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01-31-2011, 08:41 PM   #1
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Help With lens marks

Just bought a lens and it came with these strange brownish smear marks. It appears the marks are inside the front element and not the exposed part
The lens is a SMC Pentax-M 1:1.4 50mm

















Is this something I should be worried about.
Thanks for your help in advance

- RTH


Last edited by jersey_m; 01-31-2011 at 10:12 PM. Reason: Added more photos
01-31-2011, 10:24 PM   #2
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I have no idea what those marks are (looks like some kind of a chemical burn maybe), so I would say only worry if they are noticeable on your photos. If you cannot notice them in photos then they are nothing but annoying.

**Maybe you can ask a professional camera repair/cleaner to see if they know what caused that.
01-31-2011, 10:57 PM   #3
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It shouldn't be very hard to take that front element off to see if it can be cleaned. Something like the rubber tip from a crutch can be used to turn the ring that holds the front element in place.
02-01-2011, 05:29 AM   #4
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Thanks for your responses. Is removing the front element something, an inexperienced person can easily accomplish?

02-01-2011, 05:56 AM   #5
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You might need something like this.
Spanner Wrench(1/32") Great Tool for Lens - eBay (item 360335584435 end time Feb-10-11 21:49:13 PST)
02-01-2011, 05:57 AM   #6
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If the marks are showing on the images, you really have nothing to lose, and it will be a great learning experience. If you cannot see the marks in your shots, just leave it alone, unless you are feeling a little daring.

If you look closely, just inside the rim of the lens you will see some threads. The ring with all the white lettering is actually a huge screw with a hole in the middle. If you unscrew that, the front element should come right out.

There is a special tool that fits into two notches on opposite sides of the ring. I forget what they call it. If you cannot get one, something that can apply friction to the ring, like the rubber tip of a crutch will work. Just press down and turn counter-clockwise.
02-01-2011, 06:09 AM   #7
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Spanner wrenches are only necessary if the filter ring is damaged. All you need to open a Pentax lens is a lens ring.

Lens Ring Tool Set

Also keep in mind that lenses made in Japan don't use Phillips head screws, they use JIS head screws.

Screwdriver, JIS Type S Set, 5Pc Steel
02-01-2011, 04:33 PM   #8
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Thanks for your responses. I am a bit apprehensive about disassembling the lens. Here are some photos taken with it. It seems the marks are not showing up on the pictures to my untrained eye. Any of the experts think otherwise?

Outside picture


Indoors



Indoors


Thanks

02-01-2011, 07:12 PM   #9
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Don`t take it apart yet, shoot some more in bright sunlight and see how that turns out.
Your previous images look OK to me.
02-01-2011, 08:16 PM   #10
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I have removed a front element before without incident but it was on a lens worth $15. I might be a bit more cautious with that 1.4. But keep in mind that removing any element can have dire consequences because the glass is set in a VERY precise manner and if any of them are off by a hair your focus will be out of whack. Good Luck.
02-01-2011, 08:29 PM   #11
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BTW, were these marks disclosed to you when you bought the lens? I hope it was discounted appropriately given the damage.
02-01-2011, 08:33 PM   #12
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Thats why I am very apprehensive about performing any lens surgery. If the marks (which according to someone I showed (not a camera pro) thought was the coating coming off ??) are not detrimental to the image quality I would want to keep the lens and not worry too much.

Unfortunately we don't have sun in the forecast in New Jersey for another day or two, so I am unable to take pictures in bright sunlight

Thanks
02-01-2011, 08:42 PM   #13
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QuoteOriginally posted by KxBlaze Quote
I have removed a front element before without incident but it was on a lens worth $15. I might be a bit more cautious with that 1.4. But keep in mind that removing any element can have dire consequences because the glass is set in a VERY precise manner and if any of them are off by a hair your focus will be out of whack. Good Luck.
I have disassembled a Super Tak 50/1.4 (ver. 2) including all the elements and reassembled without any change in focus. The Super Tak 50/1.4 (ver.1) is not a easy to disassemble. The elements are glued together. I have also opened a M 50/1.7, but I did not disassemble it. The M is built quite a bit differently than the Tak.

---------- Post added 02-01-11 at 10:44 PM ----------

QuoteOriginally posted by jersey_m Quote
f the marks (which according to someone I showed (not a camera pro) thought was the coating coming off ??) are not detrimental to the image quality I would want to keep the lens and not worry too much.
There are two things that it could be. One would be the elements separating and the other would be oil on the element.
02-01-2011, 09:48 PM   #14
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Elements separating or oil - both are irreversible right? Without expensive repairs?

BTW i looked at the lens from the back directly at a 100W lamp. I could see the marks from from the rear they appear transparent (although I can make out the boundaries of the marks) They do not appear brown as they do from the front though and are quite faint (I have to look at the 100W bulb from the rear)
02-01-2011, 10:38 PM   #15
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Separating elements would usually manifest itself at the edges first. Oil is cleanable. +1 on Boriscleto's suggestion on the lens rings. Cheap to purchase and once you get past the first lens, they'll save you a fortune.

I take lenses apart all the time to clean them of internal dust (but would never leave one like that). It, from your photos, looks like somebody scrubbed at it with some sort of pen. Perhaps a hard object wrapped with a lens tissue or something like that. It doesn't look like a 'natural' occurring anomaly.
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