Equipment & Techniques > Medium Format / Film / Digital Backs – and Large Sensor Photography

Requesting comments on the Rodenstock HR Digaron 40mm

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jam275:
I was wondering if anyone would share their experience using the Rodenstock 40mm Digaron.  I currently shoot with an Alpa STC using a PhaseOne IQ4 150.  I have a Schneider 47mm Apo Digitar that I use along with Rodenstock 90m and 23mm Alpagons.  The Schneider lens is great in terms of size and image circle, but I can tell it's not as sharp as the Rodenstocks that I have.  I was thinking of purchasing the 40mm lens to take its place (or maybe the 50mm if people recommend it). 

I've read some posts about the retrofocus design of the Rodenstock compared to the symmetric design of the Schneider and how it causes more "moustache" distortion.  I was wonder how big a deal this is.  I've seen some photos posted by other members with the 40mm and they look quite good.  Do the lens profiles in CaptureOne help correct this distortion?

I shoot both landscape and architectural photography.  Thanks in advance for any insight you can provide.

John

dkaufman:
The Rodenstock 40mm is one of their best lenses. It is sharp almost to the edge of the image circle although there is a hard stop that produces a bit of a geometric pattern as you approach the image circle. I also have the Schneider 47mm lens and use both plus five other lenses on an Arca Swiss M-Line Two with various digital backs, now an IQ4 150. The problem with the 40mm lens is its 90mm image circle size which is much smaller than the 47mm lens' 113mm image circle. If you are using movements you have to decide between the two lenses based on the degree of movement and whether or not you are stitching. The 47mm starts smearing as you approach about two-thirds of the way towards the edge of the image circle, at the image edges with more than about 10-15 mm of horizontal movement, but the 40mm is limited to about 15mm movement in both directions with the IQ4150 in a horizontal (landscape) orientation, and less with camera rise (back fall). Without movements my 47mm lens is very sharp, but of a different quality than the Rodenstock. The Rodenstock has a nicer rendering quality, less clinical looking.

As for distortion, there are several ways to correct. One possibility is using Capture One software's distortion  correction, which includes a panel to input your movements. Another possibility is Alpa's lens correction software which is excellent but only runs under 32 bit versions of Photoshop (CS6). I believe a third way may be DxO software but I have never used it. If you use movements or stitching you definitely need software correction for architectural subjects. It's possible but very difficult to fully correct the Rod 40mm distortion without software assistance.

David Kaufman  www.davidkaufmanphotography.com

Paul2660:
To me the problem with both the 32mm and 40mm Rodenstocks, is retrofocus distortion.  Objects towards the edge of the frame elongate and flatten.  Very easy to see with car tires, trash cans, telephone poles, net anything with "known" dimensions.  The 32mm I have is worse than my 40mm, but both lenses exhibit it to some degree.  This is not correctable in C1, LR, or any other software I have tried.  If you shift the lenses, especially the 32mm, you will see if even more as you have pushed the limit of the optical design by moving to the edge of the IC.

40mm is much lighter, does not need a CF for best capture, as the 32mm does.  Both have 90mm IC's as I recall.  Both will show a hard vignetting as you hit the edge of the image circle, due to the IC indicator placed in the lens by Rodenstock.  The Schneider lenses will not show the hard vignette, only a slight much more manageable one. 

Rodenstock may have worked on the issue of the retrofocus distortion with newer copies, my lenses date back to 2016 and 2015. 

Paul

epines:
It's a great lens. Sharp to the edge of the image circle, as others have mentioned. Nicely sharp even wide open at f/4 (but of course improves with stopping down). The moustache distortion is pretty insignificant, in my opinion. Not a big deal, even when shooting straight on to the front of a building. You'll notice it, but it's correctable.

ben730:

--- Quote from: Paul2660 on May 05, 2021, 07:31:22 pm ---To me the problem with both the 32mm and 40mm Rodenstocks, is retrofocus distortion.  Objects towards the edge of the frame elongate and flatten. 

--- End quote ---

Paul
I have seen the mustache distortion of the 32 mm.
But I never saw a "retrofocus distortion" towards the edge of the frame.
I thought wide angles always distort (elongate and flatten) in the edges, also the Schneiders.
It's perspectival distortion.
Regards,
Ben
 

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