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Author Topic: Tech cam wide angles surprisingly poor?  (Read 2039 times)
torger
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« on: March 03, 2012, 12:57:29 PM »
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In my quest for a potential upgrade to digital medium format for my landscape photography I have so far learnt a lot. It seems like it could be a worthwhile step to take, but there is one remaining worry -- wide-angle performance of Schneider Digitar and Rodenstock Digaron tech cam lenses.

I've only found a few test images but they show somewhat discouraging results. I'm not interested in the ultra-wides, but 35, 43 mm does not look too good either. At first, I thought it was some testers that were overly demanding, but after seeing some more test images myself I'm concerned.

What I see is
 - fast dropoff in sharpness from the center and out, even at f/11
 - decentering issues, fuzzier on one side than the other
 - extreme color casts, possibly beyond correction or with large loss of DR and dead colors

One particular eye-opening test is the one I found at Capture Integration, where an IQ180 was used with shift to stitch the whole image circle. Unfortunately they did not use center filters, but the loss of DR seems considerably larger than 2 stops that the center filter will provide. However I do know that the IQ180 is not supposed to perform that well with the Schneider 35mm and 43mm concerning color cast so I did not take too large notice about that. I've also seen some test shots with a P45+ which better corresponds to my target equipment (36x48mm ~40 megapixels).

Here's a link to Capture Integration tests: http://www.captureintegration.com/tests/lens/ I appriciate it *very* much that someone actually does these tests. Not all of us has a high-end photo gear dealer around the corner that can let us test stuff.

I have myself done similar test with my 5Dmk2 and TS-E 24mm II, which FOV-wise corresponds quite well to a 36x48mm (smaller than IQ180) on a 35mm lens. Since the TS-E 24mm has retrofocus design there's no color cast issues and less vignetting as expected, but also less sharpness loss for larger shifts. It may seem unfair pixel-peep-comparing 21 megapixel vs 40 megapixel, which it is, but I see it like this, one of the main reasons for me to move to a larger format is to gain resolution. That is move from a well-performing ~20 megapixel system to a per-pixel equally well-performing ~40+ megapixel system.

When I started study this I thought the deal was getting both more and sharper pixels corner-to-corner, and in addition to that have good tilt/shift-ability. However, after what I have been able to find so far it does not seem to be as simple as that.

With no movements the lenses seems to provide ok performance, although for example the 35mm Schneider struggles a bit with the larger IQ180, and the 43mm Schnieder had in the CI test considerable sharpness loss without movement likely due to some decentering issue. And this is at f/11!

Generally it seems like I can forget shifting as much as I can with my TS-E 24mm. I rarely go beyond 25% of the image height but even those shifts seems to be tough for the Schneiders and Rodenstocks (have not seen tests on the Digaron W 32 though, possibly better, but at 5100 it is a bit too pricey for me). Possibly tilt gives similar problems (have not seen tests).

From focal lengths ~60mm and up these lenses do seem to perform as I was expecting, great corner-to-corner performance, good deal of shift possible. But if the moderate wides are mediocre and allow only for minimal shifts (shift often more important for wides!) it is indeed a HUGE minus.

Any comments? Is there something fishy with the tech cam wides, or have I just looked at the wrong tests?
« Last Edit: March 03, 2012, 01:01:25 PM by torger » Logged
BartvanderWolf
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« Reply #1 on: March 03, 2012, 01:16:21 PM »
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... but I see it like this, one of the main reasons for me to move to a larger format is to gain resolution. That is move from a well-performing ~20 megapixel system to a per-pixel equally well-performing ~40+ megapixel system.

When I started study this I thought the deal was getting both more and sharper pixels corner-to-corner, and in addition to that have good tilt/shift-ability. However, after what I have been able to find so far it does not seem to be as simple as that.

Hi,

You'll get more resolution, but a lot of that is because you don't have to enlarge as much for a given output size.
Large glass is harder to correct than smaller glass diameters.

