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Rodenstock Aperture only Option

TheDude

Member
Most definitely
Me being sloppy, meant with my (rhetorical) question Digaron lenses.

My understanding is that any stopping down of Digaron lenses will result in a loss of resolution (due to diffraction). But of course sometimes there is no alternative in order to get the necessary depth of field.
 

dchew

Well-known member
Rodenstock recommends as a working aperture for most Digaron lenses ONLY f5.6. For some Digaron lenses also f8 is recommended.

I wonder, why not simply have a fixed aperture of f-stop 5.6?

Is anyone still stopping down lenses for depth of field?
All the time.

I don't know where the "ONLY f/5.6" comes from. Here is a link to their brochure where they recommend a range from f/5.6 - f/11 (several of the lenses referenced have a maximum aperture of f/4):
http://www.rodenstock-photo.com/Archiv/Objektive digitale Fotografie e.pdf

"The HR Digaron-W/SW lenses with a little bit smaller working aperture (optimum: f/5.6 to f/8 or f/8 to f/11) and a larger image circle diameter for sensors up to 40x54 mm provide almost the same extraordinary characteristics."

Dave
 

TheDude

Member
All the time.

I don't know where the "ONLY f/5.6" comes from. Here is a link to their brochure where they recommend a range from f/5.6 - f/11 (several of the lenses referenced have a maximum aperture of f/4):
http://www.rodenstock-photo.com/Archiv/Objektive digitale Fotografie e.pdf

"The HR Digaron-W/SW lenses with a little bit smaller working aperture (optimum: f/5.6 to f/8 or f/8 to f/11) and a larger image circle diameter for sensors up to 40x54 mm provide almost the same extraordinary characteristics."

Dave
If you look at page 6, recommended "Working f-stop" for Digaron-S lenses: three lenses (23mm, 28mm, and 180mm) have f5.6-8 and three lenses (35, 60, and 100mm) have ONLY f5.6 as recommended working apertures.

But I stand corrected that the 90mm Digaron-SW has a recommended working apertures of three stops, f5.6-11, and all other Digaron-W lenses have a recommended working apertures of two stops, f5.6-8. p.15
 
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dougpeterson

Workshop Member
I received the lens yesterday (2 days from London to my front door). The aperture is 9 blades and operates very smoothly and is continuous. F stop numbering ends at f22 but the aperture closes beyond that. It appears to be extremely well made with very tight physical tolerances - unlike Copal 0 shutters.

I've attached a quick iPhone image......

Victor
Yes, as mentioned in our review (https://www.dtcommercialphoto.com/t...ve-the-king-the-end-of-the-copal-shutter-era/) the tolerances and build quality are significantly better than the legacy copal design. Rodenstock was tired of their lenses performance coming out of whack when people used them on copal shutters that weren't originally designed with heavy lens elements and modern high resolution tolerances in mind.

A hugely valued improvement.
 

dougpeterson

Workshop Member
Rodenstock recommends as a working aperture for most Digaron lenses ONLY f5.6. For some Digaron lenses also f8 is recommended.

I wonder, why not simply have a fixed aperture of f-stop 5.6?

Is anyone still stopping down lenses for depth of field?
This thread is starting to groundhogs day.

As posted here earlier in this thread.

Diffraction is not a hard-wall limit; it's just something to keep in mind. At the extreme end, for example, it's a great reason why you should avoid f/32 in almost any situation with almost any modern digital camera.

But very often the (incredibly small) loss of detail that results in stopping down from f/5.6 to f/8 is a totally worthwhile (very small) compromise in exchange for more depth of field and greater confidence of focus in the field. Even at 150mp our raw file testing indicates f/13 or f/14 (along with the diffraction correction tool in Capture One and proper sharpening) will often be a reasonable choice even for those making large prints in scenes were homogeneity of focus is more important than an A++ of pixel detail and focus stacking is not an appropriate tool.

I can't think of a single customer of ours that exclusively uses f/5.6. It would be borderline comical to adopt that mentality.
 

Paul2660

Well-known member
Me being sloppy, meant with my (rhetorical) question Digaron lenses.

My understanding is that any stopping down of Digaron lenses will result in a loss of resolution (due to diffraction). But of course sometimes there is no alternative in order to get the necessary depth of field.
I am sure that’s true. I generally start at f8 and at times go to f14. Never have used 5.6 as the resulting hyper focal is too shallow for me.

Results at these apertures may not be the best possible but with C1 and some the 3rd party software solutions out there for sharpening I feel it’s still a good range.

Paul C
 

TheDude

Member
Even at 150mp our raw file testing indicates f/13 or f/14 (along with the diffraction correction tool in Capture One and proper sharpening) will often be a reasonable choice even for those making large prints
Thank you for your informative reply. Yes, I agree, to have an adequate depth of field is much more important even if there is some (theoretical) loss of resolution due to diffraction.

I only have a CFV-50c digital back and since resolution is relatively low, I never gave diffraction much attention nor noticed any loss of resolution due to diffraction. However, I assumed that with P1's IQ4 much higher resolution one might start to see the effects of diffraction at an even moderate stopped down aperture.
 
