Schneider Kreuznach 28 LS: poor corners perfomance or I'm too picky?

[pasman]

Hi guys,

Few days ago I acquired SK 28 LS lens, and only today had a chance to test it. I have two other SK lens: 80 and 110 and they're spectacular. So I've expected nothing but to be amazed by 28 LS (though I've read mixed reviews about it) and that it will tear apart my Nikon D800e with 14-24.

Maybe I'm blind but I think its not tearing Nikon apart at all. 14-24 is stellar lens but SK 28 is 6k lens and honestly I've thought that it will be better.

Below is 100% crops of left upper corner, middle and bottom and right upper corner e.t.c. Both frames were shot at f/11, Nikon was at 18mm. Apparently (as I just learned from P1 website), 35mm equivalent of 28 LS is 17mm but I've used Capture Integration focal length calculator.

Nikkor 14-24 (click for full-size):


SK 28 LS (click for full-size):


If someone interested in raw:
Nikon: https://www.dropbox.com/s/lb9mghxy1dnlx6x/BPP_1142.NEF
P1: https://www.dropbox.com/s/7svv5g0eqgulolt/CF002000.IIQ

What do you think? Do my copy suck or I'm paranoid?

I have an Mamiya 45 AF which is as sharp as SK 28 if not sharper. SK has better contrast though.

I will be grateful for your input.

 

[torger]

I've looked at the raw files in rawtherapee without any lens corrections applied to see the "raw" lens performance.

Both lenses have laaarge chromatic abberations along the sides (we're talking cyan shifted 5 pixels to the left and red 5 pixels to the right, it's a lot, attached example), and I'd say that on that metric both the 28LS and the 14-24 Nikon perform about the same, that is if you'd have 80 megapixel in the Nikon instead of 36 you'd see about the same result when pixel peeping.

With lens corrections applied in the raw converter you get a lot better performance though, as shown in your crops. Based on what the starting point is, I would be happy with the outcome.

I can only say that the 28LS does not seem to be any sharper than the Nikon zoom, but I don't know if that is how it's supposed to perform or not. Hopefully someone experienced with this lens will reply. As far as I know the SLR lenses are typically designed to be used together with raw converter lens corrections so the optical design is compromised a bit (otherwise it would be hugely complex), so seeing large chromatic abberation without lens corrections applied should be normal. So I would not be surprised if this is normal performance, actually rather the opposite, I would expect this performance from an ultra-wide general-purpose SLR lens.

Keep in mind that it's very hard to make ultra-wide angle lenses sharp in corners, and you cannot expect to get the same type of corner sharpness in an SLR type of lens as you get in tech cam lenses (which can be made sharper thanks to lacking mirror box and allowing color cast, small largest aperture and huge vignetting, can't make a lens that's great at everything). I'm used to looking at results from the tech cam Rodenstock Digaron-W 32 and Scheinder Digitar 28mm, and they are in an entirely different league when it comes to corner sharpness (they are designed to perform well without lens corrections applied), but even them has visible sharpness falloff in corners even before shifting.

So yes I think you're too picky but please wait until someone experienced with exactly this lens replies.

 

[Sarnia]

Today I had a similar disappointment with my SK 24mm XL lens. On my Leaf Aptus 75 @ f8 set at infinity the corners were very smudgy. I thought the lens had really good DOF capabilities. More testing required!

 

[pasman]

torger, thank you! I feel a little relieved.

 

[f8orbust]

Today I had a similar disappointment with my SK 24mm XL lens. On my Leaf Aptus 75 @ f8 set at infinity the corners were very smudgy. I thought the lens had really good DOF capabilities. More testing required!

With those settings on an Aptus 75, your depth of field is going to be from 5m to infinity. If anything was closer than 5m, it is going to be oof.

Try focussing at f11 (best aperture for this lens) and focus at about 4m; on an Aptus 75, this should give you a depth of field from about 1.9m to infinity - hopefully the corners will tidy up.

