version or right (two finger click on Mac) to open in a new tab or to save to compare the images with another app.
Awesome sharpness and details from edge to edge at 2x. I think this is the peak in performance for this lens.
3X Test Results
Mejiro Genossen FL1030 2.5/95 Float Lens
Magnification: 3x
Sharpest aperture: f/2.8
Note: for best results I recommend the use of a front lens shroud for better contrast control.
Click on any image to open a larger version or right (two finger click on Mac) to open in a new tab or to save to compare the images with another app.
The results at 3x are very good but not as impressive as 1-2x. The best aperture for the FL1030 at 3x is f/2.8 for this copy at least. Resolution at f/2.5 was maybe slightly higher at 3x but there is less contrast and more of what looks to me like spherical aberration (spherical aberration is perceived as halos of glare around high contrast edges).
Final Test Results
The FL1030 is highly recommended. This lens was designed to provide high resolving power without any chromatic aberrations for large fine pitch sensors and the FL1030 delivers. The chromatic aberration control and consistency across the frame is really impressive.
Special thanks to the team at Mejiro Genossen for making this test possible.
April 2022 Update:
Stray Light Control and Resolving Power
The FL1030 test results gave me an idea that there could be an issue that my testing methodology, specially the lighting being used for the test, could be limiting the resolving power of the lens. I checked with Mejiro about my theory and they explained that the FL1030 was designed for use with fresnel illumination technology where the light NA (numerical aperture) is controlled to match the NA of the lens. This type of lighting was originally developed in the micro-lithography industry for stepper lenses and is now used in machine vision in high resolution installations.
Fresnel illumination uses high intensity LEDs, a condenser lens, an aperture to control illumination NA, and a fresnel lens to tightly control the output for uniform distribution. The condenser lens focuses light, controlled by an aperture, and projected by the fresnel lens to match the aperture of the lens. The diffused lighting used in this test limits the resolving power of the lens by reducing contrast due to glare caused by stray light creating ghosting. Partially coherent illumination like fresnel illumination can see increases in resolving power of up to 150% over incoherent illumination ( diffused light from a cloudy sky or a diffuser dome are forms of incoherent light).
Mejiro FL1030 vs Macro Varon 4.5/85 CAS
The FL1030 resolving power of 100 lp/mm from 1-3x across a 62mm image circle is pretty amazing since this means the lens is a perfect match for any of the modern digital sensors with 3.xx micron pixel pitch. The Macro Varon, for example, can only reach the 100 lp/mm figure at 1x.
Curious to see the difference in resolving power between the high powered FL1030 and a slower high-end lens, I decided to shoot a few frames with a Macro Varon 4.5/85 line scan lens with the same identical setup I used with the FL1030 and used identical processing for the image samples below. I was really curious to see what kind of difference would be visible going from f/4.5 to f/3.0 at 2x. You can compare image samples from the two below. There is definitely a difference that is easy to make out, but the difference is not as great as I expected, and this is with a subject with extremely fine detail. So I think it’s unlikely you'd ever notice a difference in real world use except by side-by-side comparison and measurement with a subject with lots of micro-detail.
Click on any image to open a larger version or right (two finger click on Mac) to open in a new tab or to save to compare the images with another app.
The FL1030 f/3.0 lens is definitely sharper when compared at 100% but both lenses really are excellent. Comparing the images using a web browser though, I’m not sure you will be able to see the differences, this is due to the fact that all web browsers smooth out details and sharpness. For best results right-click or two-finger click and save-as and open the images in an OS preview app, Photoshop app or an image viewing app like PhotoMechanic where you can compared the images side-by-side or even better in a stack, A-B style.
Mejiro FL1030 1x MTF Data
Officially the FL1030 can resolve over 100 lp/mm from 1 to 3x. MTF data provided by Mejiro Genossen.
Mejiro FL1030 2x MTF Data (with Macro Varon)
The Macro Varon can resolve 100 lp/mm only at 1x looking at Schneider MTF data. Unfortunately Schneider does not provide wavelength weighting for the MTF data so it was impossible to have Mejiro generate a directly comparable graph. I’ve never seen the Macro Varon MTF data published anywhere online before so I wanted to include it here anyway even though file quality is poor.
