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This is really amazing...
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PostPosted: Sun Jun 27, 2010 9:24 am    Post subject: This is really amazing... Reply with quote
Please, have a look at this:


These pics show an old close-up filter that my dad has used before it fell down and cracked. I had it in a drawer until I coincidentally found it today.

I tested it on a Tessar lens. Now, you decide which pictures are taken with and which ones without the close-up lens:

A1:


A2:


B1:


B2:


I have seen several reports in the web that claim that a crack is hardly visible but each time you see it for yourself, it's amazing!


PostPosted: Sun Jun 27, 2010 11:25 am    Post subject: Reply with quote
I can not tell the difference, either. "Good" to hear this. Cool


PostPosted: Sun Jun 27, 2010 11:31 am    Post subject: Reply with quote
The 'certo6' web site, which now seems to have gone under, used to have a picture of a Planar lens with a huge gouge in it, I think made by a Dremel tool that went out of control, yet the photographs it took showed no sign of the damage. Lots of small fine blemishes affect image quality far more than one big one.


PostPosted: Sun Jun 27, 2010 11:33 am    Post subject: Reply with quote
alex wrote:
The 'certo6' web site, which now seems to have gone under, used to have a picture of a Planar lens with a huge gouge in it, I think made by a Dremel tool that went out of control, yet the photographs it took showed no sign of the damage. Lots of small fine blemishes affect image quality far more than one big one.


+1 only lot of small scratch (lot really) full covered haze or fungus impact picture quality.


PostPosted: Sun Jun 27, 2010 11:40 am    Post subject: Reply with quote
According to the bokeh, B1 is taken with the cracked lens.

Take a look at : http://www.lensrentals.com/news/2008.10.30/front-element-scratches


PostPosted: Sun Jun 27, 2010 2:16 pm    Post subject: Reply with quote
The lens problem will only show up if you shoot into sun with a small aperture setting at infinity


PostPosted: Sun Jun 27, 2010 2:27 pm    Post subject: Reply with quote
stingOM wrote:
The lens problem will only show up if you shoot into sun with a small aperture setting at infinity

+1
wide open sensor dust is invisible, close to F11 & check again


PostPosted: Sun Jun 27, 2010 4:36 pm    Post subject: Reply with quote
stingOM wrote:
The lens problem will only show up if you shoot into sun with a small aperture setting at infinity

The "B" situation was difficult and could have easily created flare!
The lens was shot at f4.

And even if such a crack is only visible from f11 on, this underlines what I wanted to show. How often do you shoot with f11 directly into the sun?

What I wanted to express is that we shouldn't be too paranoid about small scratches on the front lens!


PostPosted: Sun Jun 27, 2010 4:37 pm    Post subject: Reply with quote
CarbonR wrote:
According to the bokeh, B1 is taken with the cracked lens.

Take a look at : http://www.lensrentals.com/news/2008.10.30/front-element-scratches


Nope, B2 was shot with the cracked lens.


PostPosted: Sun Jun 27, 2010 4:40 pm    Post subject: Reply with quote
LucisPictor wrote:


What I wanted to express is that we shouldn't be too paranoid about small scratches on the front lens!


+1


PostPosted: Sun Jun 27, 2010 5:24 pm    Post subject: Reply with quote
stingOM wrote:
LucisPictor wrote:


What I wanted to express is that we shouldn't be too paranoid about small scratches on the front lens!


+1


That depends on the focal lenght.
A bastard tried to sell me a scratched Distagon 4/18 and I grant you, the scratch was visible even wide open.
On a tele lens, the same scratch might have been invisible (although scratches may decrease the contrast)


PostPosted: Mon Apr 11, 2011 5:18 pm    Post subject: Reply with quote
I know it's an old thread, but most interesting, and explains a lot about my badly battered example of a Sigma Superwide II, and how I get decent shots with it... Fungus, Scratches... it's got em. While it's certainly not as bad as the lens in the article, people freak when they see it in use.

Excuse the IQ, it's taken on Her Ladyships point 'n shoot.



PostPosted: Wed Apr 13, 2011 8:32 am    Post subject: Reply with quote
From the decreased contrast I'd say A1 & B2 are the cracked lens versions.
Neither is noticable without comparing side by side - clearly still highly usable. I must give my helios (came with a gouge) a try.


PostPosted: Mon May 23, 2011 9:30 am    Post subject: Re: This is really amazing! Reply with quote
maxfire02 wrote:
Hi Lucis Pictor!

Well you said that we should not care about small crackers and scratches on the front lenses, as the image quality depends on focal length.

but at what focal length these small crackers may hinder the image quality badly?

Question

Thanks


Hi. That is a justified question.

One seller once tried to explain to me that it wouldn't be a problem the wider the lens was because all the "bad" light would be dispersed, but I have different experiences. I think the wider a lens the more problematic a scratch is, because this dispersion can create flare.
The thing is that small scratches are hardly visible no matter which lens you use, unless you shoot directly in a "flaring" scenario. Wink


PostPosted: Mon May 23, 2011 10:36 am    Post subject: Reply with quote
Read some time ago in Amatuer Photographer that if you have deep scratches on the front element of a lens, fill that scratch with matt black paint. Supposed to be an okay thing to do


PostPosted: Mon May 23, 2011 3:19 pm    Post subject: Reply with quote
trev wrote:
Read some time ago in Amatuer Photographer that if you have deep scratches on the front element of a lens, fill that scratch with matt black paint. Supposed to be an okay thing to do


Yes, not a bad idea! This might reduce the internal (in the scratch) reflections.


PostPosted: Mon May 23, 2011 4:56 pm    Post subject: Reply with quote
Yes, it's a tried and true remedy.
And the longer the focal lenght, the more effective the remedy (just try to put one finger in front of a 135mm lens and focus on infinity... you'll notice barely any change)
Of course if you use a 20mm lens stopped down to f/11 or more, something nasty will show. Meaning that like any remedy, it can not work miracles...


PostPosted: Mon May 23, 2011 5:32 pm    Post subject: Reply with quote
Orio wrote:
stingOM wrote:
LucisPictor wrote:


What I wanted to express is that we shouldn't be too paranoid about small scratches on the front lens!


+1


That depends on the focal lenght.
A bastard tried to sell me a scratched Distagon 4/18 and I grant you, the scratch was visible even wide open.
On a tele lens, the same scratch might have been invisible (although scratches may decrease the contrast)


You are right, scratch marks on the front lens element does not really affect the IQ on short focusing distances. But for a WA lens, it is a different story.
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