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10-07-2019, 11:43 AM   #1
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Is this a lens problem?

I had my Pentax k1000 CLA'd recently much to my delight.


One thing they said about my lens was that the aperture blades were on the edge of starting to get sticky and that the lens has smudges in the optics... any suggestions on how to remove the smudges? ive attached a picture. Would this even effect image quality if the smudges are on the outer edge?




With regards to the aperture blades im not sure if they were just saying this to try and get more money off me..
how do i tell if what they say about the aperture blades is true?


Any help would be much appreciated!

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10-07-2019, 12:17 PM   #2
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Hard to tell from the photo whether the marks are on the inside or outside of the rear element. They look like wiping/cleaning marks to
me.

As for the sticky aperture; it's altogether possible the blades are getting a little sticky and perhaps you haven't noticed because you have
used the lens for so long. There may also be tell tale signs of oil droplets within the lens, another sign the aperture blades needs cleaning.
The smudges on the outside could be related to that, though typically oil from the aperture blades would be deposited on the inner elements.

What is the lens? It's clearly a K or M series.
10-07-2019, 12:21 PM   #3
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the problem with the blades is called oily blades, when the grease gets onto them they became sticky or slow opening / closing, you will get inaccurately exposition...
To fix this - you have to disassemble the lens and clean the blades by ethanol or isopropyl alcohol.
Smudges - if they are not inside - clean them by a lens cleaning solution, if they are inside - disassemble and then clean. If you do not , yes, they will impact the image quality. On the other hand, if it is fungus, it will contaminate the other your lenses.
What is the lens, by the way?
10-07-2019, 12:29 PM   #4
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QuoteOriginally posted by tvdtvdtvd Quote
Hard to tell from the photo whether the marks are on the inside or outside of the rear element. They look like wiping/cleaning marks to
me.

As for the sticky aperture; it's altogether possible the blades are getting a little sticky and perhaps you haven't noticed because you have
used the lens for so long. There may also be tell tale signs of oil droplets within the lens, another sign the aperture blades needs cleaning.
The smudges on the outside could be related to that, though typically oil from the aperture blades would be deposited on the inner elements.

What is the lens? It's clearly a K or M series.
Thank you both for the replies, it is a 40mm pancake lens.

Here's the thing- i live in the UK but bought the lens in the US, got my camera serviced at another store in the US and they told me about the problem with the lens. I didnt have enough time to take it back to the original store. They've told me they'll look at it because its under warranty but it'd mean sending it to the US which is why i'd like to do it myself. I feel ripped off because it was the store that sold me the lens that told me the camera needs serviced and then they sell me a lens which needs serviced!

10-07-2019, 12:34 PM   #5
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QuoteOriginally posted by confusedcitizen Quote
Thank you both for the replies, it is a 40mm pancake lens.

Here's the thing- i live in the UK but bought the lens in the US, got my camera serviced at another store in the US and they told me about the problem with the lens. I didnt have enough time to take it back to the original store. They've told me they'll look at it because its under warranty but it'd mean sending it to the US which is why i'd like to do it myself. I feel ripped off because it was the store that sold me the lens that told me the camera needs serviced and then they sell me a lens which needs serviced!
Is this a secondhand lens?
10-07-2019, 12:34 PM   #6
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QuoteOriginally posted by Vasyl Quote
the problem with the blades is called oily blades, when the grease gets onto them they became sticky or slow opening / closing, you will get inaccurately exposition...
To fix this - you have to disassemble the lens and clean the blades by ethanol or isopropyl alcohol.
Smudges - if they are not inside - clean them by a lens cleaning solution, if they are inside - disassemble and then clean. If you do not , yes, they will impact the image quality. On the other hand, if it is fungus, it will contaminate the other your lenses.
What is the lens, by the way?
thanks, there is no sign of oil on the aperture blades and when i move the trigger on the back of the lens they move freely without hesitation.

I've tried to clean the outside and nothings budging. Should i use a lens cleaner solution on the inside?

---------- Post added 10-07-19 at 12:37 PM ----------

QuoteOriginally posted by MarkJerling Quote
Is this a secondhand lens?
Yes! Its a smc pentax - m 1:2.8 asahi
10-07-2019, 12:37 PM   #7
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not sure it matters but which 40mm lens is it

40mm Lenses | PentaxForums.com
10-07-2019, 12:41 PM - 1 Like   #8
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QuoteOriginally posted by confusedcitizen Quote
thanks, there is no sign of oil on the aperture blades and when i move the trigger on the back of the lens they move freely without hesitation.

