Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-25-2020, 10:38 AM   #1
New Member




Join Date: Jul 2020
Posts: 11
Reassemble aperture ring on my SMC PENTAX-A 1:1.4 50mm

I am an astrophotographer and noticed some dust shadows when taking flat fields the other night before shooting the comet. I took off the bayonet back and lifted the aperture ring. I should not have done that. The detent pin and its TINY spring and two other small, thin pieces of silver metal came out without me seeing where they came from and how they were situated. I am heading to Wyoming to shoot in 48 days. I am looking for help. Does any have a diagram of how these parts fit back together. Does anyone know someone reliable who to whom I could send the lens for cleaning and reassembly that could get it back to me in less than 48 days? Does anyone know of a video somewhere that would tell me what I need to know? At this point, I would live with the dust if I can just get the ring reassembled properly. Thank you all for your help.

07-25-2020, 11:09 AM   #2
Site Supporter
Site Supporter
c.a.m's Avatar

Join Date: Jan 2013
Location: Ottawa, Canada
Photos: Gallery | Albums
Posts: 4,171
I can't locate an exploded parts diagram for the A 50/1.4, but here are a couple of references for an A 50/2 and A 50/1.7. They both refer to those tiny parts.


Pentax-A 50mm f1.7 Aperture ring repair - PentaxForums.com

In the second thread, several posters have added useful information, such as the dimensions of a spring and ball.

Here's an exploded parts diagram for the A 50/1.7. I imagine that the configuration at the rear mount end would be similar to the 50/1.4. (If required, the password is "Pentax", upper case P)


http://www.pentax-manuals.com/manuals/service/smca5017.pdf

- Craig
07-25-2020, 11:14 AM   #3
New Member




Join Date: Jul 2020
Posts: 11
Original Poster
QuoteOriginally posted by c.a.m Quote
I can't locate an exploded parts diagram for the A 50/1.4, but here are a couple of references for an A 50/2 and A 50/1.7. They both refer to those tiny parts.

Pentax-A SMC 50mm f2 Disassembly - YouTube

Pentax-A 50mm f1.7 Aperture ring repair - PentaxForums.com

In the second thread, several posters have added useful information, such as the dimensions of a spring and ball.

Here's an exploded parts diagram for the A 50/1.7. I imagine that the configuration at the rear mount end would be similar to the 50/1.4. (If required, the password is "Pentax", upper case P)


http://www.pentax-manuals.com/manuals/service/smca5017.pdf

- Craig
Those are them! Now I will try the reassembly...
07-25-2020, 11:21 AM   #4
Site Supporter
Site Supporter
c.a.m's Avatar

Join Date: Jan 2013
Location: Ottawa, Canada
Photos: Gallery | Albums
Posts: 4,171
QuoteOriginally posted by Spica66 Quote
Those are them! Now I will try the reassembly...
Super. May I offer a couple of suggestions?


- To reduce the risk of losing the small parts, reassembling them within a large bag (e.g., Ziploc freezer bag) can be helpful.

- Sometimes it's tricky to reassemble the aperture-ring spring and ball (the ball likes to drop out). A small dab of grease on the ball or end of the spring will help to hold it in place.

- Take your time, and don't force anything.

- Craig


Last edited by c.a.m; 07-25-2020 at 04:14 PM. Reason: typo
07-25-2020, 12:44 PM   #5
New Member




Join Date: Jul 2020
Posts: 11
Original Poster
QuoteOriginally posted by c.a.m Quote
Super. May I offer a couple of suggestions?


- To reduce the risk of loosing the small parts, reassembling them within a large bag (e.g., Ziploc freezer bag) can be helpful.

- Sometimes it's tricky to reassemble the aperture-ring spring and ball (the ball likes to drop out). A small dab of grease on the ball or end of the spring will help to hold it in place.

- Take your time, and don't force anything.

- Craig
Well, the detent flew out of the bag. It is part number X506. Anyone know where I can buy one? Or send it someone who knows what they are doing? I reassembled it as a manual aperture-only lens for now, but it still needs the dust out of it...
Attached Images
 
07-25-2020, 01:16 PM   #6
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 10,508
The ball bearing is a 1.5mm bearing. You can buy like a pack of 100 on eBay for like $5 (I don't remember, was under $10). US seller. As loing as you still have the spring you should be ok. Since you are in the US PM me and I can send you a couple.

The spring on the pin mechanism looks a bit mangled. You might want to turn it around and put the mangled portion inside the pin.
07-25-2020, 01:26 PM   #7
Site Supporter
Site Supporter
c.a.m's Avatar

Join Date: Jan 2013
Location: Ottawa, Canada
Photos: Gallery | Albums
Posts: 4,171
QuoteOriginally posted by Spica66 Quote
Anyone know where I can buy one?
You might try uscamera. They have part X508 listed, so you could ask whether they have any related parts.

Pentax 45315-0-X508 A/M Selecting Plate | USCamera Pentax parts +USCamera

07-25-2020, 01:37 PM   #8
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 10,508
The detent usually refers to the small ball bearing the puts the "click" in the click-stops on the aperture ring. Thus my confusion.

You're looking for what is commonly referred to as the "A" pin. USCamera may have it.

Edit: Ok, I transferred all my Pentax documents from my old computer to the new one. The part you want is X506. From the 50mm 1.7 exploded diagram

O-X508-00000A - (O denotes assembly) - pin, plate and spring
X508-01 - Plate
X506 - pin
X509 - spring

If USCamera has the spring you may as well replace it too.

