I don't understand the point of the centre filter with a large image circle lens like the 43XL. Straight shots with no movements no problem but as soon as you move the lens away from the centre of the sensor the filter doesn't match the fall off pattern and are you not just back to digital correction?
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Is the IQ180 the end for Schneider lenses ? compared to Rodenstock
- Thread starter Christopher
- Start date
Don Libby
Well-known member
Thanks Woody - didn't think it would matter which camera. It's the relation of the lens to the back that does. I'm using the tech wideangle now that I have the P65 and like what it does.
Woody Campbell
Workshop Member
The point of the cw filter is that it compensates for drop off, so an lcc image will appear flat gray where ever it's taken.
Woody Campbell
Workshop Member
I did one major screw up in the above chain of posts. My friend and partner in crime on the IQ 180, Lance Shad, is at Digital Transitions in New York (and the view is out their window across 35th Street) not the other place that I named in my second post. But you knew that because you didn't see palm trees. Mea culpa, mea culpa, mea culpa . . . . Digital Transitions is an outstanding dealer. Fortunately I was still able to edit the post so if you're seeing this for the first time you won't know what I'm talking about.
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Woody Campbell
Workshop Member
I'm in the same happy boat with my H4D-60, which is the same sensor as the P65.
Of course. I definitely want to put back into this forum, given how much I've gotten from it.
The fall-off is a function of the lens. Since the filter sits on the lens and moves with it as it's shifted, then the filter by default compensates for the fall-off pattern. Yes, the fall-off gets stronger as you shift because you are by definition reaching the outer edges of the IC and also because of increasingly oblique light angles exiting the lens (i.e. potentially leading to mechanical vignetting and compounded by photons having to squeeze into pixel wells at these steep angles). But the general shape of the fall-off remains the same. With shift, the filter becomes less efficient at compensating for the amount of fall-off, but it's still better than relying solely on software for pushing exposure in dark corners. The filters are not perfect but they begin to bring the edges and centre of the IC closer in exposure values.
The filters are optimised exposure-wise for zero movements as a default base value, but this does not negate their usefulness. Software can help get us the rest of the way towards a more evenly exposed frame.
The alternative would be to fix the filter in place, say at the sensor plane. But as you shift the lens then the filter would be useless to compensate for the fall-off pattern because the IC is moving relative to the fixed plane of the filter. It will in fact make matters worse because you will end up with the dark edges of the filter overlapping with the dark edges of the IC (imagine two donuts on a parallel plane being shifted relative to each other).
Centre filters are a fact of life when using super-wide lenses with large IC's, whether we are talking about digital MF or 4x5 film. They are notoriously difficult to produce, having to be image neutral, colour neutral and match the fall-off pattern of a particular lens. I'm guessing Schneider would probably prefer not to have to produce centre filters anymore given their insistence that everyone make use of their PS plugin. Fortunately, enough people yelled loud enough about the 43mm XL. I'm sure there some people insisting on a filter for the 28mm Super-Digitar (I would do the same if I owned it).
One "good" thing is that I bet there will be lots more updated lenses and perhaps even a new lens range from Schneider in the next few years. I bet they are working on them already – there is no way that they could not have anticipated all this high-res sensor angst. The 28mm Super-Digitar looks like the beginning of a new direction for Schneider with regards to their tech lenses. Better start saving.
Woody Campbell
Workshop Member
Its the 35 R that has the distortion issue. Im traveling now and hope to try this early next week.
dougpeterson
Workshop Member
Sorry guys we're going to have to run our tests again. Some variables were not controlled that are essential to getting a good illustration of what part of the image circle is fully usable, somewhat usable, and not usable for both the 60 and 80mp sensors.
Thanks for the well wishes re: my health. My doctor saw me very quickly and antibiotics have worked their magic. Still a bit worn down from all the travel lately but no complaints.
We'd love to run all the relevant lenses (28/35/43/47/60 Schneider and 23/28/40 Rodenstock) at the same time and are looking for a focal length or two that we don't have in stock right now. If you have a Cambo mount lens in this field and want to offer up one of your lenses please PM me. We can compensate with discounted rentals and the satisfaction you've helped us clarify this subject for the community. Test will be this Wednesday and/or Thursday in Miami.
Doug Peterson (e-mail Me)
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Thanks for the well wishes re: my health. My doctor saw me very quickly and antibiotics have worked their magic. Still a bit worn down from all the travel lately but no complaints.