Cheers,
Bart
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dchew
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« Reply #2 on: March 03, 2012, 02:27:51 PM »
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torger,

I think there is a bit of truth to everything you say, but I also think you are throwing a lot of stuff in a pot, mixing it together and coming up with incorrect conclusions.  I have the SK43 on an IQ180/Alpa STC (also had it on a P65+ for several months), I have tested the Rodi 40HR, and I have the 24 TS mkII (on a 5DII).  I will attempt to address some of your concerns:

  • Color cast:  Unfortunately there is no center filter for the 43xl (yet).  I can shift about 10mm with the 43xl and get what I would call "unnoticeable" results after applying the LCC-technical wide angle in Capture 1.  Up to 15mm I would call "acceptable." These terms obviously depend on the person, but it is in the context of my experience with the 24 TS mkII.  Big note:  This is on the IQ180, which is the worst combination for color cast.  With your "target equipment" this would be significantly improved.
  • Regarding sharpness, I do not share your concern.  On my screen at 100% view, I can get results with the 43/IQ180 just as sharp as the 24TSmII, and that equates to an image 110" wide  Smiley vs about half that for the Canon.  This of course given the shift limitations above.  Frankly I think this is where these Tech Cam lenses excel.
  • The Rodi 40HR does not have near the color cast issues the 43xl does.  However, it too needs an LCC even without shifting.  If anything it is equal to or better in resolution compared with the 43xl.
  • The Capture integration test was done primarily to document and address color and shift issues with the new backs.  I do not know what their focus point was, nor what the DoF calculates out to (yes, even at f/11).  But that wasn't the point of their testing.
  • I do not have any decentering issues with the 43xl, the 40hr, 70hr, or sk150.  I do have a slight issue with my 100hr-s.  This is the opposite of your conclusion that the longer lenses are fine and the wide lenses have issues
  • Since I use an Alpa, I cannot comment on tilt since I cannot do that with wide angle lenses (yet).  I focus blend with Helicon Focus.

So, my experience is essentially the opposite of your conclusions, with the exception of color cast.  If you were looking into a 54x40 sensor, I would say the two lenses you highlight (43xl/35xl) would be your worst choice given your interest in shifting as far as possible.  However, on a 48x36 sensor I think the 43xl is an excellent choice. I do not have any direct experience with the 35xl other than a few shots on a PODAS event.  When I want the highest resolution available in my bag, especially when shifting is required, I will use the Alpa/IQ180/43xl, not the Canon/24TSmII.  Personally I don't think it is even close.

The bottom line is, regardless of location you need to find a dealer that will work with you.  My dealer, although not an Alpa rep at the time, got me everything I needed.  

Dave
« Last Edit: March 03, 2012, 02:45:27 PM by dchew » Logged

torger
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« Reply #3 on: March 03, 2012, 03:26:26 PM »
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Large glass is harder to correct than smaller glass diameters.

Yes, but I have also heard that retrofocus designs are harder to correct than symmetrical designs, so I was kind of hoping that the short flange distance and the vignetting / LCC hassle that comes with it would actually give something in performance back. It probably does, just not as much as I thought it would.

To make a sanity check, I mounted the TS-E 24mm on the APS-C 7D and shifted diagonally to correspond to a fullframe corner, and took a shot at f/8 (tried one at f/5.6 too, about same result, less diffraction but less sharp too). This corresponds to what the extreme corner of a 45 megapixel 36x24mm sensor would look like on the lens, unshifted. It as been slightly deconvolution sharpened. Not exactly super sharp, but no disaster for an extreme corner. Anyway, from this result I can safely say that the extreme corner of a 35mm Schneider at f/11 on a 36x48mm 40 megapixel P45 is clearly sharper (of course).

So indeed, one gains quite a bit with the larger format. Guessing some from what I've seen so far, putting a 35 megapixel sensor in a 36x24mm system stress the optics about the same as the 80 megapixel IQ180 does, looking on the wide tech lenses.
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dchew
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« Reply #4 on: March 03, 2012, 03:55:01 PM »
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43xl, IQ180, shifted 10mm f/11, bottom right corner @100%:

« Last Edit: March 03, 2012, 03:57:08 PM by dchew » Logged

torger
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« Reply #5 on: March 03, 2012, 03:56:27 PM »
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Thanks for the response Dave, it's great to hear from people with practical experience.

I did not think the TS-E 24mm combo would outperform the medium format system, it is only 21 megapixels we're dealing with. However, what I aim at is to get a system that performs well within the movements I do in my photography. If the lens can resolve 21 megapixels with 25% movements without blurry corners, then it performs well for the resolution, which I think the TS-E 24mm does. Pushing in a 40 megapixel sensor in there would yield an other result.

