Re: Nikon D200 (for alt)

Pam,

I don't think you can really generalise sensibly on CMOS vs CCD,
although too many have done so. Fringing is certainly not limited to
CCD, and I think may depend more on other aspects of the design,
although I think all sensors suffer to some extent. Purple fringing
isn't a great problem on any of the DSLRs I've used, only noticeable in
a small percentage of images with ultrawide lenses, and can usually be
greatly reduced if not eliminated by software. I can find images that
show it in my collection, but I can't think of one print I've made that
shows it. Similar pictures on film would show various defects as well of
course, including a similar amount chromatic aberration, but also other
defects such as halation. Not to mention grain. If film was the new
technology we would all be getting worked up about that and how it
destroyed image integrity.

The good news is that cameras such as the Nikon D200 and Canon 5D give
us rather better than normal 35mm quality for what even a few years ago
would have seemed a ridiculously low price. The D70 which I used for a
year or so was a good 35mm replacement and cameras of this quality are
now very cheap (mine cost me around $750 almost 18 months ago.) The D200
is really a very nice camera to use, the first digital I've felt this
about; a decent viewfinder, every control you need to hand, great
autofocus and no noticeable shutter lag. I don't expect to be shooting
any normal 35mm film now, there is just no point. My Mamiya 7 still has
an edge, though I think that's more to do with the lens than the fact it
is using film, but I wouldn't bother with 645 any more. I'm assured the
5D is less noisy at high ISO, but the D200 certainly beats film by a
large margin in that area too. I'm still shooting 6x12 too.

Regards,

Peter

Peter Marshall
petermarshall@cix.co.uk
_________________________________________________________________
My London Diary http://mylondondiary.co.uk/
London's Industrial Heritage: http://petermarshallphotos.co.uk/
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and elsewhere......

Pam Niedermayer wrote:

> Well, then, the chip makers need to be more careful and/or more
> sophisticated. If there is that electronic bleed in all chips, such as
> CPU's, the governors that turn a bit on and off take care of it
> (seldom does the amount of electricity passing through a gate
> correspond precisely to on/off). Based on what I saw of CMOS photos a
> few years ago, that didn't seem to have the fringing, I assumed the
> problem was with CCD's. This could, of course, be a fawlty [sic]
> assumption. I probably know just enough to be dangerous.
>
> So, I guess digital will remain a 35mm/snapshot replacement for me for
> the foreseeable future.
>
> Thanks,
> Pam
>
> Tom Ferguson wrote:
>
>> ...
>>
>> "Bleed" is what I "think" Pam was worried about. Unfortunately,
>> separating the three color channels won't fix the problem. When you
>> photograph a junction of very bright and very dark (backlit branches)
>> in digital you often get a "fringe" distortion in a green/cyan/purple
>> color. What usually causes this is that pixel set #1 (RGBG) gets the
>> backlit sky (very strong light) and pixels set #2 gets the edge of
>> the branch (very weak light). Some of the electrical charge generated
>> by pixel set #1 "bleeds/leaks" into the adjacent pixel set #2. This
>> causes the fringing.
>>
>> In general, larger sensors have less of this problem. The little
>> pocket sized digital cameras use a chip about 1/8 inch, bad bleeding.
>> The DSLRs use a chip about 1 inch, much less bleeding, the really $$$
>> medium format chips (closer to 2 inches) are even better. I haven't
>> seen any great difference in the current DSLRs, even between the APS
>> and full sized versions :-(
>>
>> Some folks claim this purple fringe is a lens issue. To a small
>> extent I agree. Wide angel lenses with small exit pupils and any
>> truly poor lenses with astigmatism (or is it chroma??) will, on a
>> digital, often give a similar looking error. In my experience, the
>> sensor bleed issue is the far bigger problem.
>>
>> ...
>
>
>
Received on Tue Feb 7 16:04:20 2006