Rodenstock Linos Rodagon 28mm f/4 machine vision lens

This is the Linos / Rodenstock Rodagon 4/28 machine vision lens with an M32.5 mount and M30.5 x 0.5 filter threads. Unfortunately these don’t come up on the used market very often so prices are often too high for these lenses, over $100. The main competitor of this lens, the Schneider Componon 4/28, is a lot more common so prices are much lower than the Rodagon thankfully. I purchased the unit here for $80 in 2019 from an online camera shop in South Korea. That is quite a lot for the lens and it’s not worth any more than that since a Componon 28 can be purchased for less than $50 on eBay in 2019. New this lens is about $750.00 in the US for the latest f/2.8 version.

This lens uses very small optics, the front element is only 10mm in diameter and the rear is 9mm across. High performance optics don’t have to be big, look at the Lomo 3,7x for example but you have to assume small optics are used to cut costs. The Schneider Componon 4/28 is 18mm and 14mm across and is a stronger performer than the Rodagon, especially in the corners.

Testing the Rodagon 28mm f4 at 3.2x MAGNIFICATION

2500 PIXEL IMAGE SAMPLE

Click on the image below to view a larger version in a Lightbox viewer, but this will only be the largest size image if your screen/window is large enough. The size of the image sent to your device is based on the screen size. The below is 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.

For best results I use this lens in a stacked configuration. Stacking lenses, also called coupling lenses, is a technique where you mount a lens in reverse, or face-to-face, on a second lens, usually a telephoto lens. With the rear lens set to infinity focus and with the front lens reverse mounted there is no loss of light due to extension. Together the combination has the potential to resolve more than either of the lenses setup for close-focus with extension.

An f/4 lens focused at 2x magnification by extension would have an effective aperture of f/12 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 using the formula effective aperture = nominal aperture * Magnification. You can predict the maximum possible resolution from a certain lens by using the simple fact that a wider aperture = higher potential resolution.

CROP IMAGES AT 100% VIEW

Below are the center and far corner crops at 100% view in Photoshop.

To see a larger of the crop image just click the image, 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 to save and view the image full size.

Center crop at 100% view in Photoshop

Far upper left corner crop at 100% view in Photoshop

2x TEST SETUP

Front lens: Schneider Kreuznach 4/60 APO-Componon lens reverse mounted
Rear lens: Schneider Makro-Symmar 120 line scan lens normally mounted focused at infinity
Stacked lens nominal aperture: f/4.0
Stacked lens effective aperture: f/8.0

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 I ran a stack of images in 4 micron steps 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.

Rodagon 28mm f/4 all-metal industrial body M32.5 mount

Rodagon 28 TECHNICAL DETAILS

Linos Rodagon 4.0/28 lens (current lens)
Lens applications: Machine vision, line-scan, quality control
Part number: 0701-389-000-20
Filter threads: M30.5 x 0.5
Barrel type: Metal
Optics: 6 elements in 4 groups
Mount: M32.5 x 0.5
Iris: 5 blades
Nominal maximum Aperture: f/2.8
Magnification range: 0.05x (0.2x..0.03x)
Coverage: 32mm
Current Retail Price: $740.
Typical used price: $200-300.

These are 4 types of the Rodagon 28 that you see on the used market:

Rodagon 28mm f/4 all-metal industrial body M32.5 x 0.5 mount, older model as seen above.
Rodagon 28mm f/2.8 all-metal industrial body M32.5 x 0.5 mount, latest current model.
Rogagon 28mm f/4 plastic enlarger lens body 39mm Leica thread mount, discontinued.
Rogagon 28mm f/4 metal enlarger lens body 39mm Leica thread mount. older model dating back to the 1980s and later.

It’s likely that there are even more types of Rodagon 28 out there that I have never seen since the more popular lens like the Schneider 28 Componon have at least 8 different models that you see for sale. Looking at Rodenstock’s lens data sheets the two industrial versions look like they have a similar optical design with the two enlarger lenses being different.

In 2016 I picked up a used 2.8/28 Rodagon in the all-metal barrel but the strange thing was that google had no entries for the lens and it was not even listed on Linos or Rodenstock price lists. It looked like the lens didn’t officially exist. Now in 2019 in the latest and most up-to-date Linos listing in the US, the 2.8/28 is the only version of the 28mm Rodagon currently available, so the f/4 version looks like its been discontinued and replaced by the 2.8/28 Rodagon.

RATING

What I Like:
Image quality is good when setup in a stacked configuration
All-metal body and mount
Decent CA correction

What I Don’t Like:

Typical enlarger lens corner performance drop off
Hard to find on the used market

3.2x test: rodagon 28mm f/4 vs The Schneider componon 28mm f/4

Rodagons can perform very well so it will be very interesting to see how the lens stacks up against the Componon 28 and M-Componon 28, a couple of my favorite lenses of all time and the best performers that I have ever tested in this focal range.

