Scratched the rear element of a Canon 24-70 F2.8 I

[littlewildcat]

I borrowed this lens and took it out for shooting last weekend. The rear lens cap was not tightly screwed on causing the rear element badly scratched with visible coating damage. I have heard that a rear element scratch is detrimental.

I put it on my 40D and took some pics. The scratches did not seem to have any adverse effects.

What are the settings (aperture and focal length) you wonderful people here would suggest for a full test to diagnose the possible problem ?

I understand that it would cost a lot to get the element replaced or to get it repair. I might have to buy it.


Anyway, please advise me and suggest what I can do about it.

Thanks.

 

[Mt Spokane Photography]

Get a estimate from Canon or a authorized Canon repair center.
Set the lens to f/22 like you would for a sensor check and compare that with a wide open image.

You can get a estimate at Midwest Camera by e-mail, see what they say.

http://www.midwestcamera.com/authorized.html

 

[ahab1372]

You might find this interesting: http://www.lensrentals.com/blog/2011/08/the-apocalypse-of-lens-dust

With or without visible impact on image quality, the owner will probably insist on having it repaired or replaced.

 

[littlewildcat]

Get a estimate from Canon or a authorized Canon repair center.
Set the lens to f/22 like you would for a sensor check and compare that with a wide open image.

You can get a estimate at Midwest Camera by e-mail, see what they say.

http://www.midwestcamera.com/authorized.html

Thank you for the suggestions. I have sent an inquiry to MidWest Camera already and will contact the local Canon Service center afterwards.

You might find this interesting: http://www.lensrentals.com/blog/2011/08/the-apocalypse-of-lens-dust

With or without visible impact on image quality, the owner will probably insist on having it repaired or replaced.

If I can tolerate with the scratches (if there is only very little adverse effect on IQ)and don't have to send it for repair, which I think is going to cost as much as the value of the lens (I guess $850 to $950), I think I will buy it. Your post is really interesting and comforting. Thanks.

 

[Pi]

Are you sure that it is scratched? Sometimes those are just marks that you can clean up.

If it is, it looks like it is easy to replace it:

Canon EF 24-70mm f/2.8 L USM Lens Repair - Err 99 / 01

Or, see this:
http://www.lensrentals.com/blog/2013/01/a-peak-inside-the-canon-24-70-f4-is

Of course, you need the glass element.

 

[littlewildcat]

Sounds interesting but I don't think I can handle it. Thanks.

 

[littlewildcat]

Update : 1. Canon Canada charges $259(plus tax and delivery) for basic repair. Will report later for their full quote when it become available.


2.Get a quote from Midwest Camera repair "Replace the rear element is $258.00 + return shipping, includes clean, lube and adjust" which I think is more than reasonable.

Mt Spokane Photography. Thank you very much.

 

[Viggo]

Jeez!! 258? That's what they charge for an AF calibration off warranty here. You lucked out on that one. Good for
You!

 

[Digbydriver]

I don't even lend books. They never come back the same. If they DO come back.

 

[littlewildcat]

I bought it finally. $800.

Price not bad for a UW(2009) L lens. (compared to similar item online)

I tested it thoroughly from f2.8 to f22, 24mm to 70mm. Also shoot into bright light too. Doesn't seem to have any issue. I will use for a while before sending it for repair after I have saved up enough money.

After repairing, I may be able to sell it for $800 to 900. They cost of repair will be considered the rental for this L lens.

BTW, I do lend and borrow things but if I do any damage to them, I will be responsible. lol