Question about Sony FE lenses technical design

I saw comments that Sony FE lenses have longer height because of edge to edge sharpness due to short flange back. Compare to other brands, none of them have extra adapter size of height like that but Sony FE lenses. Check the red circle compares to other lenses. If sony intended to design like that, is it true that they wanted to get the edge to edge sharpness due to short flange back? If not, I want to know why. I contacted Sony but Im not able to get any pieces of information since he wasn't a technician.

Trying to split the answer.

If we take a undemanding optical design, like a 135mm Elmar's lens head or the Pentax 100mm f4 bellows we have a few optical elements pretty distant from the sensor (or film) and what we'll pack between those 2 barely matters. - be it the huge mirror box of a Leica Visoflex + focusing tube or the bellows with a Pentax SLR. and yes fitting the same head on a sony demands a longer lens barrel than putting it on a Nikon.

The funnel like shaping of lens barrels you marked has a very simple not optical reason: Ergonomics. Sony decided to make tiny cameras and have to leave space for photographers' fingertips somewhere. - I think I read or heard complaints about that bit of space still not being really enough.

Its hard to tell anything about a lens from just looking at it's outer shape. Where is the rear element in relation to the mount or sensor plane? There were lenses with glass sticking out way behind the mount and others with several cm between mount and glass.

More interesting about a mount is the actual size of the hole in the camera. Canon picked a pretty big one. The Chinese Great Wall MF SLR is probably pretty challenged by using a 39mm enlarger / Leica thread.

I believe that a lot of Sony FE-mount lenses are still optical designs for the A-mount with its larger flange-to-sensor distance and that the section you circled in red accounts for that difference between FE and A mount cameras; a built-in adapter so to speak.

Yeah, that's what I heard from Sony that I chatted with a few days ago. Slow and small lenses have no issues but big and fast lenses have that kind of built in adapter size. Im not blaming it but it seems only Sony FE lenses have that kind of extra height and space which I really curious about. I contacted Sony for this but couldn't hear a clear answer since he wasn't a technician.

Trying to split the answer.

If we take a undemanding optical design, like a 135mm Elmar's lens head or the Pentax 100mm f4 bellows we have a few optical elements pretty distant from the sensor (or film) and what we'll pack between those 2 barely matters. - be it the huge mirror box of a Leica Visoflex + focusing tube or the bellows with a Pentax SLR. and yes fitting the same head on a sony demands a longer lens barrel than putting it on a Nikon.

The funnel like shaping of lens barrels you marked has a very simple not optical reason: Ergonomics. Sony decided to make tiny cameras and have to leave space for photographers' fingertips somewhere. - I think I read or heard complaints about that bit of space still not being really enough.

 

Its hard to tell anything about a lens from just looking at it's outer shape. Where is the rear element in relation to the mount or sensor plane? There were lenses with glass sticking out way behind the mount and others with several cm between mount and glass.

More interesting about a mount is the actual size of the hole in the camera. Canon picked a pretty big one. The Chinese Great Wall MF SLR is probably pretty challenged by using a 39mm enlarger / Leica thread.

Still weird that Sony FE lenses especially big and fast lenses have that extra space and height while other brands don't.

All lenses designed specifically for Sony mirrorless cameras are designed to accommodate the thick (~ 2 mm) cover glass on the sensor. This is to mitigate the smearing effect when light rays impinge on the sensor at a high angle of incidence in the corners. Lenses are also designed to reduce the angle of incidence by keeping the rear element further from the focal plane than absolutely necessary. LensRentals finds it necessary to impose a 2 mm filter at the focal plane to accurately measure the MTF of FE lenses.

The zoom lenses illustrated above have a diameter much larger than that of the mount. There is a cylindrical section at the base of the lens to match the diameter of the mount. This also provides space for your fingers when gripping the camera. You will notice that the tapered portion of SLR lenses is longer than that of the FE mount lenses when measured from the focal plane. This suggests that the long extension is for practical reasons rather than inclusion of a built-in adapter for an existing optical design.

It is easy to mount SLR lenses on the Sony using an adapter. In direct comparison, FE lenses are much sharper in the corners than adapted Nikon lenses of comparable focal length and quality. This is also true for Leica lenses, which require an adapter only about 5 mm in length. This argues strongly against the idea that FE lenses are repackaged versions of earlier designs.

All lenses designed specifically for Sony mirrorless cameras are designed to accommodate the thick (~ 2 mm) cover glass on the sensor. This is to mitigate the smearing effect when light rays impinge on the sensor at a high angle of incidence in the corners. Lenses are also designed to reduce the angle of incidence by keeping the rear element further from the focal plane than absolutely necessary. LensRentals finds it necessary to impose a 2 mm filter at the focal plane to accurately measure the MTF of FE lenses.

 

The zoom lenses illustrated above have a diameter much larger than that of the mount. There is a cylindrical section at the base of the lens to match the diameter of the mount. This also provides space for your fingers when gripping the camera. You will notice that the tapered portion of SLR lenses is longer than that of the FE mount lenses when measured from the focal plane. This suggests that the long extension is for practical reasons rather than inclusion of a built-in adapter for an existing optical design.

 

It is easy to mount SLR lenses on the Sony using an adapter. In direct comparison, FE lenses are much sharper in the corners than adapted Nikon lenses of comparable focal length and quality. This is also true for Leica lenses, which require an adapter only about 5 mm in length. This argues strongly against the idea that FE lenses are repackaged versions of earlier designs.

And where can I find that information? Any sources or proofs?

A. You heard it from me, and I've done the research so long ago it's getting dusty with age. My portfolio has several comparisons between Sony, Nikon and Leica lenses.

B. It's easy to search PNET for related threads..

C. Log into Lens Rentals | Blog

D. If you think you can evaluate a lens from it's external shape or appearance, repeat steps A, B, and C ;)