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Schneider 35 XL corner performance

gazwas

Active member
From other examples I've seen it is clear to me that far from 90mm of the image circle is usable. My guess is that with a 33-39 megapixel back 48x36mm one will not want to shift more than ~10mm with this lens. That corresponds to 74mm image circle.
The Schneider does indeed had a 90mm IC but the problem with all of the symmetrical wide lens designs from Schneider is that they suffer quite large amounts on field curvature at the expense of having virtually no distortion. Imagine a point on a football (soccer ball) with this representing the centre of the lens. As you move further away from this point, like moving towards the edge of the camera frame the focus moves further from the central point on the ball/lens. This is why as you shift the edges start to look smudgy. Stopping down will help to f16/f22 but diffraction then can effect overall sharpness.

I'm afraid you takes your pick...... symmetrical Schneider's with no distortion but field curvature or retro focus Rodenstock's with very little field curvature but moustache distortion and of course smaller IC.
 

torger

Active member
The 35mm focal length indeed seems difficult. The MTF charts of the Schneider show that it is quite good at f/11 up to 70-75mm IC, then there's a sharp slope towards the 90mm edge where the performance according to the MTF is not good at all, actually worse than my current Rodenstock Apo-Sironar digital 35mm/4.5 (not to confuse with the Digaron-S).

I do landscape so my requirements are not as tough as for the architecture photographer, but the Schneider is really scary. It seems likely that the Rodenstock Digaron-S 35/4 is sharper all the way up to its 70mm edge, and it also seems likely that I will not like the performance outside 75mm of the Schneider. If that is true, I'm in practice choosing between a very sharp lens with 70mm image circle and a sharp lens with a 75mm image circle with noticable but minor issues 65-75mm. Is those 5mm worth it? Hmm... decisions decisions...

On the other hand I don't have as extreme quality requirements, probably the Schneider is ok for my use, but I guess I got used to the feeling of pixelpeeping and thinking "boy that's sharp all the way to the edge!" rather than "that will look ok on a print" (which it usually does).

Does anyone know of any fullsize Digaron-S 35mm sample images by the way?
 

gazwas

Active member
It is a very difficult choice between those two lenses and one I often contemplate. I keep watching the for sale forum for an Arca R mount 35XL but is seems users keep hold of these lenses so they can't be all that bad.

I would love a lens in this focal length as anything wider is too much for my taste but have just continued to wait, hoping that Schneider will update the 35XL to a Super Digitar XL and address some of its issues.

The RS 32HR-W is a possible alternative but for me its way too expensive, too much distortion and is the size of an elephant gun.
 

torger

Active member
Found this old lula thread with an full resolution sample of the Digaron-S 35mm on an Aptus 75 from the time the lens was called Apo-Sironar HR.

C645+D35/3.5 vs ALPA+Rodenstock 35/4 HR

Unshifted it looks very sharp indeed. From estimates in the pictures provided in the excellent 28XL vs 28 Digaron-S review in this forum it seems like the usable image circle of that Digaron-S is actually 72mm, which would mean close to 9 mm shift in landscape and 7mm in portrait with the 48x36mm Aptus. It would be interesting with a test shot of the 35mm Digaron-S showing the image circle all the way past the edge.
 

danlindberg

Well-known member
After calibration I am very pleased with my SK 35XL. Results with rise of 10mm with sensor vertical is excellent. However, after that I do detect degradation for every mm.

This example has a downfall of 8mm with sensor horizontal. Vertially no difference in sharpness if the lens was zeroed. Very useful.

And, the lack of distortion is fab! I'm a happy camper :)

 
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torger

Active member
Very nice image Dan, as always.

10mm rise in landscape corresponds to 74mm image circle. From all the test shots I have looked at and all the discussions I've read it seems like a very realistic expectation from this lens is a 74mm IC shot at f/11, which should be shot on a back which don't have much lens cast issues. If really picky about pixelpeep sharpness one should probably not go past the 39 megapixel backs, at least when looking into corners. Zero distortion at infinity focus, small size and low weight are properties that can be considered a plus. Dark ground glass (tilting loupe probably useful), need of recessed board on some cameras and need of center filter are the disadvantages.

If one needs the full 90mm IC for large shifts, wants to shoot at larger aperture than f/11, or have a back with color cast issues disappointment may occur :).

