Steve'sDigicams

Rui · Jun 26, 2005, 11:37 AM

I recently received a lens i got off of ebay in the mail. Unfortunitly the lens seems to have a defect that the owner was unaware about.

It's a pattern of white dots that spreads over a few centimeters.

http://i-rui.com/dots on 85mm.jpg

I took a couple of test shots and can't see anything on the images itself, but my main concern would be if it's something serious that will worsen with time.

Also, I'm curious about how much something like this devalues the lens (since I was told it was optically perfect).

Any idea of what this is??

slipe · Jun 26, 2005, 11:42 AM

Take a good look at the anti-reflective coating on the lens. If that is a macro shot it could be in focus. There are also coatings between lens elements in a good lens, so you might not be able to see it. If it is on your macro photos and blurred or not visible on longer shots I would have to guess the coating isn't perfect.

Rui · Jun 26, 2005, 12:55 PM

It IS a macro shot of the lens. I'm not sure a standard lens would be able to show the dots.

The defect appears to be on the INSIDE of the front element. It is only visible when the light hits it at a certain angle.

The pattern only appears on a small area of the lens - not over the entire surface (so i don't think it's the coating)

Norm in Fujino · Jun 26, 2005, 8:48 PM

Rui wrote:

Quote:

The defect appears to be on the INSIDE of the front element. It is only visible when the light hits it at a certain angle.

The pattern only appears on a small area of the lens - not over the entire surface (so i don't think it's the coating)

Without being able to see more of the lens up close, I'd guess it is mold growing on the coating of one of the inner lens surfaces. It is not unusual in humid climates; I had a couple of enlarger lenses that got mold in them due to the humid state of my darkroom here in Japan. There's nothing really you can do about it; offhand I'd guess that sending the lens in for repair would cost more than buying a new lens. Depending on how bad the mold is, it will probably result in some degree of softening (lower contrast) in the image.

Rui · Jun 26, 2005, 11:27 PM

I brought it to a camera shop to get a salesmans advice - he thought it was probably something wrong with the coating. Although he did say there is a CHANCE it COULD be mold in early stages (there's no spidering on teh pattern) He suggested i bring it to minolta for their oppinion and perhaps a cleaning if necesary.

Just from the test shots I took I'd like to keep the lens - it's a nice 85mm F/1.4. Although i'm thinking i probably deserve some kind of componsation in return (15% money back?)
I live in canada (so does the ebay seller) - but our summers do get quite humid, and it was rather hot the day it was deleivered to me....so that could've been a factor.
Any other advice / opinions?

I'll update when i know more.

Jun 26, 2005, 11:37 AM	#1
Rui Junior Member Join Date: May 2005 Posts: 12	I recently received a lens i got off of ebay in the mail. Unfortunitly the lens seems to have a defect that the owner was unaware about. It's a pattern of white dots that spreads over a few centimeters. http://i-rui.com/dots on 85mm.jpg I took a couple of test shots and can't see anything on the images itself, but my main concern would be if it's something serious that will worsen with time. Also, I'm curious about how much something like this devalues the lens (since I was told it was optically perfect). Any idea of what this is?? Attached Images

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Jun 26, 2005, 11:42 AM	#2
slipe Senior Member Join Date: Oct 2003 Location: Indian Rocks Beach, FL Posts: 4,036	Take a good look at the anti-reflective coating on the lens. If that is a macro shot it could be in focus. There are also coatings between lens elements in a good lens, so you might not be able to see it. If it is on your macro photos and blurred or not visible on longer shots I would have to guess the coating isn't perfect.

Jun 26, 2005, 12:55 PM	#3
Rui Junior Member Join Date: May 2005 Posts: 12	It IS a macro shot of the lens. I'm not sure a standard lens would be able to show the dots. The defect appears to be on the INSIDE of the front element. It is only visible when the light hits it at a certain angle. The pattern only appears on a small area of the lens - not over the entire surface (so i don't think it's the coating)

Jun 26, 2005, 11:27 PM	#5
Rui Junior Member Join Date: May 2005 Posts: 12	I brought it to a camera shop to get a salesmans advice - he thought it was probably something wrong with the coating. Although he did say there is a CHANCE it COULD be mold in early stages (there's no spidering on teh pattern) He suggested i bring it to minolta for their oppinion and perhaps a cleaning if necesary. Just from the test shots I took I'd like to keep the lens - it's a nice 85mm F/1.4. Although i'm thinking i probably deserve some kind of componsation in return (15% money back?) I live in canada (so does the ebay seller) - but our summers do get quite humid, and it was rather hot the day it was deleivered to me....so that could've been a factor. Any other advice / opinions? I'll update when i know more.