Rodenstock Rodagon WA 40mm f/4 Line Scan Lens Test

Rodenstock Rodagon WA 40mm f/4 Line Scan Lens

The Rodagon-WA 1:4 f=40mm above is an industrial lens that shares optics with the Rodagon-WA 4.0/40 enlarger lens only without an Iris diaphragm. This lens is also shares optics with the Rodagon M42 40mm f/4, and the Rodagon F 40mm f/4. Cylinder lenses like this from Rodenstock and others can be found on the used market sold by industrial surplus dealers and salvaged from factory line scan installations.

WA designated lenses, sold by Rodenstock, Schneider, and others, are designed with extended-field for larger image circle. In my experience, these lenses are typically slower than other lenses so they don’t have the potential sharpness of other faster lenses, but they are usually very well corrected for chromatic aberrations.

This lens was sourced from an eBay dealer in Europe and was sold with a Schaeffer Kirchhoff SK 5000 JR line camera with mount, extension tubes, and mounting bracket for only $45 with free shipping and no tax. This no-frills industrial mount design is a little inconvenient to mount but for the price the performance of the lens more than makes up for it. This lens is an excellent buy while the supply lasts, you can find a link for the eBay auction at the bottom of this page.

RODENSTOCK RODAGON WA 1:4 f=40mm QUICK REVIEW

  • Excellent used price online

  • Full frame sensor coverage, 45mm image circle

  • All-metal barrel and mount

  • Good chromatic aberration control

  • Consistent sharpness across the frame

  • Highly recommended

RODENSTOCK RODAGON WA 1:4 f=40mm TECHNICAL DETAILS

Lens applications: line scanning
Filter threads: unknown front threads only. 30,5mm threads are not compatible, so this lens uses either 30mm or 29.5mm front threads
Optics: 6 elements in 4 groups
Mount: cylinder
Iris: none
Preset Aperture
: f/4
Magnification range: 0.25x to 0.05x, optimized for 0.10x
Coverage: 46mm
Current Retail Price: $524. USD
Current used price: $45.

2.5x test: Rodenstock Rodagon WA 40mm f/4 Line Scan Lens vs APO-COMPONON 2.8/40 line scan lens Vs Bogen WA 3.5/40 enlarger lens

For the best sharpness possible I tested these 3 lenses 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.

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.

Front lens: RODENSTOCK RODAGON WA 1:4 f=40mm lens reverse mounted
Rear lens: Schneider Componon 5.6/100 normally mounted focused at infinity
Stacked lens nominal aperture: f/4.0
Stacked lens effective aperture: f/10

Front lens: Schneider Kreuznach 2.8/40 APO-Componon lens reverse mounted
Rear lens: Schneider Componon 5.6/100 normally mounted focused at infinity
Stacked lens nominal aperture: f/4.0
Stacked lens effective aperture: f/10

This lens was found to be sharpest at f/4, and slightly soft at f2.8. The APO-Componon 2.8/40 is best at about 2x - 3x, at higher magnifications the performance will drop off. Also this lens works best stacked rather than focused using extension.

Front lens: Bogen WA 40mm f3.5 lens reverse mounted
Rear lens: Schneider Componon 5.6/100 normally mounted focused at infinity
Stacked lens nominal aperture: f/4.5
Stacked lens effective aperture: f/11.25
Note: this Bogen lens is also sold as a Tominon/Osawa 40mm f/3.5

CROP IMAGES AT 100% VIEW

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

Corner crop at 100% view in Photoshop

Test Results

Highly recommended.

All three lenses do a pretty good job resolving fine details in the center but the Rodagon-WA is very slightly sharper than both the APO-Componon 2.8/40, and Bogen WA 3.5/40. In the corners the Rodagon is slightly better than the Schneider with the Bogen corner quality dropping off dramatically in the corners despite being stopped down f/4.8, and extra half-stop compared to the others.

With better image quality and a larger image circle, the Rodenstock Rodagon-WA 4/40 is a easy recommendation over the APO-Componon 2.8/40, and it costs only about 1/4 of the Schneider lens.

MOUNTING THE Rodagon WA 4/40

Instead of using the front filter threads to mount the lens, I used a 42mm > 32mm step down adapter that slips tightly over the barrel with the threads facing backwards. The lens and adapter then thread into a SM2 extension tube mounted on the front of a Schneider Componon 5.6/100 lens. Mounting from the rear of the lens allows the lenses to sit very close together, without any of the space needed in typical installations with adapters between the two lenses.

Rodagon WA 4/40 stacked setup diagram

Rodenstock Rodagon WA 40mm f/4: different barrels identical optics

The same WA 4/40 lens is available in quite a few different barrel styles, at least 4 that I have seen. The types below feature normal mounts and an iris but they cost about at least 3x - 5x the cost of the industrial pre-set f/4 version on the used market, anywhere from $300 to $600 USD.

Since all 3 of the three versions share optics, they also share MTFs, the difference on the M42 version is just due to a different radius, 23 vs 22mm, causes the graph to scale a little differently. The curves are the same otherwise.

Rodagon WA 40mm f/4 notes

This lens arrived from Europe with a slight case of fungus on the front of the lens, but the problem was actually with the add-on front filter, not a lens element. You can see the filter below, inside the gold colored retainer ring. I decided not to reinstall the filter since it is not look at all like a factory installed part, and it looks like the retainer ring might cause an issue with flare. I did test the lens with and without the filter. Using the filter cause red/pink fringing to appear and the filter slightly reduces magnification from 2.61x to 2.48x. I recommend leaving the filter off when using this lens. All testing was done with the filter removed.

Rodagon WA 40mm f4 MTF Lens Data