Last edited by Not a Number; 07-25-2020 at 02:22 PM.
07-25-2020, 01:54 PM - 1 Like   #9
Pentaxian
Kozlok's Avatar

Join Date: Jun 2012
Location: Albuquerque
Photos: Gallery
Posts: 3,145
Put a piece of pantyhose over the end of your vacuum, and then vacuum around the area to find it. It's a great way to find small parts.
07-25-2020, 03:08 PM   #10
Site Supporter
Site Supporter
c.a.m's Avatar

Join Date: Jan 2013
Location: Ottawa, Canada
Photos: Gallery | Albums
Posts: 4,171
QuoteOriginally posted by Kozlok Quote
Put a piece of pantyhose over the end of your vacuum, and then vacuum around the area to find it. It's a great way to find small parts.
(Thanks for the tip!)
07-25-2020, 03:13 PM   #11
Seeker of Knowledge
Loyal Site Supporter
aslyfox's Avatar

Join Date: Aug 2016
Location: Topeka, Kansas
Photos: Gallery | Albums
Posts: 24,562
QuoteOriginally posted by Spica66 Quote
. . . but it still needs the dust out of it...
when ever someone mentions dust in a lens I remember this link that a member once posted:

QuoteQuote:
The Apocalypse of Lens Dust
By Roger Cicala Published August 2, 2011 SHARE TWEET
Apocalypse (from the Greek apokálypsis; “lifting of the veil” or “revelation”):

An event involving destruction or damage on an awesome or catastrophic scale.
A disclosure of something hidden from the majority of mankind.
How appropriate the word apocalypse is for this little article. At least once a week I see a post somewhere from a fairly inexperienced photographer who thinks a definition 1 apocalypse has occurred: “OMG, my lens has dust inside!!!! How did it get there??? What will I do?? My shoot is ruiiinned!!!!!” . . .
Lens Rentals | Blog

perhaps it might be worth the time to review

promise not to just jump to the conclusion:

QuoteQuote:
So what did we learn today?
The biggest surprise I got (it shouldn’t have been, I just didn’t think about it) was putting a fairly large foreign object on a rear element may keep the camera from autofocusing. Does it have real world implications? I don’t think so, although perhaps heavy rear element dust could interfere with autofocus accuracy.
Individual dust particles have to be HUGE before they can show up under almost any conditions. By HUGE I mean bigger than dust. Think an insect part or a small screw (I’ve seen both of those in lenses. It happens.)
Even something large probably won’t show up at wide apertures (f4 or wider probably).
A wide angle lens shows front element objects more than a moderate telephoto.
The moderate telephoto showed rear element objects more dramatically.

Remember, though, that what we really did here was look at big objects on the front and rear element of the lens. Internal dust might behave a bit differently if it was near the focal plane of the lens internally, or perhaps just in front of or behind the aperture. I’m not so curious that I’m going to take a lens apart and put a sticky note on an internal element and reassemble it to take test shots. Not yet anyway. Maybe in the winter when things are slow.

Does any of this have any real world implications? Nah. Unless you get a bug inside your lens there’s not much need to worry about dust. Until there’s so much dust that it interferes with contrast or light transmission. When is that? Well sounds like another article coming up, doesn’t it? But it would be a lot of dust.

Roger Cicala

Lensrentals.com
07-25-2020, 05:11 PM   #12
Otis Memorial Pentaxian
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 42,007
Welcome to the Pentax Forums!

QuoteOriginally posted by Spica66 Quote
I am an astrophotographer and noticed some dust shadows
QuoteOriginally posted by Spica66 Quote
but it still needs the dust out of it.
Now that the reassembly issues are being ironed out, how about those dust shadows? If you are seeing shadows on your flat frame images, chances are the dust is on the sensor or a rear-mounted filter and not in the lens. Sensor dust is much easier to deal with than lens disassembly. I use either the camera's built-in dust removal or a rocket-type blower.


Steve
07-25-2020, 08:40 PM   #13
New Member




Join Date: Jul 2020
Posts: 11
Original Poster
Here is what dust in the lens does when it is exposed (necessarily out of focus) for 30 seconds, then stacked together 30 times. A frame that is supposed to be taking care of vignetting is now removing data from inside the corners due to the dust. So, real-world, yes, it matters when you are taking images to their utmost capabilities.
Attached Images
 
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
aperture, days, dust, help, lens repair advice/help, pentax service, repair, service, smc pentax-a, smc pentax-a 1:1.4 50mm, warranty
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Reassemble aperture ring on my 50mm 1.4? Spica66 Welcomes and Introductions 9 07-26-2020 01:45 AM
Smc Pentax f 50mm f1.7 aperture ring wobbles zburatoru Pentax DSLR Discussion 8 12-29-2018 03:09 PM
Aperture ring or no aperture ring hjoseph7 Pentax SLR Lens Discussion 29 12-02-2014 03:06 PM
K-3 and FA lenses - aperture ring setting / focus ring zzeitg Pentax K-3 & K-3 II 10 11-05-2014 08:10 PM
can't reassemble my k50.2.... :( kwonjustin Troubleshooting and Beginner Help 3 02-07-2011 05:58 AM



All times are GMT -7. The time now is 08:47 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top