Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs Ė and Large Sensor Photography => Topic started by: jam275 on May 05, 2021, 10:27:47 am

Title: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: jam275 on May 05, 2021, 10:27:47 am
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
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: dkaufman on May 05, 2021, 11:25:15 am
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
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: 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.  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
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: epines on May 06, 2021, 12:04:11 pm
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.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: ben730 on May 12, 2021, 12:23:51 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. 

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
 
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: Paul2660 on May 12, 2021, 03:16:19 pm
Ben

I think from what I have seen the Schneiderís being a symmetrical design do not have same issue. I have tested my Schneider 35 against the Rodenstock 32 and 40mm and the edges look much better none of the flattening I see with the Rodenstocks. The 35 Schneider however canít be shifted very much if any on a 3100 or IQ4 so I mainly use the Rodenstocks.

My 40mm shows the issue a bit more than the 32. And past 12mm of right or left shift the problem gets much worse.


Both lenses are very sharp however so I canít complain.

Paul
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: ben730 on May 12, 2021, 03:56:01 pm
Thanks for your reply Paul.
Could you please post an example with the 35 digitar against the 32 HR.

I sold my 35 digitar long time ago and only have the 32 HR.
I compared it with the Fuji GF 30, but there is no difference concerning flattening.
I had the 28 Superdigitar and the 28 HR at the same time
and could not see any difference in distortion except the mustache.

Thanks,
Ben
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: chrismuc on May 12, 2021, 11:24:20 pm
You might see two kind of wide angle distortions:
1. Linear distortion of focal length vs. angle. The retrofocus lenses mostly have second order distortion, that means wave-/mustache shape. The Rodenstock presumably has stronger distortion than the symmetrical Schneider.
2. Perspective distortion of wide angle lenses towards the edge or corner of the image (every circle becomes oval). That effect is unavoidable and only depends on the field of view of the lens with a particular sensor size.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: adammork on May 13, 2021, 04:26:26 am
Another possibility is Alpa's lens correction software which is excellent but only runs under 32 bit versions of Photoshop (CS6).

David Kaufman  www.davidkaufmanphotography.com

The Alpa lens correction software still works under the latest photoshop - you just have to remember to click the ďload parametersĒ each time, before pressing preview or apply - even if it seems that they are loaded already - then it works - at least on our systems.

Fantastic lens, my favourite wide - kind of small and super sharp - only drawback is that for architectural work you have to deal with the distortion, itís not as strong as the 32, but itís still present - with the the 50 you can get away with no post correction for most motives with shifts less than 15mm.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: USM on May 13, 2021, 08:56:21 am
Would it be possible to get a image showing the different distortions of the Rodenstock and Schneider?
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: adammork on May 13, 2021, 10:43:16 am
I had the full line of Schneiders, now I have the Rodenstocks - simply put, you do not need to apply any corrections to the Schneiders - if you like straight lines you are forced to do it with the Rodenstocks 23, 32, 40 and to a certain degree with the 50 as well.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: Pforster on May 13, 2021, 11:05:41 am
For my Alpa STC I have the Schneider 60, 90 & 120 but the Rodenstock 40mm is my go to lens every time.
Maybe Iím not as critical as others, or because I take almost exclusively landscapes, but the distortion has never been a problem at all for me and I donít feel the need to make any corrections.
With the IQ4 150 (and the ability to crop to a mere 50mpx) it serves as a brilliant all rounder and I rarely use the SK 60 now.
Just my experience but I hope it helps.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: alan_b on May 13, 2021, 05:24:15 pm
Would it be possible to get a image showing the different distortions of the Rodenstock and Schneider?

Here are Rodie 32 (orange) vs SK 35 (blue) distortions over a reference grid (gray), centered and with 10mm rise on a landscape format IQ 4150 frame.  Distortion values are from Alpa's Lens Corrector (inverted for this illustration).
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: Gigi on May 13, 2021, 09:38:06 pm
Have the Schneider 43, which is rumored to be a later (better) lens than the 47. From examples, the 40 has a very good look, but its bigger and more delicate than the Schneiders. Might consider the 43, and then shift/stich as needed?
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: USM on May 14, 2021, 05:40:50 am
Here are Rodie 32 (orange) vs SK 35 (blue) distortions over a reference grid (gray), centered and with 10mm rise on a landscape format IQ 4150 frame.  Distortion values are from Alpa's Lens Corrector (inverted for this illustration).

Great! Thanks! Do you also have a Rodie HR 35 vs SK 35 comparison?
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: alan_b on May 14, 2021, 12:54:51 pm
Great! Thanks! Do you also have a Rodie HR 35 vs SK 35 comparison?

Sure: Rodenstock HR35 (red) vs SK 35 (blue), 10mm rise. Dashed line is 33x44mm frame.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: USM on May 15, 2021, 07:56:10 am
Thanks again!
So I can also compare the HR 32 with the HR 35.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: USM on May 15, 2021, 08:44:09 am
Would you mind to make one for the HR40?
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: David Eichler on May 16, 2021, 02:39:43 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.  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
So, retrofocus wideangle lenses exhibit greater anamorphic distortion than lenses of symmetrical design?
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: David Eichler on May 16, 2021, 02:42:47 pm
You might see two kind of wide angle distortions:
1. Linear distortion of focal length vs. angle. The retrofocus lenses mostly have second order distortion, that means wave-/mustache shape. The Rodenstock presumably has stronger distortion than the symmetrical Schneider.
2. Perspective distortion of wide angle lenses towards the edge or corner of the image (every circle becomes oval). That effect is unavoidable and only depends on the field of view of the lens with a particular sensor size.