I will myself probably go back-and-forth for a while more before I make the purchase...
 

Paul2660

Well-known member
A couple more thoughts on both. This is base on work on both a P45+ and IQ160

With the Schneider, XL 35mm I found that the Center filter was a must have other wise the amount of noise in the frames was too harsh. The Center filter is about a 2.5 stop correction to the center of the image. If you shift the lens, then the CF to me is also a must have other wise the LCC correction is really not worth it. Just too much noise. I have taken the 35 XL to 5mm, 10mm and 15mm. At 5mm it's excellent at F11 with really no saturation fall off or smearing of details. At 10mm you start to see the famous Magenta band that this lens seems to generate at least on the IQ backs. You also see some detail smearing and loss of color saturation. The LCC when viewed on the camera LCD will also show a bit of the magenta color. At 15mm all bets are off. The last 5mm are pretty worthless as you have almost total lack of color/saturation and you see a very prominent magenta band on the far side of the image. The image detail here is not recoverable and the color depending on the subject may or may not be. When I viewed the LCC on a 15mm shift, I also noticed banding in the Magenta which surprised me a bit. Amazingly, Capture One will correct for this and give you a pretty clean LCC, but even after this the amount of detail smearing rules out using this amount of shift. I base these issues on the curvature of the lens.

The 35mm Rodenstock, has a few other issues, which IMO make it even a worse consideration if you want to shift.

The aforementioned disk is a big problem. This disk has been written about in Guy's review of the 28mm Rodenstock. Apparently it's there to let you know when you have hit the edge of the image circle. On a IQ160 back, you will hit this disk on a horizontal shift at 5mm. It's non recoverable. But you may have a even greater problem, the penumbra of the image circle. On the 28mm Rodenstock this will show as a lighter white band that follows the curve of the image circle. If you are shooting against a blue sky or any other solid subject the penumbra will create a visible mark on your shot and you can't correct for it, the LCC will not effect it either. This effectively makes your shift only worth 2mm or so. Due to the layout of the IQ160 sensor I believe you hit the penumbra faster on a shift than on a rise. When Guy tested his 28mm Rodenstock he was mainly testing rise and it doesn't seem to show up as fast. I have wondered if the 32HR has the same disk and penumbra issues. Since the 35mm Rodenstock and 28mm have the same image circle 70mm, it's very possible that you will have this same issue with the penumbra on it. At least on the 28mm these issues are really a compromise to a great optic as you can shift this lens to even 12mm and you will see no loss of detail to smearing or color/sat loss. However due to the penumbra marks and the disk you pretty much can't use most of the shifted image.

The other concern on the 35mm Rodenstock is that it still will vignette on both a P45 and IQ160. Enough that I would still like to have a CF for it but as far as I know Rodenstock does not make a physical CF for this lens. Once again you have the issues of making the LCC do more work than it can handle and you will start to see noise build up. It's another amazing optic which to me is compromised for shifting.

I don't think there really is affordable lens that works for shifting on the newer backs in the 35mm range. To me a 8mm shift for landscape is really not worth the effort as I would need at least 15mm to really get what I looking for and 20mm would be better. The 32HR may have been redesigned to remove the disk and penumbra issue but at over 10K with the CF (and it needs the CF) it's just out of my range.

If you want to shift with 35mm, you really are going to need to consider the 35XL Schneider, if what you are shooting is more rise than shift you may be OK since you won't hit the penumbra as fast.

Paul
 

stngoldberg

Well-known member
A couple more thoughts on both. This is base on work on both a P45+ and IQ160

With the Schneider, XL 35mm I found that the Center filter was a must have other wise the amount of noise in the frames was too harsh. The Center filter is about a 2.5 stop correction to the center of the image. If you shift the lens, then the CF to me is also a must have other wise the LCC correction is really not worth it. Just too much noise. I have taken the 35 XL to 5mm, 10mm and 15mm. At 5mm it's excellent at F11 with really no saturation fall off or smearing of details. At 10mm you start to see the famous Magenta band that this lens seems to generate at least on the IQ backs. You also see some detail smearing and loss of color saturation. The LCC when viewed on the camera LCD will also show a bit of the magenta color. At 15mm all bets are off. The last 5mm are pretty worthless as you have almost total lack of color/saturation and you see a very prominent magenta band on the far side of the image. The image detail here is not recoverable and the color depending on the subject may or may not be. When I viewed the LCC on a 15mm shift, I also noticed banding in the Magenta which surprised me a bit. Amazingly, Capture One will correct for this and give you a pretty clean LCC, but even after this the amount of detail smearing rules out using this amount of shift. I base these issues on the curvature of the lens.

