I am coming back to this part of the forum after doing some testing, and I am going to disclose and share with you the test results.
Basically, I tested some Contax Zeiss C-Y lenses, Zeiss Nikon mount lenses and Zeiss Hasselblad H lenses on my Canon EOS 350 D. I shot many images including bank notes to give me RAW files. I viewed the RAW files on my DUO intel iMac. I used studio flash and test them all at f=6.5.
There are the groups I tested.
Hasselblad 50mm f4 CF with Zeiss F 50mm f2 Makro-Planar
Hasselblad 60mm f3.5 CF with Contax Zeiss 60mm f2.8 C-Y
Hasselblad 100mm F3.5 CF with Contax Zeiss 100mm f2.8 C-Y
After testing these lenses I gradually get the idea that they have similar performances by judging on the image quality. The result is consistent with what Gilbert quoted earlier.
"Resolutions on the same level
have been achieved with Carl Zeiss
lenses in Hasselblad medium format
cameras, proving that at Carl Zeiss,
medium format lenses, contrary to
popular belief, offer no lower
resolution than the very best 35 mm
lenses."
http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN02e/$File/CLN2.pdf
However, I do find an important exception to this when I am testing the following.
Hasselblad 120mm f4 Makro-Planar CF, Contax Zeiss 100mm f2.8 Makro-Planar C-Y, Zeiss Nikon F 100mm f2 Makro-Planar
What I found is the images from the Hassey 120mm is certainly inferior to the two other lenses from the smaller format. The images from Hassey simply has less punch, they stand out less from the background. The colours from the Hassy are considerable paler. They also have less contrast and sharpness. Although I would not like to admit this, the Hassey 120mm is producing images inferior to the two smaller format lenses. I did the testing at 1:2 magnification and had the same results. I thought it was unfair to the Hassey because I was using exteension tubes whereas the other two lenses had did it with floating elements. I repeat the testing at 1:5 magnification and confirm the inferiority of the Hassey.
I would be happy if someone could repeat the testing in case I am using a faulty Hassey lens but now I do believe that Hassey 120 is a bit out-dated and certainly it needs a replacement.
Although I have Contax Zeiss 120mm f4 for 645 but it is not possible to test this lens on my Canon.
In this part of the forum there are certainly some fudamental principles in optics which need to be clarified. There are different views which are opposing. I hope clever reader will get the ideas which are right.
All lenses allow light to pass. I am sure nobody will object if I say stopping down will improve the image quality. Stopping down is achieved by restricting light from passing through the lens. This is the same as the the principle of pinhole in the pinhole camera. If the pinhole is made smaller you improves the image qualities but it becomes darker. It has nothing to do with the angle of view.
Stopping down is achieved by using one aperture. What will happen if two apertures are applied,one in front and one at the back of the lenses ? If one applied apertures in this way, the angle of view is effectively reduced. If you reduce the angle of view, you are effectively converting a lens into smaller format.
It is not difficult to deduce from these principles that image quality can be improved by stopping down, reducing the size of the pinhole and reducing the format by using two apertures. These are true because I did these tricks and they work.
There are at least two reasons why stopping down leads to better image qualities. The first reason is because of the pinhole effect, and the second reason is the reducing of the effective diameter of the lens. The pinhole effect has nothing to do with lens design.
The second reason needs further explanation. The resolving power of the lens is better at the centre than the margin. Stopping down is effectively allows the light to pass the central sweet spot and cutting the light from passing the margin which is prone to aberration.
"Ever wondered why the make telescopes so very large? " One member of this forum asked.
"No, it's not to make them "faster". It is because the smaller they get, the lower their resolving power" he answered.
My answer to that question is bigger lens is faster. The faster is the lens, the less is the resolving power. Telescope is big because it is obtaining image from very dark sources, they have to be fast. The bigger the faster they are, they becomes less resolving.
"Your analogy appears to be based on the assumption that a definite amount of detail is going through a lens, and when it is distributed over a larger area, the resolution, i.e. the amount of detail per area unit, will be less, the detail less dense, than when it only has to cover a smaller area."
The bigger is the lens, the smaller is the resolving power, trust me.
Of couse, Zeiss understand this basic principle and this is why she made the quote
"Resolutions on the same level
have been achieved with Carl Zeiss
lenses in Hasselblad medium format
cameras, proving that at Carl Zeiss,
medium format lenses, contrary to
popular belief, offer no lower
resolution than the very best 35 mm
lenses."
Zeiss is great despite the fact that increasing the format tends to reduce the image quality, she maintained the standard.
