Dead AF on DFA* 1.4

Started Jan 4, 2019 | Discussions
Roland Karlsson Forum Pro • Posts: 28,984
Re: Dead AF on DFA* 1.4
1

Alex Sarbu wrote:

Roland Karlsson wrote:

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.

Yes, they do not seem to be the same high quality as the usual KA mount contacts.

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SungiBr
SungiBr Regular Member • Posts: 171
Re: Dead AF on DFA* 1.4. FIXED

This exact same thing hapened with mine DA*16-50mm, but mine lens have a veeeeery long milleage in it counter. But was long ago been converted to screwdrive, so this doesn't made any difference.

That being said, despite have abused the lens for years, I also couldn't figure out what hapened to it to have the contact bent and broke.

Maybe, another example of some bad engineering, who knowns.

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

SungiBr wrote:

This exact same thing hapened with mine DA*16-50mm, but mine lens have a veeeeery long milleage in it counter. But was long ago been converted to screwdrive, so this doesn't made any difference.

That being said, despite have abused the lens for years, I also couldn't figure out what hapened to it to have the contact bent and broke.

Maybe, another example of some bad engineering, who knowns.

More likely another example of some bad user abuse.

BryantP Regular Member • Posts: 272
Re: Dead AF on DFA* 1.4
2

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.

If for no other reason than to keep dust off or to prevent accidental scratches of the rear lens elements, I have always been very careful to use the rear lens caps when a lens is off the camera.   I certainly wouldn't put a lens in a camera bag without its rear cap.

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Dericali Regular Member • Posts: 203
Re: Dead AF on DFA* 1.4

Adam007 wrote:

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.

I think the OP's mistake was to take this lens off his camera.

If the DFA* 50mm stays on the K1 at all times then this kind of issue is 100% avoidable.

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

Dericali wrote:

Adam007 wrote:

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.

I think the OP's mistake was to take this lens off his camera.

If the DFA* 50mm stays on the K1 at all times then this kind of issue is 100% avoidable.

This is what I am finding. I got my D FA* 50/1.4 a few days before the official release and IIRC, I have changed it for a different lens twice.

BobORama
BobORama Senior Member • Posts: 2,731
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!

I just looked at the DFA* 70-200 and I could see where if the rear of the lens caught on some fabric or perhaps using the "wrong" lens cap this might happen.  My arguably bad habit is to take the cap off the next lens and put it on the one I am taking off.   Some of these caps were made in 1970,    So I guess something could happen.

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awaldram
awaldram Forum Pro • Posts: 13,271
Re: Dead AF on DFA* 1.4

Roland Karlsson wrote:

Alex Sarbu wrote:

Roland Karlsson wrote:

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.

Yes, they do not seem to be the same high quality as the usual KA mount contacts.

yep they're cheap and cheerful.

luckily there design make then easily changed they plugin in just two screws and you can replace the whole Pz assembly.

Personally I think they are the only part of a modern Pentax mount not over engineered.

i.e you bend a pogo pin and your talking serious cost for repair (but considerably harder to damage in the first place).

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supersargas Regular Member • Posts: 445
Re: Dead AF on DFA* 1.4

should this be forwarded to something like pentax feedback? perhaps this needs to be looked at from their side

OP Adam007 Contributing Member • Posts: 611
The Thrilling Conclusion

The retailer, Adorama, accepted my return, and while some of the correspondence is a bit ambiguous, I believe they simply replaced the lens with a new one.  Out of the box, it seems to work great.

One of my photography profs urged us to buy Adorama because they stand by their products, and that certainly was my experience here.  The lens was gone for about a month, which was mildly irritating, but I can't say unreasonably so.

For commenters such as Florida Sure and others who speculated that the bent contact may have gotten caught in a camera bag, I don't know.  I think lenses should be able to withstand such foreseeable use - but, I agree that out of an abundance of caution, one should recap those rear elements every time the lens goes in the bag.  Tough to do whilst on the go, but it does seem like a good idea to me.

Thanks to everyone for your advice and assistance.

Adam

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Roland Karlsson Forum Pro • Posts: 28,984
Re: The Thrilling Conclusion

Adam007 wrote:

The retailer, Adorama, accepted my return, and while some of the correspondence is a bit ambiguous, I believe they simply replaced the lens with a new one. Out of the box, it seems to work great.

One of my photography profs urged us to buy Adorama because they stand by their products, and that certainly was my experience here. The lens was gone for about a month, which was mildly irritating, but I can't say unreasonably so.

For commenters such as Florida Sure and others who speculated that the bent contact may have gotten caught in a camera bag, I don't know. I think lenses should be able to withstand such foreseeable use - but, I agree that out of an abundance of caution, one should recap those rear elements every time the lens goes in the bag. Tough to do whilst on the go, but it does seem like a good idea to me.

Thanks to everyone for your advice and assistance.

Adam

Good to see that it all ended well.

About the rear cap. There is also a piece of glass surface there that might be good to protect. And also, getting dust in there might end up in the camera and on the sensor.