The 35mm Rodenstock, has a few other issues, which IMO make it even a worse consideration if you want to shift.

The aforementioned disk is a big problem. This disk has been written about in Guy's review of the 28mm Rodenstock. Apparently it's there to let you know when you have hit the edge of the image circle. On a IQ160 back, you will hit this disk on a horizontal shift at 5mm. It's non recoverable. But you may have a even greater problem, the penumbra of the image circle. On the 28mm Rodenstock this will show as a lighter white band that follows the curve of the image circle. If you are shooting against a blue sky or any other solid subject the penumbra will create a visible mark on your shot and you can't correct for it, the LCC will not effect it either. This effectively makes your shift only worth 2mm or so. Due to the layout of the IQ160 sensor I believe you hit the penumbra faster on a shift than on a rise. When Guy tested his 28mm Rodenstock he was mainly testing rise and it doesn't seem to show up as fast. I have wondered if the 32HR has the same disk and penumbra issues. Since the 35mm Rodenstock and 28mm have the same image circle 70mm, it's very possible that you will have this same issue with the penumbra on it. At least on the 28mm these issues are really a compromise to a great optic as you can shift this lens to even 12mm and you will see no loss of detail to smearing or color/sat loss. However due to the penumbra marks and the disk you pretty much can't use most of the shifted image.

The other concern on the 35mm Rodenstock is that it still will vignette on both a P45 and IQ160. Enough that I would still like to have a CF for it but as far as I know Rodenstock does not make a physical CF for this lens. Once again you have the issues of making the LCC do more work than it can handle and you will start to see noise build up. It's another amazing optic which to me is compromised for shifting.

I don't think there really is affordable lens that works for shifting on the newer backs in the 35mm range. To me a 8mm shift for landscape is really not worth the effort as I would need at least 15mm to really get what I looking for and 20mm would be better. The 32HR may have been redesigned to remove the disk and penumbra issue but at over 10K with the CF (and it needs the CF) it's just out of my range.

If you want to shift with 35mm, you really are going to need to consider the 35XL Schneider, if what you are shooting is more rise than shift you may be OK since you won't hit the penumbra as fast.

Paul
Thank you for the above, I own the 32mm Rodenstock with the CF. In your opinion can I safely shift 10mm? What about rise and fall?
Stanley
 

torger

Active member
Thanks Paul, really great feedback.

We that use Aptus 75, Aptus 22 or other backs based on those sensors will have less of the magenta cast and noise issues. The banding I guess is this issue:
Camera systems and image software
that is also related to sensor type.

At capture integration web there's a test image available for download showing the full image circle of the 35 XL on an IQ180 without center filter. The sight is not pretty. That image together with Schneider's own MTFs is mainly what has caused me to be a bit suspicious about this lens.
Lens :: Capture Integration – Medium Format Digital Back Sales & Rental and Other Professional Photographic Equipment
In the CI image the sharpness falloff seems even worse than it should too, but could be a problem with focus during shooting (it was not made for sharpness test afaik).
 

Paul2660

Well-known member
Stanley:

I really can't speak to the 32mm HR-W. I don't know if Rodenstock put the same disk in the lens as the HR 23,28, or 35. It's a newer design and has a larger image circle at 90mm I believe. For sure the larger circle will allow for a wider shift. I also don't know if the penumbra will be as big an issue. For me on the 28mm it's pretty much rules out all shift in the horizontal since I see it as soon as 3mm. I am look back to my early tests with the 35mm to see if I had it then also. I can get about 7mm of rise before it hits and leaves a mark on the file. Again, it's very image dependent as if you were shooting a subject that didn't have a solid background, you won't really see it but you will of course see the disk. With a blue sky it's very apparent and even with a partly cloudy sky you can still see the effect/mark of the edge of the penumbra. The format of the Phase backs, will cause you to hit the penumbra sooner on horizontal shift then vertical rise.

There are other users on this forum with the 32 and hopefully they can answer that question.
 
