Dead AF on DFA* 1.4

Started Jan 4, 2019 | Discussions
Alex Sarbu Forum Pro • Posts: 11,584
Re: Dead AF on DFA* 1.4. FIXED

Adam007 wrote:

So, I tried cleaning the contacts again. I noticed one of the two gold contacts on the lens was bent in the wrong direction (outward). I pressed it back into place, and voila! It looks like this:

Look closely at the contact on the left (just above the screw).

Oh, the power zoom contacts - introduced a few decades ago, cvasi-abandoned and then reused to provide power for the in-lens AF motors, and now the KAF4 aperture mechanism.

They do occasionally break, unfortunately - not often, but I've heard about a case or two.

Two things: I assume this got bent while changing the lens, but I’ve changed lenses a zillion times, and this seems a bit unlucky. Also, I’m a little surprised there is no redundancy here; this contact is sill sticking out a bit from the lens body, and if it gets jostled again, it might not be such a quick fix.

At least it should be an easy repair ( very little disassembly is required).

Thanks to everyone, particularly those who insisted this sounded like a lens-body communication problem. And if anyone has suggestions about that stray contact (I think it’s best to leave well enough alone, but I don’t know), I’d love to hear from you.

No suggestion I'm afraid, other than the obvious make sure it won't break and fall into the lens/camera.

Alex

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MightyMike Forum Pro • Posts: 40,578
Re: Dead AF on DFA* 1.4

Alex Sarbu wrote:

MightyMike wrote:

Sounds like a communication problem, you might consider checking of the screws on the mount plate are tight, if that does nothing for you it will have to be serviced

Yeah, lens and camera side.

But don't you need a JIS screwdriver for that? AFAIK using Philips ones can damage the screws.

Alex

It probably can, but so long as you don't overdo it and are careful I'm sure you can get away with it.

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Mike from Canada
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MightyMike Forum Pro • Posts: 40,578
Re: Dead AF on DFA* 1.4. FIXED

Great to see this fixed, however what a problem, I hope this isn't a sign of cost cutting but rather just a one off fluke.

Adam007 wrote:

So, I tried cleaning the contacts again. I noticed one of the two gold contacts on the lens was bent in the wrong direction (outward). I pressed it back into place, and voila! It looks like this:

Look closely at the contact on the left (just above the screw).

Two things: I assume this got bent while changing the lens, but I’ve changed lenses a zillion times, and this seems a bit unlucky. Also, I’m a little surprised there is no redundancy here; this contact is sill sticking out a bit from the lens body, and if it gets jostled again, it might not be such a quick fix.

Thanks to everyone, particularly those who insisted this sounded like a lens-body communication problem. And if anyone has suggestions about that stray contact (I think it’s best to leave well enough alone, but I don’t know), I’d love to hear from you.

-- hide signature --

Mike from Canada
"I am not a great photographer! God is a great creator! All I do is capture His creation with the tools He has provided me."
'I like to think so far outside the box that it would require a telephoto lens just to see the box!' ~ 'My Quote :)'
http://www.michaelfastphotography.com/galleries/VP-BDI_3a.jpg
http://www.airliners.net/user/SpeEedy/profile/photos?sortBy=photoFavoriteCount

OP Adam007 Contributing Member • Posts: 611
Re: Dead AF on DFA* 1.4

On more follow-up:  the pin bent itself back out of position. “Fixed” yet again, but I can’t take the chance of it failing permanently outside of warranty. Back it goes.

Thanks again!

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Roland Karlsson Forum Pro • Posts: 28,984
Re: Dead AF on DFA* 1.4. FIXED

MightyMike wrote:

Great to see this fixed, however what a problem, I hope this isn't a sign of cost cutting but rather just a one off fluke.

It looks kind of strange with those contacts bent like that. I have now looked at my lenses with internal AF. The contacts have no tendency at all at being bent.

You guys that have a DFA* 50/1.4, can you take a look at your contacts? And maybe take a picture how they should look?

