Would this affect image quality? (rear element chip)

[md2008]

Hi,

I recently purchased a 40mm summicron-c and found this chip on the rear element. Do you believe a lens defect of this kind will affect the image quality? And if so, would it affect sharpness, contrast, resolution? I did run a test roll through and I don't see any image defects, but I'm not familiar with the normal qualities of this lens so can't say whether the images are optimal or below-par. What type of images should be taken to test for possible effects of this lens defect?

Thanks for your help.

[ErnestoJL]

Hi, welcome to the forum.
Of course, a chip on the glass surface will degrade picture quality. To which extent, it probably can be defined only upon a close inspection of a couple of pictures taken with another (same) lens, of same subject and preferably of a lens test pattern.
Many years ago, I´ve seen an uncoated prewar Zeiss Sonnar 1.5 having lots of chips in the outer front surface. It looked really awfull, however the pictures taken with it seemed to be good.
I guess that if the chip surface isn´t really big, the defects wouldn´t be something to worry about.
Hopefully, your lens was underpriced at the time of purchase.
Cheers
Ernesto

[ferider]

Welcome to the forum !

The chip doesn't look bad to me. You might want to fill it black with a sharpie to avoid flare.

You will only see impact, if any, when the lens is closed down to f11 or further.

It's a great lens. Enjoy !

Roland.

[M. Valdemar]

I don't think there would be any perceptible image degradation whatsoever.

You can make images with a near-destroyed lens in some cases and still get good images.

[Mackinaw]

Originally Posted by ferider

Welcome to the forum !You will only see impact, if any, when the lens is closed down to f11 or further.

Agreed. I had an old Canon 35mm lens once, with a coating defect on the rear element (about the size of the chip), that did produce a mushy spot on the negative when stopped down to f11 - F16. I finally bit the bullet and had John Van Stelton re-coat the back element.

Jim B.

[Kin Lau]

You probably won't notice it 90% of the time, but you might get more flare if you shot into a lightsource.

As for how bad a lens can be, check this out http://www.lensrentals.com/news/2008...ment-scratches

[Olsen]

Originally Posted by Kin Lau

You probably won't notice it 90% of the time, but you might get more flare if you shot into a lightsource.

As for how bad a lens can be, check this out http://www.lensrentals.com/news/2008...ment-scratches

Ha, ha, ha!

Why do we buy all these expensive lenses with these impressive FMT charts for...?

[neelin]

Originally Posted by md2008

Hi,

What type of images should be taken to test for possible effects of this lens defect?

stop down to f16/22
& take overexpose a shot of a smooth light grey surface. I had what i thought a piece of sensor dust on my digicam & it ended up being a small fleck of dust on the rear element. Focus is probably irrelevant for the test shot, however take it at one second & move the camera around, this will blur any texture in the photographed surface & show only the lens defect. In my case rear element dirt when stopped down is significant as shown on my M8.\
robert

[ErnestoJL]

Originally Posted by Kin Lau

You probably won't notice it 90% of the time, but you might get more flare if you shot into a lightsource.

As for how bad a lens can be, check this out http://www.lensrentals.com/news/2008...ment-scratches

Well, hmmmmm... the Sonnar I mentioned wasn´t that bad...
It´s clear, just get the picture, no matter how good or bad the lens shows.
Enjoy the lens!!!

Cheers
Ernesto

[md2008]

Thanks for the replies. I picked up the lens through the big auction house - no mention of the chip in the description. The seller was good enough to offer to take it back for a full refund or give a partial refund if I keep it. I'm leaning towards keeping it. I'll post some pics in a bit as soon as my negs dry.

[awilder]

Filling in the chip with flat black paint will work far better than a black "Sharpie" which is not fully opaque. After that, image degredation will be nil but unfortunately resale value may take a hit unless you got a sweet deal from the start. The bottom line is this, if you tend to be anal retentive on these matters, it's best to return the item for a ful refund if opportunity presents itself. If it's for shooting purposes only and your happy with the test shots, keep it especially if you got a good deal on the purchase.

[George S.]

Take some test shots, and if there's a problem return it and get a full refund. There's plenty of those lenses available. If there's no problem, keep it and get a partial refund because of the resale value issue and the fact that he didn't mention it in the ad, then happily enjoy it.

They say defects in the rear element _generally_ do matter more than in the front element, but, even saying that, I don't think you'll see any degradation in actual use.

[md2008]

Here are some photos from this lens in practical use. I did find a mark which looks like round water mark on pictures of light colored monotones e.g. sky, wall - nothing that can't be cloned out and you have to really look for it. The surrounding image area doesn't seem to be affected. I think I'll keep this lens. I'll end up paying $250 for this lens after the partial refund - cosmetically and mechanically, the lens is pristine; it's just this chip that's the problem. What would you do? Thanks to everyone who replied to this thread.

[md2008]

A few more pics with this lens.

[Gary E]

The 40 Summicron-C is a favorite lens in my collection. Your shots look good as I can't even see any issues from the chip.

I am in the same dilemma with a DR Summicron. It has a similar look to your chip except mine seems to flare out to the coating a little; I thought it might be the beginning of a fungus attack. But unlike you I didn't get a chance to go out to run a test roll with this lens. The rest of the lens is in fantastic shape, so I'm up in the air if I should keep this or return it for a refund. Though your photos makes me think I should keep mine and send it out for a CLA.

[astroman]

A local shop had a nikon 400 2.8 was on consignment for a pro sport shooter it had a nice big chip on the front element and suprisingly had no effect on the image quality,nothing that was noticeable anyway.Go figure?

[peterm1]

A single chip or scratch on a lens element produces less image degradation than you would think. Effects are mainly seen when you shoot against the light. But a scratch or chip on the rear element IS worse than one on the front element.

The thing you may wish to try is to cover the chip with some black marker ink. Strangely that can eliminate unwanted effects like bright spots from the chipped area of lens - by eliminating the unwanted / irregular light that comes from the chip. (The black spot itself tends to get smooshed out by the averaging effect that you get from the other light coming out of the rear of the lens. I have seen it work so its worth a try.

[Beemermark]

Don't ask me why but chips, scratches, cleaning marks, etc rarely have any effect if they are on the front lens element but any marks on the rear element affect both resolution and contrast. That said the "chip" on your lens is so tiny I seriously doubt if it will have any affect. If you like the pictures then don't worry. However if your the type that will worry about it I suggest you send it back. The lens is common enough it should be easy to find another one.