Pentax FA 31mm limited repair guide

sungibr · 09-08-2018, 08:32 PM

Hi folks

I have a FA 31mm and this week I droped it on the floor and damaged the lens hood. And aside from scratches around some corners and in the aperture ring, the lens didn't suffered additional damages and are working just fine.

But the hood are loose now, wooblin quite significantly. It is not totaly loose and are still in place, but I guees that some screw or other sort of fixing must have been broke.

My problem is, I can't disassembled the lens to reach the hood. I can't find a way to open the lens past the focus ring, as I can't find any screw or pin to remove to open the lens further.

I like to DIY repair and didn't find a complete schematics or some other guide. The one that I can find around the net doesn't show the hood section, only the parts I could reach.

Any other tips?

Thanks

HYS · 09-08-2018, 10:59 PM

Sad story... Please don't drop your lenses

HarisF1 · 09-09-2018, 01:33 AM - **1 Like**

It's a complicated one when you first do it, but isn't so hard when you know what to do.

By opening up the front, you only get access to the front elements and the hood (and infinity adjustment). You need to open the lens from the back in order to remove the focusing ring.

Put tape on contact pins to make sure they don't fall out.
Remove 5 mount screws and take off mount.
Remove the pin holder and 4 large screws for the rear of the lens.
Remove the large flathead screw on the brass aperture guide, then remove aperture pin assembly (no screws).
Remove 2 screws to remove the screwdrive gears.
Remove the aperture ring.
Now the rear of the lens comes off and you have access to the focus position brush (electrical contacts). Remove the two screws and gently put it aside without damaging it.
Three screws are now visible on the bottom of the focus ring and these can be undone. This ring will not come off the lens completely without further disassembly which is not required.
The infinity screws from the front of the lens are also removed, and when you lift the focus ring away you will have access to the helicoid.
There is a thin black retainer ring on the top on of the helicoid/lens focus guides that may have come loose. You should try and thread that back without removing the helicoid screws to avoid any alignment issues.

EDIT: I just read your post back. You need a friction tool to remove the vanity ring, then three screws to remove the hood assembly, and three more screws attach the hood to the filter ring. I'm keeping the rest of the post here in case someone wants to open up their FA31 in the future.

**aslyfox** · 09-09-2018, 03:18 AM - **2 Likes**

before working on your lenses or camera, perhaps you might want to look at this thread:

Cross-head screws - a caution:

Posted By: pacerr, 10-22-10, 11:03 (Offline)

Those screws that look like Phillips 00 and 000 in Japanese cameras and lenses? They aren't. They're JIS cross-heads and life's a lot simpler using JIS screw driver bits on 'em.

Whether you do this only once and run into trouble, or intend to do it often, it's worth your sanity to do it with the correct JIS tools so you don't risk stripping a screw head. T-shirts should be available for those that have been there, done that!

Sooner or later, you'll be sorry if you don't use the JIS bits since the Phillips bits make great roto-rooters in JIS screw heads because they don't fit all the way into the cross slots as you can see here:

Read more at: Cross-head screws - a caution: - PentaxForums.com

sungibr · 09-09-2018, 03:20 PM

Originally posted by HYS

Sad story... Please don't drop your lenses

Thanks for the answer

I found that chart, but it doesn't have the hood assembly schematics.

---------- Post added 09-09-18 at 07:22 PM ----------

Originally posted by HarisF1

I just read your post back. You need a friction tool to remove the vanity ring, then three screws to remove the hood assembly, and three more screws attach the hood to the filter ring. I'm keeping the rest of the post here in case someone wants to open up their FA31 in the future

Thank you. This vanity ring is the ring around the front element? So I just need to remove it to fix the hood?

HarisF1 · 09-09-2018, 09:23 PM

Yes, that's the correct ring.

When you remove it, you'll find three screws that fix the hood assembly and filter ring to the rest of the lens. Remove these and you can separate the hood and filter ring by unscrewing three more screws on the underside of of the filter ring.

Originally posted by sungibr

Thanks for the answer

I found that chart, but it doesn't have the hood assembly schematics.

---------- Post added 09-09-18 at 07:22 PM ----------

Thank you. This vanity ring is the ring around the front element? So I just need to remove it to fix the hood?

sungibr · 09-11-2018, 03:32 AM - **1 Like**

Thank guys. I finally fix the hood.

The drop did damaged the screws and I had to replace then.

Now its strong as ever.

photoaki · 06-20-2021, 04:21 PM

Originally posted by HarisF1

Yes, that's the correct ring.

When you remove it, you'll find three screws that fix the hood assembly and filter ring to the rest of the lens. Remove these and you can separate the hood and filter ring by unscrewing three more screws on the underside of of the filter ring.

I have the same problem with the hood.
I see the vanity ring, but what kind of friction tool would work on it?

HarisF1 · 07-01-2021, 09:49 AM

Any normal friction tool would be fine - those grey rubber types that come packed like Russian dolls are what I use.

photoaki · 07-01-2021, 04:03 PM

Yes, I figured it out and got it fixed.
Funny thing (maybe not), I searched friction tool on Amazon, which came right up including a note that I had purchased it months earlier. How do you like that for forgetfulness?

Pretty easy with the right tools.
The screws that hold the hood are super tiny, thread on the holder was stripped, so I used some locktite on it.
Fabulous lens, but this part of its design could be improved.

