>
> I had promised to take a good look at your tests when I got back home
> from my trip and had a better monitor and image viewing tools. But now
> that I'm back and have taken a closer look at some of the images and
> the
> test conditions I'm afraid I have to disavow my offer.
>
> The first thing I noted was very significant exposure differences
> between some of the images. I couldn't imagine how that could be
> unless
> some of the lenses weren't actually closed to the specified aperture.
> But then I noticed you were shooting in aperture priority mode. That's
> a decision I just don't understand when you supposedly have a fixed
> scene with fixed lighting. To me that demands a fixed, manually
> controlled exposure. I suppose it might be part of your criteria to
> see
> if a lens delivers proper exposure on your E-P1 in that mode but I
> don't
> consider it a test of the imaging capability of the lens.
Ok, I did want to see how the E-P1 handled exposure measurement for these
lenses, interesting that the exposure is not more uniform when it's coming
off the sensor rather than a separate metering system. The only lens where
the camera "knew" the actual aperture was the ZD 50/2 where I used an
Olympus MMF-2 adapter.
> The next problem was resizing for the web. I had assumed that all of
> the images would be available in full size or nearly so. I'm not at
> all
> comfortable that a 450x600 image (where each pixel is an average of 45
> of its neighbors) begins to tell the whole story. I suppose the small
> images are OK for a gross comparison but if two images appear similar
> then a larger and perhaps full size image might be required to break
> the
> tie.
I could upload the full res images if anyone's interested. I was mostly
interested in comparing how the lenses differed in rendition for web use
anyhow so didn't think it was worth the time and web space of uploading all
the images at full res.
>
> Finally, I had hoped to do side-by-side comparisons using comparison
> viewing software but, with only one image per page, loading the images
> to my own machine for comparison would be just too tedious.
I have no idea how you would want to deal with the images, I thought the
most obvious would be 2 browser windows (tabs) and switch between them.
>
> I thought you had a very interesting idea and liked the test rig. But
> I
> don't think I can reliably compare anything without a great deal of
> work
> and, given the image size and exposure problems, I'm not sure whether
> my
> judgments would be valid.
>
> Chuck Norcutt
>
>
> On 4/23/2011 9:09 AM, Wayne Harridge wrote:
> > A couple of weeks ago I assembled a stack of "normal" lenses,
> adapters and
> > an E-P1 to shoot a comparison to see how each lens rendered the scene
> I had
> > set up. The lenses ranged in focal length from 45mm to 58mm and
> included a
> > few zooms set at 50mm. This link:
> > http://lrh.structuregraphs.com/test/lens_02_f22.htm shows the setup
> which I
> > hoped would help to differentiate the rendering of the different
> lenses, in
> > particular bokeh. Note the elements which normally show up bad
> bokeh:
> > sticks, specular reflections (aluminium foil on a stick, candelabra
> against
> > the wall), striped wallpaper. I used a 500W photoflood for lighting,
> > tungsten WB on the E-P1, ISO 400, aperture priority mode. The images
> were
> > only resized to 450x600 for the web with no other post processing.
> Note
> > that the E-P1 doesn't maintain consistent exposure when the lens is
> stopped
> > down.
> >
> > The comparison page is here:
> >
> > http://lrh.structuregraphs.com/test/50mm_comparison.htm
> >
> > Any comments welcome, in particular I'd like to know which lens you
> think
> > has the best rendition of the subject.
> >
> > Also let me know if you find broken links or any other problems.
> >
> > ...Wayne
> >
> > Wayne Harridge
> > http://lrh.structuregraphs.com/
> >
> >
> --
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