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06-30-2020, 12:34 AM   #1
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DA 50mm 1.8 aperture stuck after drop

Hi there. The DA 50mm 1.8 is one of my favorite lens. I shoot the K-30 and now the K-70 and also own a DA 35mm 2.4

I dropped this lens accidentally the day before my third child was born. The back of the lens came apart (plastic fascia that says made in Vietnam can off) but otherwise I thought it was unscathed, or so I thought.

Using it to take photographs in the delivery room they were over exposed at at apertures greater than 1.8. Very strange at the time.

I have looked at it and it appears the mechanism that recoils the aperture is not working (see video).

Also at the bottom portion of the lens a small metal prominence that i can see on my other pentax lenses is not there. Videos and photos attached.

Anyone else had this problem? Is it worth repairing- DIY(given the cheapness of lens and the pandemic)? Professionally? Or get another plastic fantastic? I'm already on my second DA 35mm 2.4.....

Thank you

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06-30-2020, 01:58 AM   #2
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There is one possibility: Change the damaged plastic-mount for a good metal-mount:
Here on this German forum there are photos but nobody took photos during the work.

It is pretty easy, I have done it (sadly without photos) once on a DA35.
It is the same work on the DA50.


You find a cheap FA28-80 or F28-80 and you need a dremel or similar to shorten the hight of the metal mount.
So about 30 min. work and you have a DA50 limited.

other threads:
Swapping out the plastic mount on a DA 35/2.4? - PentaxForums.com
Transplanting DA lens mount to DA L? - PentaxForums.com
Replacing DA-L 35/2.4 Mount - PentaxForums.com
DA 35mm F2.4 - Plastic Mount Question - PentaxForums.com
Pentax 55-300mm DA L plastic mount repair/replacement - PentaxForums.com
Can the plastic lens mount on cheap Pentax lenses be replaced? - PentaxForums.com

And if you dare DIY, take photos!
Step by step!

Last edited by photogem; 06-30-2020 at 02:08 AM.
06-30-2020, 02:03 AM   #3
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I would say get another lens. Even trying a DIY, I think you would have problems getting parts.

At the moment here on the forums, there is a 50 1.8 for sale. The same seller on the same page also has a Pentax F 50mm 1.7.

AF Lenses, F, FA, DA, DFA, 6 Primes, 8 Zooms, 18mm-250mm, Sigma, Tamron, Tokina - PentaxForums.com

I am not connected with mightymike. He does have a lot og good items for sale though.

Last edited by bigdavephoto; 06-30-2020 at 02:06 AM. Reason: to let people know I am not connected with the seller.
06-30-2020, 02:39 AM   #4
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welcome to the forums, you will find friendly members and knowledge here

unfortunately I cannot help with your immediate problem

the marketplace can be sorted by country/region:

The Pentax Marketplace | Buy & Sell Pentax Cameras and Lenses (UK) - PentaxForums.com

The Pentax Marketplace | Buy & Sell Pentax Cameras and Lenses (EU) - PentaxForums.com


Last edited by aslyfox; 06-30-2020 at 03:12 AM.
06-30-2020, 05:09 AM   #5
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I'm wondering if the aperture mechanism a little deeper into the lens has come adrift. It's not too hard to get one step further into the lens by removing the 5 screws that hold the mount (noting these will be JIS screws not Phillips Head). There will be (or should be) a spring attached to the aperture mechanism. See if this is in place and not dislodged or jammed in something. Assuming the mechanism is somewhat similar to the M series lenses I have played with, the spring simply hooks onto a little post at each end so it could have jumped off. You should also be able to move the aperture lever with the mount removed and follow transfer of its motion. Before disassembling, look at some of the posted guides to ensure the little electrical communication balls don't go everywhere.

Perform your disassembly over something like a folded tea towel. If something drops out it is less likely to bounce away into the far and hard to search recesses of your room.
06-30-2020, 08:50 AM   #6
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For the time, money and effort spent on acquiring donor lenses and grafting the parts you may as well just replace the lens. Having it repaired will probably cost more than it would to replace the lens.
06-30-2020, 08:51 AM   #7
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Welcome to the Pentax Forums!

I was lucky enough when I accidentally dropped my DA 50/1.8, that it actually bounced off the Pergo flooring. Sorry that yours did not fair as well.

As for repair of your lens...I suspect that it was not designed as repairable. Good luck on your efforts and take heart that a replacement will not be hard to find.


Steve
06-30-2020, 11:11 AM   #8
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QuoteOriginally posted by bigdavephoto Quote
I would say get another lens. Even trying a DIY, I think you would have problems getting parts.

At the moment here on the forums, there is a 50 1.8 for sale. The same seller on the same page also has a Pentax F 50mm 1.7.

AF Lenses, F, FA, DA, DFA, 6 Primes, 8 Zooms, 18mm-250mm, Sigma, Tamron, Tokina - PentaxForums.com

I am not connected with mightymike. He does have a lot og good items for sale though.
Shipping from USA to UK is even more expensive then it was few years ago, additional VAT.
Not just VAT on the item itself but also on the shipping costs.
Even a focusing screen can become quite expensive.

DIY is pretty easy, on ebay UK a FA28-80 is around $ 15.
With a little bit of luck because damaged even cheaper.

06-30-2020, 02:38 PM   #9
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QuoteOriginally posted by photogem Quote
Shipping from USA to UK is even more expensive then it was few years ago, additional VAT.
Not just VAT on the item itself but also on the shipping costs.
Even a focusing screen can become quite expensive.

DIY is pretty easy, on ebay UK a FA28-80 is around $ 15.
With a little bit of luck because damaged even cheaper.
I don't normally open up the profile of members. I go by what is listed over here <------ to the left. Also, the seller in the link I posted is from Canada not the US. Shipping from Canada might be cheaper but I don't know.

I was making a suggestion on the information I had.
06-30-2020, 07:56 PM   #10
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QuoteOriginally posted by bigdavephoto Quote
I don't normally open up the profile of members. I go by what is listed over here <------ to the left. Also, the seller in the link I posted is from Canada not the US. Shipping from Canada might be cheaper but I don't know.

I was making a suggestion on the information I had.
The take-away from your comment is that working replacements are both readily available and cost-competitive relative to sourcing suitable parts and the risk of botching the repair. I agree with your suggestion.


Steve
07-02-2020, 01:43 AM   #11
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QuoteOriginally posted by bigdavephoto Quote
I don't normally open up the profile of members. I go by what is listed over here <------ to the left. Also, the seller in the link I posted is from Canada not the US. Shipping from Canada might be cheaper but I don't know.

I was making a suggestion on the information I had.
Doesn't matter if Canada or USA, VAT 20% + GBP8 handling-fee which Royal Mail always charges

So a used DA50 from Canada comes more expensive than a new one from amazon.uk.


If I can buy a part that is pretty simple to modify so that it fits, it's not much risk.
The lens isn't working right now, so to spend $ 10-15 and trying a repair which if one doesn't have 2 butcherhands isn't that difficult,
well, no worry about botchering anything except one's anxiety or fear.

There is actually only one difficult part which just needs quiet and attentiveness:
The contacts and springs:
http://www.bigeye.url.tw/photogr/pk18_55/pk18_55_130.jpg
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