So that's one of the main reasons I consider moving to medium format. But if I then discover that the lenses don't really handle movements with 40 megapixel sensors as well as my old system did with its resolution, then I would be a bit disappointed. I would then either have to accept blurry corners, not print as big as I hoped for, or avoid those compositions. Kind of moving backwards in flexibility.

The focal lengths I'd want to get a good range of FOVs with 36x48mm would be 35, 47, 72 and 120. I have through this researched realized that unfortunately the 35 and 47 focal lengths won't work that well with a P65+/IQ180 -- to steep angle of light. I think it would be nice if Phase One (or some other) continued to develop the 36x48mm sensor size. For tech cameras looks like an ideal size with current lenses, the increase to 53x40mm size seems to reduce movement flexibility a bit more than I'd like. After P45+ there's no back to upgrade to if one wants to stay on that size.
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torger
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« Reply #6 on: March 03, 2012, 03:59:28 PM »
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43xl, IQ180, shifted 10mm, bottom right corner @100%:

Wow! Now I am impressed. That's the kind of results I want to see.

I wonder why there is this variability in results though. If it is just me, or if there actually is some issues with precision, that it is luck if you get a lens that performs as good as a 40 - 80 megapixel sensor can resolve.

From 135 DSLR world I know that lenses vary in sharpness due to precision limits in manufacturing. You can even find stats from lens rental shops, and lenses do vary but within a reasonable interval (at least so far, Nikon D800 36 megapixel maybe will change that :-) ), and those that are bad are obviously bad.

I wonder if it is the same with these lenses, or if there is larger variations and more of those that are slightly off but not totally bad. I was kind of planning to get some lenses second hand and stuff, which is low risk in the DSLR world, but if lens misalignment issues are frequent maybe one have to make all buys via one dealer to get reasonable quality guarantees.
« Last Edit: March 03, 2012, 04:14:53 PM by torger » Logged
dchew
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« Reply #7 on: March 03, 2012, 04:21:25 PM »
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In my opinion a lot of this has to do with focusing.  I mentioned I focus stack sometimes.  That was the case here, so I could actually focus down there in the bottom corner.  Try setting up your 24ts again, live view focus on that jar at 10x (if that is not what you did last time).  I bet your results improve with that lens.

I don't think it is luck.  the 40hr had similar results with my camera and back, and I am not one who gets that lucky. Smiley

Dave
« Last Edit: March 03, 2012, 04:26:47 PM by dchew » Logged

torger
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« Reply #8 on: March 03, 2012, 04:45:33 PM »
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Try setting up your 24ts again, live view focus on that jar at 100% (if that is not what you did last time).  I bet your results improve with that lens.

I did that. I'm quite good at the technique stuff so if the equipment can make sharp pictures they usually become sharp (the image content may suck anyway, but that's an other story). However, that test was a 7D (4.3um pixel size) diagonally shifted to the full-frame corner, an experiment to see how a 45 megapixel DSLR sensor (if we ever see one) would look like in the corner. Possibly the lens performs better close to infinity, but I don't think it will be much better than that. The lens is being a bit outresolved.

Being able to get higher resolution in a single shot without outresolving lenses awakened my desire for medium format.

My expectation when started investigating was that a 40 megapixel 48x36mm sensor shifted 10mm would at f/11 have corners so sharp that it would be virtually impossible to see if it was in the center of the lens or not. It was harder to find out than I thought if this was a realistic expectation or not. I'm still not sure if it is.

(Of course corners will in a real picture generally not be in complete focus though, unless stacking or tilt works in the scene, but I invest to have the peak performance there.)
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Paul2660
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« Reply #9 on: March 03, 2012, 04:59:06 PM »
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Tonger (very good questions)

Dave, Schneider has announced a physical CF for the 43XL, not sure when it's going to ship.  I hope to get a cost
from Schneider on Monday.

Here are the part numbers: I also listed the 60mm Schneider.  Thanks to Guy Mancuso from getdpi.com for this info.  Smiley

1069162, Centerfilter II i, (Apo-Digitar 5,6/ 43mm)
1069161, Centerfilter II h, (Apo-Digitar 5,6/60 mm)

Some more thoughts on wides and tech cameras. My results are pretty much the same as Dave with the 43XL, I am using a IQ160 however.  At the time of
my upgrade from a P45+, I considered the IQ180,  but since I knew I wanted to start working with a tech camera, I stayed with the smaller chip set.  There have been many posts of the IQ180 and results with the various wide Schneiders and Rodenstocks.   It seems that you are limited to only the 32mm Rodenstock if you want to do any serious shifting.  The 32mm has about a 9.5K price point with the Center filter and I knew that for now I didn't want to make that large an investment.   I have shot the 28HR, Rodenstock, 43XL Schneider and 60mm Schneider on the IQ160 and the results are most impressive.  

