I picked up a low cost K 300mm, with hood issues last week. The felt was so worn, the hood would slide open and closed just by tilting the lens. Below are my steps on how I removed the hood, and repaired the felt strips holding the hood.

Note: This is an account of what worked for me. I will try my best to include pictures and descriptions of items, but my lack of technical terminology may be frustrating to some.

Step 1: Making a low cost lens "wrench"

After some searching, I ran across a thread that pointed to a youtube video on how to remove the Name Ring using a cap, and electrical tape. So I started my search in the kitchen misc. snack cup cabinet. I found an old Dole fruit cup container that fit the lens nicely, and added some layers of electrical tape around the rim for increased friction to grip the ring.



Insert taped cup in end of lens. Turn counter clockwise while pressing down.



Step 2: Removing the hood

Had a bit of surprise, when I thought the Name Ring was rotating, when it was actually the outer lens group. The Name Ring did no budge, but since my goal was to access the hood, I was OK with this.




Step 3: Inspect the felt on the hood and outer lens group

After a quick inspection, I saw that the felt on the OD of the outer lens group was compressed to the point of being level with the groove the felt is installed in. The felt strip that was on the ID of the hood was still proud of it's groove. Therefore I determined that I only need to replace the felt on the OD of the outer lens group. If you need to replace the hood felt as well, I would follow the same steps as described for the element felt.

Felt on the OD of the outer lens group.


Felt on the ID of the lens hood.



Step 4: Removing the old felt

If you have ever worked on a wind instrument (my daughter plays clarinet in band) this is very similar to replacing the cork in the joints of the instruments.
Find the starting point of the existing felt, and peel up a starting edge. The original felt looks like it was installed with a double sided tape. It will most likely still be stuck to the lens when you are done pulling the felt strip off.

felt removed, tape is still there.


Find another starting point, and pull the tape strip off the lens. Clean any residue from the felt groove in the lens group. I used Isopropyl Alcohol.


Step 5: Cut a new strip of felt

For this I used a piece of 1mm thick adhesive backed polyester fiber felt. I had a piece of felt border leftover from a home theater screen build, and cut the width on a picture trimming board. I original bought the felt from Amazon (this is the upc number that can be copy and pasted 695087743478)

I set the original felt on the section that I was cutting off, ensure a proper fit. Measuring would work here too. I also cut the new felt longer than needed, and just trimmed it to fit when installing.




Step 6: Install the new strip of felt

At this point, it may be a good idea to double check the felt groove on the lens group. Making sure any tape residue, dirt or dust is cleaned from the groove.
Peel away the cover on the adhesive side of the felt, and center on the groove. Work the new felt around the lens group, while keeping it in the groove for the felt. Verify the new felt is adhered to the lens group, and no bumps or creases are present. This new felt will provide ample thickness to hold the hood, and any irregularities in the install, may cause the hood to be extremely tight.




Step 7: Clean and assemble

Take the time to insure any dust is removed from the inside of the lens (rocket blower works well here). To re-install the lens group, start by sliding the group through the lens hood ( like you have the hood extended). Carefully insert the group in the lens body, and slowly turning clockwise. Apply only light pressure while turning, do not force the threading action, which may lead to cross threading the element group ( maybe destroying the threads). I took two or three tries to verify that the threads were properly engaged, before I continued to tighten.
Retract the lens hood on the lens body, and use the "wrench" to finish tightening the element group.


Any questions, let me know!

Thanks

[Unregistered User 8]

SMC-K 300 f4 Hood Felt Repair

Very well done David !!

[Riggomatic]

Very well done David !!

Thank you!

[BigMackCam]

Yes, indeed - an excellent job. Well-documented too... I don't own that lens, but I'm sure we'll have members that find this very useful

[Riggomatic]

Yes, indeed - an excellent job. Well-documented too... I don't own that lens, but I'm sure we'll have members that find this very useful

Thank you! I always enjoy taking things apart .

[yucatanPentax]

I picked up a low cost K 300mm, with hood issues last week. The felt was so worn, the hood would slide open and closed just by tilting the lens. Below are my steps on how I removed the hood, and repaired the felt strips holding the hood.

Note: This is an account of what worked for me. I will try my best to include pictures and descriptions of items, but my lack of technical terminology may be frustrating to some.

I love "How - to's" like these, even if I don't have the exact lens in question. A person never knows at what point you might have the exact lens or problem, plus it gives various ideas for other problems to be encountered. Thank you for sharing this procedure. Great documentation and providing the resources or materials really was the icing on the cake. I wouldn't have thought about using a picture trimmer to cut off a thin felt strip (maybe I'm not imaginative enough). So, yes, much appreciated. Two thumbs up!