The second kind of distortion is not perspective distortion. It is called anamorphic distortion, volume deformation, or volume anamorphosis.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: alan_b on May 18, 2021, 02:14:01 am
Would you mind to make one for the HR40?

Here you go: Rodenstock 40 HR W at infinity, 10mm rise. (IQ 4150 frame w/ dashed 33x44 lines in red.)

FYI, the free Alpa Corrector PS plugin and a selection of distortion charts is available on their site here:
https://www.alpa.swiss/products/900-100-010-alpa-acam-lens-corrector-plug-in (https://www.alpa.swiss/products/900-100-010-alpa-acam-lens-corrector-plug-in)

Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: alan_b on May 18, 2021, 02:32:19 am
The second kind of distortion is not perspective distortion.

Yep, it's expected and "correct" in a rectilinear projection.

Quote
It is called anamorphic distortion, volume deformation, or volume anamorphosis.

Is that a commonly accepted term?  I thought it was something DXO made up.

I learned to manually construct perspective drawings in architecture school, back before inexpensive 3D modeling software was widely available.  If the angle of view was too wide, we'd usually find a way to fudge/compress the extreme stretching at the edges so things looked somewhat normal.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: USM on May 18, 2021, 04:23:40 pm
Here you go: Rodenstock 40 HR W at infinity, 10mm rise. (IQ 4150 frame w/ dashed 33x44 lines in red.)

FYI, the free Alpa Corrector PS plugin and a selection of distortion charts is available on their site here:
https://www.alpa.swiss/products/900-100-010-alpa-acam-lens-corrector-plug-in (https://www.alpa.swiss/products/900-100-010-alpa-acam-lens-corrector-plug-in)

Found everything. Thanks again.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: David Eichler on May 23, 2021, 07:38:17 pm
Volume anamorphosis might be something DxO made up or got from an obscure source, but anamorphic distortion is a widely used term, though most usage of the term relates to anamorphic projection for theater display.

Broadly speaking, perspective distortion might cover this effect, since each part of the film or sensor plane has a slightly different perspective. However, perspective in photography most often relates to the position of the entire sensor or film plane, so I think it is best to limit usage of the term to that kind of perspective, in order to avoid confusion.

Yep, it's expected and "correct" in a rectilinear projection.

Is that a commonly accepted term?  I thought it was something DXO made up.

I learned to manually construct perspective drawings in architecture school, back before inexpensive 3D modeling software was widely available.  If the angle of view was too wide, we'd usually find a way to fudge/compress the extreme stretching at the edges so things looked somewhat normal.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: Analogous on June 06, 2021, 02:36:32 pm
The Alpa lens correction software still works under the latest photoshop - you just have to remember to click the ďload parametersĒ each time, before pressing preview or apply - even if it seems that they are loaded already - then it works - at least on our systems.

Fantastic lens, my favourite wide - kind of small and super sharp - only drawback is that for architectural work you have to deal with the distortion, itís not as strong as the 32, but itís still present - with the the 50 you can get away with no post correction for most motives with shifts less than 15mm.


A slight tangent to original topicÖ

But, how have you been able to get the Alpa Lens Corrector plug-in to work with the latest Photoshop (CC 2021 on Mac)? With it loaded into the plug-ins folder it doesn't show up anywhere that I can see, definitely not appearing under the "automate" menu as Alpa documentation describes. Other plug-ins are all managed through the Creative Cloud application, and there's no way to add outside plug-ins through that.

Doing architectural work with the HR 32 can often reveal noticeable distortion, particularly in straight verticals extending through the frame. Would be extremely helpful to have the Alpa Corrector to adjust for this. Or is there another way to address this distortion without using the Alpa Lens Corrector?
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: Analogous on June 06, 2021, 07:32:31 pm
SOLVED!
It took a little trial and error, but I figured out the issue.
For anyone that's interested, or runs into this problem in the future, there is one very important detail.Ö

The Alpa Lens Corrector plugin doesn't currently appear to work (doesn't even show up) with the newest universal version of Photoshop CC 2021 designed to work on the Apple M1 chip. It does however still work with older versions.
So, on a newer Apple M1 machine, you'll need to run an older Intel based version of Photoshop (via Rosetta II) to keep using the Alpa plugin.
Hopefully this will change in future updates. But this is the case as of now.
Title: Re: Requesting comments on the Rodenstock HR Digaron 40mm
Post by: Rod.Klukas on July 20, 2021, 07:57:47 pm
One thing I have not seen noted, is the 40mm, as many said is a really good lens especially if the central or mustache distortion is corrected. 

I must say though it is a lens that requires a lens shade, as it is quite prone to lens flare.  With a shade no issues, but without, I have seen many users have an issue, including myself.

The issue with the 47mm is that it was not designed with the resolution of the 150mm back in mind either.  Both the 40mm and 50mm will have better resolution than the 47mm and a 150mm back.

Hope this helps.