Jim

 

[Pemihan]

Jim, how do you calculate something like that?

Peter

With those settings on an Aptus 75, your depth of field is going to be from 5m to infinity. If anything was closer than 5m, it is going to be oof.

Try focussing at f11 (best aperture for this lens) and focus at about 4m; on an Aptus 75, this should give you a depth of field from about 1.9m to infinity - hopefully the corners will tidy up.

Jim

 

[Sarnia]

Thanks, Jim, I'll try that. I've tracked down a DOF table for the lens so I'll refer to that and run some tests. It's a crazily small lens (in Alpa mount) and will make a great travel combo. I'm looking forward to getting better acquainted with its unique characteristics.

 

[Bill Caulfeild-Browne]

I have the Mamiya 28 which I believe is the same optically. It's very good at f11 when used with C1 and the corrections C1 applies. Still, I do add a bit of corner sharpening if it's important.

 

[f8orbust]

@Peter - a great little program called Barnack (it's free BTW).

@Sarnia - since you're using an Alpa, you have the option of mounting the lens in any of four orientations. So, if you're still having issues with corner performance, rotate the lens 180˚, reattach it, and shoot the same scene again, and see if the corner performance is identical or has 'moved'. If it's the latter then there may be an issue with the alignment of the front and rear groups.

 

[Ken_R]

Hi guys,

Few days ago I acquired SK 28 LS lens, and only today had a chance to test it. I have two other SK lens: 80 and 110 and they're spectacular. So I've expected nothing but to be amazed by 28 LS (though I've read mixed reviews about it) and that it will tear apart my Nikon D800e with 14-24.

Maybe I'm blind but I think its not tearing Nikon apart at all. 14-24 is stellar lens but SK 28 is 6k lens and honestly I've thought that it will be better.

Below is 100% crops of left upper corner, middle and bottom and right upper corner e.t.c. Both frames were shot at f/11, Nikon was at 18mm. Apparently (as I just learned from P1 website), 35mm equivalent of 28 LS is 17mm but I've used Capture Integration focal length calculator.

Nikkor 14-24 (click for full-size):


SK 28 LS (click for full-size):


If someone interested in raw:
Nikon: https://www.dropbox.com/s/lb9mghxy1dnlx6x/BPP_1142.NEF
P1: https://www.dropbox.com/s/7svv5g0eqgulolt/CF002000.IIQ

What do you think? Do my copy suck or I'm paranoid?

I have an Mamiya 45 AF which is as sharp as SK 28 if not sharper. SK has better contrast though.

I will be grateful for your input.

I think your 28mm lens looks normal from what I have seen posted. As it has been discussed it is a good lens but out on the very edges of the frame quality drops. You can always crop in a tad. If you want solid edge to edge performance I have yet to use an SLR lens that betters the Rodenstock HR-W lenses I have. The performance of the wide angle tech lenses is just in another galaxy. Even when shifted 15mm my 40mm HR-W is quite sharp almost to the very end of the image circle (on my IQ160).

There are some very nice medium format wide angle SLR lenses made but I think only the Mamiya / Phase 28 covers full frame 645. I know the Hasselblad 28mm does not and obviously the superb Leics S 24, 30 and 35mm lenses do not being designed for their smaller than 645, 30x45mm sensor.

 

[Ed Hurst]

The original Pentax 645 25mm DFA also covers full frame 645 (but the more recent variant, the 25mm DA, only covers the cropped sensor found on the 645D and 645Z). I have the latter lens, so cannot speak for how well the DFA works in the corners of a full frame 645 image.

 

[pasman]

I have the Mamiya 28 which I believe is the same optically. It's very good at f11 when used with C1 and the corrections C1 applies. Still, I do add a bit of corner sharpening if it's important.

Bill, thank you. Do that image looks as sharp as yours Mamiya? Corner sharpening helps a lot, yes.