TEST SETUP

Front lens: Rodenstock Rodagon 4/28 Componon lens reverse mounted
Rear lens: Mejiro 5.6/90 line scan lens normally mounted focused at infinity
Stacked lens nominal aperture: f/4.0
Stacked lens effective aperture: f/12.8

Front lens: Schneider Kreuznach 4/28 M-Componon lens normally mounted
Rear lens: Mejiro 5.6/90 line scan lens normally mounted focused at infinity
Stacked lens nominal aperture: f/4.0
Stacked lens effective aperture: f/12.8

Front lens: Schneider Kreuznach 4/28 Componon lens reverse mounted
Rear lens: Mejiro 5.6/90 line scan lens normally mounted focused at infinity
Stacked lens nominal aperture: f/4.0
Stacked lens effective aperture: f/12.8

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 I ran a stack of images in 4 micron steps 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.

3.2x test: 100% view center crops

Click on the image below to see a larger version of the image below with a dark background in a lightbox viewer. Or you can always 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 to save and view the image full size.

Center-crops-100-percent-view-at-3.2x-V-R-R-lens-R-S-S-www-Closeuphotography-com.jpg

The Rodagon does well in the center here at 3.2x at 100% view, nice and sharp without any CAs that I can see. But, both the M-Componon 28 and the regular Componon 28 do a slightly sharper, more convincing job.

3.2x test: 100% view Off-center crops

Click on the image below to see a larger version of the image below with a dark background in a lightbox viewer. Or you can always 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 to save and view the image full size.

Off-Center-crops-100-percent-view-at-3.2x-www-Closeuphotography-com.jpg

Off-center at 100% view the Rodagon image quality slips slightly, where the two Schneider lenses are almost maybe a little better here than the center. Linos quotes a slightly larger image circle of 32mm vs 30mm for the SK lens. After looking at these images I doubt the Rodagon has a larger image circle.

3.2x test: 100% view corner crops

Click on the image below to see a larger version of the image below with a dark background in a lightbox viewer. Or you can always 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 to save and view the image full size.

Corner-crops-100-percent-view-at-3.2x-V-R-R-lens-R-S-S-www-Closeuphotography-com.jpg

In the extreme far corners the Rodagon image quality slips even farther. The M-Componon and Componon continue to do an excellent job even this far away from the center.

3.2X TEST results

The Rodagon 28 is slightly better than average lens but I would not recommend paying more than $50 for one since you can pick up a nice used Componon 28 for that price. The Rodagon 28 is not at the same level performer as the Schneider Componon 28, which is the top 28mm macro lens as far as I have seen in testing.

Quick notes on other 25-28mm lenses that you should know about

All the lenses below have been through my office at least once, like the Minolta 30mm Rokkor CE was tested and sold (no filter threads and excessive CAs), or others like the Componon 28, which I own probably 12 copies in different mounts and versions, and are highly recommended.

Minolta 30mm Rokkor CE: Not recommended.
M39 x 26 tpi, Leica thread mount. No filter threads. Excessive chromatic aberration problems. Can be expensive.

Minolta E. Rokkor 30mm F4.5 enlarger lens: Not recommended.
M39 x 26 tpi, Leica thread mount. No filter threads. Chromatic aberration problems.

Rodenstock Omegaron 25mm f/4 enlarging lens: recommended.
M32.5mm x 0.5mm mount. Sleeper lens. Low cost and decent quality. No filter threads.

Schneider Componon 4/28: Highly recommended.
M39 x 26 tpi, Leica thread mount is most common. Excellent image quality. Good used prices online. Perfect APS-C coverage.

Schneider Componon 2.8/28 Machine Vision Lens: Highly recommended.
V38 mount, All metal housing, even better image quality than the 4/28. Perfect APS-C coverage.

Schneider M-Componon 4/28 Macro Lens: Highly recommended.
44mm V-mount, M29.5-0.5 threaded adapter for Copal #0 shutter mount most common. Great image quality and coverage. Perfect APS-C coverage.

Schneider Xenon 2/28 printing machine lens: Highly recommended.
25mm mount. Good APS-C coverage. Amazing image quality but a little hard to find on the used market.

Schneider Xenoplan 2/28 machine vision lens: recommended.
C mount is most common. Poor APS-C coverage. Amazing center sharpness. Very recommended for smaller sensors.

Voss 25mm f/3.5 enlarging lens: Not recommended.
M39 x 26 tpi enlarger mount. Soft and poor corners at f/4-5.6. Very soft at f/3.5.

LENS DATA

From Rodenstock “ Rodenstock MTF curves are calculated. The reality is when you measure MTF curves on the MTF machine with a lens it could have a tolerance of -10 % at the most."