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- From nrothschild@nmctech.com Sun Jun 01 14:39:55 2003
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To: <colonial-coins@yahoogroups.com>
Subject: Digital Confusion
Date: Sun, 1 Jun 2003 17:27:33 -0400
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From: "Neil Rothschild" <nrothschild@nmctech.com>
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I wanted to address a couple of issues here because there may be some
confusion.
DIGITAL ZOOM
-----------------------
The digital zoom feature is simply cropping your photo. It does not add
information. It is really there for people that do not have software that
can crop a photo.
Shooting any image at, say, 3x optical and cropping a piece out is the
IDENTICAL image that a digital zoom at, say, 10x would do when zoomed into
the same image area. The camera is actually "upsizing" a portion of the
image, the same thing you could do with Photoshop by increasing the image
size. No new information is added but it does result in a smoother look.
But again, you can do the same thing with image processing software.
ZOOM Vs MACRO
------------------------
I use a Nikon Coolpix 900. I always use the macro setting for coins. I
have never shot using the zoom settings and have never seriously tried
zooming in on dates or other small areas of the coin.
If you are shooting a full frame coin image you do NOT want to be using the
zoom settings. You need to have a camera with a good macro capability and
use it. The quality of most zoom lens settings on digital cameras is
suspect and that is not what it is intended for. Zoom lenses are optimized
to shoot at long or infinity distance, not very short distances. That is
the difference between a zoom lens and a macro lens. Completely different
optical physics.
With 35mm SLR cameras, if you want to shoot tiny things you don't buy a zoom
lens you buy a macro lens.
IMAGE QUALITY VS MEGA PIXELS
-----------------------------
My Nikon Coolpix 990 is 2 mega pixel (1200x1600) and was state of the art
when I bought it. I have experimented with the club's Coolpix 990 and I
find that the additional pixels is somewhat wasted because the limits of
magnification are not the pixel count but a combination of lens quality,
platform stability (tripod) and a greater than desirable minimum aperture
setting.
Aperture is the "F Stop setting". Decreasing aperture (which increases the
F stop setting so don't get confused here) INCREASES depth of field, which
is the minimum and maximum distance in focus. When shooting a full frame
coin, the depth of field is probably less than a millimeter, which means
that you can't get the high points of the coin and the fields of the coin in
focus because they are too far away from each other!
So, adding pixels beyond some number is similar to digital zooming- you are
adding information and "magnifying" the image but not adding information.
APERTURE SETTINGS
------------------------------
My Coolpix 900 has, I think, a minimum aperture setting of about F/6. For
good macro work, you need to be shooting at F/16 and preferably F/22. When
I shopped digital cameras, there were none that offered F/16 or better
aperture settings. It probably has to do with the cheap lenses that are
used.
Even if such an aperture was available, it raises issues with exposure speed
(SLOW!) and lighting to speed up the exposure. Especially with field work
(shooting at shows and conventions).
CONCLUSIONS
-------------------------------
I have not shopped cameras since I bought the 900 but, in general, a fast
look at a digital camera's lens will tell you that that is not where the
money is. The money is in the electronics. Even a $1,000 (then) Collpix
900 has a cheap lens. A good macro lens is a $500 investment all by itself.
These digital cameras are, for the most part, built for consumers who are
not connoisseurs of things photographic. They are full on gadgets, loaded
with mega-pixels and more or less use junk lenses, which is the heart of the
camera. You may not consider yourself a "camera connoisseur" but when you
are trying to shoot a 1 inch coin full frame (or even key into specific tiny
areas) you are getting into a highly technical side of photography and you
are in "connoisseur-land".
So.... when looking for a camera, concentrate on lens quality and make sure
it has a good usable macro capability.
I think a 2 or 3 mega pixel camera with a really good macro lens would take
killer photos. Add more pixels and it will improve some more. At the time,
the Coolpix 900 was considered the best around for macro work, but it by no
means compares to a good Nikon SLR macro lens. Again, I am not up on the
current offerings but I suspect that the basic lens quality is no better
because prices are coming down but lens manufacturing costs are not.
This is an area where a group session at C4, with many different cameras
present, will prove or dis-prove the above. As much as the knowledge side,
getting a bunch of cameras together (and learning to sue them properly!)
will be very valuable.
One more thought... I have compared the output of my coolpix with the work
done by Angel and Bill Noyes. They are using 35mm SLR macro lenses, doing
everything that I just said can't be done with modern "cheap" digital
cameras. I believe that, when viewed on a computer screen, the output of a
modern digital camera can be as good as, or better than, the print output of
those SLR cameras. Which is an interesting inconsistency. I do believe
that digital is the way to go, hands down, but that would take a very long
post to fully explain.
I can say for sure that the coolpix resolution is better than the print
images I have seen and scanned. I think it has to do with the losses
involved in analog film processing- negative to print film.
Regards,
Neil
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