Ken_R, thanks! I'm not yet ready to go technical. So I will rely on PP and cropping in extreme cases.

 

[Pemihan]

Thanks Jim..

Peter

@Peter - a great little program called Barnack (it's free BTW).

@Sarnia - since you're using an Alpa, you have the option of mounting the lens in any of four orientations. So, if you're still having issues with corner performance, rotate the lens 180˚, reattach it, and shoot the same scene again, and see if the corner performance is identical or has 'moved'. If it's the latter then there may be an issue with the alignment of the front and rear groups.

 

[Sarnia]

Jim[/QUOTE]@Sarnia - since you're using an Alpa, you have the option of mounting the lens in any of four orientations. So, if you're still having issues with corner performance, rotate the lens 180˚, reattach it, and shoot the same scene again, and see if the corner performance is identical or has 'moved'. If it's the latter then there may be an issue with the alignment of the front and rear groups.[/QUOTE]

Good tip, thanks. :thumbup:

 

[jagsiva]

28mm & 32mm Lens Comparison - DT Blog

Shows the differences between 28D, 28LS and tech lens (32HR in this case)

 

[torger]

28mm & 32mm Lens Comparison - DT Blog

Shows the differences between 28D, 28LS and tech lens (32HR in this case)

Judging from the JPEGs and looking into corners the 32HR is best, the 28D second and 28LS worst, and Pasman should definitely not worry about his copy.

That link was also posted on this forum at the time when the test was made:

http://www.getdpi.com/forum/medium-...8mm-vs-schneider-28mm-vs-rodenstock-32hr.html

Concerning the supremacy of the 32HR one should keep in mind that with tech cams you generally adapt a style where you make compositions with a shifted lens so looking at the performance without shift is a bit theoretical - you'll use more of the image circle in practice and then put more stress on the lens. But anyway a truly impressive thing with the 32HR which does not really show here is that while the 28LS and probably 28D too rely on digital lens corrections in C1 to reach that performance the 32HR performs like that without lens corrections. Oh well, color cast correction is required, but that's due to sensor limitations, not lens.

 

[GrahamWelland]

I have the 28D and to be honest the images here look pretty similar to what I get in the extreme corners although it will get better stopped down. On center and across most of the frame it is a stellar lens

I've often heard of the 28 described as a great 30mm lens - ie be prepared to treat it like a 30mm and crop if necessary.

 

[Paul2660]

IMO it's more like a great 35mm lens. And it's not filter friendly.

If you want detail to the corners in MF the Rodenstock 28mm is the only way to go (affordable). The 32 Rod has become just a bit too expensive at 10k by the time you add the mount of your choice. Plus it needs the CF for optimal performance on shifts, add another to 1K.

32rod is delicate, heavy and can have issues with the Copal shutter becoming misaligned due to the mass of lens weight in front of the shutter.

The 60MP backs push the Phase One LS quite a bit. The 80MP backs even more. Also the LS and D (Phase One or Mamiys) and the non LS share the same number of elements and groups. Optically pretty much the same lens one just has a Leaf shutter.

Paul

 

[Bill Caulfeild-Browne]

This is pretty much the full frame with the Mamiya 28 mm. But as you can see, with this shot sharp corners don't matter as there's no detail there anyway.

I love the lens. I even got rid of my 35 mm because when shots with this lens are cropped, they're at least as good as the 35 mm full frame.

 

[pasman]

28mm & 32mm Lens Comparison - DT Blog

Shows the differences between 28D, 28LS and tech lens (32HR in this case)

Thank you, I saw it and in that comparision 28LS looked good for me.

torger, for me 28LS looks a bit better than 28D in that test. I'm not ready for technical camera yet.

Graham, I shot at f/11. You mean stopped down more than that?

Paul, as long as it not marvelous 80 or 110 I'm ok with it. Leaf shutter is good thing to have.

Bill, excellent photo!