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Author Topic: Sharpening up  (Read 1541 times)

Tony Hubcaps

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Sharpening up
« on: February 01, 2014, 07:32:39 PM »

Hi -

I have a shot I really like and I want to try and squeeze an exhibition quality A3 print
out of it if possible.  (By 'exhibition quality' what I mean is, in this particular case, it must
not have any areas which look clearly out of focus - they don't have to be the crispest
or sharpest but they do need to look acceptable).

The problem:- it was shot in very windy conditions with a Canon 24-105mm at 24mm.
The exposure was 200th at f11.  Overall it's fine - it's not the best onscreen, but I reckon
it will make a decent print.  Except at the edges.... in my experience this canon zoom
does work well at 35mm and longer, but at 24mm the edges tend to become slightly blurred.
I'm guessing really but I'm thinking that the windy conditions have exacerbated this a bit.

Anyway, I wondered if anybody has any suggestions for a PS trick or similar that might help the
blurred edges print a bit better.

Thanks
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David Eichler

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Re: Sharpening up
« Reply #1 on: February 01, 2014, 08:31:48 PM »

Hi -

I have a shot I really like and I want to try and squeeze an exhibition quality A3 print
out of it if possible.  (By 'exhibition quality' what I mean is, in this particular case, it must
not have any areas which look clearly out of focus - they don't have to be the crispest
or sharpest but they do need to look acceptable).

The problem:- it was shot in very windy conditions with a Canon 24-105mm at 24mm.
The exposure was 200th at f11.  Overall it's fine - it's not the best onscreen, but I reckon
it will make a decent print.  Except at the edges.... in my experience this canon zoom
does work well at 35mm and longer, but at 24mm the edges tend to become slightly blurred.
I'm guessing really but I'm thinking that the windy conditions have exacerbated this a bit.

Anyway, I wondered if anybody has any suggestions for a PS trick or similar that might help the
blurred edges print a bit better.

Thanks

You can't create resolution where none exists to begin with. You can sometimes create the illusion of greater sharpness with increased contrast or acutance (edge contrast).

As for the Canon 24-105 lens, you should be able to get reasonably sharp corners at the wide end at f:11 if the lens is in proper adjustment and you use it properly. Perhaps your lens is out of alignment. That said, this lens, and the original Canon 24-70 are known to have strong field curvature at the wide end, which can make getting sharp corners more difficult. You can overcome or minimize the effect in part by how you chose the point of focus.
« Last Edit: February 01, 2014, 10:22:50 PM by David Eichler »
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Tony Hubcaps

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Re: Sharpening up
« Reply #2 on: February 03, 2014, 07:03:25 AM »

You can't create resolution where none exists to begin with. You can sometimes create the illusion of greater sharpness with increased contrast or acutance (edge contrast).

That's the sort of thing I mean.  Where the corners are less than perfect I find the application of some heavy handed
sharpening can 'tighten things up' a bit, so that the poor image quality becomes less obvious.

I wondered if anybody had any PS tricks or similar, that did the same kind of thing only better.
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PhotoEcosse

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Re: Sharpening up
« Reply #3 on: February 03, 2014, 09:35:48 AM »

As you say it is only the edges that are blurry, ask yourself if you really need to print right to the edges?

It maybe that by cropping, say, 10% all the way round, you will end up with a better shot.
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Tony Hubcaps

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Re: Sharpening up
« Reply #4 on: February 04, 2014, 04:26:00 PM »

As you say it is only the edges that are blurry, ask yourself if you really need to print right to the edges?

It maybe that by cropping, say, 10% all the way round, you will end up with a better shot.

It's a good point but alas, it all needs to be in there.
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Christoph C. Feldhaim

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Re: Sharpening up
« Reply #5 on: February 04, 2014, 04:31:34 PM »

No way of selective, masked sharpening with some deconvolution and apply it only to the edges, maybe in a 50% opacity reduced layer or something?

Tony Hubcaps

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Re: Sharpening up
« Reply #6 on: February 04, 2014, 04:53:36 PM »

That's what I generally do at the moment.

Deconvolution??
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Christoph C. Feldhaim

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Re: Sharpening up
« Reply #7 on: February 04, 2014, 05:04:16 PM »

That's what I generally do at the moment.

Deconvolution??

We have a large thread about it here:
http://www.luminous-landscape.com/forum/index.php?topic=45038.0

LR does deconvolution sharpening when you pull up the detail slider,
PS does it in "Smart Sharpen" when you chose Lens Blur and click the "more accurate" checkbox.

Wikipedia tells this:
http://en.wikipedia.org/wiki/Deconvolution

There's a bunch of sharpening tools implementing deconvolution sharpening, many from astrophotography sites.

I personally use Topaz InFocus as PS plugin, which has a nice deconvolution
sharpener which allows to sort of guess the point spread function.

Cheers
~Chris

Tony Hubcaps

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Re: Sharpening up
« Reply #8 on: February 04, 2014, 10:30:59 PM »

Brilliant

I'll read the thread
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Schewe

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Re: Sharpening up
« Reply #9 on: February 05, 2014, 01:20:14 AM »

BI'll read the thread

Not for nothing, this may give you some basic understanding..."Out of Gamut: Thoughts on a Sharpening Workflow".
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