09-08-2018, 08:32 PM	#1
sungibr Senior Member Join Date: Jan 2011 Location: Sao Paulo Photos: Albums Posts: 149	Pentax FA 31mm limited repair guide Hi folks I have a FA 31mm and this week I droped it on the floor and damaged the lens hood. And aside from scratches around some corners and in the aperture ring, the lens didn't suffered additional damages and are working just fine. But the hood are loose now, wooblin quite significantly. It is not totaly loose and are still in place, but I guees that some screw or other sort of fixing must have been broke. My problem is, I can't disassembled the lens to reach the hood. I can't find a way to open the lens past the focus ring, as I can't find any screw or pin to remove to open the lens further. I like to DIY repair and didn't find a complete schematics or some other guide. The one that I can find around the net doesn't show the hood section, only the parts I could reach. Any other tips? Thanks

09-09-2018, 03:20 PM	#5
sungibr Senior Member Join Date: Jan 2011 Location: Sao Paulo Photos: Albums Posts: 149 Original Poster	Originally posted by HYS Sad story... Please don't drop your lenses Thanks for the answer I found that chart, but it doesn't have the hood assembly schematics. ---------- Post added 09-09-18 at 07:22 PM ---------- Originally posted by HarisF1 I just read your post back. You need a friction tool to remove the vanity ring, then three screws to remove the hood assembly, and three more screws attach the hood to the filter ring. I'm keeping the rest of the post here in case someone wants to open up their FA31 in the future Thank you. This vanity ring is the ring around the front element? So I just need to remove it to fix the hood? Last edited by sungibr; 09-09-2018 at 03:28 PM.

09-11-2018, 03:32 AM - 1 Like	#7
sungibr Senior Member Join Date: Jan 2011 Location: Sao Paulo Photos: Albums Posts: 149 Original Poster	Thank you Thank guys. I finally fix the hood. The drop did damaged the screws and I had to replace then. Now its strong as ever.

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09-09-2018, 01:33 AM - 1 Like	#3
HarisF1 Veteran Member Join Date: Apr 2016 Posts: 543	It's a complicated one when you first do it, but isn't so hard when you know what to do. By opening up the front, you only get access to the front elements and the hood (and infinity adjustment). You need to open the lens from the back in order to remove the focusing ring. Put tape on contact pins to make sure they don't fall out. Remove 5 mount screws and take off mount. Remove the pin holder and 4 large screws for the rear of the lens. Remove the large flathead screw on the brass aperture guide, then remove aperture pin assembly (no screws). Remove 2 screws to remove the screwdrive gears. Remove the aperture ring. Now the rear of the lens comes off and you have access to the focus position brush (electrical contacts). Remove the two screws and gently put it aside without damaging it. Three screws are now visible on the bottom of the focus ring and these can be undone. This ring will not come off the lens completely without further disassembly which is not required. The infinity screws from the front of the lens are also removed, and when you lift the focus ring away you will have access to the helicoid. There is a thin black retainer ring on the top on of the helicoid/lens focus guides that may have come loose. You should try and thread that back without removing the helicoid screws to avoid any alignment issues. EDIT: I just read your post back. You need a friction tool to remove the vanity ring, then three screws to remove the hood assembly, and three more screws attach the hood to the filter ring. I'm keeping the rest of the post here in case someone wants to open up their FA31 in the future.

09-09-2018, 03:18 AM - 2 Likes	#4
aslyfox Seeker of Knowledge Join Date: Aug 2016 Location: Topeka, Kansas Photos: Gallery \| Albums Posts: 24,583	before working on your lenses or camera, perhaps you might want to look at this thread: Cross-head screws - a caution: Posted By: pacerr, 10-22-10, 11:03 (Offline) Those screws that look like Phillips 00 and 000 in Japanese cameras and lenses? They aren't. They're JIS cross-heads and life's a lot simpler using JIS screw driver bits on 'em. Whether you do this only once and run into trouble, or intend to do it often, it's worth your sanity to do it with the correct JIS tools so you don't risk stripping a screw head. T-shirts should be available for those that have been there, done that! Sooner or later, you'll be sorry if you don't use the JIS bits since the Phillips bits make great roto-rooters in JIS screw heads because they don't fit all the way into the cross slots as you can see here: Read more at: Cross-head screws - a caution: - PentaxForums.com

09-09-2018, 09:23 PM	#6
HarisF1 Veteran Member Join Date: Apr 2016 Posts: 543	Yes, that's the correct ring. When you remove it, you'll find three screws that fix the hood assembly and filter ring to the rest of the lens. Remove these and you can separate the hood and filter ring by unscrewing three more screws on the underside of of the filter ring. Originally posted by sungibr Thanks for the answer I found that chart, but it doesn't have the hood assembly schematics. ---------- Post added 09-09-18 at 07:22 PM ---------- Thank you. This vanity ring is the ring around the front element? So I just need to remove it to fix the hood?

06-20-2021, 04:21 PM	#8
photoaki Senior Member Join Date: Jul 2009 Posts: 187	Originally posted by HarisF1 Yes, that's the correct ring. When you remove it, you'll find three screws that fix the hood assembly and filter ring to the rest of the lens. Remove these and you can separate the hood and filter ring by unscrewing three more screws on the underside of of the filter ring. I have the same problem with the hood. I see the vanity ring, but what kind of friction tool would work on it?

07-01-2021, 09:49 AM	#9
HarisF1 Veteran Member Join Date: Apr 2016 Posts: 543	Any normal friction tool would be fine - those grey rubber types that come packed like Russian dolls are what I use.

07-01-2021, 04:03 PM	#10
photoaki Senior Member Join Date: Jul 2009 Posts: 187	Yes, I figured it out and got it fixed. Funny thing (maybe not), I searched friction tool on Amazon, which came right up including a note that I had purchased it months earlier. How do you like that for forgetfulness? Pretty easy with the right tools. The screws that hold the hood are super tiny, thread on the holder was stripped, so I used some locktite on it. Fabulous lens, but this part of its design could be improved.