Adam007 wrote:

So, I tried cleaning the contacts again. I noticed one of the two gold contacts on the lens was bent in the wrong direction (outward). I pressed it back into place, and voila! It looks like this:

Look closely at the contact on the left (just above the screw).

Two things: I assume this got bent while changing the lens, but I’ve changed lenses a zillion times, and this seems a bit unlucky. Also, I’m a little surprised there is no redundancy here; this contact is sill sticking out a bit from the lens body, and if it gets jostled again, it might not be such a quick fix.

Thanks to everyone, particularly those who insisted this sounded like a lens-body communication problem. And if anyone has suggestions about that stray contact (I think it’s best to leave well enough alone, but I don’t know), I’d love to hear from you.

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/Roland
Kalpanika X3F tools:
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Roland Karlsson Forum Pro • Posts: 28,984
Re: Dead AF on DFA* 1.4
1

MightyMike wrote:

Alex Sarbu wrote:

MightyMike wrote:

Sounds like a communication problem, you might consider checking of the screws on the mount plate are tight, if that does nothing for you it will have to be serviced

Yeah, lens and camera side.

But don't you need a JIS screwdriver for that? AFAIK using Philips ones can damage the screws.

Alex

It probably can, but so long as you don't overdo it and are careful I'm sure you can get away with it.

I recommend a JIS. I have destroyed screws on at least one old lens before I got myself a JIS screw driver. If the screw is sitting hard you are going to destroy it.

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/Roland
Kalpanika X3F tools:
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Alex Sarbu Forum Pro • Posts: 11,584
Re: Dead AF on DFA* 1.4. FIXED

Roland Karlsson wrote:

You guys that have a DFA* 50/1.4, can you take a look at your contacts? And maybe take a picture how they should look?

Of course, the contacts are not normally bent nor raised from their support - here's my sample:

Alex

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Roland Karlsson Forum Pro • Posts: 28,984
Re: Dead AF on DFA* 1.4
1

James O'Neill wrote:

And a huge proportion of failures seem to result in a post here.

That is always so. I assume a very high percentage of those active in a forum will tell about their misfortunes.

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/Roland
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TBLF Senior Member • Posts: 1,038
Re: Dead AF on DFA* 1.4. FIXED

Adam007 wrote:

So, I tried cleaning the contacts again. I noticed one of the two gold contacts on the lens was bent in the wrong direction (outward). I pressed it back into place, and voila! It looks like this:

Look closely at the contact on the left (just above the screw).

Two things: I assume this got bent while changing the lens, but I’ve changed lenses a zillion times, and this seems a bit unlucky. Also, I’m a little surprised there is no redundancy here; this contact is sill sticking out a bit from the lens body, and if it gets jostled again, it might not be such a quick fix.

Thanks to everyone, particularly those who insisted this sounded like a lens-body communication problem. And if anyone has suggestions about that stray contact (I think it’s best to leave well enough alone, but I don’t know), I’d love to hear from you.

I'm so happy for you! And, for the community that it is not an internal motor or circuit issue. I'm not 100% sure what I would do in your shoe's, but I think I'd be keeping a sharp eye on it, and find out the EXACT expiration date of your warranty, so as to know when you have to decide by, as to weather you want to send in to have that contact looked at.  Good job.

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EricV

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egk4260 Contributing Member • Posts: 774
Re: Dead AF on DFA* 1.4. FIXED
9

I would disagree with just watching it closely and calling at end of warranty. With issues like this there is always the potential that the servicing agent will deem the damage related to misuse rather than design related or an isolated QA miss. I think the longer he waits the more likely this would be the case, further decreasing his chances of warranty repair or replacement. User repairs involving bending contacts and using screwdrivers could be considered repairs done outside the authorized network.

Send it in, push hard for warranty coverage, but get it corrected. They may well consider it not a warranty issue, but he paid for top tier optics, he may as well have a reliable top tier lens.

OP Adam007 Contributing Member • Posts: 611
Re: Dead AF on DFA* 1.4
2

Thanks, All.  It goes back at the end of the trip, under the retailer’s warranty.  Contact broke off completely.

i can’t say there was anything unusual in my handling  of this lens - except that I was always extra careful because it’s so new and expensive.  While I can’t identify exactly what went wrong here, I think the contact was unable to withstand normal use.  I’ll press that point as strongly as needed with the retailer.