I've tried to clean the outside and nothings budging. Should i use a lens cleaner solution on the inside?

---------- Post added 10-07-19 at 12:37 PM ----------



Yes! Its a smc pentax - m 1:2.8 asahi
If those smudges don't move if you clean the outside of the rear element, then someone will need to open the lens and clean the inside. Unless you know what you're doing, I would advise against that.

If the aperture blades are moving freely, and you're not seeing evidence of sticky blades, then I would leave it alone.

10-07-2019, 12:44 PM   #9
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QuoteOriginally posted by aslyfox Quote
not sure it matters but which 40mm lens is it

40mm Lenses | PentaxForums.com
Here it is!


SMC Pentax-M 40mm F2.8 Reviews - M Prime Lenses - Pentax Lens Reviews & Lens Database
10-07-2019, 12:45 PM   #10
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Put another way... If the blades get stickier, you will notice it in photos or in the response to manual activation of the lever. The smudges are along the outside edge. Shot some test shots and decide if that's an issue for your use.
10-07-2019, 12:58 PM   #11
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the OP might keep an eye out on the forum's market place

it can be sorted by country

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

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

in case another lens might be of interest
10-07-2019, 01:12 PM - 1 Like   #12
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Sticky aperture blades can be a problem, but smudges on the optical surfaces mostly aren't too problematic. Lensrentals had a test once where they - if I remember correctly - had a fly in a lens and it had left all sorts of stuff when dying in the lens and it had no or only a very minimal effect on the image. As UncleVanya has said: first find out if it is a problem for your images. If not, enjoy the lens.
10-07-2019, 01:16 PM   #13
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QuoteOriginally posted by HoutHans Quote
. . . . Lensrentals had a test once where they - if I remember correctly - had a fly in a lens and it had left all sorts of stuff when dying in the lens and it had no or only a very minimal effect on the image. . . .
I think this is the one you are talking about:


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
10-07-2019, 01:17 PM - 1 Like   #14
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QuoteOriginally posted by HoutHans Quote
Sticky aperture blades can be a problem, but smudges on the optical surfaces mostly aren't too problematic. Lensrentals had a test once where they - if I remember correctly - had a fly in a lens and it had left all sorts of stuff when dying in the lens and it had no or only a very minimal effect on the image. As UncleVanya has said: first find out if it is a problem for your images. If not, enjoy the lens.
When my dad worked for a camera store they would get customers that were hyper worried about specs of dust settling on the new lens they bought. One way to show them this was not a big deal was to take a small square of lens cleaning tissue (.5cm x .5cm) and put some cleaner on it to wet it and stick it on the front of the lens. Then the client would be directed to look into the viewfinder and invariably they were shocked that they couldn't see it and could still focus etc. Then he would show them the same square placed on the rear element. Which was not invisible. His point was made - keep the rear of the lens clear of debris and don't sweat minor smudges and dirt that may get on the front.
10-07-2019, 03:31 PM   #15
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I think that smudge is element separation. The Pentax-M 40mm f2.8 is prone to separation in a pair of elements in the rear lens group. The very thin layer of glue between the lenses breaks down. It looks like something that'll clean right off, or one or more of the other issues suggested.

You could attempt to clean the rear element. You can probably remove the rear group with a lens spanner in the outermost slots, without removing the mount. An improvised lens spanner can be made from an old compass, dividers or needlenose pliers with tips ground to fit the slots.

Oil can evaporate from the grease used to lubricate the focus threads, and end up deposited on the aperture blades and interior lens surfaces on either side of that. Sometimes it is visible on the blades, sometimes not. The grease used by Pentax doesn't usually do that. If you can get the rear element cleaner or notice that the blades close slowly from wide open to f22, it's oil. You can see guides to disassembling other Pentax M series lenses in the Maintenance section. The 40mm is similar to most of those.

If I'm right, my suggestion is to just ignore it. The glue can be dissolved and the elements reglued, but this is generally not worth the trouble for that lens. I have an SMC Pentax-F 70-210 zoom with element separation in the front group, and it doesn't affect shots very much if at all. Here's my attempt to show it in a photo. The cloudiness around the edges sometimes has a gasoline on a puddle look.


Last edited by Just1MoreDave; 10-07-2019 at 03:40 PM.
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