
Disassembling the Sony FE 135mm F/1.8 GM - luu
https://www.lensrentals.com/blog/2019/06/disassembling-the-sony-fe-135mm-f1-8-gm/
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neilv
> _There’s also a bit of glue, or possibly just sealant, around the second
> group, too. Since the element fell right out once the screws were removed
> we’ll go with sealant, since that sounds better than ineffective glue._

"The element fell right out" is one of the reasons I've never considered
trying to peek inside a lens.

I had a Canon EF 17-35/2.8L (on which I got a really good deal used, because
the model is known to be a bit soft, and IIRC parts were no longer available).
I banged it at an event (a July 4th exhibition of the ship USS Constitution),
the hood didn't soften the impact enough, I held my breath and didn't look at
any exposed entrails. I sent it to Canon, with an explanation to the effect of
"the front fell off", along with monetary tribute. The lens came back not only
repaired perfectly, but calibrated to what might've been better than new. In
my living room is a poster-sized print of a crowd photo taken with this lens,
and all the great happy facial expressions reacting to something happening are
clear and sharp.

~~~
jeanlucas
I love people/street photography, would you mind sharing the poster?

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neilv
I was actually personally very averse to doing street photography, but there
seemed to be a fuzzy overlap with photojournalism. In my rules for myself, the
difference was when newsworthiness trumps privacy/imposition.

This particular image was when I was learning photojournalism, had just left
practicing fluffy stuff at a street fair (e.g., visually appealing image of
vendor making candied popcorn), and the crowd I was in suddenly parted, to
something newsworthy, and muscle memory kicked in.

I didn't try to publish it, because it turned out to involve a celebrity (who
I didn't recognize until a real photojournalist told me), and I had a rule
against shooting that, but it was a happy enough image that I had a print made
for myself.

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mauvehaus
As an FYI for anybody getting ready to take apart their own lens to repair it,
be aware that Japanese made lenses frequently use JIS screws [0], not Philips.
If they aren't super tight, you can get away with using Philips, but you
wouldn't want to make a regular thing of it.

I've had a no-name 28mm lens apart a couple of times to clear oil off of the
aperture blades. The old manual everything lenses are relatively
straightforward to get apart. Be aware of the minuscule ball bearing that
engages the detents in the aperture ring. It's spring-loaded, which might be
obvious to you, but wasn't to me the first time I took the lens apart.

[0]
[https://en.wikipedia.org/wiki/List_of_screw_drives#JIS_B_101...](https://en.wikipedia.org/wiki/List_of_screw_drives#JIS_B_1012)

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penagwin
> It's spring-loaded, which might be obvious to you

In my experience it's never "obvious" until it flies across the room :D

~~~
blattimwind
I assume everyone who ever took a manual lens apart has at least one lens with
a cine-style aperture ring... that is, without detents.

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3JPLW
If you enjoyed this, you'll probably also really enjoy the video teardown of
the Sony OSS 16-50mm kit lens. It's cool for two reasons — one is that it's a
zoom lens, but the really awesome part is that it has an optical stabilization
element. There's also a bit more focus on the electronics and motors.

[https://petapixel.com/2016/02/09/this-teardown-of-a-sony-
e-m...](https://petapixel.com/2016/02/09/this-teardown-of-a-sony-e-mount-lens-
shows-optical-steadyshot-in-action/) (blog bait summary — but with a bit more
text)

[https://www.youtube.com/watch?v=g9umAQ1-an4](https://www.youtube.com/watch?v=g9umAQ1-an4)
(the actual video)

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lmilcin
Regardless of weather sealing lenses will get dusty if they breathe. If any
outside lenses move the internal volume of air must change and that means air
is being exchanged with the outside.

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IgorPartola
Couldn’t you make a lens with a vacuum inside?

