[ma318]

The focusing ring on my DA 16-45 was stuck so I took the lens apart to determine the cause of the problem. I was able to determine one of the internal plastic parts had couple of pieces broken off it and was jamming the focusing ring. I sent Pentax Canada, located at Mississauga, Ontario, an email last night (service@pentaxcanada.ca) asking them whether they sell parts for my lens. This morning I got a reply from a Pentax parts technician indicating that they do sell parts for it. I sent him an email this morning with the description and photo of the part. In about 4 hours later, he replied to me with the part number and cost. I then called him with the number he sent me and placed the order for the part this afternoon. $9.50 for the replacement part and $10 for shipping which I think is reasonable. I am very impressed with the service offered by Pentax Parts Service in Canada! This is the first time I had to deal with Pentax Service Canada and so far they have shown to be very responsive to even a little guy like me.

Photo#1 shows what the lens looked like after it was taken apart.
Photo#2 shows the pieces that were broken off
Photo#3 & #4 show where the pieces were broken from

(I bought this lens from e(vil)bay as part of a camera set but the seller did not indicate a problem with this lens. He ended up refunding some money to account for it.)

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Last edited by ma318; 07-30-2009 at 11:24 AM.

[PentHassyKon]

Wow!....
Let us know how it works out.
Be great if you could show/share how it went taking one of these babies apart.
I too have a 16-45, hopefully I don't expect to get the problem you had but it would be good to know how easy (or hard) it will be to take apart and re-assemble it.

[ma318]

I already had the lens put back together when I placed the order for the replacement part. The focus ring works now but it could still jam when the lens is focused at infinity and tilted upward. I could "un-jam" it by pushing the front of the lens forward. I will take better pictures of the repair process when I take the lens apart again to install the new part. The first time taking it apart was slow-going and difficult for me. I think the second time around should be a lot easier. Of course if you take your lens apart, you do it at your own risk. I would not recommend it if you are not good at using small tools or have not taken stuff apart before. It also requires a lot of patience and good eyesight to put it back together as some of the screws and spring contacts are very small.

I could not find any information on how to take the front element housing of the DA 16-45 apart. With older lens, I read you would first use a tool to rotate the front engraved ring to get it off. I found by trial and error that the front engraved ring is just a piece of nylon ring glued to the front element housing. I used a tiny jewelry screw driver and tweeter to slowly pry and lift it off. Once off, you would see two holes on the front element housing and you would use these two holes as anchoring points to rotate the front element housing off. I made a tool using stuff that I already had in the house to do this. I found that I had to use a heat gun (or hair dryer if you don’t have a heat gun) to heat the front part up a little before I could get it to rotate. Once the front element housing is off, you would have to start at the rear of the lens and unscrew petty much every screw off, one group of screws at a time, to dismantle the lens. I use a tiny jewelry screw driver from my watch repair kit. It is important to have a good and tough screw driver otherwise you may have trouble unscrewing the tiny screws.

Wherever possible, I also used masking tape and a pen to make alignment marks on pieces that fit together before I dismantle them so I know how far to tighten them later or how to orientate them for re-assembly. I also used masking tape to tape up each group of screws and related parts. I wrote on the tape identifying where they come from to make it easier to re-assemble everything together later.


(I suspect the lens must have been dropped with the front hitting something in order for the plastic pieces inside to break off like that. I doubt you would get this problem with normal usage.)

photo #1: the tool I put together to unscrew the front element (small vise, parts from a clamp, 2 jewelry screw drivers)
photo #2: how I use the tool (note: I taped a piece of paper on the lens to somewhat protect it. I think this is the most hazardous part of the repair process. Any slippage here could cause scratches on the lens.)
photo #3: how the front looks like with the front element rotated off

[Just1MoreDave]

You should be proud of your repair ability. Old prime lenses are pretty easy, Russian lenses a bit harder, but new zoom lenses seem to have a thousand tiny parts. Everything you remove makes you wonder if you'll ever get it back together and working.

[code4code5]

I was brave enough to take apart an old Vivitar 200mm M42 lens, but I don't think I would ever have the cojones to try to work on an AF lens. Congratulations on not having to sell a 16-45 "lens in a bag" on eBay. I know that would be my result!

[Pentax_XTC]

OK... I tinker with stuff, but you are a braver man then I! Thanks for all the internal parts shots though! I wonder, with all that I have heard about the SDM motor problems on this lens, could you post a picture of the SDM motor assembly? There have been some questions about its build and layout on other posts.

Thanks

[PentHassyKon]

.......... I wonder, with all that I have heard about the SDM motor problems on this lens, could you post a picture of the SDM motor assembly? .........

Unfortunately, the lens in question here - DA 16-45 is not an SDM lens - it is screw drive.

[Pentax_XTC]

My Bad. I jumped at the thought of a DA*16-50 being cracked open and jumped on a reply. Still more than I would be willing to do on a lens myself!

[ma318]

That's right. There is no motor in the 16-45. The external focusing ring is driven by a short shaft with gear on both ends which is in turn driven by another small gear assembly inside the lens which is then in turn driven by the camera's auto focus screw. It is a very simple but effective design. Maybe that's why it is reliable. But with this design, it is difficult to provide water proofing at the lens' auto focus screw interface.

photo #1: showing the auto focus gear/shaft (taken out of the lens)
photo #2: showing the gear/shaft and the focus position sensing electronics (looking into the front of the lens)
photo #3: showing the gear/shaft and the zoom focal length sensing electronics (looking into the rear of the lens)

[res3567]

That's right. There is no motor in the 16-45. The external focusing ring is driven by a short shaft with gear on both ends which is in turn driven by another small gear assembly inside the lens which is then in turn driven by the camera's auto focus screw. It is a very simple but effective design. Maybe that's why it is reliable. But with this design, it is difficult to provide water proofing at the lens' auto focus screw interface.

photo #1: showing the auto focus gear/shaft (taken out of the lens)
photo #2: showing the gear/shaft and the focus position sensing electronics (looking into the front of the lens)
photo #3: showing the gear/shaft and the zoom focal length sensing electronics (looking into the rear of the lens)

My hats off to you!

You seem to have a great skill; like a craftman; a watchmaker.

When I was younger I could do stuff like that; now my patience a memory seem to be going away!

Years ago I took apart an 85mm MF screw mount lens( not Pentax) and it is still in pieces!

[jimmiknut]

Great thread ma318
After i read your post i came over a 16-45 lens that had the same problem. I managed to repair it also, though i got some parts over from when i reassembled the lens. But it seems to work good anyway

[solisti]

Could someone with experience of the DA16-45 tell how you tighten the front of the lens? Mine suffers from the loose barrel syndrome enough to impact on the picture quality.

[altopiet]

Could someone with experience of the DA16-45 tell how you tighten the front of the lens? Mine suffers from the loose barrel syndrome enough to impact on the picture quality.

+1...

[glasbak]

Could someone with experience of the DA16-45 tell how you tighten the front of the lens? Mine suffers from the loose barrel syndrome enough to impact on the picture quality.

Pentax designed it this way, you can fix it by replacing this lens with the tamron 1:2.8 17-50, its slightly more expensive, and heavier, but faster and optical much better.

[altopiet]

Pentax designed it this way, you can fix it by replacing this lens with the tamron 1:2.8 17-50, its slightly more expensive, and heavier, but faster and optical much better.

I bought a used copy of the lens, are you actually saying that it is the same with a brand new one?

For the price I've paid I get pretty good results, I would just like to know if by somehow tightening it somewhere, I might get even better results