Just one question. Why would you drop down to pixel viewing (100%) to
evaluate the images? Ever since reading Bruce Frasier's book on
sharpening I've used 33% to evaluate sharpening for print or, for that
matter, how any image is likely to look in print. Frasier's rationale
was that evaluating the look of a print on a monitor needed to account
for the difference in resolution between print and screen. If your
monitor has 100 pixels/inch and you're going to print at 300 dpi viewing
the image at 100/300 or 33% will give you the best impression of what
the print will look like. When used for sharpening his method is to
sharpen what you see on screen until it looks just slightly "crunchy".
The reason is that printing on paper will have a slight softening effect.
So, if a final print or even on-screen image view will never be anywhere
near 100% why would you evaluate the image at that level?
Chuck Norcutt
On 3/26/2012 8:45 PM, Ken Norton wrote:
> I've almost decided that I've bitten off something larger than I can
> chew. Here's what I did:
>
> I wanted to do a bokeh comparison test of several lenses. On the E-1.
> I do consider the crop-sensor format a viable point of reference
> because most poeple are now using the OM Zuikos on Four-Thirds and
> Micro Four-Thrids cameras. So, I take the camea, mount it on a tripod
> and photograph what I think is a flowering pear tree in a strong wind.
>
> Yeah, the wind, but for bokeh testing, that's really not an issue.
>
> I shot the 50mm lenses at 1.5m from the tree and included a sidewalk,
> bench and another tree in the background. For the 100mm lenses, I
> backed off to 3m. The 200mm to 6m and the 300mm at 9m. Oh, and the
> 24mm was in there someplace too, but you get the idea.
>
> Then I repeated the test with the 50mm and 100mm lenses at 1m distance
> to the flowers themselves, making sure I had flowers in front of and
> behind the point of focus.
>
> So, I've been comparing the images of matching apertures...
>
> Where are the stinking differences? If I showed the images full-frame
> at 800 pixels width, you are really hard pressed to tell the
> difference between the 50/1.8 and 50/1.4, or the 100/2.8 and 100/2.0.
> In a full-frame presentation you really have to nitpick to see the
> differences and even when you do see the differences you are hard
> pressed to say that a picture is from one or the other. However, when
> you drop down to pixel viewing, the differences to become visible. In
> fact, much more than just visible!
>
> I'm looking for suggestions here. BTW, the differences are so
> significant that I just made a management decision regarding lens
> selection for my primary kit this spring.
>
> AG
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