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lmilcin
If the lens does not breathe there would be no advantage (it can just be
airtight without being vacuum) and if the lens breathes (ie changes internal
volume) it means the motor would have to work against atmospheric pressure
which would be extremely difficult in a lens to do reliably.

~~~
penagwin
Counter question: Why not fill lenses with Nitrogen? I know outdoor cameras
CCTV cameras do this (more so to prevent condensation from internal moisture).

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grozzle
You'd still have to compress the nitrogen going one way to zoom, and pull the
nitrogen against air pressure going the other way. Focus motors powerful
enough to do that, plus including movable airtight seals to keep the nitrogen
inside, would make the lens a serious chunk bigger, heavier and more
expensive.

The dust that gets inside from breathing while zooming rarely affects image
quality to any meaningful degree. Excessive humidity can lead to fungus
growing on the glass though, which really can ruin your contrast. It's
normally good enough to keep your lenses in a box with some silica desiccant
during summer to prevent that.

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chaosite
That was a fun read. I enjoy reading tear-downs like this, even if the fault
was something they weren't able to fix.

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PaulHoule
I also like it that Sony was cool with them doing this.

Despite Sony's insistence on DRM they make some very repairable hardware. For
instance, it is dead easy to replace the controller switches, battery, and
other parts on the Playstation Vita where the flex cables are very well
routed.

~~~
adestefan
In general I've found electronics from the major Japanese companies easy to
open, well labeled, and designed in a logical manner.

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sdfjkl
Nice writing, and very educational for someone who never had reason to take a
lens apart. Explains part of why they're so expensive! :)

I think it's a bit more glue than I like, but still reasonably serviceable for
something with small parts in a restricted space. About on par with a Toshiba
laptop, not as good as a Thinkpad (based on my experience with now outdated
hardware repairs).

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emptybits
I love the Lensrentals teardowns! I _just_ finished reading this teardown of a
then-flagship Sony camera that was exposed to saltwater.

[https://www.lensrentals.com/blog/2017/10/about-getting-
your-...](https://www.lensrentals.com/blog/2017/10/about-getting-your-camera-
wet-teardown-of-a-salty-sony-a7sii/)

Or if you're a Nikon fan, here's their teardown of a Nikon flagship a year
later. Note that this camera wasn't suspected of exposure or abuse, so not
really a comparison but I'm fascinated by how modern pro cameras are built,
their weaknesses, and how they may or may not be serviceable.

[https://www.lensrentals.com/blog/2018/10/teardown-of-the-
nik...](https://www.lensrentals.com/blog/2018/10/teardown-of-the-
nikon-z7-mirrorless-camera/)

~~~
blattimwind
wrt. casing at least Nikon's pro offerings were always top notch in terms of
body ruggedness etc., although up to 2008 or so they did have occasional
issues with the rubber coming off at the edges. Some problems with chemical
resistance as well. Newer models use a different, notably stronger adhesive.
Fewer problems wrt. chemicals it seems, too.

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hobofan
I once had to open an old 24mm Pentax lens that my parents handed down to me
when I started photography. The aperture was stuck due to some old grease, and
with that the lens barely unusable. The fix was pretty easy, and the whole
process of understanding all the tiny mechanics of a lens were a lot of fun,
but at the same time it was incredibly stressful to have those optical
elements so exposed.

I couldn't image doing the same thing with a current lens that also has all
those electronics in there.

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ComputerGuru
I just disassembled (and didn't bother putting back together) a Sony 16-50mm
f/3.5-5.6, the build quality here seems to be better. That was a lot of
plastic and parts didn't really "click" in place so much as "mashed in there."
I've had to replace this lens twice already (and it's only a very, very part-
time camera for me); I am significantly less careful with my Nikkor equipment
and never had any issues there.

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mschuster91
The Sony camera stuff is _really_ built like tanks and can pack a load of
abuse. Thanks for the submission, that explains the "why" :)

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deaps
I found this disassembly very interesting. Thanks for posting.

I've taken _a lot_ of stuff apart in my days, but never an expensive camera
lens. I've owned, just off the top of my head, a 70-200 f/2.8, 50 f/1.8, 85
f/1.8, and a 105 f/2.8 macro lens back in the day when digital was just
starting to catch on.

There are times where I miss photography...I always assume I'll get back into
it at some point.

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bryanmgreen
Great read - I'm excited for the Sony 35mm 1.8 teardown.

