fungus or oil?

[jarodfwh]

hi all , just receive a 50/1.8 from a seller, notice some defect that the seller did not mention, is this a oil speck or worst fungus?

anyone can estimate how bad this will effect the final picture?

currently i do not had a m39 to nex adapter to test on my nex5n. thanks

 

[-Nash-]

If thats on the rear element the images will most likely turn out hazy.
I'd return it for a refund - but on the other hand a cleaned Canon 50mm f/1.8 is a nice lens to have...

 

[Mackinaw]

Are we looking at the front or back of the lens?

Jim B.

 

[jarodfwh]

from the back of the lens... or is it the famous haze in canon lens?
its either in the middle or rear element....

contacting the seller now for a full refund.

 

[Mackinaw]

Haze is common in a lot of lenses that are 50+ years old, no matter the manufacturer.

Haze is just that, haze. This looks like something else entirely. The Canon 50/1.8 has two cemented lens groups, one directly in front of the aperture, one directly behind. If the gunk is on the inside of the rear element, it can probably be easily cleaned. If it is lens separation, an expensive fix. Not that it matters, since you'e asking for a refund.

Jim B.

 

[Dez]

The famous, or more likely infamous Canon haze forms on the rear surface of the front half of the lens, and is usually trivial to clean off. With the black 50 f1.8 however, it is sometimes impossible to remove, and will seriously reduce contrast. If you grip the lens forward of the aperture ring, the whole front section will unscrew, exposing this area. If you have removable haze on that surface, clean it off carefully with normal lens cleaning fluid, and you're good to go. If not, for sure return it.
I can't say I have ever seen this common problem look so bad as the picture you sent along, so I would tend to agree that you are more likely seeing a more serious problem with element separation.

Good luck,
Dez

 

[jarodfwh]

The famous, or more likely infamous Canon haze forms on the rear surface of the front half of the lens, and is usually trivial to clean off. With the black 50 f1.8 however, it is sometimes impossible to remove, and will seriously reduce contrast. If you grip the lens forward of the aperture ring, the whole front section will unscrew, exposing this area. If you have removable haze on that surface, clean it off carefully with normal lens cleaning fluid, and you're good to go. If not, for sure return it.
I can't say I have ever seen this common problem look so bad as the picture you sent along, so I would tend to agree that you are more likely seeing a more serious problem with element separation.

Good luck,
Dez

hi all thanks so much for the feedback, here is another photo that i just notice there are some difference in the color of the rear element, this is not normal as well right?

 

[Mackinaw]

Optical glass can vary as to color hue. Coatings can change the color of an element too.

It's hard to judge the color of the rear element in the latest pic. To me, it looks gray, or neutral.

Jim B.

 

[jarodfwh]

Optical glass can vary as to color hue. Coatings can change the color of an element too.

It's hard to judge the color of the rear element in the latest pic. To me, it looks gray, or neutral.

Jim B.

hi Jim, if you look more closely, the part that is circled in red appear white in contrast with the outer rim which is more yellowish
please refer to the picture above for clearer comparison

 

[Mackinaw]

I'm having a real hard time seeing any difference in colors. I'm sure it's there, but it just doesn't photograph well. If it is minor, I wouldn't worry about it.

Jim B.

 

[Dez]

The last picture you sent, with or without a yellowish tinge, is a far cry from the first one. Have you succeeded in removing the crud from your lens?

Cheers,
Dez

 

[clayne]

Oil haze. What you're seeing is separation of *oil* not the lens, which has evaporated and deposited on the rear element. Very common in older lenses and very easy to fix if you have a spanner. If you don't know what a spanner is, don't even try.

 

[Highway 61]

With the black 50 f1.8 however, it is sometimes impossible to remove, and will seriously reduce contrast.

I can confirm that for having serviced several black 50 f1.8 Canon RFs lenses.

On the first photo we can see balsam desintegration at the periphery of the lens with the typical "golden droplets". This may cause vignetting and cannot be repaired easily.

Hence the yellowish tint on the edges.

About the haze or whatever it is here : I have seen the very same thing once in a 50 f1.8 black, and it turned out to be acid fungus having grown on the oily deposits, all the largest white spots being linked by mycelium filaments having etched the glass, hence the geometric pattern we can also see here, as if the glass had been cleaned with a ScotchBrite pad.

But - hard to tell from a photo.

You will have to look closely at the sick element with a macro lens or whatever magnifying you have at hand. Acid fungus etchings can easily be seen if you put the glass surface under an oblique light source.

 

[jarodfwh]

The last picture you sent, with or without a yellowish tinge, is a far cry from the first one. Have you succeeded in removing the crud from your lens?

Cheers,
Dez

the photo was taken from a different angle, the spot show up more clearly if there are more light.

thank all, i think even if its an oil haze , i won't take the risk of needing to open up the lens, especially the rear element, i will stick with asking for a refund instead.

 

[Dez]

Probably the best bet. Even if it is only oil on the back of the front group, it is always a toss-up whether or not it can be removed. It wouldn't do to try to remove it, find you can't, and then have the vendor refuse to accept the lens back because you had "tampered" with it.

Cheers,
Dez

 

[farlymac]

Mine looked like this when I started.


Canon 50mm f1.8 Cleaning 2 by br1078phot, on Flickr

And like this when I finished.


Canon 50mm f1.8 Cleaning 8 by br1078phot, on Flickr

PF

 

[Dez]

Mine looked like this when I started.


And like this when I finished.

/QUOTE]

Nice! Looks like you got lucky. Black Canon 50 f1.8 lenses can be had quite cheaply if they are foggy, and if you succeed in cleaning them end up as a bargain giving marvelous results. I have a cosmetically near-perfect one bought on ebay for $90 which also cleaned up perfectly, and now lives on my Bessa R.





I have always wondered why the etching problem is specific to this lens. I have never seen it in the contemporary f1.4's or 1.2's or in any of the Canon lenses of other focal lengths.

Cheers,
Dez

 

[Frontman]

Definitely oil. Getting the lens clean will be hit or miss. The oil is always on the inside of the rear element, getting to it is easy. Remove the lock ring on the rear of the lens, the focusing barrel/helicoid will come off. Be careful not to lose the brass spacer rings. The grip the rear element group and twist counter-clockwise to remove the rear element group.

Clean off the haze with a wet cotton swab and a touch of toothpaste. Sometimes the haze comes off completely, sometimes the coating will be a bit damaged, sometimes the coating is permanently etched and cloudy. The cloudiness can be removed with toothpaste and much patience, but this will remove the coating as well.

When putting the lens back together make sure the brass spacers are in place, and line up the guide pin to the slot in the focusing barrel. Then thread in the lock ring.

 

[Dez]

The oil is in my experience on the surfaces abutting the aperture blades. The easiest way to get at this area is by simply grabbing the front of the lens tightly and twisting. The whole front group unscrews, giving access to both surfaces. Somehow it seems more often to affect the back surface of the front group than the front surface of the back group (not element).

Cheers,
Dez

 

[farlymac]

I think it depends on how it was stored which group of elements is affected.

BTW, if you click on my photos, it will take you to the set where I worked on the lens. I went in through the back.

PF