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02-13-2012, 12:45 PM   #1
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Spots on SMC lens after water spray.

I got a bit of fresh water splatter from a river on the lens of my SMC-A lens, you only can see them at the right light angle of light so they likely will not effect the pictures at all but I think they may be hard water spots or something. I had to put the lens away with the spots on it because it was below freezing and the spots instantly froze, when I tried to clean it later with a lens pen and even the zeiss pre moistened lens cleaning cloths (wetwipes for camera) nothing seems to be able to take the few spots off. I can't imagine water being able to eat the SMC coating so I don't think its damaged. At least I hope not, this lens was perfect before.

I plan to get a clear filter but I can't afford what it costs to get a good coated one (any suggestions?)

02-13-2012, 12:49 PM   #2
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Lenspen or alcohol aren't effective on removing water spots. Just moist a clean t-shirt with water and wipe it should do.

I personally like HOYA HD filters which are easy to clean.
02-13-2012, 03:09 PM   #3
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I would dampen a lens cleaning cloth with regular distilled water from grocery store. Try wiping it gently with it.
02-13-2012, 09:06 PM   #4
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OK, I don't understand why that worked perfectly, only that the lens is like new again. Thanks a ton.

Following the suggested gear link from our main page I ended up with this choice which is the brand you suggested also:
Hoya 67mm Ultraviolet UV(0) Super Multi-Coated (S-HMC) X67UV B&H
According to the back of the original lens cap my SMC-A 35-105 is 67mm, and this seems to be the most neutral non light effecting filter with at least as good in quality for glass and coating as my lens I hope, and after this panic attack its already on order.

02-13-2012, 11:54 PM   #5
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HOYA HD filters are much easier to clean, though HMC SUPER is slightly more flare resistance.
02-14-2012, 01:56 AM   #6
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QuoteOriginally posted by PPPPPP42 Quote
OK, I don't understand why that worked perfectly, only that the lens is like new again. Thanks a ton.

Following the suggested gear link from our main page I ended up with this choice which is the brand you suggested also:
Hoya 67mm Ultraviolet UV(0) Super Multi-Coated (S-HMC) X67UV B&H
According to the back of the original lens cap my SMC-A 35-105 is 67mm, and this seems to be the most neutral non light effecting filter with at least as good in quality for glass and coating as my lens I hope, and after this panic attack its already on order.
I think the reason the water worked but the alcohol did not is to do witht he chemistry of what you got on the lens.

Water, even fresh, unless deliberately deionised (like in a chemistry lab, or for photo chemicals) will have some slats disolved in it. Salts are ionic, and disolve in water because whilst water is molecular the hydrogen and oxygen in th molecule have different polarity and so can bond enough witht eh ions of the slat to enable a solution. But in alcohol there is no such charging of parts of the molecules, so the alcohol is good for disolving greasy things, such as finger prints, but not ionic things such as salt deposits. So the (water) moist material was able to disolve the salt, and the absorbent material lifted it away from the surface resulting in a cleaned surface.

Several months ago on the manualfocus forum I saw several messages to the effect that Pentax coatings are much less affected by fungus etching the surface than the other famous brands. Therefore,m according to those people, a fungus affected Pentax lens is more likely to be fully restorable than the others. The effect of the soiling on the coating would depend on the chemistry of the soil and the coating. I will not be conducting experients with my lenses. I will not be a scientist, and I will listen to stories from others on these things.

I always use filters for protection. In many years I have had to replace a few filters, but that is much cheaper than if the damage had happened to any one of my lenses. In the words of my local camera shop - 'cheap insurance'.
02-15-2012, 11:54 AM   #7
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QuoteOriginally posted by PPPPPP42 Quote
OK, I don't understand why that worked perfectly, only that the lens is like new again. Thanks a ton.
You sprayed water on the lens. The residue that you saw was dissolved in that water. Rewetting it with water dissolved the residue, allowing it to be removed.
Most of what gets on a lens will come off with a bit of breath on the lens and gently cleaning with an old but clean cotton t-shirt type of fabric. Other solvents can actually do damage, so it's best to use them as a last resort.
Also, more damage is done to lenses by over cleaning than all other reasons combined.
I almost never clean my lenses. A little dust won't hurt anything, but a cleaning mark caused by abrading the glass will ruin a lens.
I also don't use "protective" filters. Lenses aren't as frail as people like to think they are.
02-15-2012, 12:17 PM   #8
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QuoteOriginally posted by Wheatfield Quote
Lenses aren't as frail as people like to think they are.
And they certainly aren't as frail as filter makers would like you to think they are.

02-15-2012, 12:25 PM   #9
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QuoteOriginally posted by monochrome Quote
And they certainly aren't as frail as filter makers would like you to think they are.
Should add they aren't as frail as they used to be. I've found many used lenses from the 40s-60s that have badly scratched front elements or coatings. All of these were cleaning damage. However, some of the optical glass in the 50s was about as soft as chalk, and the early coatings were done for optical properties, ignoring durability. (Version 1 Leica Summicron 50 was notorious for scratching easily.)
That changed by the time multi-coating came in. So I don't worry about buying used SMC Pentax lenses, but like to check out older ones more closely.
02-15-2012, 01:51 PM   #10
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QuoteOriginally posted by TomB_tx Quote
Should add they aren't as frail as they used to be. I've found many used lenses from the 40s-60s that have badly scratched front elements or coatings. All of these were cleaning damage. However, some of the optical glass in the 50s was about as soft as chalk, and the early coatings were done for optical properties, ignoring durability. (Version 1 Leica Summicron 50 was notorious for scratching easily.)
That changed by the time multi-coating came in. So I don't worry about buying used SMC Pentax lenses, but like to check out older ones more closely.
And there is the downside to ahving a lifetime of nothing but Pentax. I've just recently acquired my first non-multicoated lens (Auto-Takumar 55/1.8) and. other than an XA and an early Olympus digital, never owned anything else.
02-15-2012, 04:45 PM   #11
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I need the filter mainly to prevent having to clean the lens itself, some of the shots I was getting were in areas where occasionally you get random water sprays and with the freezing weather it was starting to piss me off when I would lose the lens for the day because it became a lenscicle and the truck was too far away to just run and thaw it. My old version of this SMC-A 35-105 had a few small nicks in the lens from accumulated oopses over the years, didn't effect the image but id much rather have them in the filter since I trudge through some dense forest or unstable areas with the potential for it to rub on things. You only can be so careful and accidents aren't called deliberates for a reason. If it actually works as a UV haze filter, then bonus.
02-15-2012, 05:24 PM   #12
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QuoteOriginally posted by monochrome Quote
And they certainly aren't as frail as filter makers would like you to think they are.
I did an experiment once on a non-functioning Pentax zoom with SMC coating. I used steel wool (super fine #0000) to "clean" the front element fully expecting to see scratches. To my surprise nothing happened. The lens afterwords looked nicely cleaned and polished.

The follow up experiment with fine sand paper was not that positive though

The moral or the story is that it literally requires some strong abrasive like the grit in sand paper to scratch an SMC coated lens, so do not afraid to clean a lens if you have to.
02-15-2012, 07:38 PM   #13
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But remember the grit might be in the muck stuck on the lens.
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