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Author Topic: Soft Images  (Read 3847 times)

Etienne Cassar

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Soft Images
« on: June 03, 2007, 12:10:27 pm »

I have two canon lenses, an EF 28-80mm 1:3.5-5.6 III USM which is 12yrs old, and an EF 75-300mm 1:4-5.6 III USM which is 8yrs old. I was having a lot of problems lately trying to get sharp images. All of them are coming out really soft. Not only that but I am also getting a lot of colour fringing around the outlines. Something is absolutely wrong with these lenses.
I decided to grab the 28-80mm and look from the rear element onto a piece of black surface while working on the zoom and focusing rings. Suddenly I noticed that the lens is completely dirty, and wiping the front element didn't remove the dirt. Any ideas of what could have happened to these lenses and how to resolve the problem?Mark as helpful
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DarkPenguin

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Soft Images
« Reply #1 on: June 03, 2007, 02:42:11 pm »

So what changed?  Lenses usually don't change in tandem.  That would seem (to me anyways) indicate an issue with the body.  Did you just get these lenses?  Switch to digital?  Change from jpeg to raw?  Change from RSP to ACR?  Etc.

As an aside, the 75-300 is soft and very prone to CA.  So if you are stepping outside its performance window (that window being something like 75-200 and, guessing, probably f8-f11) you're going to get iffy results.
« Last Edit: June 03, 2007, 02:43:16 pm by DarkPenguin »
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francois

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« Reply #2 on: June 03, 2007, 02:53:23 pm »

You can try to focus manually and see if your photos are soft or not. Depending on where you live and/or store your lenses, fungus may have ruined your lenses.

I would tend to agree with DarkPenguin, if both lenses became problematic it usually indicates a body problem.
« Last Edit: June 03, 2007, 02:55:15 pm by francois »
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Francois

Etienne Cassar

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« Reply #3 on: June 03, 2007, 06:10:35 pm »

I don't think it is the body.  The front element of both lenses looks smudged, and it doesn't get clean no matter how hard I try polish it with lens paper.  I am afraid that it is in fact a lens fungus, but I am not sure.  I should be getting a new lens, the EF 24-105mm F4 IS this week, and so will be able to tell if the problem is the body if I get soft images with this as well.
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francois

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Soft Images
« Reply #4 on: June 04, 2007, 03:23:25 am »

Quote
I don't think it is the body.  The front element of both lenses looks smudged, and it doesn't get clean no matter how hard I try polish it with lens paper.  I am afraid that it is in fact a lens fungus, but I am not sure.  I should be getting a new lens, the EF 24-105mm F4 IS this week, and so will be able to tell if the problem is the body if I get soft images with this as well.
[a href=\"index.php?act=findpost&pid=120946\"][{POST_SNAPBACK}][/a]
The issue might be on both sides of the front element and/or even on other elements. Try with your new 24-105 and keep us posted.

Good luck!
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Francois

Etienne Cassar

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« Reply #5 on: June 07, 2007, 04:23:37 am »

[attachment=2601:attachment]Finally I got my new EF24-105mm F4L IS lens.  Marvellous piece of equipment I must say.  Much better results.  However I think that my camera is front focusing a little bit.  Took a couple of pics of my cat, taking care to focus on the eyes.  The result is perfectly sharp eyes and nose, but I am not quite sure about the ears.  Can you comment please.  Thanks
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Andy M

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Soft Images
« Reply #6 on: June 07, 2007, 04:54:57 am »

Take any filters off the lenses and shoot again.
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Etienne Cassar

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« Reply #7 on: June 07, 2007, 10:32:10 am »

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Take any filters off the lenses and shoot again.
[a href=\"index.php?act=findpost&pid=121557\"][{POST_SNAPBACK}][/a]
There are no filters on the lens
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Digiteyesed

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« Reply #8 on: June 07, 2007, 10:41:53 am »

Quote
As an aside, the 75-300 is soft and very prone to CA.  So if you are stepping outside its performance window (that window being something like 75-200 and, guessing, probably f8-f11) you're going to get iffy results.
[a href=\"index.php?act=findpost&pid=120927\"][{POST_SNAPBACK}][/a]

Agreed. I've got the same lens and I use it strictly for macro work with extension tubes these days (a combination that produces surprisingly excellent results). My experience is that the lens works best around f8 and below 180mm. The CA is an absolute disaster when you go above that. I dropped $1850 on the 100-400 EF L when I realized how much the wasted time colouring out the CA in Photoshop was costing me.
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DarkPenguin

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Soft Images
« Reply #9 on: June 07, 2007, 11:08:24 am »

Quote
[attachment=2601:attachment]Finally I got my new EF24-105mm F4L IS lens.  Marvellous piece of equipment I must say.  Much better results.  However I think that my camera is front focusing a little bit.  Took a couple of pics of my cat, taking care to focus on the eyes.  The result is perfectly sharp eyes and nose, but I am not quite sure about the ears.  Can you comment please.  Thanks
[a href=\"index.php?act=findpost&pid=121548\"][{POST_SNAPBACK}][/a]

If the eyes are sharp canon will call it good.  The AF makes sure that the point of focus is sharp not that the camera is focused directly on that spot.  In other words they know they have some DOF to play with and they do.  (At least with the consumer cameras.  I assume the 1 line has tighter tolerances.)
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