LensRentals Leica SL 24-90mm F2.8-4 teardown
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The Leica SL 24-90mm F2.8-4 may not break any new technical ground, but when the SL’s ‘kit’ lens made its way to LensRentals headquarters, the team endeavored to take a careful look inside. With the solidly constructed lens partially disassembled, they got a closer look at its impressive number of moving elements. Take a look at some of the highlights here, and for a full look inside the 24-90mm head over to LensRentals.
Weather-sealing
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Sliding the rear of the lens off took a little muscle according to LensRentals’ Roger Cicala, ‘as it’s very tightly sealed by the thick, greenish weather gasket underneath.’ Leica promises this keeps the lens protected from dust, moisture and splashes.
The inner barrel assembly
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With the zoom key and six screws in the internal chassis removed, the outer assembly of the lens barrel can be removed, and Cicala finds that ‘the zoom and focus rings are one modular assembly connected to the main chassis.’
Not all focusing mechanisms are created equally
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With the inner barrel exposed, part of the 24-90mm’s focus-by-wire linkage can be seen. Says Cicala: ‘I won’t argue with those who prefer a mechanical focusing linkage, and I agree that some electric focusing mechanisms feel sloppy and inaccurate. But I’ll add that they aren’t all made equally, and the Leica focus feels quite good and seems very accurate.’
A ‘complex dance’ of moving elements
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With the casing and front barrel removed, the lens’ helicoid grooves are visible. These allow the moving elements to travel on their separate paths. ‘This is a really nice example of the mathematical formulas involved when you move elements. Notice none of those grooves are parallel; as you zoom the lens the various elements move in a rather complex dance.’
Focusing assembly up close
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Although they’d sworn not to do a full teardown, Roger and company wanted a better look at the focusing group so out it came. And that’s where things got interesting.
‘You can see the stepper motor (green line) of course. The actual focusing element is what Aaron is holding the group by. The larger group in the center is where the entire assembly is attached to the helicoid. One of the first things we notice (red arrows) is this group has 3 pairs of adjustable eccentric collars. These were thoroughly glued in place so we left them alone, but it seems each pair has one collar for tilt and another for centering of this group. None of the other moving groups had eccentric adjustment collars visible.’
A peek at IS
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The teardown stops at this point, but not before a glance up the barrel toward the image stabilization unit. While those screws tempt Cicala and crew, memories of finicky IS systems kept them from going any further.
See the entire peek inside the SL 24-90mm at LensRentals.com
Articles: Digital Photography Review (dpreview.com)