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dougpeterson

Workshop Member
I only have a CFV-50c digital back and since resolution is relatively low, I never gave diffraction much attention nor noticed any loss of resolution due to diffraction. However, I assumed that with P1's IQ4 much higher resolution one might start to see the effects of diffraction at an even moderate stopped down aperture.
If you compare an image on your CFV-50c taken at f/8 and f/22 you'll quickly see a marked difference. Even f/16 will be meaningfully softer. That does NOT mean those aperture are not the right choice in some situations; only that, if you don't need them for a particular shot (either for the depth of field, confidence in focus, or extending the shutter speed) that you're better off avoiding them.

Note that the difference is more easily noticeable when using a raw processor that extracts extreme levels of detail from a raw file. I'm very biased, but I think it's pretty objectively clear in any comparison you do that Capture One does this better than any other raw processor. In other words if you use a raw processor that doesn't latch on to all the fine detail available in the f/8 shot then you won't miss it as much comparing it to an f/22 shot where that detail isn't in the raw data. For example, comparing an f/8 and f/22 image in Capture One 5 would not show as much of a difference as comparing them in Capture One 12; the level of detail in the f/22 shot would be (essentially) the same in both cases but the level of (accurate/faithful/correct) detail in the f/8 shot will be better in Capture One 12 due to its improved raw processing math.
 

JimKasson

Well-known member
Diffraction is not a hard-wall limit; it's just something to keep in mind. At the extreme end, for example, it's a great reason why you should avoid f/32 in almost any situation with almost any modern digital camera.

But very often the (incredibly small) loss of detail that results in stopping down from f/5.6 to f/8 is a totally worthwhile (very small) compromise in exchange for more depth of field and greater confidence of focus in the field. Even at 150mp our raw file testing indicates f/13 or f/14 (along with the diffraction correction tool in Capture One and proper sharpening) will often be a reasonable choice even for those making large prints in scenes were homogeneity of focus is more important than an A++ of pixel detail and focus stacking is not an appropriate tool.
Right. The way to think of this is managing the four sources of blur -- pixel aperture, lens aberrations, diffraction, and defocus -- to maximize sharpness in those portions of the image in which it is important. I thought I was pretty good at doing that by intuition and experience, but a few months ago I wrote some software to optimize focus distance and aperture for a given camera to minimize blur for subject matter at specific distances, which I measured with a laser rangefinder. I found that in general I was not quite as aggressive in stopping down as I should have been. It was a useful training exercise, even though I'd have to bring a laptop along to run my optimizer in the field.

Here are a few examples:

https://blog.kasson.com/nikon-z6-7/ff-examples-of-optimal-blur-management/

https://blog.kasson.com/the-last-word/optimizing-aperture-and-focus-distance-an-example/

You can buy an iPhone app called True-DOF that will not do the optimization for you, nor will it compute the effects of pixel aperture blur or lens aberration blur, but it will show you the combined effects of diffraction and defocus blur. If you play around with that for a while, you'll also get a quantitative sense about how far to stop down.

Jim
 

Peegeenyc

New member
Lens cap = $20.00. FPS = $8000.00. Seems like a no brainer to me!:D

Victor
Yeah, ha ha, but... can you get a lens cap on and off in 1/100 of a second? How about 1/1000th? Didn't think so.

The point was that you may need a fast shutter speed to freeze action without rolling shutter issues from ES, so.. for an aperture only lens I simply pointed out that you can use a Focal Plane system like the ones I mentioned to accomplish that.

Let's face it, with these back coming in at $45,000, and lenses at $4000 to $14,000, to spend $7800 on a fast, reliable shutter solution that works for each and every lens, is not so outlandish.
 

TheDude

Member
If you compare an image on your CFV-50c taken at f/8 and f/22 you'll quickly see a marked difference. Even f/16 will be meaningfully softer. That does NOT mean those aperture are not the right choice in some situations; only that, if you don't need them for a particular shot (either for the depth of field, confidence in focus, or extending the shutter speed) that you're better off avoiding them.

Note that the difference is more easily noticeable when using a raw processor that extracts extreme levels of detail from a raw file. ... that Capture One does this better than any other raw processor.
Thank you for your detailed reply. My image cropping and print size was such that I never felt that the print lacked in resolution. And I never felt an urge to test what and where the limits of resolution are.

Unfortunately, Capture One does not support Hasselblad CFV-50c (raw files), we have to use Phocus (for better or worse).
 

Paul2660

Well-known member
Yeah, ha ha, but... can you get a lens cap on and off in 1/100 of a second? How about 1/1000th? Didn't think so.

The point was that you may need a fast shutter speed to freeze action without rolling shutter issues from ES, so.. for an aperture only lens I simply pointed out that you can use a Focal Plane system like the ones I mentioned to accomplish that.

Let's face it, with these back coming in at $45,000, and lenses at $4000 to $14,000, to spend $7800 on a fast, reliable shutter solution that works for each and every lens, is not so outlandish.
The issue of rolling shutter from my experience is over blown at least for most landscape work. I have shot in 35 mph winds with shutter speeds of 1/250 to 1/500 or faster with no new issues. This is with natural subjects trees, leaves, grasses etc. Rolling shutter issues seem much more prevalent with video.

For flash work or subjects such as cars, running people or animals, etc the rolling shutter effect I am sure will be problematic.

ES requires a tripod for my use on MF so far that is the only restriction I have found. But hand holding the IQ4 with an Alpa FPS would be most likely possible. Love the idea of the FPS just can’t get my head around the entire Alpa price points.

Paul C
 
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