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Re: [OM] (OM) Resolution question

Subject: Re: [OM] (OM) Resolution question
From: "Brian Swale" <bj@xxxxxxxxxxxxxxx>
Date: Wed, 27 Jul 2011 00:49:28 +1200
Piers wrote
> 
> Can't tell from your cropped image where the point of focus was, Brian.
> Don't know which part of the frame you have cropped, don't know what else
> was in the frame, very hard to draw any conclusions, but would opine that
> if (as I assume) you used AF, hard to see what the AF might have had as a
> target  given the subject matter.
> 
Chuck wrote:
> 
> I'm with Piers.  You haven't given use enough information to be able to
> evaluate the photo.  As he says, we don't have the full image in order to
> evaluate this piece in context.  One question in my mind is what was the
> focal length and shutter speed.  If I look at lower left I see a light
> colored rectangle.  I don't know what it is but its edges seem to be much
> sharper than the branches of the trees.  If the focal length is long
> enough and/or the shutter speed slow enough what we may be seeing is
> motion blur of the fine branches in the breeze.
> 
> Finally, evaluating a full pixel crop is a pretty tough test.  I 
> normally view and evaluate images on-screen at 25-30% of the resolution
> required for a given print size.  You describe the image as a "lossless"
> crop but it's certainly not lossless at the pixel level if what we have is
> a JPEG.  Also, we don't know how or if this image has been sharpened. 
>   Even a moderate amount of sharpening makes a big difference to this
> image.  If this image was a JPEG straight out of the camera then it has
> had sharpening applied according to the camera's settings.  If it was
> originally shot in raw and you haven't sharpened it then there is a flaw
> in your process.  Digital is not film.  *All* digital images require
> sharpening after image capture (including scanned film).  The camera will
> do it for you if a JPEG (using some not necessarily correct assumptions
> about the final size of the image).  But you are responsible for the
> sharpening if shot in raw mode.
> 
John Hermanson wrote
> 
> No, something definitely off there.
> 
Jim wrote
> 
> I use the original 14-54 on both the E-1 and E-510, and it can produce
> sharp images, though occasionally the AF does not use the portion of the
> image that I intended to be in focus.  To me, this appears to be a focus
> issue, but, as Chuck notes, it is hard to make a judgment from this small
> image.
> 
 Boris wrote:
> 
> My very first thought was " This looks like an unsharpened RAW image". 
> This is exactly how they come out of my A200 (but then, they sharpen
> pretty well).
> 
> I agree with Piers and Chuck:  One needs additional information in order
> to evaluate the image.

I have added to
http://www.brianswale.com/zuikoholics/July-2011/July-2011.htm

Immediately below the loss-less crop, I have included a 1400 px-wide 
resized jpg.

>From that you can see that there was essentially *no* wind - look at the 
waves (ripples) on the clear (unfrozen) water. Those golden willow branches 
wouldn't move in that light breeze, and the reeds alongside them weren't 
moving perceptibly either.

I was using *one* autofocus point - in the middle of the viewfinder. I pointed 
at the trees and after focus confirmation completed pressing the shutter. I 
may have recomposed after focus confirmation.

As you can see, the items of most interest as far as resolution go, are all 
about the same distance away; in this case about 400 metres/yards. Maybe 
a bit less.

According to FastStone Image Viewer, the parameters of the image are
Exposure 1/400 sec; no exposure bias. f/8, ISO 200. focal length 28mm

I have the camera set so that no extra processing that I might have under 
my control, is done. No sharpening, no extra saturation etc etc.  Just the 
basic image.

FastStone Image Viewer DOES have a loss-less crop facility for JPGs.. The 
author says that's what it is, and I have no reason to disbelieve him.

The image is somewhat lacking in contrast because the sun, when it finally 
showed its face, was somewhat behind me. There is practically no side-
illumination modelling effect.

I accept that digital images need sharpening to some degree or other. 
Usually this combination doesn't need much at all before the gains are 
cancelled by the losses.

In THIS case, and many others recently, the images straight from the 
camera are much less sharp than I have come to expect.

To what degree this is due to the fine nature of the subject matter in this 
case, I don't know. It's possibly biassing my opinion.

If anybody is desperate to see the full image, I can try and upload it. My host 
has a marvellous upload facility; when files get a bit large and Filezilla 
client 
just drops the connection, their software comes home with the bacon.

I did not shoot RAW. As you can see from the histogram and the image, 
there is no need to recover highlights etc, therefore no need for RAW. 
Under these conditions, if I have to make any small adjustment to saturation 
or sharpening, it will be done in no more than 2 steps, and any improvement 
that the use of RAW might offer will be quite imperceptible.

I don't have the most recent (ie last 4 years) iteration(s) of Photoshop, and 
do all my adjustments in FastStone Image Viewer which does all I see the 
need for.  Most of the time.  I don't have too much patience with some of the 
manipulation I see done. (not referring to Jim Nichols). It's out of my league 
anyway. Sometime maybe, but not in the foreseeable future; just too 
expensive, and I'm not interested in piracy these days.

Other images. I share my house with 3 other people, and the little 8 year old 
lady is one of them. We had snow a couple of days ago, and she thought 
that was marvellous. 2 shots. Then I have uploaded 4 of the 36 shots I took 
in sequence mode. She was having a ball :-)

Very often she doesn't want me to photograph her, or if she agrees she puts 
on such an act with multiple different poses and faces that I give up (she is a 
born actor, and she and her friends endlessly rehearse all kinds of acts 
including those designed to cause severe panic in caregivers..If I suspect 
her of doing this I rely on my intuition and call her bluff. Works very well. 
This time she forgot about all that crap. In case you are wondering about her 
ethnicity, she is about 50% Maori, 50% Northumberland, but looks more 
Maori than that..  She is going to be a big girl when she grows up. Two years 
ago I could lift her easily. Now, no way !!

Brian Swale. 
-- 
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