Basically, I tested some Contax Zeiss C-Y lenses, Zeiss Nikon mount lenses and Zeiss Hasselblad H lenses on my Canon EOS 350 D. I shot many images including bank notes to give me RAW files. I viewed the RAW files on my DUO intel iMac. I used studio flash and test them all at f=6.5.
There are the groups I tested.
Hasselblad 50mm f4 CF with Zeiss F 50mm f2 Makro-Planar
Hasselblad 60mm f3.5 CF with Contax Zeiss 60mm f2.8 C-Y
Hasselblad 100mm F3.5 CF with Contax Zeiss 100mm f2.8 C-Y
After testing these lenses I gradually get the idea that they have similar performances by judging on the image quality. The result is consistent with what Gilbert quoted earlier.
"Resolutions on the same level
have been achieved with Carl Zeiss
lenses in Hasselblad medium format
cameras, proving that at Carl Zeiss,
medium format lenses, contrary to
popular belief, offer no lower
resolution than the very best 35 mm
lenses."
http://www.zeiss.com/C12567A8003B8B6F/EmbedTitelIntern/CLN02e/$File/CLN2.pdf
However, I do find an important exception to this when I am testing the following.
Hasselblad 120mm f4 Makro-Planar CF, Contax Zeiss 100mm f2.8 Makro-Planar C-Y, Zeiss Nikon F 100mm f2 Makro-Planar
What I found is the images from the Hassey 120mm is certainly inferior to the two other lenses from the smaller format. The images from Hassey simply has less punch, they stand out less from the background. The colours from the Hassy are considerable paler. They also have less contrast and sharpness. Although I would not like to admit this, the Hassey 120mm is producing images inferior to the two smaller format lenses. I did the testing at 1:2 magnification and had the same results. I thought it was unfair to the Hassey because I was using exteension tubes whereas the other two lenses had did it with floating elements. I repeat the testing at 1:5 magnification and confirm the inferiority of the Hassey.
I would be happy if someone could repeat the testing in case I am using a faulty Hassey lens but now I do believe that Hassey 120 is a bit out-dated and certainly it needs a replacement.
Although I have Contax Zeiss 120mm f4 for 645 but it is not possible to test this lens on my Canon.
In this part of the forum there are certainly some fudamental principles in optics which need to be clarified. There are different views which are opposing. I hope clever reader will get the ideas which are right.
All lenses allow light to pass. I am sure nobody will object if I say stopping down will improve the image quality. Stopping down is achieved by restricting light from passing through the lens. This is the same as the the principle of pinhole in the pinhole camera. If the pinhole is made smaller you improves the image qualities but it becomes darker. It has nothing to do with the angle of view.
Stopping down is achieved by using one aperture. What will happen if two apertures are applied,one in front and one at the back of the lenses ? If one applied apertures in this way, the angle of view is effectively reduced. If you reduce the angle of view, you are effectively converting a lens into smaller format.
It is not difficult to deduce from these principles that image quality can be improved by stopping down, reducing the size of the pinhole and reducing the format by using two apertures. These are true because I did these tricks and they work.
There are at least two reasons why stopping down leads to better image qualities. The first reason is because of the pinhole effect, and the second reason is the reducing of the effective diameter of the lens. The pinhole effect has nothing to do with lens design.
The second reason needs further explanation. The resolving power of the lens is better at the centre than the margin. Stopping down is effectively allows the light to pass the central sweet spot and cutting the light from passing the margin which is prone to aberration.
"Ever wondered why the make telescopes so very large? " One member of this forum asked.
"No, it's not to make them "faster". It is because the smaller they get, the lower their resolving power" he answered.
My answer to that question is bigger lens is faster. The faster is the lens, the less is the resolving power. Telescope is big because it is obtaining image from very dark sources, they have to be fast. The bigger the faster they are, they becomes less resolving.
"Your analogy appears to be based on the assumption that a definite amount of detail is going through a lens, and when it is distributed over a larger area, the resolution, i.e. the amount of detail per area unit, will be less, the detail less dense, than when it only has to cover a smaller area."
The bigger is the lens, the smaller is the resolving power, trust me.
Of couse, Zeiss understand this basic principle and this is why she made the quote
"Resolutions on the same level
have been achieved with Carl Zeiss
lenses in Hasselblad medium format
cameras, proving that at Carl Zeiss,
medium format lenses, contrary to
popular belief, offer no lower
resolution than the very best 35 mm
lenses."
Zeiss is great despite the fact that increasing the format tends to reduce the image quality, she maintained the standard.
