keskiviikko 9. joulukuuta 2015

DPReview: 'Built like a tank where it counts' - LensRentals tears down Canon EF 35mm F1.4 L II

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

Roger Cicala at LensRentals has a great job - he gets to take things apart whenever he wants, and get paid to do it. And even better, he gets to pay himself to do it. Roger just got his hands on Canon's new EF 35mm F1.4 L II, and just like us, he's been very impressed. But, it must be said,  for very different reasons. Click through this slideshow for a quick look at what he found behind the red ring, and if this whets your appetite, read Roger's full tear-down at lensrentals.com.

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

This is the plastic ring which sits at the front of the all of the elements of the 35mm, underneath the cosmetic nameplate.

According to Roger, 'In most lenses rings like this hold the front element in place, but in this case, it seems the entire purpose of this ring is to improve weather resistance [...] It fits tightly around the glass and into the front barrel of the lens, and it has a rubber gasket for further sealing internally.'

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

Where most lenses use only three lightweight screws to attach the filter barrel, but the Canon EF 35mm F1.4 L II uses six 'long, strong and deeply threaded' ones. 

Behind the screws, Roger's team found that 'each hole contained a brass reinforcing spacer with a spring around it. So basically each of the 6 screws passes through the brass spacer and screws into the front barrel, with a spring maintaining tension. This is an expensive way to do things and obviously serves a purpose.'

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

With the rear barrel removed, two more layers of rubber felt sealing gaskets were revealed and a 'a very, very robust eccentric collar set [...] used to optically adjust the rear group.' (that's the notched, circular object towards the top of the rear group in this image).

In Roger's words. 'we consider thick nylon collars robust, brass collars very robust, but these massive heavy collars with a center locking screw are beyond anything we've seen outside of super telephoto lenses and the 70-200 f/2.8 IS II'.

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

Unusually, even for weather-resistant lenses, the EF 35mm F1.4 L II features tough, moisture-resistant tape underneath the rubber focusing ring, to prevent water getting underneath and into the main body of the lens (the tape has been removed in this image).

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

'With the focus ring off, we can see another set of robust optical adjustment collars that adjust group 2. (Later experimentation hinted that these were primarily centering collars, with the rear collars primarily adjusting tilt.)'

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

As the disassembly progresses, the EF 35mm F1.4 L II seems to get more and more robust - 'With the USM motor and barrel off we can see the focusing helicoids and the heavy metal rollers that move the focusing elements within the helicoid. In almost every lens, these would be small nylon washers over a screw, not the relatively huge metal rollers we see in this lens.'

'Built like a tank where it counts' - LensRentals Canon EF 35mm F1.4 L II teardown

Roger's team took a closer look at those helicoid rollers.

'When you look close up you see these aren't just sliding posts, there are actually tiny ball bearings inside them. There's also a spring tensioning system around one of the rollers. [...] By this point I was really rather awestruck by the amount of careful over-engineering that went into making this lens. Nobody, and I do mean nobody, else is engineering lens mechanics like the newer Canon lenses.'

Roger's final analysis: 

'[The EF 35mm F1.4 L II is] designed thoughtfully and logically. Things that will inevitably get damaged on any lens, like the front element and filter ring, are designed to be replaced easily.  There are some things inside, particularly with the tensioning screws and springs, that I'm not certain I understand the purpose of, but I am certain there is a purpose. If I had to summarize the mechanical design of this lens, I would say simply that no expense was spared, no corner was cut.'



from Articles: Digital Photography Review (dpreview.com) http://ift.tt/1XY22Be
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