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90mm 4.5 APO-Digitar

danlindberg

Well-known member
Great Dave! Now I long even more for mine ;) I should be getting it next week. With my smaller sensor it should be perfectly fine for flatstitching landscapes! Thank you for the preview :thumbs:
 

dchew

Well-known member
For those of you who are really curious about this Schneider 90mm Apo-Digitar, I did some more testing and loaded up some raw files. As usual, even simple testing is fraught with “error bars.” Basic focus errors are impossible for me to completely eliminate at this level, so please keep that in mind. All images include a focus ruler so you can check for yourself. I can see focus shift (or operator error?) even between f/8 and f/11, so viewer beware and have a look at the ruler.

This is the usual boring bookshelf subject. I apologize for that, but it is the best controlled environment I have.* The test goes basically like this:
Equipment:
Schneider f/4.5 90mm Apo Digitar (SAD)
Rodenstock f/5.6 90hr-sw (HRSW)
Alpa STC
IQ3100
RRS 34L tripod w/leveling base
Arca Swiss Cube

Shooting process:
Tethered to C1
Electronic shutter w/ 2 sec delay
Wide open down to f/11 in 1-stop increments
No filters
No LCC
Focus on LensAlign
Shoot, judge focus accuracy, reshoot if necessary
White balance on LensAlign

Shoot two series: One on-center with no movements, a second shifted horizontally 18mm, which equates to a 98mm image circle at the image corner. I moved the camera in order to keep the shifted scene roughly the same as the unshifted scene.

I usually shoot between f/8 and f/16. Even with C1 Diffraction Correction enabled, diffraction at f/16 is pretty clear, so I didn’t bother shooting above f/11. There is one image at f/13 with the SAD in order to see if there was any further improvement at the extreme edge, but I couldn’t detect anything significant. Note the SAD aperture runs in ½ stops from f/5.6 to f/32. There are two positions wider than f/5.6. Wide open is f/4.5, so I assume the detent between f/4.5 and f/5.6 is a 1/3 stop increment.

Results:
If you are in the market for this lens, I suggest you download some of the raw images and make your own assessment. Again, please pay attention to the LensAlign ruler. I do think a few images are slightly front or back focused. Here is an example at f/11. HRSW (left) looks back focused, SAD (right) looks front focused.



In general, the unshifted images are essentially identical at f/11. I am surprised at how similarly these two lenses render in both contrast and color. If you hide the image names, I wouldn’t be able to tell the full-scene images apart, aside from knowing the HRSW is very slightly wider.



Here is the shifted image with image circle diameters (not radius) written in to give you a reference of how it was shifted:


At lower apertures, my previous post summarized the results:


At f/11, The SAD is excellent out to about 72mm, where it slowly falls behind the HRSW. By 98mm I’d call it very good. The HRSW is excellent everywhere. Considering the official image circles are 92mm (SAD) and 120mm (HRSW), I’d say the SAD does remarkably well.

For me, this is where the rubber meets the road:


This is at the extreme edge shifted 18mm, so mid-90mm IC to 98mm. This is the difference between 0.9 lbs / $3000 and 2 lbs / $9000. If you need to shift this far and beyond, AND there will be important stuff in that area of the image, then the HRSW is clearly better.

Raw files are here:
https://www.dropbox.com/sh/kb4wc91hojt33ei/AACDtrdSqX3Q3YQIuNBHXsOva?dl=0
(well, they will be soon - 5 more to go; I’m uploading from a DSL connection…)
Naming should be straight forward:
Example: Cntr_Sk90_11_9200
Cntr / Edge refers to the image without shift (Cntr) and with 18mm horizontal shift (Edge)
Sk90 / Rodi90hr refers to the lens
f-stop is next
Image number

Dave

*Please don't judge my audio equipment; that little thing hasn't been hooked up in the 17 years we've lived here!
 
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RLB

Member
Dave, thanks for the extensive test of these two 90mm lens options. I feel there is another viable consideration based on extensive tested we have done; Rodenstock 90mm APO-Sironar Digital (magenta ring). With an image circle that is far larger than Schneider non-copal APO-Digitar, in fact, slightly larger than the Rode HR-SW, this lens includes a traditional copal 0 shutter, is 30% lighter than the HRSW and physically smaller (virtually splitting the size and weight between the two lenses you tested). Examples of the Rode APO-Digitar can be found that are very clean, sharp and purchased for under $1,800, which is 1/2 of the cost of the Schneider and 1/5 of the cost of HRSW. Optically I'd put the the Rode APO-Digitar closer to the HR-SW in performance (when we tested ours on the IQ4) but not by much. The SDK as you point out is the smallest and lightest option at a reasonable price point. Personally, I find the price jump that Rode's and SDK's have made in the past several years extraordinary.

R
 
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CAMBOUSA

Member
Schneider continues to make new manufacturing runs when properly motivated by the quantity of the order. For example, we (DT) continue to commission new production runs of the Schneider 72 Digitar and Schneider 120ASPH for use on the DT RCam.
And while we are on the subject, I'd like to bring attention to the following post on Facebook last month from Cambo HQ!

Screen Shot 2019-05-15 at 12.28.54 PM.jpg
 

jng

Well-known member
Hi Blake,

Are there any plans by Cambo to sell the 90 Apo-Digitar and/or other focal lengths (e.g., 120mm) in aperture mount for the WRS? Just asking for a friend... :eek:

Thanks.

John
 

CAMBOUSA

Member
Hi Blake,

Are there any plans by Cambo to sell the 90 Apo-Digitar and/or other focal lengths (e.g., 120mm) in aperture mount for the WRS? Just asking for a friend... :eek:

Thanks.

John
Delivery should begin sometime in June (Jokingly I was told somewhere between June 1st and the 30th when I pressed for more information) of all current Rodenstock HR optics mounted in Rodenstock Aperture Only (AO) will be available for WRS. These will be available as standard WRS or T/S varieties depending on which lens is chosen.

Since it has the same size opening as the Copal-0 standard, I believe that retrofitting older lenses is possible. It would likely be done at Rodenstock (with the mounting into WRS mount being handled by Cambo), however I haven't received a 100% confirmation on the process or pricing yet.

Earlier this month I delivered the latest price sheet to all of the US dealers that contains pricing info. Please reach out to your dealer of choice for more info!

**Edit**
Totally didn't answer your question. When it comes to the older SK Apo-Digitar lenses, I don't think any others are available at this time outside of the 80mm mentioned below. And that in itself is a whole different beast. I don't have any pricing on it, but I'd be happy to see what I can dig up.
 
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