DA21 Bug: Bump'n'Stick

dantekgeek · 10-14-2010, 12:57 PM

I adore my lil' DA21; and its without a doubt one of my most used lenses. As a result (and because I tend to be unintentionally hard on my gear), I've discovered a weird quirk in the design of the lens, and was wondering if anyone else has experienced the same thing.

In short, a blow (or bump) of sufficient force to the front of the lens will cause the focus mechanism to bind; not completely, but it will jam up and feel as if the barrel is rubbing against itself.

The first time this happened, my heart sank– my favorite lens, ruined! Being a student, I hardly had the disposable income to replace it. After trying unsuccessfully to fix it by gentle tapping or turning, I gave up. Luckily, after moping around town the rest of the afternoon, the lens got *another* bump, and just like in the movies, everything was working perfectly again!

Being the worry-wart that I am, I did thorough tests to make sure everything was indeed working fine, and it was. Focus is fast, smooth, and accurate.

Since then, I've had the lens bumped a few more times, and every time, another fortuitous (or pained and carefully aimed) bump fixes it. Finally, the last time it happened, I experimented a bit and found that simply gripping the front barrel tightly and turning it counter-clockwise about half a millimeter fixes the problem every time, and that turning it the other direction can reproduce it.

I'm far from an expert on what goes on inside a lens, so I was wondering if someone might be able to shed some light on what might be happening in these situations, and if there's anything I can do to "tighten up" the mechanism (I figure being able to turn the barrel isn't a *good* thing).

Rory · 10-14-2010, 01:00 PM

No light to be shed. Feel lucky it's fixed, and take better care of your gear until you can financially afford to be rough on it.

dantekgeek · 10-14-2010, 01:04 PM

Originally posted by Rory

No light to be shed. Feel lucky it's fixed, and take better care of your gear until you can financially afford to be rough on it.

I absolutely feel lucky. The ironic thing is that 99% of the time I'm incredibly over-protective of my gear; its only when I'm working (shooting concerts or events) that things tend to get messy (but that's just part of the job, isn't it).

Rory · 10-14-2010, 01:13 PM

Well, shooting engagements and weddings tend to be less rough than a concert, so I can understand. However, just like framing, you need to be completely aware of your surroundings when shooting a concert to try to minimize damage or injury.

dantekgeek · 10-14-2010, 01:17 PM

Originally posted by Rory

Well, shooting engagements and weddings tend to be less rough than a concert, so I can understand. However, just like framing, you need to be completely aware of your surroundings when shooting a concert to try to minimize damage or injury.

Right. Being aware of your surroundings is equally as important as anything else. Unfortunately, its hard to control the actions of others which might lead to things getting broken (being slammed into the stage, against other people, etc)

10-14-2010, 12:57 PM	#1
dantekgeek Senior Member Join Date: Oct 2008 Location: NYC Posts: 100	DA21 Bug: Bump'n'Stick I adore my lil' DA21; and its without a doubt one of my most used lenses. As a result (and because I tend to be unintentionally hard on my gear), I've discovered a weird quirk in the design of the lens, and was wondering if anyone else has experienced the same thing. In short, a blow (or bump) of sufficient force to the front of the lens will cause the focus mechanism to bind; not completely, but it will jam up and feel as if the barrel is rubbing against itself. The first time this happened, my heart sank– my favorite lens, ruined! Being a student, I hardly had the disposable income to replace it. After trying unsuccessfully to fix it by gentle tapping or turning, I gave up. Luckily, after moping around town the rest of the afternoon, the lens got another bump, and just like in the movies, everything was working perfectly again! Being the worry-wart that I am, I did thorough tests to make sure everything was indeed working fine, and it was. Focus is fast, smooth, and accurate. Since then, I've had the lens bumped a few more times, and every time, another fortuitous (or pained and carefully aimed) bump fixes it. Finally, the last time it happened, I experimented a bit and found that simply gripping the front barrel tightly and turning it counter-clockwise about half a millimeter fixes the problem every time, and that turning it the other direction can reproduce it. I'm far from an expert on what goes on inside a lens, so I was wondering if someone might be able to shed some light on what might be happening in these situations, and if there's anything I can do to "tighten up" the mechanism (I figure being able to turn the barrel isn't a good thing).

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10-14-2010, 01:00 PM	#2
Rory Inactive Account Join Date: Jul 2010 Location: Chicago Photos: Gallery Posts: 672	No light to be shed. Feel lucky it's fixed, and take better care of your gear until you can financially afford to be rough on it.

10-14-2010, 01:04 PM	#3
dantekgeek Senior Member Join Date: Oct 2008 Location: NYC Posts: 100 Original Poster	Originally posted by Rory No light to be shed. Feel lucky it's fixed, and take better care of your gear until you can financially afford to be rough on it. I absolutely feel lucky. The ironic thing is that 99% of the time I'm incredibly over-protective of my gear; its only when I'm working (shooting concerts or events) that things tend to get messy (but that's just part of the job, isn't it).

10-14-2010, 01:13 PM	#4
Rory Inactive Account Join Date: Jul 2010 Location: Chicago Photos: Gallery Posts: 672	Well, shooting engagements and weddings tend to be less rough than a concert, so I can understand. However, just like framing, you need to be completely aware of your surroundings when shooting a concert to try to minimize damage or injury.

10-14-2010, 01:17 PM	#5
dantekgeek Senior Member Join Date: Oct 2008 Location: NYC Posts: 100 Original Poster	Originally posted by Rory Well, shooting engagements and weddings tend to be less rough than a concert, so I can understand. However, just like framing, you need to be completely aware of your surroundings when shooting a concert to try to minimize damage or injury. Right. Being aware of your surroundings is equally as important as anything else. Unfortunately, its hard to control the actions of others which might lead to things getting broken (being slammed into the stage, against other people, etc)