We'd love to run all the relevant lenses (28/35/43/47/60 Schneider and 23/28/40 Rodenstock) at the same time and are looking for a focal length or two that we don't have in stock right now. If you have a Cambo mount lens in this field and want to offer up one of your lenses please PM me. We can compensate with discounted rentals and the satisfaction you've helped us clarify this subject for the community. Test will be this Wednesday and/or Thursday in Miami.
Doug Peterson (e-mail Me)
__________________
Head of Technical Services, Capture Integration
Phase One Partner of the Year
Leaf, Leica, Cambo, Arca Swiss, Canon, Apple, Profoto, Broncolor, Eizo & More
National: 877.217.9870 *| *Cell: 740.707.2183
Newsletter | RSS Feed
Buy Capture One 6 at 10% off
Woody, I think there has been a bit of confusion because you refer interchangeably to the Rodenstock 35mm and HR 32mm in your comparisons.
Woody Campbell
Workshop Member
Doug - Glad you're feeling better - we missed you.
nope
Guy Mancuso
Administrator, Instructor
Okay folks . Welcome to the Getdpi debate team
Here in one corner weighing in at SDHC 32gb we have Yup and in the other corner we have weighing in at CF 32gb we have Nope.
Let the debate continue 3 minutes per round for 3 rounds winner gets a free DVD disk. LOL
Here in one corner weighing in at SDHC 32gb we have Yup and in the other corner we have weighing in at CF 32gb we have Nope.
Let the debate continue 3 minutes per round for 3 rounds winner gets a free DVD disk. LOL
Don Libby
Well-known member
You can provoke some of the problems shown with and discussed in the context of the IQ180 with the P40.
Schneider 28mm, wide open (5.6), shifted from 0 to 25 mm, all on P40+.
The Schneider 43mm fares a bit better (if this is of any interest, I could post a similiar LCC sequence for the Schneider 43mm, shifted from 0 to 30mm).
I have no first hand experience of IQ180 files but, at the time being and with my limited experience, I don't think we see a new or up to now unknown problem.
Chris
Schneider 28mm, wide open (5.6), shifted from 0 to 25 mm, all on P40+.
The Schneider 43mm fares a bit better (if this is of any interest, I could post a similiar LCC sequence for the Schneider 43mm, shifted from 0 to 30mm).
I have no first hand experience of IQ180 files but, at the time being and with my limited experience, I don't think we see a new or up to now unknown problem.
Chris
It actually is the same thing no matter what back assuming there are no micro lenses. The critical angle is a function of the sensor pixel pitch. LCC "correction" code also neds to deal with the fact that the cells are not actually uniformly spaced and of consistent pitch; DALSA sensors have additional poly-silicon conductors spaced through the array which the raw processors need to take care of especially as acute angles cause them to cast long shadows.
My pet theory is that there is a specific angle which becomes problematical at a given pixel pitch. That angle determines the widest angle fov that can be accommodated. Note that this FOV is almost independent of sensor size since it is the angle that determines criticality. Thus a large sensor will go critical at a longer focal length than a small sensor but both will go critical at about the same fov for the given pixel pitch.
So what all the hubbub really is all about is folks adjusting to a 5.2 micron pixel pitch and trying to make sense of lenses based on favorites determined with a sensor of different pixel pitch and size.
I propose that a proportional slide-rule would do an adequate job of predicting the results.
thanks
-bob
My pet theory is that there is a specific angle which becomes problematical at a given pixel pitch. That angle determines the widest angle fov that can be accommodated. Note that this FOV is almost independent of sensor size since it is the angle that determines criticality. Thus a large sensor will go critical at a longer focal length than a small sensor but both will go critical at about the same fov for the given pixel pitch.
So what all the hubbub really is all about is folks adjusting to a 5.2 micron pixel pitch and trying to make sense of lenses based on favorites determined with a sensor of different pixel pitch and size.
I propose that a proportional slide-rule would do an adequate job of predicting the results.
thanks
-bob
Chris, those results with the 28mm are quite a surprise to me and look really clean considering its such a wide lens. I'd be really happy with 10mm of movement with this lens. I thought the new 28mm super digitar however was a retrofocus design lens so possibly helping with the issue compired to the usual symetrical Schneider wide lens designs (35XL and 43XL).