Thanks again for all the advice and support.

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(unknown member) Veteran Member • Posts: 6,680
Re: Dead AF on DFA* 1.4
4

Roland Karlsson wrote:

James O'Neill wrote:

And a huge proportion of failures seem to result in a post here.

That is always so. I assume a very high percentage of those active in a forum will tell about their misfortunes.

People who are happy with their gear just use the stuff. People who are having problems seek out forums such as this for advice. Human nature skews forums such as this into inflating one off problems into epidemics.

People have to ignore this basic fact when trying to score cheap hit points on a brand.

TBLF Senior Member • Posts: 1,038
Re: Dead AF on DFA* 1.4
2

Adam007 wrote:

"Contact broke off completely."

Ouch! Yeah, sometimes it is easy to forget how fragile certain parts of our equipment are, and it's a miracle things like this don't happen more often, with all the lens on/off the camera mounting. The clearances are tight, and all it takes is a bur or slight misalignment to catch at the wrong moment and pull that contact away.  Sorry it didn't make it through your trip, but returning it sooner than later sounds like it would have been the best course anyway. Let us know how it goes.

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EricV

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johnami
johnami Senior Member • Posts: 1,203
Re: Dead AF on DFA* 1.4
1

Funny how someone's misfortune can lead to oneself taking a good hard look his own camera equipment.

The contacts we are talking about only exist on certain lenses like the DFA 50 and DA 300 mm. I have never really taken much notice of them. But as you have mentioned, these are expensive pieces of equipment and we try to take special care. In my case it means leaving the lens on the body as much as possible. It's such a big heavy unit anyway that when it's on I know I will use it 😇. If it was off, maybe not...

Difficult to understand how the contacts were bent out of position😳...We all know that when removing a lens you push a button and turn anticlockwise and turn clockwise when attaching a lens. Physically it isn't possible do it back to front. So I don't believe the contacts were damage when changing lenses. So how? I can't see Pentax sending out lenses with bent contacts, certainly with the new star range....Mystery...What about the little screws on each side...could they become loose? Have to get to the bottom of this Watson..

Perhaps you'll get some info from Pentax once the lens is repaired. They are certainly already reading this post..

Nice lens the DFA 50mm, but when I compare it to my FA 85mm star, I wonder how big a new 85 mm could be...Cheese..

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Alex Sarbu Forum Pro • Posts: 11,584
Re: Dead AF on DFA* 1.4

johnami wrote:

The contacts we are talking about only exist on certain lenses like the DFA 50 and DA 300 mm. I have never really taken much notice of them.

These power contacts exist on:

- the old power zoom lenses

- the D FA and DA lenses with in-lens autofocus motors (about 20 lenses and counting)

Alex

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Florida Suse
Florida Suse Regular Member • Posts: 487
Re: Dead AF on DFA* 1.4

johnami wrote:

Funny how someone's misfortune can lead to oneself taking a good hard look his own camera equipment.

The contacts we are talking about only exist on certain lenses like the DFA 50 and DA 300 mm. I have never really taken much notice of them. But as you have mentioned, these are expensive pieces of equipment and we try to take special care. In my case it means leaving the lens on the body as much as possible. It's such a big heavy unit anyway that when it's on I know I will use it 😇. If it was off, maybe not...

Difficult to understand how the contacts were bent out of position😳...We all know that when removing a lens you push a button and turn anticlockwise and turn clockwise when attaching a lens. Physically it isn't possible do it back to front. So I don't believe the contacts were damage when changing lenses. So how? I can't see Pentax sending out lenses with bent contacts, certainly with the new star range....Mystery...What about the little screws on each side...could they become loose? Have to get to the bottom of this Watson..