Mejiro FL1030 3x MTF Data
What is a Float Lens?
The phrase float refers to the aberration correcting floating element group controlled by the magnification setting ring. Ideally, all lens aberrations like field curvature, corner softness, spherical and chromatic aberrations, even focus breathing, could be adequately compensated as you focus a lens closer. But in reality most lenses have poor performance at their closest focusing distance. Compensation is very difficult at close distances. One effective solution used by lens manufacturers is the use of “Float” system. This design compensates for aberrations at different magnifications by changing the axial distance between individual lens elements or groups. The float system moves groups of lens elements closer or farther apart, sometimes at different rates, to correct aberrations at various magnifications. This system, controlled by cams, is set with a geared magnification ring. This ring is either controlled automatically by a small stepper motor, or directly by hand. The FL1030 float ring works exactly as advertised, images made during this test are sharp and free from lateral chromatic aberrations (LaCA) and longitudinal chromatic aberrations (LoCAs) from 1.0 to 3.0x.
Mejiro Genossen FL1030 2.5/95 Float Lens
FL1030 TECHNICAL SPECIFICATIONS
Mejiro Genossen FL1030 2.5/95 Float Lens
Part Number: MG1011
Type: variable-magnification high-resolution large format float lens
Focal length: 95mm (+/- 2%)
Optical structure: unknown
Numerical aperture: 0.059 @ 1x, 0.110 @ 2x, 0.146 @ 3x
Resolution: 4.67 µm @ 1x, 2.5 µm at 2x, 1.88 µm at 3x
Aperture for best image performance: f/3.8 @ 1x, f/3.0 @ 2x, f/2.8 @ 3x
Aperture range: f/2.5 - f/4.3 (f/4.3 is the minimum aperture)
Iris type: circular, 13 blades
Sensor: up to 16k/3.5 μm & 12k/5 μm (large format line and area scan)
Maximum sensor size: 62mm image circle
Resolving power: 1.0x: 100 lp/mm, 2x: 166 lp/mm, 3x: 250 lp/mm
Distortion: 0.044% @ 1x, -0.029% @ 2x, -0.035% @ 3x
Working Distance: 148mm @ 101mm @ 2x, 85mm 3x, front glass to subject
Manufacturers recommended magnification range: 1.0x - 3.0x
Reference wavelength: 546.07nm (e-line, green)
Wavelength range: 436nm - 656nm
Lens interface: V65, 65mm V-mount
Filter thread: M49 P= 0.75mm
Weight: 992g
Source: Lens made in Japan
Retail price: $
The Mejiro Genossen Float Lens Lineup
Mejiro optics are unknown outside the industrial optics industry. Currently I own three Mejiro lenses, the 4.0/110 FL0530, 5.6/90 OTH075 and 5.6/90 OTH100, and these are some of my favorites and some of the highest performing lenses that I own!
The FL1030 is one of the two floating element variable magnification lenses in the FL lens group sold by Mejiro to cover a 62mm in diameter image circle down to a 3.5 μm pixel pitch. The other lens in this FL series, the Mejiro Genossen FL0530 4.0/110 Float lens has been tested here on Closeuphotography.com, you can find the full test with this link: https://www.closeuphotography.com/mejiro-float-lens. Mejiro also makes two other float lenses, the MG-1014 and the MG-1015 that cover 43mm diagonally, for 0.1x - 0.47x, and 0.018x - 0.15x magnification ranges.
Mounting the FL1030
Mejiro makes rigid 100mm V-mount tubes designed to mount on Dalsa line scan cameras. Unfortunately these V-mount tubes will not work properly due to differences in FFD (flange focal distance is the distance from the mounting flange to the image sensor plane), the Dalsa cameras have an ultra short FFD. RafCamera designed a custom V65 to M72 adapter that was a perfect solution to allow me to test the FL1030 lens.
You can find RafCamera via this link: https://rafcamera.com/