Pentax DA 70mm Limited - Possible oily residue inside lens?

Started 4 months ago | Questions thread
resistingLBA Junior Member • Posts: 27
Re: Pentax DA 70mm Limited - Possible oily residue inside lens?

Wahid Khan 1961 wrote:

resistingLBA wrote:

Mine has oil as well on the aperture blades, thus tends to be slow to close it. I couldn't clean it completely, although opening it several times.

I've opened and repaired a few lenses in the past, so not daunted by such a task if doable. Never attempted a repair, or needed to, on a 'premium' lens though. I'm happy to attempt a clean-up myself if you can help with a link to open up the lens and get access to the the element in question.


I had on my todo list to do it again, so here it is.

But before that, a disclaimer: I take no responsibility for whatever you do, or anyone who reads this does. Whatever happens, i am out of it. When this disclaimer/limitation cannot apply do to your local laws, or for whatever reason, including that you do not agree, do not even start, stop here and do not read the rest. By reading what follows you confirm you read and understood this part. You have been warned.

0. You need a PH 00 Screwdriver. Read it all first then start doing the steps.

1. So, here is how mine looked like.


The oil is there. the blades where closing, but much too slowly.

2. The plan is to take out the optical groups, and then when only metal is left, clean somehow the aperture assembly. Here depicted the back optical group (the inner metal ring), it needs to be unscrewed. It doesn't protrude enough to grasp it, thus there is need to unscrew some screws. DO NOT unscrew any of the screws that you can see in this image. This is an important difference to other lenses.


3. What you need to unscrew are those screw instead.


They come alone, there is a single pair. In this pair unscrew only the one on the left.

After you take them all (3 iirc) out, you will be able to lift the plastic ring (see 2.) that has stamped on it "Assembled in Vietnam".

4. And this is what you get. Now you can unscrew the back optical block (the cylinder in the middle with the lens. Whether or not the first time there was need for some force, I cannot remember.

It looks like the post editor has a limitation, the next steps in the next post

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