Been reading this thread but, haven't commented because I've been thinking about this mystery and I think. . .

that it will be very important to keep that plastic cap that goes on the back part of the lens on every time the lens is not attached to the camera.  Not saying the OP did not do this or this is what could have caused contacts to bend out but, I'm thinking that it could easily snag on a piece of fabric or another piece of gear in a camera bag or any place when not covered or protected with the cap. Seems like an easy piece to get caught on anything because it sticks up and catches easily. Will have to be conscious of never having this lens capless on the back end, even in camera bag or pouch.

Perhaps you'll get some info from Pentax once the lens is repaired. They are certainly already reading this post..

Nice lens the DFA 50mm, but when I compare it to my FA 85mm star, I wonder how big a new 85 mm could be...Cheese..

johnami
johnami Senior Member • Posts: 1,203
Re: Dead AF on DFA* 1.4

Alex Sarbu wrote:

johnami wrote:

The contacts we are talking about only exist on certain lenses like the DFA 50 and DA 300 mm. I have never really taken much notice of them.

These power contacts exist on:

- the old power zoom lenses

- the D FA and DA lenses with in-lens autofocus motors (about 20 lenses and counting)

Alex

Thanks Alex...Just proves how many lenses I don't have..😉

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Roland Karlsson Forum Pro • Posts: 28,984
Re: Dead AF on DFA* 1.4

Florida Suse wrote:

Been reading this thread but, haven't commented because I've been thinking about this mystery and I think. . .

that it will be very important to keep that plastic cap that goes on the back part of the lens on every time the lens is not attached to the camera. Not saying the OP did not do this or this is what could have caused contacts to bend out but, I'm thinking that it could easily snag on a piece of fabric or another piece of gear in a camera bag or any place when not covered or protected with the cap. Seems like an easy piece to get caught on anything because it sticks up and catches easily. Will have to be conscious of never having this lens capless on the back end, even in camera bag or pouch.

I am a little surprised.

I always thought those contacts were solid metal ones. At least that is how the look at my lenses having them. But, now it seems they are only thin metal ones bent over a plastic base. And looking closer, that might be the same on my lenses, but I am not sure.

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johnami
johnami Senior Member • Posts: 1,203
Re: Dead AF on DFA* 1.4

Roland Karlsson wrote:

Florida Suse wrote:

Been reading this thread but, haven't commented because I've been thinking about this mystery and I think. . .

that it will be very important to keep that plastic cap that goes on the back part of the lens on every time the lens is not attached to the camera. Not saying the OP did not do this or this is what could have caused contacts to bend out but, I'm thinking that it could easily snag on a piece of fabric or another piece of gear in a camera bag or any place when not covered or protected with the cap. Seems like an easy piece to get caught on anything because it sticks up and catches easily. Will have to be conscious of never having this lens capless on the back end, even in camera bag or pouch.

I am a little surprised.

I always thought those contacts were solid metal ones. At least that is how the look at my lenses having them. But, now it seems they are only thin metal ones bent over a plastic base. And looking closer, that might be the same on my lenses, but I am not sure.

They are the same....

https://github.com/kalpanika/x3f

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Alex Sarbu Forum Pro • Posts: 11,584
Re: Dead AF on DFA* 1.4

Roland Karlsson wrote:

Florida Suse wrote:

Been reading this thread but, haven't commented because I've been thinking about this mystery and I think. . .

that it will be very important to keep that plastic cap that goes on the back part of the lens on every time the lens is not attached to the camera. Not saying the OP did not do this or this is what could have caused contacts to bend out but, I'm thinking that it could easily snag on a piece of fabric or another piece of gear in a camera bag or any place when not covered or protected with the cap. Seems like an easy piece to get caught on anything because it sticks up and catches easily. Will have to be conscious of never having this lens capless on the back end, even in camera bag or pouch.

I am a little surprised.

I always thought those contacts were solid metal ones. At least that is how the look at my lenses having them. But, now it seems they are only thin metal ones bent over a plastic base. And looking closer, that might be the same on my lenses, but I am not sure.

All the lenses I've seen (and paid attention to those contacts) are the same. I call those contacts "Canon-style", to differentiate them from the typical Pentax contacts introduced with the KA mount.

Alex

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