I have worked with both Canon 24TS-E over the past 5 years and in 2010 upgraded my 24 to the new version.  Really a totally different experience in quality.  So I have a Canon 5D MKII and will sometimes take comparisons between the Medium Format and 35mm.   Best cast here is get a demo tech camera and shoot it with your Canon setup so you can judge the results.

Color Cast, yes it's there and you have to shoot a LCC pretty much everytime if you want to totally eliminate it, it just becomes part of the workflow.  It slows you down, however I was aware of this switching to a tech camera.

Sharpness, I think if you called Capture Integration, (in Atlanta), they would give a very good report on the wides on both the 180 and 160.  Right now on getdpi.com there is very good review of the 28HR (Rodenstock) and 28 Digitar Schneider, here is a link:

http://forum.getdpi.com/forum/medium-format-systems-digital-backs/34991-rodenstock-28mm-hr-vs-schneider-super-digitar-28xl-3.html

I found that the 28HR was best from F5.6 to F8 and after than you did start to see diffraction start to creep in.  The 28HR is going to give you about 5mm of shift max before you start to see the edge of the image circle, so to me it's strength is not in shifting as much as having a 28mm lens in Medium format that is sharp from corner to corner.  I shot the Mamiya 28mm for years and it just wasn't that good a lens.  Basically a very 35mm lens once you cropped out the corners which were mostly very soft/ smeared / or full of CA.  When compared to the 28HR, it's no comparison.  That lens will hold detail to from infinity to about 10 feet and if you add just a small amount of tilt, you can bring that to about 6 feet.  The image quality is strong, with good contrast and no detail smearing all the way to the edges of the frame and CA is non-existent.  The Rodenstocks are actually designed to be used from F5.6 to F11 Max, (this from the Rodenstock lens literature).  The 28HR would benefit from use of the Rodenstock center filter as you pick up about 2.5 stops of exposure.

43XL, on the IQ160(which is the same chip as the P65+) this is an amazing lens.  Color and contrast are stunning and I feel on a IQ160, you can get by without a center filter as falloff on is nominal.  Color cast is easily corrected by shooting an LCC.  Shift, I have taken the 43XL to 20mm of shift on the 160 and found it to be about 90% useable.  After 18mm, you will start to see a bit of detail smearing and maybe just a bit of saturation loss.  Here the use of a physical center filter would help and Schneider has announced one, but it's still not shipping.  43XL is small, light weight and takes a front filter with no problems.  When shifted to 20mm with 2 77mm on the front I did not pick up any hard edge vignetting from the filters.  Unlike the Rodenstock, which is very sharp at F5.6, I found the 43XL starts to shine more in F8 to F16 range.  I did not see any diffraction issues at F16.  Here again if you add in a bit of tilt you can really start to grab an amazing range of focus.  With 1 degree of tilt on a Rm3di, you can get 7.5 feet to infinity all in very sharp focus.  There have been reports of the 43XL not working as well on the IQ180 mainly due to strong Magenta cast and many seem to prefer the 40mm Rodenstock instead.

60XL, to me as sharp as the 43XL.  Color cast correctable with a LCC.  I have shifted this lens 30mm on a Rm3di (30mm left, 20mm right using the cameras default rise and fall as shift).  Light fall off is pretty harsh by 25mm but it was still correctable with the LCC.  No color/saturation fall off.  Detail/resolution as good as the 43XL and seems to shine again in the F8 to f16 range.  I felt I was starting to see diffraction at F16 on this lens, but only slight.

Best case, is you really have to pick a dealer, one that will allow you to either demo the equipment with your back( very key) or will meet you and provide a demo session.  You can read about these lenses all day long, but unless you take one out and get the hard results to from your back you really can't get a feel for what you are going to see.   I found Capture Integration (Atlanta) very helpful here and felt they provided added value both in providing equipment for me to use, a back (both IQ180 and P65+) and a full day to shoot.   If possible make sure you check out at least 2 brands, I looked at Cambo and ARCA and went with ARCa.  I would also submit you post this same question on www.getdpi.com as there are many users over there that have shot all the various wides on the IQ180.   No matter which option you pick, it's a big investment and a dealer relationship is important (I feel much more than when looking at a Phase One and DF body and lenses option as there is a ton of data out there on this equipment).

