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You are here: Home / GFX 100 / Rodenstock 75/4 Apo-Rodagon D on GFX 100S at 1:2

Rodenstock 75/4 Apo-Rodagon D on GFX 100S at 1:2

October 5, 2021 JimK 2 Comments

This is one in a series of posts on the Fujifilm GFX 100S. You should be able to find all the posts about that camera in the Category List on the right sidebar, below the Articles widget. There’s a drop-down menu there that you can use to get to all the posts in this series; just look for “GFX 100S”. Since it’s more about the lenses than the camera, I’m also tagging it with the other Fuji GFX tags.

Yesterday, I tested the Rodenstock 75mm f/4 Apo-Rodagon D on a GFX 100S at 1:1, and found it to be an excellent performer. Today, I’m testing it at 1:2, where — spoiler alert — it doesn’t do nearly as well.

Here’s the test procedure:

  • GFX 100S
  • Foba camera stand
  • C1 head
  • Lens focused to get to 1:1 magnification
  • ISO 100
  • Electronic shutter
  • Indicated f/4 through f/8 in whole-stop steps
  • Exposure time adjusted in M mode
  • Cognisys rail, 100 exposures, 80 um step size
  • Initial focus short of target
  • Convert RAF to DNG using Adobe DNG Converter
  • Extract raw mosaics with dcraw
  • Extract slanted edge for each raw plane in a Matlab program that Jack Hogan originally wrote, and that I’ve been modifying for years.
  • Analyze the slanted edges and produce MTF curves using MTF Mapper (great program; thanks, Frans)
  • Fit curves to the MTF Mapper MTF50 values in Matlab
  • Analyze and graph in Matlab

Here are the results:

The vertical axis is MTF50 in cycles per picture height. Higher is sharper. The horizontal axis is f-stop.

  1. The blue and red columns are for the Rodenstock lens on axis, with, respectively, a horizontal and a vertical edge.
  2. The yellow and purple columns are for the Rodenstock lens at the right edge with, respectively, a horizontal and a vertical edge.

The edge performance is poor.

Here are microcontrast results, with the contrast at a quarter of the pixel pitch being the definition of microcontrast.

 

Well, you can’t win ’em all.

GFX 100, GFX 100S, GFX 50S

← Rodenstock 75/4 Apo-Rodagon D on GFX 100S at 1:1 Illuminants for scanning →

Comments

  1. Helmut Kunde says

    October 5, 2021 at 12:31 pm

    Dear Jim,

    I am following your test with great interest.

    With all lenses it is always very important to know the image scale for which they have been calculated. Otherwise, one quickly compares apples with pears. I am pleased to see that the Apo-Rodagon D 1: 4 75mm 1: 1 can hold its own against new, very expensive lenses. But it is only very good at 1: 1. The first version of the lens was so sensitive to scale that you could already notice a drop at 1: 1.1. The current version is a little less sensitive. At 1: 2 you should definitely prefer the Apo-Rodagon-D 2x 1: 4.5 75mm. As far as I know, 2x refers to projection, e.g. 35mm film on 6×7 cm. If necessary, you should use it in the retro position. For larger formats or larger working distances there is the Apo-Rodagon-D 1: 5.6 120mm, optimized for 1: 2/2: 1, recommended for the range 1: 5 to 2: 1. It is comparable / optically identical to the Apo-Macro-Sironar digital 1: 5.6 120mm.

    If you are very critical, like you, it is definitely worth playing with the distances in the aperture air space – 0.1 mm more or less can be very noticeable in terms of edge sharpness or field curvature, especially in view of the filter packages in front of the Sensors.

    The Leica Apo-Macro-Elmarit-R 1: 2.8 / 100 should only be used at 1: 1 – 1-2 with the Leica Elpro 1: 2 – 1-1 FOR R 2.8 / 100. A normal spacer ring only creates chaos due to the floating elements (as with the Fujinon GF 120mm F4 Macro and many other, similar lenses).

    A very good 1: 1 lens is also the Nikkor AM ED 120mm 1: 5.6. Even old repro lenses such as an Apo-Ronar 1: 9 / 150mm, Apo-Tessar 1: 9/140, Apo-Saphir 1: 10/100 should not be forgotten if you also want to stop down a bit.

    A Mamiya-Sekor Macro 80mm 1: 4 with matching the special Macro Spacer is not to be despised either. Likewise, of course, the Mamiya 140 macros for 6×7.

    Best regards
    Helmut Kunde

    Reply
  2. JimK says

    October 5, 2021 at 1:08 pm

    Thanks for the comments. The SK and Rodenstock 105 HR and 75 Rodagon lenses are so close to diffraction-limited at 1:1 that I can’t imagine an f/9 lens being an improvement, even if it is an excellent lens.

    I used to have a Nikkor AM ED 120mm 1: 5.6. Now I’m sorry I sold it.

    Reply

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