But I agree - lose lens caps, both rear and front are annoying things.

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Dericali Regular Member • Posts: 203
Re: The Thrilling Conclusion
6

Adam007 wrote:

I agree that out of an abundance of caution, one should recap those rear elements every time the lens goes in the bag. Tough to do whilst on the go, but it does seem like a good idea to me.

No, this should be done out of common sense, not 'an abundance of caution'.

If you're exposing any of the electronics of a lens (or camera) and chucking it the bag exposed you can't expect your gear to last very long.

Good that you got your replacement, but nobody should be storing or transporting lenses with either the front or rear unprotected, that's gear preservation 101.

OP Adam007 Contributing Member • Posts: 611
Re: The Thrilling Conclusion
2

Dericali,

Let's say you were at a photography event with 100 other photographers.  Inexplicably, they are all using prime lenses, and the conditions require people to switch lenses frequently.  What percentage of photographers, in your opinion, will replace front and rear caps every time they put a lens back into the sling bag or lens pouch - a process they might repeat dozens of time before packing everything up for the day?

If you think the answer is more than 10%, then we simply disagree.  Northrup had a video about ignoring your front cap, and the inimitable Ken Rockwell has said the same thing.  Whether or not they are right is beside the point; this perspective isn't exactly coming from Mars.

You might be conflating optimal practice with typical practice, in your appeal to "common sense".  For all kinds of reasons, it's obviously safest to replace both caps every time.  But down here on planet earth, it is down to manufacturers to take note of the fact that this doesn't happen very often.  And I'm going to reiterate what I wrote a month ago - this rear contact design is susceptible to damage in a way that other Pentax designs aren't.  My FA Limiteds weren't exactly cheap - but they don't suffer from this problem.  I'm sure there is a technical explanation for why Pentax has moved in this direction.  And I'm sure someone at Pentax pointed out the risks of doing so.

To an extent difficult to gauge in an online conversation, the difference between us appears to be one of emphasis.  I agree that using the caps is the safest approach - scratching the rear element, fingerprints, carrying dirt near the sensor - these are all good reasons to be careful.  Had I done that, there would be no discussion from me on Pentax's design choices.  Getting a tiny and ridiculously fragile, yet vital, contact caught by the soft material of a camera bag interior was, until now, not some obvious risk one should consider when handling lenses normally.

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Alex Sarbu Forum Pro • Posts: 11,574
Re: The Thrilling Conclusion

Adam007 wrote:

Dericali,

Let's say you were at a photography event with 100 other photographers. Inexplicably, they are all using prime lenses, and the conditions require people to switch lenses frequently. What percentage of photographers, in your opinion, will replace front and rear caps every time they put a lens back into the sling bag or lens pouch - a process they might repeat dozens of time before packing everything up for the day?

If you think the answer is more than 10%, then we simply disagree. Northrup had a video about ignoring your front cap, and the inimitable Ken Rockwell has said the same thing. Whether or not they are right is beside the point; this perspective isn't exactly coming from Mars.

You might be conflating optimal practice with typical practice, in your appeal to "common sense". For all kinds of reasons, it's obviously safest to replace both caps every time. But down here on planet earth, it is down to manufacturers to take note of the fact that this doesn't happen very often. And I'm going to reiterate what I wrote a month ago - this rear contact design is susceptible to damage in a way that other Pentax designs aren't.

You are right: the contacts can get caught in something, and if they're no longer flush with their support...

However, let's put this in perspective: these contacts are wildly used - on older Power Zoom lenses, and on "all" Pentax K-mount lenses with in-lens AF motors. We have tons of people here with SDM, DC and PLM lenses...

Yet we very rarely hear about such occurrences. Yes, many people are cautious with their gear - but these defects are simply rare. You see, it's not enough to put the lens unprotected into you bag - which is bad by itself. The contacts have to get caught on something and twisted from their flush position.

("all" because there is an irrelevant exception - the first K-mount AF lens, the AF 35-70 f/2.8 usable on the ME-F).

I'm sure there is a technical explanation for why Pentax has moved in this direction. And I'm sure someone at Pentax pointed out the risks of doing so.

I believe the usual contacts - the ones on the mount itself - are unsuited for power delivery.

Interestingly, these "power zoom" contacts appear to work better than the relatively similar ones on some other brands. And clearly better than the famous CF pins

Getting a tiny and ridiculously fragile,

Let's not exaggerate.

Alex

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OP Adam007 Contributing Member • Posts: 611
Re: The Thrilling Conclusion

Alex, I appreciate your technical insights, which help me understand why Pentax would move to something like this, if not this exact design.

I think my contact was defective, because nothing unusual happened, it was pretty new, and I've used my other Pentax lenses - including those with the same design - the same way (in the same camera bag) without a problem.

I don't know if this is best thought of as a manufacturing defect, but it certainly is a design choice that makes the lens highly susceptible to failure in the event of a manufacturing defect (or, if you prefer, normal-but-not-perfect use).

I don't think I'm exaggerating.  I was a handier when I was a kid than I am now.  I can remember contacts  like these in kids toys that are impossible to "pry up" without tools.  That might've been a good design feature for Pentax to consider here.

