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Another scratched lens test
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PostPosted: Mon Mar 28, 2011 4:38 pm    Post subject: Another scratched lens test Reply with quote

I have this badly scratched Industar-61 LD:




It was replaced with another with minor scratches. Here I present images taken with both shot @f4


1. Scratched @ minimum focus distance




2. Unscratched @ minimum focus distance




3. Scratched




4. Unscratched





5. Centre crop, scratched on left




Surprisingly little difference.


PostPosted: Mon Mar 28, 2011 5:19 pm    Post subject: Reply with quote

Nice test, this proves that front element scratches doesn't affect image quality very much. I think a test with a scratched rear element would have been much worse?!? Surprised


PostPosted: Mon Mar 28, 2011 5:32 pm    Post subject: Reply with quote

Well in theory a scratched lens must make a difference Wink


PostPosted: Mon Mar 28, 2011 5:38 pm    Post subject: Reply with quote

Excalibur wrote:
Well in theory a scratched lens must make a difference Wink

+1 Smile Thank you for sharing this nice evidence!


PostPosted: Mon Mar 28, 2011 6:28 pm    Post subject: Reply with quote

Interesting results! I'd be keen to see some comparative shots at, say, f8 though. That's when we should see some change, if there is a difference Smile


PostPosted: Mon Mar 28, 2011 7:14 pm    Post subject: Reply with quote

To my eyes there is no difference.

I suppose if it's a good lens and scratched then it's still a good lens.

What would the scratches do apart from cause a slight loss of contrast?

I suppose with modern digital PP little flaws are not so much of a problem as in the past.

My Pentacon 1.8 has what looks like chips missing out of the coating but you can't see anything in the images it takes:



PostPosted: Mon Mar 28, 2011 8:07 pm    Post subject: Reply with quote

Nordentro wrote:
I think a test with a scratched rear element would have been much worse?!? Surprised

Ooooh yes, much worse.

Front element scratches are really only a problem with wide lenses, especially ultra-wides. Rear element scratches however, do not discriminate. They WILL noticeably affect your image in some way; it doesn't matter if the lens is an ultra-wide or a telephoto.


PostPosted: Mon Apr 18, 2011 9:54 pm    Post subject: Reply with quote

What would you classify as an ultra wide lens? What focal length, to see the effect?


PostPosted: Mon Apr 18, 2011 10:16 pm    Post subject: Reply with quote

I don't currently have any scratched lenses to test, but I know that a couple of my lenses are sensitive to front element dust. Slight to moderate amounts of front element dust don't seem to have any noticeable effect on sharpness, but I do notice an issue with flare. My most dust sensitive lens seems to be my Nikkor 25-50/4 Ais. When it's perfectly clean, it has minimal flare--not quite as good as my 28/2 Ai, but quite usable. A little dust, and flare increases rapidly enough to become a problem.

I would guess that damaged front glass probably would increase flare significantly.


PostPosted: Mon Apr 18, 2011 10:43 pm    Post subject: Reply with quote

I suppose the flare is worse in front of brightly lit subjects? When is the flare the worst?


PostPosted: Mon Apr 18, 2011 11:22 pm    Post subject: Reply with quote

The absolute true doesn´t exist for me.

In some situation (front light o very clear background) the front scratches can be a bad thing. The same with the front element with abundance of clean marks (not affect only the coated) like the dispersion filter for portraits.

Rino.


PostPosted: Mon Apr 18, 2011 11:28 pm    Post subject: Reply with quote

estudleon wrote:
The absolute true doesn´t exist for me.

In some situation (front light o very clear background) the front scratches can be a bad thing. The same with the front element with abundance of clean marks (not affect only the coated) like the dispersion filter for portraits.

Rino.


It is an interesting situation, for an artist, that is. I suppose the scratches could be taken advantage of in some scenarios. You never know what you are going to get.


PostPosted: Mon Apr 18, 2011 11:35 pm    Post subject: Reply with quote

There aren't my prefer situations. I like to win at random.

A lot of notes in each pic, where were the subject to measure the light, or to do the focus at, ets.

All cientificaly taken. The same situation, the same aperture, shutter and focus at, very similar pics.

Rino


PostPosted: Mon Apr 18, 2011 11:50 pm    Post subject: Reply with quote

I just got a super scratched lens. It is the worst I have ever seen anywhere. It is worse than anything bad that I own, no matter how careless or beat up they are. It is like someone took a razor blade and cut into the glass. It is an awfully deep set of scratches. I have a real problem with it because the seller was dishonest and said they were cleaning marks and secondly because of the amount I paid or he charged. I have a real big problem with that. Cleaning marks are superficial; these are genuine flat out scratches and knicks. The worst thing is that he is a camera seller so he absolutely knew what he was selling and was lying about it!

Take the scuff marks that Revers had posted above and deepen it by about ten to twenty times! The guy even showed a pic of his lens but deliberately hid these capital S scratches! On top of that, he lied about it when asked!


PostPosted: Tue Apr 19, 2011 5:28 am    Post subject: Reply with quote

newton wrote:
I just got a super scratched lens. It is the worst I have ever seen anywhere. It is worse than anything bad that I own, no matter how careless or beat up they are. It is like someone took a razor blade and cut into the glass. It is an awfully deep set of scratches. I have a real problem with it because the seller was dishonest and said they were cleaning marks and secondly because of the amount I paid or he charged. I have a real big problem with that. Cleaning marks are superficial; these are genuine flat out scratches and knicks. The worst thing is that he is a camera seller so he absolutely knew what he was selling and was lying about it!

Take the scuff marks that Revers had posted above and deepen it by about ten to twenty times! The guy even showed a pic of his lens but deliberately hid these capital S scratches! On top of that, he lied about it when asked!


Try to contact the seller and solve the problem. If the seller wont apply or dont cooperate, put him on the bad seller thread on mflenses and open a ebay case (if bought there) Wink


PostPosted: Tue Apr 19, 2011 8:09 pm    Post subject: Reply with quote

Interesting that the only difference is a bit of shadow detail loss. Look at the branch shadows on the park bench in the split screen, for instance.

I'm curious about the unscratched lens you used for comparison. It seem that many of the differences could come from a slightly better lens (Vivtar or similar versus Quantaray, for instance.)

+1 on being surprised there's no meaningful difference.