How big are your scratches - will a scratched lens still work?

[Jimm]

I'm debating purchasing a lens with a small scratch due to its heavily discounted price. Its from Ebay (yes I've read the posts ref the pro's / con's buying from here) but as it has undergone a service I'm considering it as working. However it does have a scratch which the seller says has no effect on the image quality. (Its a Canon EF USM IS 28-135mm F/3.5-5.6)

So my questions is, has anyone got scratches on their lenses which don't bother them, if so how big are they? Conversely if you've got a scratch that bothers you, how much does it effect your image and is it photoshop'able out?

thanks

[Hansm]

Depents where the scratch is located. Scratches on the front element normally do not harm the image quality.
Scratches on the beck element can have negative effect, but I had a Hassy 80mm lena with a scratch on the back element and it didn't influence the imagequality.
The best woild be to check the lens yourself and do some tests. Don't know if this is possible?

[inkista]

Just food for thought:

http://www.lensrentals.com/blog/2008...ment-scratches

[Jimm]

@ inkista that's amazing, it almost make you think what all the fuss about a tiny scratch on anything!

[pabloisme]

generally the closer to an element the less anything is seen, go on try it! go to a mesh fence and take a few snaps moving in ................ till you are right up close

so if the mark is small I cant see there is a big problem unless it is macro stuff

[kdoc856]

That link has an AMAZING image. guess I can relax more than I thought

[inkista]

@ inkista that's amazing, it almost make you think what all the fuss about a tiny scratch on anything!

Well, image quality is one thing.

Resale value is a whole 'nother beast.

[Dave Humphries]

Reduced contrast, or flare if a wide scratch on front element and you shoot into the sun, or bright lights often, are going to be the main problems.

[rpcrowe]

There have been quite a few completed auctions for the 28-135mm f/3.5-5.6 IS lens on eBay UK. Here is a selection of completed auctions with the green prices the completed auctions and the red prices; the auctions were not completed (usually because the price was too high)

http://www.ebay.co.uk/csc/i.html?_nk..._dmd=1&_ipg=50

You can figure out what the lens has been going for and decide if the price is reasonable enough to accept a flawed lens. You can also offer a lower price if the auction is not completed. Remember, you will have the same problems reselling this lens as this seller has. It might be worth paying a few more quid and getting a lens in better condition...

[Jimm]

ah thanks rpcrowe, didn't know you could look at completed sales like that on ebay. I've spent a month watching everything and then reviewing what they went for, same principal just long way round. Thanks

[krispix]

Hi James,
If it's of any use, I've bought loads of stuff on eBay. From cameras and lenses, to radios and car parts. I've never had a problem and eBay's protection scheme is there if you do.
If the lens on offer has a small scratch, it will as others have said, only make a difference depending on where it is and how deep. Also, the lighting on the subject.
However, from your description it sounds as if it's pretty small. You also say it's heavily discounted. On that basis I would go for it. You'll probably have to discount it yourself if you ever want to get rid of it, but so be it.

[rpcrowe]

ah thanks rpcrowe, didn't know you could look at completed sales like that on ebay. I've spent a month watching everything and then reviewing what they went for, same principal just long way round. Thanks

ADVANCED SEARCH ON EBAY

1. Navigate to the group in which your item should be found - in this case camera lenses.

2. Click on the word "advanced" to the right of the blue "SEARCH" button.

3. This opens the Advanced Search parameters section.

4. Enter the description of the item in the "KEYWORDS OR ITEM NUMBER" box. I entered "28-135mm f/3.5-5.6 IS".

5. Use the drop down menu to the right of that box to select how the search parameters should be applied. In this case, I selected "Exact words, exact order".

6. Drop down to the "SEARCH INCLUDING" section and check the "Completed listings" box.

7. Now the search selection will provide the results of the completed listings. You can further narrow the seach by selecting several additional parameters such as dates of the auctions, etc. I usually don't bother with that.

NOTE: This appears to be valid for both ebay USA and eBay UK auctions...