Again, from different perspectives, we are arguing over matters of inflection.  I think this is a pretty dumb way for a lens to fail, but if it's indeed a manufacturing defect, then no one else may have this problem.  Great!  My concerns here are addressed to some specific choices made by Pentax, and don't impugn Pentax or its quality control generally.

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Alex Sarbu Forum Pro • Posts: 11,574
Re: The Thrilling Conclusion
1

Adam007 wrote:

Alex, I appreciate your technical insights, which help me understand why Pentax would move to something like this, if not this exact design.

Thank you.

IMO - I don't think I've made it clear enough - it is an older design which they kept because it works satisfactorily. I won't call it the best, definitely not the ruggedest.

I'd like a better/more rugged design, of course. I don't expect anything, given the low failure rate.

I think my contact was defective, because nothing unusual happened, it was pretty new, and I've used my other Pentax lenses - including those with the same design - the same way (in the same camera bag) without a problem.

It might be a slight manufacturing issue - the contacts just slightly not flush with their support, thus more prone to get caught on things. Only a very careful visual inspection would catch that, as the lens is otherwise in a working state when leaving the factory.

If you're not the first one to touch that lens, maybe a 3rd-party tested the lens and was careless.

Or, it was just bad luck on your part.

I don't know if this is best thought of as a manufacturing defect, but it certainly is a design choice that makes the lens highly susceptible to failure in the event of a manufacturing defect (or, if you prefer, normal-but-not-perfect use).

Indeed, it's a design choice. Just like Canon/Nikon's contacts, or the ever bending CF pins.

I don't think I'm exaggerating. I was a handier when I was a kid than I am now. I can remember contacts like these in kids toys that are impossible to "pry up" without tools. That might've been a good design feature for Pentax to consider here.

Again, from different perspectives, we are arguing over matters of inflection. I think this is a pretty dumb way for a lens to fail, but if it's indeed a manufacturing defect, then no one else may have this problem. Great! My concerns here are addressed to some specific choices made by Pentax, and don't impugn Pentax or its quality control generally.

It's not fun when it happens to you.

Alex

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Dericali Regular Member • Posts: 203
Re: The Thrilling Conclusion
2

Adam007 wrote:

Dericali,

Let's say you were at a photography event with 100 other photographers. Inexplicably, they are all using prime lenses, and the conditions require people to switch lenses frequently. What percentage of photographers, in your opinion, will replace front and rear caps every time they put a lens back into the sling bag or lens pouch - a process they might repeat dozens of time before packing everything up for the day?

If you think the answer is more than 10%, then we simply disagree. Northrup had a video about ignoring your front cap, and the inimitable Ken Rockwell has said the same thing. Whether or not they are right is beside the point; this perspective isn't exactly coming from Mars.

You might be conflating optimal practice with typical practice, in your appeal to "common sense". For all kinds of reasons, it's obviously safest to replace both caps every time. But down here on planet earth, it is down to manufacturers to take note of the fact that this doesn't happen very often. And I'm going to reiterate what I wrote a month ago - this rear contact design is susceptible to damage in a way that other Pentax designs aren't. My FA Limiteds weren't exactly cheap - but they don't suffer from this problem. I'm sure there is a technical explanation for why Pentax has moved in this direction. And I'm sure someone at Pentax pointed out the risks of doing so.

To an extent difficult to gauge in an online conversation, the difference between us appears to be one of emphasis. I agree that using the caps is the safest approach - scratching the rear element, fingerprints, carrying dirt near the sensor - these are all good reasons to be careful. Had I done that, there would be no discussion from me on Pentax's design choices. Getting a tiny and ridiculously fragile, yet vital, contact caught by the soft material of a camera bag interior was, until now, not some obvious risk one should consider when handling lenses normally.

I don't see pros changing lenses a bunch at shows. However let's say that they are. If they're putting the lenses into a bag where each lens is partitioned by soft dividers, e.g. as in the low pro back packs, then it's possibly fine as a temporary measure. If they're jangling against other lenses or hard objects then I'd say they're nuts. It also depends if the bag /sling is being thrown around etc.

What kind of show is that they don't have a few extra minutes in a day to take gear of their gear? Is it a war zone, or is it a boring AF trade fair?

And remember that replacing rear caps is super easy because every lens has the same fitting one. If you get into the habit of changing the rear caps, you're going to take about an extra second per lens.

When I look at the metal contacts on the new Pentax DFA lenses, they don't look fragile, and they look a lot like the contacts on other lenses like the Canon EF mount. I don't think they would easily get damaged if you're sliding them into a soft part of a bag, but it could happen if you grated them on the zip or something.

I''ve never worked with a pro that put lenses in a bag uncapped. Leave them around uncapped when using them on a shoot, sure, but not put them, front or back uncapped, in contact with other things. Maybe you got some advice to the contrary - and maybe this advice came from people you respect, and are even widely respected (Northrup isn't) - but that doesn't stop it being bad advice.

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