Digital BW, The Print

John,

> Was the image shot in RAW format? 

Yes.

> The AA filter in the XT should not allow those types of defects.

One tester of the XT noted that the Anti-Aliasing (AA) filter of the XT
appeared to be weaker than what was used on the 20D.  The reviewer commented
that the result was slightly higher sharpness but a bit of a problem with
some line patterns on, for example, shirts. 

I think extreme flare and color fringing caused the "double edge" of the
tree-sky boundary.  And the stair-stepping only showed up as a clear digital
artifact on the one little branch at about a 30 degree angle to the left of
the windmill.  These conditions won't show up much in most images.


> I just got back a 9600 color print on HPR at the insane size of 30 x 45
> inches.  It was shot with L glass on my Rebel XT, and I'm quite pleased
> with it.  Where hung, you can't get closer than 6 feet to it, so it looks
> excellent.  I also have a 1Ds, so I do have something to compare it to.  I
> experimented quite a bit with the res-up and sharpening before getting the
> results I settled on.

Overall, I'd say the image I worked up would have benefited from more pixels
and, obviously, more latitude.  However, while the image quality is not up
to my medium format Tech Pan, I'm quite satisfied with the results.  I see
the camera not as a replacement for the MF TP, but as a replacement for the
Fuji Zi 645 and Tmax 100 or T400CN that I use in it when I'm having to do
fast shooting.  While the Tmax 100 would have been sharper, I don't think it
would have been able to render the creamy-smooth high tones of the fog and
windmill in the fog.  The grainlessness (low noise) of the Canon really
shows and is very much appreciated.  Also, combining bracketed images with
the digital camera was far easier than with a film camera.  Even when I keep
the film shots together (un-cut) for scanning, the alignment shifts as I go
from one area of an image to another.  With the digital frames, each one is
exactly the same (except for wind movement of leaves, etc.).

So far, so good -- not perfect, but good.

Paul
www.PaulRoark.com 
_______________


> 
> -----Original Message-----
> From: DigitalBlackandWhiteThePrint@yahoogroups.com
> [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Paul
> Roark
> Sent: Saturday, July 02, 2005 1:04 PM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Artifacts with Digital images
> 
> 
> In working the Windmill image (see my web page below) up to 16 x 20, I
> found
> 2 defects in the 8 mp Canon XT/350D image.  First, there was what looked
> almost like a double edge at the boundary between the dark tree trunks and
> the bright, foggy sky.  I think it was caused by flare and the different
> responses of the RGB sensors.  Second, there was visible stair-stepping in
> some of the twigs that stick into the sky.  These seem to have resulted
> simply from the lack of enough pixels.  I seem to be able to have cured
> both
> problems.
> 
> For the edge between the dark tree and bright sky, using a singe color
> channel from the shot that was 2 stops under exposed resulted in a very
> good
> edge.
> 
> For the stair-stepped twigs, increasing resolution (image pixel size) 250%
> in Genuine Fractals took care of them.  It did a significantly better job
> of
> this than did the Photoshop image size algorithm.
> 
> Paul
> www.PaulRoark.com
>