p.10 #1 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Siddhu wrote:
Just read the comments about Zeiss glass and this new lens on DPreview ..... there's an incredble amount of loathing towards Zeiss.
I did not realize to what extent that Zeiss (and Leica) stir up such negative emotions in people!
Very few folks at DPR like Zeiss. I once asked a question about a Zeiss lens long ago and received one THE most hellacious verbal beatings I've ever seen. Post after post after post ripping me for thinking of throwing away good money on Carl Zeiss "trash".
I would not go to DPR for any good opinions on Carl Zeiss lenses.
p.10 #4 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Everyone wants to feel good about choices they made. I think most people in developed countries have experienced so much overload on all sensory organs that they are unable to sense any subtle variations, for example the difference between results produced by different lenses.
Same people won't see much difference between a tea made from a tea bag and a tea made in a Japanese tea ceremony. And yes, there may not be much difference after all - it's all in the eye of a beholder. Who is to judge?
Mar 16, 2012 at 10:37 PM
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p.10 #5 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Yes it's very expensive. But "only" 500 euro more than the 21/2,8 or 35/1,4 is better than I expected
p.10 #6 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Ataboy wrote:
Everyone wants to feel good about choices they made. I think most people in developed countries have experienced so much overload on all sensory organs that they are unable to sense any subtle variations, for example the difference between results produced by different lenses.
Same people won't see much difference between a tea made from a tea bag and a tea made in a Japanese tea ceremony. And yes, there may not be much difference after all - it's all in the eye of a beholder.
Very well said!
Ataboy wrote:
Who is to judge?
At least you should have some experience of your own, _hands on_ experience. The vast majority of posters on DPR forums do not excel in this regard.
p.10 #8 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
OK. Something I've always wondered about with Zeiss lenses when loking at their MTF's. Why does Zeiss design their lenses to do this? It appears in so many of their lenses it must be design choice they make. Does anyone have any insight as to why they make that choice? What is their reasoning? Is it purely a cost consideration to allow the MTF to fall off in the extreme corner? http://www.boncratious.com/images/ZeissLens-corners.jpg
p.10 #9 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Lotusm50 wrote:
OK. Something I've always wondered about with Zeiss lenses when loking at their MTF's. Why does Zeiss design their lenses to do this? It appears in so many of their lenses it must be design choice they make. Does anyone have any insight as to why they make that choice? What is their reasoning? Is it purely a cost consideration to allow the MTF to fall off in the extreme corner? http://www.boncratious.com/images/ZeissLens-corners.jpg
It was found that the MTF in the Zeiss PDF for f/5.6 is wrong (its actually the exact copy of the f/4 MTF for the 25/2).
Speculation is that the right MTF is contained in this link...
p.10 #10 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Lotusm50 wrote:
OK. Something I've always wondered about with Zeiss lenses when loking at their MTF's. Why does Zeiss design their lenses to do this? It appears in so many of their lenses it must be design choice they make. Does anyone have any insight as to why they make that choice? What is their reasoning? Is it purely a cost consideration to allow the MTF to fall off in the extreme corner? http://www.boncratious.com/images/ZeissLens-corners.jpg
I see this only in SLR lenses. RF lenses have better MTF in the extreme corners for similar focal lengths.
p.10 #11 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
I suspect cost and weight are quite major factors.
Suppose you want to scale up the radius of the lens by ~10%, to push that last 2mm of poor performance off the sensor. Since the surface area of glass needed goes as the square and the volume as the cube, this requires polishing ~20% more glass surface area, with ~30% more weight in glass. I suspect one would then be looking at a $4k lens instead of $3k.