Paul
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Paul Caldwell
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torger
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« Reply #10 on: March 04, 2012, 10:52:20 AM »
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Thanks for the helpful replies. Since I'm located far up north in Sweden the dealer bit will not be too easy. I don't think there is a single dealer in Sweden that do both digital backs and tech cams. I'm also the worst customer, medium format market is for pros with a business not demanding amateurs on tight budgets. It's not fair getting loads of help from a dealer and then go shopping a digital back on ebay. So my plan is kind of doing this on my own. Possibly the risk of doing that is too large though.

The wides is the largest risk as I see it. Long lenses (should) have less tolerance issues, are lower cost, there are plentiful of FOVs to choose from, and they work well regardless sensor. On the wides it is (for my style of photography) more important that the FOV is just right, and there are some really expensive lenses down there and there are question marks around performance (especially shifted) and sensor combinations.

The LCC calibration shot is no problem for me, I'm the multi-shot type of guy anyway, the worry I have about that is that too much dynamic range is lost or too complicated distortions (uncorrectable) occur. Clearly choosing the right back and use center filters will be important there.

The Schneider 35 is 2300 (ok), the Rodenstock 32 is 5100 (too expensive for my budget), the Rodenstock 35 has too small image circle, the 28 is too wide for my style.

There's a huge difference on the budget between getting the Schneider 35 and 47 (2300 + 1500) compared to getting Rodenstock 32 and 50 (5100 + 3000). There also cannot be helical mounts, Arca-Swiss and ALPA mounts stress my budget too much. I've investigated the Linhof Techno and it seems ok, wides will be a bit challanging to focus due to dim ground glass, but I think I can manage a 35mm.

So, well, when I look at it like this, I realize that my budget equation (and not desiring ultra-wides) practically narrows down the wide angle choices to one solution - Schneider 35XL and 47XL with Copal shutters on a lens board and digital view cam like the Techno. That's a 4000 lens solution, compared to 10000 for an Arca-Swiss RM3Di/Rodenstock solution, and even more expensive for ALPA. To me that's unfortunately the difference between "go" and "no go", so I just can't pick the solution that performs best, I must pick a solution I can afford and verify that it performs adequately within my expectations.

Digital backs equation means second hand discontinued products - always going to be several years after "the latest", so what is on market today is what I'll use in 10+ years. It narrows down to P25(+) as a shorter term entry point, then P45(+) which probably would be long term and then possibly P65+ although it seems to be less suitable for the wides. There's some other brands too to look into, but I know there are backs that are particularly unsuitable for tech cam wides so it is a careful choice to make.
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Brian Hirschfeld
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« Reply #11 on: March 05, 2012, 06:42:15 PM »
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Take a look at the Hartblei Hcam which I review on my website here, I hate to always mention it and try to keep it low key in discussions like these, but I did my tests mostly with the Canon 24mm TSE II lens, http://brianhirschfeldphotography.com/2012/02/24/in-depth-review-of-the-hartblei-hcam-b1/ and found it to preform very very well. You get the resolution of the digital back, with your already owned Canon 24mm and technical camera like shooting experience. Just a thought, I want to point out again I have no affiliation to this company other then the fact that I was asked to review their product. In my review, I found it to be very capable of the things you seem to want from a camera. That said, you could easily I am sure, content yourself with something like a Linhof Techno, with a standard focal length lens, and a DB and with some work achieve very nice results as well.
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« Reply #12 on: March 05, 2012, 09:30:12 PM »
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I second everything Paul 2660 writes regarding the Schneider 43mm lens. I am using it on a Hasselblad H4D50 back and I find that I can safely shift mr Arca Swiss RM3DI 15mm in either direction and maintain sharpness while exhibiting some magenta cast issues which are correctable with an LCC and employing "scene calibration" in Phocus.
When using just 1 degree of tilt, I am amazed at the depth of field; although I must admit that focus stacking achieves the same/similar result.
Although it is a lot of work, I enjoy stitching 9 images together (shifting and rise and fall), but keeping track of the images and the LCC's requires a good deal of concentration. IMO, adding narrative to an image in many cases vastly improves the final result; a technical camera is without equal in this regard.

Stanley
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