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Old Aug 24, 2007, 8:24 PM   #1
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I've had a K100D, 18-55mm kit lens and Da 50-200mm lens for about 6 months. I'm now looking at used lenses. I understand what sellers are talking about when they say no scratches, no fungus, no dust. Now for my dumb question - when it says aperature blades are dry and snappy, no oil, I wonder how would any oil get in there to begin with?
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Old Aug 24, 2007, 8:57 PM   #2
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the focusing helicoils have to have grease on them. some times what happens is the grease gets into the aperture mechanism and it freezes the blades so they do not move when you close down the ap. you state that you understand about what they are talking about the other problems.. BUT do you really know how to see the prob if it's there?? i've gotten many lenses that were free and clear when they were down and out.. looking and ''seeing'' are 2 different things.

roy
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Old Aug 25, 2007, 1:12 AM   #3
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Basically, all grease is oil in a soap base. Over time, and with varying temps, the oil separates, and can flow into places it wasn't intended to. Some of the volatiles also can end up condensing on the lens surfaces, causing a film, and spots.

I recently got a used lens with non functional autofocus, but the seller claimed the glass was clean with no sctatches or fungus. Wrong. Specks everywhere. Couldn't get a sharp image out of it at any aperture. Shold have returned it, but I love to tinker, so ended up totally disassembling it, cleaning, and fixing the focus problem at the same time. Works dandy now.

brian
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Old Aug 25, 2007, 2:35 AM   #4
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VTphotog wrote:
Quote:
Basically, all grease is oil in a soap base. Over time, and with varying temps, the oil separates, and can flow into places it wasn't intended to. Some of the volatiles also can end up condensing on the lens surfaces, causing a film, and spots.

I recently got a used lens with non functional autofocus, but the seller claimed the glass was clean with no sctatches or fungus. Wrong. Specks everywhere. Couldn't get a sharp image out of it at any aperture. Shold have returned it, but I love to tinker, so ended up totally disassembling it, cleaning, and fixing the focus problem at the same time. Works dandy now.

brian
Ahh! Brian another man after my own heart. Way to go on the fix. Never say die!!

Dawg
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Old Aug 25, 2007, 2:41 AM   #5
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a200user wrote:
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I've had a K100D, 18-55mm kit lens and Da 50-200mm lens for about 6 months. I'm now looking at used lenses. I understand what sellers are talking about when they say no scratches, no fungus, no dust. Now for my dumb question - when it says aperature blades are dry and snappy, no oil, I wonder how would any oil get in there to begin with?
The Grease was used to dampen and lubricate the focus mechanism as Roy said. They used what grease was available then and most of the old lens if kept out of extreme high temps still have a feel to them you don't get with the new plastic lens bodies today. Today when they are cleaned and regreased you have better choices in the grease you can use. With no grease the focus and zoom would feel loose and move too freely. And it was no dumb question either. I'm sure a lot of folks reading this just said "Oh that's why"!!!

Dawg
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Old Aug 25, 2007, 1:43 PM   #6
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If you have an old lens with oil on the aperture blades (like my old Kiron 80-200 does), and you get them cleaned - does that mean that the problem won't return later on? I keep telling myself to just junk the lens because I could buy a used one cheaper than I can get mine fixed, but I can't quite do that. I keep looking for reasons to keep it and find out what type of lens it really is when it's working right. At the time he gave it to me I was still shooting film and had the lovely F 70-210. The Kiron wasn't as sharp as the Pentax, but it might have been because it was shooting wide open all the time, rather than because it's an inferior lens to the Pentax. I definitely won't bother if the oil will come back later on.
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Old Aug 25, 2007, 2:07 PM   #7
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Thanks for the information. I'm heading out to a picnic today at a friends house. He's into RC model planesso I'm going to challenge myself and the DA 50-200mm provided the wind cooperates. We have thunderstorms in the area today, but if I get any keepers I'll post them.

Thanks again all for the answer to my question. I have an SMC-A 50mm F2 on the way from eBay, my first venture into the used market. I've read that this lens is not regarded highly but I thought I would go cheap for my first experience with a manual focus lens. This one the seller claims to be new in the box; never used.
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Old Aug 25, 2007, 4:21 PM   #8
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mtngal wrote:
Quote:
If you have an old lens with oil on the aperture blades (like my old Kiron 80-200 does), and you get them cleaned - does that mean that the problem won't return later on? I keep telling myself to just junk the lens because I could buy a used one cheaper than I can get mine fixed, but I can't quite do that. I keep looking for reasons to keep it and find out what type of lens it really is when it's working right. At the time he gave it to me I was still shooting film and had the lovely F 70-210. The Kiron wasn't as sharp as the Pentax, but it might have been because it was shooting wide open all the time, rather than because it's an inferior lens to the Pentax. I definitely won't bother if the oil will come back later on.
Harriet,
There are much more technical people than myself here, but my understanding is that the modern grease used in the repair of these old lenses is stable enough we should not have to worry about it in our lifetime.
Tim
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Old Aug 25, 2007, 10:17 PM   #9
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a200user wrote:
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Thanks for the information. I'm heading out to a picnic today at a friends house. He's into RC model planesso I'm going to challenge myself and the DA 50-200mm provided the wind cooperates. We have thunderstorms in the area today, but if I get any keepers I'll post them.

Thanks again all for the answer to my question. I have an SMC-A 50mm F2 on the way from eBay, my first venture into the used market. I've read that this lens is not regarded highly but I thought I would go cheap for my first experience with a manual focus lens. This one the seller claims to be new in the box; never used.
The 50 F/2 is a very nice lens. I have one and use it quite often. The 50 1.4 and the 1.7 and 1.8's are supposed to be better as they are faster and you are not shooting wide open at f/2 with them but if your just into photos for fun the f/2 will do. Here are a few slow shutter speed night photos I took with my 50mm f/2 lens.

Dawg
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Old Aug 26, 2007, 3:11 AM   #10
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"My" camera repairman, who is very experienced (just retired after a lifetime of practice) told me that the problem often occures after the lens have been exposed to heat. Most typical case is when the camera and lens have been laying in the car, exposed to sunlight.

That's why many long teles have a white or silver colour, to prevent thegrease from "steaming" when the lens is standing on a tripod in the sun for hours.

my 2 cents

Kjell
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