Dust in used lenses ?

stevebrot · 12-21-2012, 08:30 PM

A few specs of dust are a fact of life with vintage gear and should not be cause for concern. More than a few and you start losing contrast. This is particularly true in the rearward elements. How much should you tolerate from a purchase perspective? It depends on your tolerance. Though I would be quick to point out that I have a Tamron 28/2.5 and a Pentax-M 50/1.7 that I purchased new in 1982. Both lenses have had a full life in the rugged outdoors and have been on thousands of miles of dusty trail. Both are in very good to excellent condition and neither have any visible internal dust due in part to reasonable care over all those years to keep the gear clean.

Steve

(...nope, not for sale...)

Last edited by stevebrot; 12-21-2012 at 08:38 PM.

stevebrot · 12-21-2012, 08:41 PM

Originally posted by Heelers

Generally it sounds like dust closer to the sensor is more critical than the focal end.

It is not the closeness to the sensor, as such. The rear elements are simply more critical to the lens function. It would take too many words to explain.

Steve

**ramseybuckeye** · 12-21-2012, 10:33 PM

Originally posted by Heelers

Almost all of the 55-300's I have looked at say this. Is this lens prone to dust? Any feedback on buying used lenses over the Internet is greatly appreciated!

Thanks ~~ Yale

I would say yes the 55-300 is prone to dust, mine does attract a lot of dust, but mostly on the outside of the front element and is easy to just blow or brush off. The few specs that are on the inside don't seem to affect the performance of the lens.

You can get great buys and duds over the internet, you need to be careful. I am leery of any camera/lens combination sold as a "student camera", just a hunch. If you are buying a lens and the description says that it works great they should have the evidence (photos) to show it. Some listings seem to intentionally mislead by giving a little info on a lens and having photos of the lens that do not show the widest aperture, or just way out of focus. But often the sellers have inherited the equipment and really are clueless. You can look at completed sales on ebay and the Marketplace, and calculate market price. Many of the "buy it now" prices on ebay are way overpriced. You can also look at the prices paid in PentaxForums reviews, but those don't really give you current market prices. Do your research, be careful, and take calculated risks. I've taken some risks and been disappointed on a few and rewarded on many. And if you get a lens and don't really want to keep it, you can sell it, just be honest in your description.

bgwatson99 · 12-28-2012, 12:43 PM

Originally posted by mikeSF

for the most part, i don't worry about internal dust and know that i can usually open the lens and clean it if need be.

that said, if you shoot wide open bokeh circles like this pic below, you can often see all the internal dust inside each little circle, so even a single contaminant becomes pretty obvious...i wish i had the OOC version because i cloned out several bits of dust from the image before it was useable.

very nice. Thanks for sharing!

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12-21-2012, 08:30 PM	#16
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	A few specs of dust are a fact of life with vintage gear and should not be cause for concern. More than a few and you start losing contrast. This is particularly true in the rearward elements. How much should you tolerate from a purchase perspective? It depends on your tolerance. Though I would be quick to point out that I have a Tamron 28/2.5 and a Pentax-M 50/1.7 that I purchased new in 1982. Both lenses have had a full life in the rugged outdoors and have been on thousands of miles of dusty trail. Both are in very good to excellent condition and neither have any visible internal dust due in part to reasonable care over all those years to keep the gear clean. Steve (...nope, not for sale...) Last edited by stevebrot; 12-21-2012 at 08:38 PM.

12-21-2012, 08:41 PM	#17
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Heelers Generally it sounds like dust closer to the sensor is more critical than the focal end. It is not the closeness to the sensor, as such. The rear elements are simply more critical to the lens function. It would take too many words to explain. Steve

12-21-2012, 10:33 PM	#18
ramseybuckeye Site Supporter Join Date: Apr 2009 Location: Hampstead, NC Photos: Gallery Posts: 17,292	Originally posted by Heelers Almost all of the 55-300's I have looked at say this. Is this lens prone to dust? Any feedback on buying used lenses over the Internet is greatly appreciated! Thanks ~~ Yale I would say yes the 55-300 is prone to dust, mine does attract a lot of dust, but mostly on the outside of the front element and is easy to just blow or brush off. The few specs that are on the inside don't seem to affect the performance of the lens. You can get great buys and duds over the internet, you need to be careful. I am leery of any camera/lens combination sold as a "student camera", just a hunch. If you are buying a lens and the description says that it works great they should have the evidence (photos) to show it. Some listings seem to intentionally mislead by giving a little info on a lens and having photos of the lens that do not show the widest aperture, or just way out of focus. But often the sellers have inherited the equipment and really are clueless. You can look at completed sales on ebay and the Marketplace, and calculate market price. Many of the "buy it now" prices on ebay are way overpriced. You can also look at the prices paid in PentaxForums reviews, but those don't really give you current market prices. Do your research, be careful, and take calculated risks. I've taken some risks and been disappointed on a few and rewarded on many. And if you get a lens and don't really want to keep it, you can sell it, just be honest in your description.

12-28-2012, 12:43 PM	#19
bgwatson99 Inactive Account Join Date: Dec 2012 Posts: 8	Originally posted by mikeSF for the most part, i don't worry about internal dust and know that i can usually open the lens and clean it if need be. that said, if you shoot wide open bokeh circles like this pic below, you can often see all the internal dust inside each little circle, so even a single contaminant becomes pretty obvious...i wish i had the OOC version because i cloned out several bits of dust from the image before it was useable. very nice. Thanks for sharing!