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    • rtwPaul

      So much for the Nikon and Canon claims that a larger mount is necessary for fast lenses. Phillip Reeve shows an exclusive first look at NiSi 75mm F/0.95 FE prototype lens at Photokina. While this is the first still lens from the Chinese filter manufacturer, they earlier in the year announced NiSi Cine Prime lenses.

      Like the pre-announced Nikon 50mm F0.95 Z lens, this lens will be manual focus only…however it’s expected to retail for considerably less than $6,000…

      Of course this will not be the first F0.95 fullframe E-mount lens. The Mitakon 50mm F/0.95 Lens is available from B&H Photo & Amazon lists for - $849

    • bstrong

      I've been wondering about this ever since the latest Nikon and Canon mirrorless announcements.

      The Leica M-mount has a 44mm diameter and Leica has had a 50mm f/0.95 Noctilux for years. Clearly there must be some other reason. Maybe it's the distance from the mounting flange to the sensor?

    • rtwPaul

      i wondered as well but then thought is it a way to get people to buy new glass, along with their new camera.

      If you buy good quality galss it can last a lifetime, its not always about the camera or the shot sometimes its just about marketing and sales IMO

    • zi

      In a pinhole camera you need very little mount diameter to support the pinhole itself.

      For a typical, large aperture, long telephoto lens and with a short flange-focus distance, typical in digital mirrorless cameras, you may need a very large mount diameter. This is especially true of more complicated lenses with autofocus and electronic apertures. Long zooms need more room for the multiple lens groups and helical threads to control the groups, all of which is more complicated to design and engineer. (Just tear apart one of these lenses to see what I'm talking about.)

      My point is that for an interchangeable lens camera system which also needs to support the needs of full lens automation with longer focal lengths and/or complicated multi-group long zooms, you need a large flange diameter. A large aperture lens further complicates the issues, requiring a broader internal path for the image.

      See the following lens cutaway to gain a basic understanding of how modern lenses are constructed:

    • zi

      See above how the lens mount restricts the final lens element size? There is very little left for the bayonet mount thickness, and not too much space for electric power and control wires.

    • Chris

      Ziggy, you always amaze me with how much knowledge you have. Dunno if you guys saw, but this Nikon engineer did a really good job of explaining not just the aperture but also how you fit in the motor for autofocus, etc., while drawing backwards on the glass:

      And I will shamelessly copy one of the comments from that YouTube video:

      Parampreet Dhatt1 Although the Leica M-mount has the same mount diameter as the Nikon F-mount (44mm), it has a much shorter flange distance (27.5mm vs 46.5mm for the F-mount), which allows designing of f/0.95 lenses. However, due to the limitations of the smaller mount diameter, lenses like the Leica Noctilux 50mm f/0.95 lens have significant vignetting problems (the vignetting on the Noctilux is around 4 EVs!). The much larger mount diameter of the Nikon Z-mount (55mm), combined with the short flange distance (16mm), will allow in more light and help with designing of large aperture lenses (f/0.95 and beyond) with much lower vignetting and better sharpness.

    • bstrong

      Ah ha! Thank you for this explanation. After I posted my initial thought regarding the Leica M-mount, I also reminded myself that not only are the lenses manual focus, but they also have a minimum focus distance of around 3 feet. Your post backs up the idea that there is a lot more to it than just the diameter of the mount.

    • dr

      The dof of an f/ .95 lense is also pretty limiting at a distance of 3 feet. It's razor thin. At f/1.4 I'm constantly finding portraits where one eyeball is in focus and the other is blurry because it is justa hair past the focal plane

    • dr

      At middle distance shooting, you get some pretty useful high iso shutter speed. That helps with freezing mild motion. So low light candids are a well suited use case for these too.

    • dr

      Autofocus usually struggles to find contrast in low light, so it helps to depend on phase detect if your system has it, or just manually set focus using whatever aids are available, eg: focus peaking or just the dof markings on the lens.

    • bstrong

      When shot wide open at f/1.4, yes there is vignetting. I wouldn’t consider it severe though. In fact I prefer the look of a little vignetting and sometimes add it in post.

    • marchyman

      Leica Q (28mm fixed lens) at f/1.7 uncropped

      I'm not seeing much vignetting. The camera processor plays a part in even raw image output, though. Vignetting compensation could be taking place there. I don't remember exactly what is done other than distortion removal.

    • Chris

      Here's the chart of vignetting for the Leica 50mm f/0.95 lens. Wide open, the corners are down about 3.2 stops. I can see where a broader mount really helps with that aperture, I just don't know how often I would use an aperture like that. I do use 1.4 at 85mm all the time.

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