[Colin Southern]

Just food for thought:

http://www.lensrentals.com/blog/2008...ment-scratches

Excellent example.

I think it makes a mockery of the so-called "image degradation caused by putting filters in front of lenses" (*high-contrast scenes excluded of course).

[Gingerbaker]

Excellent example.

I think it makes a mockery of the so-called "image degradation caused by putting filters in front of lenses" (*high-contrast scenes excluded of course).

That's not what it tested, though, is it?

[Colin Southern]

That's not what it tested, though, is it?

They weren't really testing anything anyway - just demonstrating how little effect things around the front element of a lens have on an image. If one wanted actual filter -v- non-filter side-by-side tests then one can easily find a zillion of them on the net (all of which I might add - with the noted exception of extreme contrast scenes - demonstrate that visibly they make no difference what-so-ever).

[Gingerbaker]

They weren't really testing anything anyway - just demonstrating how little effect things around the front element of a lens have on an image. If one wanted actual filter -v- non-filter side-by-side tests then one can easily find a zillion of them on the net (all of which I might add - with the noted exception of extreme contrast scenes - demonstrate that visibly they make no difference what-so-ever).

My point was that your conclusion that "it makes a mockery of the so-called "image degradation caused by putting filters in front of lenses" was unjustified. That still stands.

And I have seen demonstrations around the web that, contrary to your assertion that "all of which I might add - with the noted exception of extreme contrast scenes - demonstrate that visibly they make no difference what-so-ever" do, in fact have demonstrated notable lack of contrast. Additionally, what exactly is a "high-contrast" scene, and when do you think the average photographer might recognize it and actually remove his UV filter?

Because virtually all urban night photography is high-contrast, and ghosting and flare is easily seen with certain camera-filter combinations if there is any artificial lighting present whether indoors or out. And many daylight situations, including virtually any shots near the axis of the sun would be considered high-contrast, are they not? Seems to me that a lot, if not the lion's share, of photographic opportunities might well be considered to be "high-contrast. When, if ever, do you remove your UV filter, Colin?

Here is a most interesting thread from dpreview, which, among many other interesting points, has a quote from Canon arguing against using a flat filter (on a supertelephoto) because of flaring; has an example of simple test demonstrating a loss of contrast (and increased flaring) caused by a UV filter in an indoor shot; contains good information on the lack of need for any UV filtering additional to that incorporated in sophisticated multi-coatings used today; and bounces around most of the issues in a good conversation about the topic.

Here, Michael Johnston of the Online Photographer argues against their use, and here, Thomas Hogan does as well.

Demonstrations of UV filters causing multiple flaring in urban night photography here and a comparison of no filter, cheap filter, and expensive multi-coated UV filter here.

[inkista]

Excellent example.

I think it makes a mockery of the so-called "image degradation caused by putting filters in front of lenses" (*high-contrast scenes excluded of course).

No, no, no. THIS is the lensrentals blog entry that does that.

I'm tellin' ya. It's really really worthwhile to read Roger Cicala's lensrentals blog entries, particularly the ones on lenses and optics. (Although even the ones where they're just being silly are fun, too.)

[Colin Southern]

My point was that your conclusion that "it makes a mockery of the so-called "image degradation caused by putting filters in front of lenses" was unjustified. That still stands.

Well I disagree. I'm referring to the zillion times I hear people say "I don't use a UV filter for protection because I don't want to degrade the quality of my images" and in a similar vein "becuae it's an extra piece of glass it MUST degrade image quality" whereas in real-world shooting (with exceptions as noted) visually, it doesn't make any difference.

And I have seen demonstrations around the web that, contrary to your assertion that "all of which I might add - with the noted exception of extreme contrast scenes - demonstrate that visibly they make no difference what-so-ever" do, in fact have demonstrated notable lack of contrast.

I suspect that most are by people who have already made up their mind and are going out of their way to CREATE unusual conditions to prove their "point".

Additionally, what exactly is a "high-contrast" scene, and when do you think the average photographer might recognize it and actually remove his UV filter?

In the context of the "debate", scenes of relatively low light levels but with relatively bright point light sources.

