2024-04-14 •
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apochromatic, botched design, imcompetence crisis, Leica, Leica 35mm f/2 APO-Summicron-SL ASPH, Leica 50mm f/2 APO-Summicron-SL ASPH, Leica 75mm f/2 APO-Summicron-SL ASPH, Leica 90mm f/2 APO-Summicron-SL ASPH, Leica APO-Summicron, Leica APO-Summicron-SL, Leica M, Leica SL lenses, Leica SL3, Leica Summicron, Leica Summicron-SL, unstable lens focus
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I was puzzled at the extra-strong focus shift of the 75/2 APO as shown in Deck and Roof, strong to the point of ridiculous. This seemed wrong optically, yet it was consistent with the the direction of the focus shift and the field curvature in Yellow House at Dusk. Seemingly bearing no explanation other than optical focus shift.
And yet, I now have proof that the focus shift is largely the result of unstable lens focus, making it unreliable to take more than one frame without the focus glitching to the distance with each frame (but sometimes/often and not always). Flaky and erratic. At least with the 75/2 APO and 90/2 APO and 35/2 APO and 50/2 APO.
Leica SL3: Unstable Lens Focus
Leica 90mm f/2 APO-Summicron-SL ASPH Apeture Series: Deck and Roof
A camera this unreliable is an unprofessional toy. Stay away from the Leica SL3 until Leica fixes this problem is my advice. If it can be fixed—what if it is lens electromechanical issue and not fixable? The good news would be a firmware fix, if that is possible. However, my expectation based on past experience working with Leica is for Leica to ignore the issue.
f2 @ 1/2500 sec electronic shutter, ISO 100; 2024-04-11 11:30:03
LEICA SL3 + Leica 90mm f/2 APO-Summicron-SL ASPH
RAW: Enhance Details, +10 Whites, +10 Clarity, AI Denoise 10, +10 Vibrance
[low-res image for bot]
2024-04-14 •
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diffraction, digital sensor, field curvature, Fujifilm, Fujifilm medium format, medium format, optical focus shift, Sony, Sony A7R, Sony A7R II, Sony A7R III, Sony A7R IV, Sony A7R V, Sony mirrorless
Very interesting sensor developments! Sony has recently announced 2.9 micron photosite sensors also.
NewShooter: Blackmagic Design URSA Cine & URSA Cine 17K
The Blackmagic Design URSA Cine 12K Camera at only $14995 has a new sensor that might be appropriate for a Sony A7R VI. Or at least a sensor using similar tech. As it stands the sensor is most appropriate for video (eg a low pass filter and other features), and is RGBW so it’s not ideal for a still camera.
That said, the core technology for a 100-megapixel 35mm format camera is now in production. Or soon will be. The sensor is just a little bit cropped from the usual 35.7 X 23.8mm (eg Sony A7R V) but perfectly fine.
- 35.63 x 23.32mm
- RGBW (NOT a Bayer sensor)
- 12288 X 8040 resolution = 98.8 megapixels
- 2.90 micron pixel pitch (1.3X smaller than Sony A7R V or Fujifilm GFX100 II)
- Claimed 16 stops of dynamic range.
The sensor is “BlackMagic designed” but I’m guessing it’s fabbed by Sony.
100 megapixels for 35mm format, 170MP for medium format
Sony A7R V
The pixel pitch of 2.90 microns is a factor of 1.30X vs the 3.76 microns of Sony A7R V and Fujifilm GFX100 II. This is hard core, equating to 172 line pairs per mm. Contemplate that vs the 40 lp/mm MTF charts still in popular usage.
The pixel pitch of both the 17K and 12K sensors imply a future ~170-megapixel Fujifilm GFX100 III or Hasselblad X3D 170-C.
Sure would be nice to see Sony enter the medium format game to keep Fujifilm alert and aggressive.
At a time when Nikon and Canon remain at ~45 megapixels and the 60MP Leica SL3 has only just debuted*, can we say game-over if Sony moves quickly and before the others?
Image quality
The extra pixels are much more about total image quality than resolution. About eliminating digital artifacts like moiré and staircasing and spurious detail, at least with most lenses and by f/5.6. About smoother/cleaner edges and tonal transitions.
Sharpness gains on a 100MP will be minimal and not just from lenses. Two factors are at loggerheads with respect to gains in sharpness on a 100MP 35mm-format sensor. A squeeze from both ends.
Pixel pitch vs depth of field
The 2.9 micron pixel pitch means requires about 2/3 stop more in terms of depth of field eg f/10 instead of f/8. In practical terms, this is unworkable.
Even on the existing 60MP Sony A7R V f/8 is noticeably degrading micro contrast and resolution startingg, with the effects of f/10 much more severe. This is easy to see just by comparing f/5.6 to f/8 using a top-grade lens. Using f/10 on even tinier pixels will just look like mush even if the lens is the best available.
Pixel pitch vs diffraction
Diffraction dulling at any specified aperture is the same regardless of sensor or format. However, the effects are relative to the size of the photosites. The smaller the photosites, the lower the micro contrast and the lower the resolving power. At some point this is de facto zero resolving power due to too-low contrast.
Diffraction with 2.9 micron pixels occur 2/3 of a stop earlier eg f/6.3 instead of f/8. Using f/8 on a 100MP sensor will not produce more detail than with a 60MP sensor with its 3.76 micro pixels. You will be forced to use f/6.3 and that is right on the edge of tolerable.
And that’s assuming a world class lens, the very best.
Approximate diffraction spot size (Airy Disc) relative to photosite size on 45/60/100 MP sensors
Practical gains in detail?
Those two challenges leave negligible room for resolution gains except of with very thin DoF requirements. And if sharpness is desired outside a small area, the lens had better have nil field curvature and negligible focus shift.
Yet serious performance problems from those two factors are readily and obviously seen in a laughably poor performance with $5K top-of-the-line lenses like the Leica 75mm f/2 APO-Summicron-SL ASPH.
CLICK TO VIEW: Sony Mirrorless + Credible Lenses for 100 Megapixels
Sensor Sizes