RF lenses tend to do a lot better because they can be much more symmetric designs (easier to make without large aberrations), rather than the complex, highly asymmetric retrofocus designs needed to clear the mirror of an SLR.
p.10 #12 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
I should have said SLR lenses, as it is what I meant. It is clearly present in their SLR lenses and not with their rangefinder lenses. I do think cost and size have something to do with it, but perhaps not exclusively. It is as present in the 50mm lenses, which are not particularly expensive or big. Further, do we see the same rapid fall-off into the extreme corner with equivalent lenses from other manufacturers? Further, Zeiss must know that there is a large segment of users that criticize their lenses becuase of exactly this feature -- they aren't sharp in the corner so they dismiss them (just read the forums across the web and you'll see this to be true). While I think this is an unreasonably narrow way to assess a lens, it nonetheless exists. The reason why most people (not all) think that 21mm Distagon is so great is becuase it doesn't do this (or at least not to the same extreme extent). So from a sales and marketing perspective, it isn't clear why Zeiss persists in designing this way.
p.10 #13 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
The MTF are measured at infinity, and the lens performance does normally change at closer distances. In one of Dr. Nasse's papers, talking about the difference between the 50 P and MP, he does mention that the field curvature in the P helps to create an increased sense of depth (probably what we call 3D) while the MP with its flatter field curvature will be better for corner to corner sharpness but the image will not be as lively. I think the drop that is seen in the MTF in the corners is what the field curvature looks like when the lens is focused at infinity. Probably a design trade off in order to create that specific threedimensional Zeiss look.
p.10 #14 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Lotusm50 wrote:
I should have said SLR lenses, as it is what I meant. It is clearly present in their SLR lenses and not with their rangefinder lenses. I do think cost and size have something to do with it, but perhaps not exclusively. It is as present in the 50mm lenses, which are not particularly expensive or big. Further, do we see the same rapid fall-off into the extreme corner with equivalent lenses from other manufacturers? Further, Zeiss must know that there is a large segment of users that criticize their lenses becuase of exactly this feature -- they aren't sharp in the corner so they dismiss them (just read the forums across the web and you'll see this to be true). While I think this is an unreasonably narrow way to assess a lens, it nonetheless exists. The reason why most people (not all) think that 21mm Distagon is so great is becuase it doesn't do this (or at least not to the same extreme extent). So from a sales and marketing perspective, it isn't clear why Zeiss persists in designing this way.
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You could also see the trade-off in terms of IQ distribution across the frame. For a given weight / cost /size constraint set, do you want ...
100% IQ across the center 90% of the frame, and 60% in the outer 10%, or
80% IQ across the center 100% of the frame
p.10 #15 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
Lots of people criticize Zeiss lenses for being way too big and expensive, too; you can't please everyone.
I think one reason that you may associate bad corner performance with Zeiss MTFs is that Zeiss is one of very few manufacturers that provide useful MTFs for all their lenses. Most other makes of SLR wide lenses also have fairly mediocre far corner performance; you just never see the MTFs to back this up. A whole lot of the Leica R MTFs show the same issue; I suspect you'd see the same from everyone else, too, if the MTFs were readily available.
p.10 #16 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
All my Zeiss lenses are great into the corners. The only weird ones which have extreme corner issues are 50MP for which the corner problem goes away at f5.6.
The other one is the new 25/2 with the above mtf which has a problem in the corners at infinity.
Some field curvature.
p.10 #17 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
This new 15 has some of the old zone B dip action units mtf.
I think there are two different design styles, the 25 mtf curve stays high and flat across the frame to the corners and then drops like a rock, whereas new 15 dips down quite a bit and then goes back up some for the corners.
When I look at the images, the MTF in the Zeiss PDF must be wrong, because I see very sharp corners. The MTF's from Lloyd Chamber are more in line with what I see.
p.10 #19 · Zeiss Distagon 2.8/15 ZE official, release in May 2012
wayne seltzer wrote:
This new 15 has some of the old zone B dip action units mtf.
I think there are two different design styles, the 25 mtf curve stays high and flat across the frame to the corners and then drops like a rock, whereas new 15 dips down quite a bit and then goes back up some for the corners.
Many of the Leica M lenses are like this as well (perhaps R also, I just haven't looked at MTFs for those), especially the faster designs. Perhaps a result of lens design to compensate and average out field curvature? I would think that if left uncorrected in a 15mm design, field curvature would become very evident and problematic.
