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02-01-2008, 07:47 AM   #1
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Dust in 50mm 1.4 M

So I bought a used SMC M 50mm 1.4 on ebay.

I know, you ebay, you take your chances.

It was listed as mint, no scratches, no fungus.

When I got it, it indeed had no scratches and no fungus, however, there were some sizeable dust particles (2-3) on the interior elements ( I made sure it wasn't on the outsides with a little lens paper and cleaning solution, but alas they were on the interior elements.

I paid about 72 + shipping for the lens, mostly because it was listed as mint. I was unhappy with the visible dust clumb/particles inside. I guess my question is, how much of a problem should they be? If I return it, I'll get screwed on shipping, etc, and I'll need to find another 1.4.

Are dust particles actually a problem? Am I being too picky?

02-01-2008, 08:28 AM   #2
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Don't worry about the dust unless it is very big. It's a normal thing with almost any lens except the weather sealed DA* should be immune from it.

It happens when the lens is zoomed or rotated to focus. the barrel moves in and out and it sucks in a very small amount of air. Dust should have no effect on picture quality 99.9% of the time. Even a new lens will show this after a few weeks of use.

Go shoot and enjoy the new lens.
02-01-2008, 08:40 AM   #3
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Thanks, that takes a load of my mind. There's just one particle that seemed of actual worry-size, the rest were fairly minute. I was just upset that after having gone to the trouble and expense of finding the lens I reall want, and having it be scratch and fungus free, that the dust would make it moot.
02-01-2008, 08:44 AM   #4
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I really wouldn't worry about it. Just do some test shots against a clean white or gray surface. Unless that dust is really HUGE it will not show up at all.

02-01-2008, 09:04 AM   #5
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QuoteOriginally posted by jmbower Quote
Are dust particles actually a problem? Am I being too picky?
No, if there are a few dust particles in the lens - it doesn't affect the picture quality.

Are they extremely small dust particles, or are they larger chips of old black paint from inside the lens barrel?
02-01-2008, 09:23 AM   #6
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hmm..good question. It does look dark. I'm not sure how exactly to take a pic of it.

Is there any safe non-invasive way to try to dislodge it from that surface?

I don't think I'm up for opening that bad boy up and poking around its innards, and I don't want to exacerbate the problem

I'm also not sure how best to take a picture of it.
02-01-2008, 10:21 AM   #7
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Does your dust look worse then this? If not I wouldn't worry about it too much. A few specks are not likely to cause any trouble.
02-01-2008, 10:24 AM   #8
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heh no I'd say they look darker, but nowhere near that prolific. there's a yellowish glob in that pic on the right, can't tell if it's dust or reflection, but I'd say my big particle is smaller than that but bigger than the other specks.

Thanks all, I'll do some test shots and hopefully stop worrying about it.

02-01-2008, 11:05 AM   #9
Ed in GA
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I had an M-50 F/1.4 for sale on e-bay with a BIN or Best offer sale.

I was honest enough to mention that it has some dust in it but was otherwise perfect.

I kept getting offers of $30, $40 & $50. I, of course, rejected all of those.

Unfortunately, the lens didn't sell and I still have it.

Compared to the one Fritz linked to. Mine was very clean.
02-01-2008, 11:27 AM   #10
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how much would you figure it was worth?

I paid around 70, plus shipping. I've seen it go lower and higher. I know when they come up here they tend to be higher priced, but also obviously it carries less risk.

I'll try to post pics for your review tonight
02-01-2008, 11:32 AM   #11
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well what i do is go to a gas station that has a tire pump and use it to blow in to the back of the lens there is ust enf space to let some of the air in it tends to blow it out of the mane part of the lens
02-01-2008, 11:38 AM   #12
Ed in GA
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My BIN was $85.. $70 was my taking price.

I may look at nathamcombs suggestion and get my compressor going tonite and see if I can blow the dust out of it.
02-01-2008, 02:18 PM   #13
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QuoteOriginally posted by nathancombs Quote
well what i do is go to a gas station that has a tire pump and use it to blow in to the back of the lens there is ust enf space to let some of the air in it tends to blow it out of the mane part of the lens

DO NOT, I repeat DO NOT use compressed from a tire pump at a gas station! That air is not clean, oil free or dry. You do not know what kind of dirt and oil and moisture is in that air. More than likely since that air is only intended to be used to fill tires it has not been filtered or dried. If you want to use compressed air to blow the dust out of a lens make sure the compressor has a filter and and dryer on the air line or buy those cans of compressed air from a computer or camera store.

Last edited by Sprags; 02-02-2008 at 06:43 PM.
02-01-2008, 05:16 PM   #14
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I totaly AGREE WITH Sprags on this NEVER EVER use compressed air of any kind on any of your gear. Especially from a gas station. EEEK!! (I'll stop yelling now).

Just take some pictures. the lens is fine. Have fun and post some great shots sometime soon.
02-01-2008, 05:32 PM   #15
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Using compressed air from a can or compressor to blow into a lens is a big no-no in my opinion. Not only are you likely to introduce more dust into the lens, but because compressed air is cold, you could leave condensation into the lens. Moreover there is a risk of having oil or propellent coming out from the nozzle if it is not filtered.

One method that was suggested to me is to use a small vacuum cleaner in a dust free area. Extend the lens to the minimum focusing distance. For most lenses that don't have internal focusing, this will extend the lens barrel and move the last elements inwards. Very carefully vacuum the edges of the lens openings. That might dislodge the dust inside. Worked for me many years ago with a Minolta 50 mm lens that had a big speck of dust. Obviously proceed with care.
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