Hi Torger,
very old Thread, but what have you done? Do you sell the 35mm Digitar? You have a Techno and with my information you need a special lensboard for the techno with the Digitar 35mm. Do you bought this board? Thank you.
 

torger

Active member
I have the 35xl yes, with the special lens board. I bought it in that configuration. I'm pleased with its performance and I intend to keep it. It does through its short flange distance put stress on the sensor, color cast and crosstalk desaturation are issues to relate to. Doesn't work with all sensors.

Concerning corner performance, with my 48x36mm sensor I prefer to shift no more than 10mm, and when I shift that amount and I need sharpness (ie have details in corners) I stop down to f/16. With smaller amounts of shift f/11 works fine all the way to the corners. I use it with a center-filter and I'd say it's a must-have. Before I got a dedicated filter I used the weaker 47XL center filter on it which work well too, a little vignetting but not too much. With the 35XL center-filter you have practically zero vignetting in the shot image (it vignettes on the ground glass when focusing of course due to angle of light).

I find it to be much better than the Rodenstock Sironar-Digital 35mm I owned before.
 
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HI Torger,
thank you for your fast reply.
Could you say something about tilt with the 35mm Digitar and your sensor? I 've seen with the recessed lensboard there are extensions to the shutter lever and focus lever too. do you think you could do this selfmade to change a 35mm XL to that board? because i have a 35mm on an other lensboard.. :).
mueller
 

weinlamm

Member
I think the problem for 'changing yourselfs' should be to get the lensboard. You can't buy one from Cambo or Alpa - in both cases you have to sent the lens to them.
 
Hi Christian,
It is no problem to buy the lens board from Linhof. They sell it. This is not possible with cambo.. But with the Digitar 35 because of the deeper lens board it is different.
But Linhof sell the lens board without the lens too.
Mueller
 

weinlamm

Member
Ok. If you have a Linhof - perhaps you should try it. If it won't work you could still sent it to Linhof later. :)
 

torger

Active member
HI Torger,
thank you for your fast reply.
Could you say something about tilt with the 35mm Digitar and your sensor? I 've seen with the recessed lensboard there are extensions to the shutter lever and focus lever too. do you think you could do this selfmade to change a 35mm XL to that board? because i have a 35mm on an other lensboard.. :).
mueller
I use a Linhof Techno. I bought mine already mounted on the recessed lens board. Linhof have different recessed boards, a 6mm recessed and a 12mm recessed. If I remember correctly the 35mm Apo-Sironar Digital was on a 6mm recessed board and the Digitar 35XL is on the 12mm recessed. The 6mm would be too little for it.

There's no problem with tilting, sure the recessed board puts the lens a bit off-center but it's no problem for this wide angle. The tilt angles are usually very small for this short focal length, like 1.5 degrees or so. As said in another thread tilt is quite rarely used as hyperfocal/infinity often works just as well due to the short focal length, but I do use it from time-to-time (in open scenes with downwards shift or low tripod).

The lens is very dark in the corners of the ground glass, while Linhof's new bright ground glass makes a big difference and I rarely need to use a dark cloth, it's still very hard to look into corners and check sharpness there while adjusting tilt. So tilting I generally do from tables with this one, and it does work very well too. Table settings work better for wider angles as you generally don't need to hit as exact as with longer lenses and larger tilts (and for longer lenses you can look into corners with the loupe more easily).

Changing lens board by yourself should be no problem. I've only changed on flat lensboards before though, I guess it's a bit more tricky to get the levers there when attaching to a recessed lens board, but I don't think it should be a problem. If you don't have a lens wrench a vernier caliper works fine.
 
Hi Torger,
if i am right, you dont use the newest version of the Linhof Techno. Do you have some problems with the recessed board of the Digitar 35mm and his rapid connection and the techno with its flash shoe? With my other lensboard there is a problem of a collision of the wire trigger and the flash hot shoe..
thank you.
Mueller
 
HI Guys,
for the info. There is a angled "plug" for the wire trigger. So you dont need the rapid adapter for your wire trigger. The rapid adapter is not compatible with older technos because of the hot shoe.
I have the copal shutter, the angled wire plug, the lens... Now i need the recessed board.

Is it possible to use a deeper recessed board? like 16mm?

Mueller
 
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