Can a Scratched Lens be Repaired?

I was planning on putting up for sale my Canon 100-400mm Ver. II lens. Seems like the going rate for those in good condition is around $1100 or so give or take.
I was inspecting the lens for flaws and saw a couple (2 or 3) minor "dings" that you would have to struggle with to find those. The exterior body looks "almost" flawless.
Then came the lens glass....(GULP!). Looking at the front of the glass I myself did not notice anything. Then I looked through the rear of the camera (looking for dust) and when I held the lens at a certain angle I saw what appeared to be some very noticeable scratches (a lot actually) which were very visible to me looking from the back. I was kind of blown away. My daughter was over today and I asked her to look since her eyes are better than mine. She barely saw anything on the front of the glass but when looking through the rear of the lens she saw the same thing I saw. I was perplexed as to how the scratching on the glass can be so easily more visible when looking through the rear of the lens and barely visible looking at the glass from the front. Can someone explain that to me?

Secondly, can those scratches be repaired? Can the lens still be sellable or am I out nearly $1100?

Thx.

Shine a small flashlight through the back and look at the front, might help figure it out.

But yes, the front element can be replaced.

Totally sellable IMO. There's a Tony Northrup video where he scratches the crap out of the nifty-fifty and showed the images after. The results, from what I remembered, barely showed the scratches on the image.

Here's the video:

https://youtu.be/YcZkC​nPs45s?t=576

Bogino:
Your situation is why I always put UV filters on the front of my lenses and leave them there... and they're cheaper than a lens repair.

dangermoney wrote in post #18928153
Bogino:
Your situation is why I always put UV filters on the front of my lenses and leave them there... and they're cheaper than a lens repair.

Depends on how many lenses you have to buy filters for vs how many front elements you would otherwise scratch.

I don't use uv filters. I'm pretty sure I've never scratched a front element and I often find a lens in my bag without a cap. UV filters would have cost me quite a bit of cash over the years, front elements are often just a few hundred bucks.

the front element can be replaced. probably cost you around $500. you'd probably be better off selling the lens as is. imo. if there are lot of scratches it could be from cleaning the lens, something I almost never do unless absolutely necessary. the coatings on some of these lenses are very soft despite what is often parroted on these forums.

tony Northrup. LMAO! dents don't hurt the way a car drives either

Left Handed Brisket wrote in post #18928158
Depends on how many lenses you have to buy filters for vs how many front elements you would otherwise scratch.

I don't use uv filters. I'm pretty sure I've never scratched a front element and I often find a lens in my bag without a cap. UV filters would have cost me quite a bit of cash over the years, front elements are often just a few hundred bucks.

oh no here we go AGAIN

just disclose it all, and you'll be fine selling it....but you'll probably get less than what a normal lens would get

I would shoot some heavily backlit shots and see if they effect the images. Otherwise, fully disclose the condition and adjust the price accordingly.

Assuming the scratches are from cleaning the front lens, I would suggest re-evaluating how you clean glass to avoid this in the future.

I also have never cleaned the front of my 150-600, 100-400 ii or the 70-200 ii when I owned it.
I just use a Giottos bulb blower to blow the lens and glass off after every use.

ed rader wrote in post #18928174
oh no here we go AGAIN

Board seems slow lately.

Also, if for some reason I need to clean the front element I usually use my tee shirt.

Left Handed Brisket wrote in post #18928448
Board seems slow lately.

Also, if for some reason I need to clean the front element I usually use my tee shirt.

that's how I damaged the front element on my 24-70L II and I mean the coating damage was so extensive I had to replace the front element and it cost me almost $500. I seldom use a protective filter but I almost never use anything but air to clean lenses

The new fluorine coating, which is intended to make it easy to wipe off dirt from the lens, seems to wipe off pretty easily itself.

Can a SHIFT key be repaired?