Update: June 2018, I have a lot more images and information on this lens coming soon so please check this page again later.
High-end industrial film scanning lenses like this Magnagon make great macro lenses because they optimized for sharp edge to edge performance at close-up distances where a typical consumer macro lenses would be at its weakest. Since these lenses were designed for transparency film duplication they have low-dispersion elements for APO or apochromatic correction even though they are not labeled as APO. So what's the catch? They can be hard to find and they are all manual, no auto-focus or auto-aperture, and the most common versions have a fixed aperture.
This lens was purchased on Ebay a year or two ago and was the first Magnagon I had seen with a variable iris. The slower, fixed aperture, f/5.6 and f/8 Magnagon versions show up a lot more often on used market. These were used in Hasselblad Flextight desktop CCD scanners. The lens is found with both Rodenstock label, and later with the Linos name on it.
The Magnagon lens aperture ring is geared, and is not removable unfortunately. Geared control rings are common in machine vision and factory automation applications.
Although this lens is marked f/4, the aperture ring is marked f/3.5, but the iris actually opens to value of f/2.8! In the image above you can see the aperture ring indicator mark set on past f/3.5 setting the iris at f/2.8.
The Rodenstock Linos Magnagon 75mm with the circualr 12 blade iris set at f/32.
This lens is sought-after for the 12 blade circular iris which really helps create a really pleasing bokeh. Most industrial Reproduction/Duplication line scan lenses use a less desirable 5 or 6 blade iris that creates ugly hexagon background shapes.
Rodenstock Magnagon 75mm circular 12 blade aperture on left is pretty rare, a 5 blade hex iris like the one on the right is more common with industrial lenses.
Since they lens is made for an industrial application the aperture has a gear for automated control but that means there are no click-stops unfortunately.
Rodenstock specs:
Rodenstock Magnagon 1:4 f=75mm
Constant optical quality at magnifications between 1:5 - 2:1
Special correction for high resolution CCD’s up to 72mm length
Optimal color correction with special glass types
RATING
Like:
Image Quality
12 blade circular iris
Full frame DSRL coverage
All metal lens body (aperture gear is plastic)
Dont like:
Aperture ring click-stops (this means that you cant set the f-stop by feel).
Aperture ring does not have a lock as most industrial lenses do
Disappointed with:
Without click-stops or a lock on the aperture ring you have to be careful not to bump or change the aperture by mistake
Lack of front threads makes mounting a lens hood more difficult
Information on this lens is almost non-existent
Aperture ring gear in not removable
Image Quality: The Magnagon has very good edge to edge performance. I am in the process of testing this lens now but it seems to perform best at 1X and larger. I will update this info as soon as get more time to shoot with the lens.
TECHNICAL DETAILS
Type: Reproduction/Duplication lens
Focal length: 75mm
Aperture: Although the lens is labeled as an f/4 lens, the markings indicate that it is an f/3.5-32 lens, but the lens iris will open to give a value of f/2.8. So the actual usable aperture range is f2/8 - f/32.
Magnification range: 1X to 2X.
Optimum working aperture: testing
Coverage: Plenty of coverage for a full frame sensor. A full frame DSLR sensor measures 43mm diagonally and the Magnagon covers this with a big 72mm image circle.
Working distance: Good.
Chromatic aberration correction: Very good from f/4.5 and smaller apertures. This lens has very clean image quality, much has much CA better than an typical enlarger lens, APO-Rodagon or Scitex 67mm. There are two types of chromatic aberrations; longitudinal color, LoCAs, also called Bokeh CAs, and lateral CAs, also called color fringing, neither are an issue with this lens. This lens is very well corrected for CAs and LoCAs.
Lens mount: Standard M39 lens mount which is 39mm x 26tpi (turns-per-inch or threads-per-inch). Also known as Leica Thread-Mount (LTM). This is the most common mount for enlarging lenses.
Filter threads: none
Normal or reverse mounting: For best image quality this lens should be mounted in reverse.
Cost: Over the years I have seen maybe 5 or 6 of these variable aperture Magnagons for sale on Ebay from $100-300 USD in good used condition. For some reason most of these lenses on the used market seem to come from Israel or China. The fixed aperture versions sell for a lot less.
Typical installation
More information and images are coming here so check back again soon.
Since this lens has a common M39 lens mount all you need to install is is a set of 39mm extension tubes and a camera mount adapter.
Lens magnification is controlled by the amount of extension. For less magnification you can mount the reverse adapter, step-up ring and lens to the camera directly. For more magnification you can add more extension tubes.
I have read a few times that the Magnagon is a re-badged APO Rodagon D 75mm M=1:1 lens but the APO Rodagon D 75mm 2X f/4.5 seems to be a lot closer of a match.
Magnagon sample images
More coming soon..
Magnagon Comparison Images
More coming soon..