Because virtually all urban night photography is high-contrast, and ghosting and flare is easily seen with certain camera-filter combinations if there is any artificial lighting present whether indoors or out.

Of course -- and for those situations, removing a UV filter would be the sensible and obvious thing to do.

And many daylight situations, including virtually any shots near the axis of the sun would be considered high-contrast, are they not? Seems to me that a lot, if not the lion's share, of photographic opportunities might well be considered to be "high-contrast.

It's going to depend on how close it is to having naked sun in the shot. If the sun IS in the shot then you'll get ghosting with or without a filter. I would however strongly dispute that - combined - "urban night photography" and "shots with the sun in them" represent "the lions share of photographic opportunities"; in fact - if you looked at every photo taken in the past year, I doubt that very many at all would fall into this classification.

When, if ever, do you remove your UV filter, Colin?

Quite often when shooting landscape, for 2 reasons (1) as previously stated (I usually shoot landscape into the light), but (2) (the main reason) Is that I'm usually using ND and GND filters, and any additional hardware creates mounting and vignetting issues.

Here is a most interesting thread from dpreview, which, among many other interesting points, has a quote from Canon arguing against using a flat filter (on a supertelephoto) because of flaring;

I think I missed it amongst all of the usual dribble.

has an example of simple test demonstrating a loss of contrast (and increased flaring) caused by a UV filter in an indoor shot

It's another CLASSIC example of someone trying to bias the "test" in favour of their position. They obviously have a strong light source at the top of the frame trying to induce conditions where the shot with the filter will induce more flare. As per usual, they're just not real-world, every-day examples.

Here, Michael Johnston of the Online Photographer argues against their use

There are arguments used all over the web, and this is merely another one. In essence, what he's saying here is:

(1) "don't worry about damaging a front element because they're tough, and if you do damage it, don't worry because it probably won't affect the IQ"; Well I've damaged one that didn't have a filter on it at the time - admittedly it didn't affect IQ, but that's still not the way I like to think (I'd call that "stinkin thinkin). On the other hand, I've had two front elements saved by UV filters. I'd also like to bet that if you looked through my galleries you couldn't tell me with 100% confidence which images were shot without a UV filters and which images were degraded by a filter being fitted. Here's a photo of one of the filters - imagine how the front element may have looked without it being there (the front element of a NZD $3600 lens was unmarked). To my this is about as silly as saying "we don't need to wear seatbelts when driving because new cars are safer in an accident, and modern medicine is better at fixing you up". And, ...




(2) You can get flare and ghosting in high-contrast situations (Doh, we knew that already - AND - he'd probably have got the same ghosting without a filter anyway) (I've certainly seen that happen enough).

and here, Thomas Hogan does as well.

So what's Thom's position ...

The proposition: "to protect the front element of your lens from accidental scratching or breakage."

Thom's reply: "I suppose. Small scratches on the front element of most lenses don't actually have much effect on optical performance, though."

Well I'm sorry, but I've never bought into this mentality, and I never will. If they're willing to take a position that "damage to a lens is OK so long as it doesn't show in the images" then that's their privilage, but it's not an approach that I'm ever going to take.

In a second quote from Thom we have "But note what I implied earlier in this discussion: adding a filter to your lens degrades optical performance. A really well made filter won't degrade performance noticeably, but it will degrade." My point exactly: A good filter won't degrade an image - shot under normal conditions - in any way that is noticeable.

Demonstrations of UV filters causing multiple flaring in urban night photography here

Um, no - that's a demonstration of ghosting. Filters make them worse - you can still get them even without a filter - but either way it's a moot point because none of this has ever been disputed. It's a high-contrast scene for which one can only remove the filter and then "hope for the best" (that will probably still require fixing).

and a comparison of no filter, cheap filter, and expensive multi-coated UV filter here.

And yet again - sigh - another extreme contrast scene.

If those are the kinds of scenes that one shoots regularly then by all means never use a filter. I would suggest that those are NOT the kinds of scenes that the majority of photographers shoot on a daily basis.