I am thinking of getting a nikon coolscan IV ED second hand, obviously
I won't know how much it has been used, can the led be replaced,or does
it last forever.
The LED in the Nikon scanners don't require regular replacement and
should last as long as any other part of the scanner, so you should not
need to worry about this.
Or is it better me getting a new Coolscan V ED?
The Coolscan IV is 2900ppi, but the Coolscan V has a higher resolution
at 4000ppi. Whether that is important to you depends on your
requirements - and how much the owner of the original CS-IV is asking
for it. ;-)
I have read alot about other scanners having florescent difffuse lamp
which lasts according to minolta website 8,000 hrs, so I stay clear of
2nd hand minolta or other brands that use the florescent deffuse lamp.
Possibly a little harsh, 8000hrs is about a year of 24/7 use. Unless
the original owner was an industrial facility that used the scanner
continuously on a shift basis, I doubt it would be much into its rated
life. The lamps are fragile too - but so are many other parts of a
scanner, you are always taking a risk buying used, but I don't think the
risk on the lamp is significantly greater than on any other part of
these precision optical instruments.
regardless of dust, which i know is a sighn of retirement, what else
should I beware of nikon LED scanners?
Well dust isn't actually a retirement issue - the scanners can generally
be cleaned. However you should be aware that dust doesn't show up as
defects on the image, but as a halo around bright areas in slides. A
good test for it is to take some unexposed developed slide film (ie.
deep black film) and mount it in the FH-3 film holder so that the
perforations are in the frame. Scan that and look at the scanned image
of the perforations, which should be bright white. If any of the white
smears into the black, just like a soft focus effect, then you probably
have some dust or fog on the optics - most likely the mirrors.
You can either have the unit serviced by Nikon, and pay them a small
fortune to do so, or have a go yourself if you feel confident
dismantling the unit and cleaning optics. There are a couple of web
sites that show how to do this - but be prepared to strip the scanner
right down to get access to the optics.
To prevent this becoming an annual activity spend a small amount of the
change from your purchase on a close fitting dust cover and fit it
religiously when the scanner is not in use.
Another thing you should be aware of are the limitations of ICE: the
feature of the Nikon (and some other) film scanners to automatically
detect and conceal dirt and scratches on film. The Nikons tend to
exaggerate defects like this more than some other scanners, because they
use a semi-collimated light source, so ICE is a big help. ICE works
best on films which used the C-41 and E-6 processes. It can work on
Kodachrome depending on the film and process batch and the density of
the image, but it often has problems. It never works on conventional
black and white film.
All of this is because the process uses a fourth LED emitting infrared
light, around 850nm wavelength. The dyes used on colour film are
transparent to this wavelength, so the image produced in the infrared is
mainly just the dirt and surface defects on the film. However, silver
oxide, the black material in normal black and white film, is not
transparent in the infrared, so the ICE process cannot tell the
difference between real image information and defects. Consequently the
ICE algorithm goes wrong in some strange ways.
The silver content of the original emulsion is bleached out of most
colour film, hence it is not a problem. Kodachrome is different in that
the process can leave a considerable amount of silver oxide in the
developed emulsion, particularly in the dense image areas, so it is a
bit of a hit and miss. If you get problems with Kodachrome turn ICE off
completely - and always do that when scanning conventional black and
white film. (Chromogenic black and white film, which is C-41
compatible, is OK.)
Finally, always use the Kodachrome setting in the software when scanning
Kodachrome film. This can help with the ICE problem, but the main
reason is that the spectral characteristics of the Kodachrome emulsions
are different to those of E-6 process films. Since the LEDs in the
scanner are very narrow wavelengths, the scanner only samples the dye
density at these wavelengths - so different spectral characteristics of
the film dye will produce a different colour balance to what you see
visually by eye (or what other scanners using broad band filters on a
white light will see). This is a type of metamerism, the same effect
that causes certain colours to appear different under different lights.
For example, a repaired car panel can appear to be a perfect colour
match to the original panels under daylight, but be completely different
from them under streetlamps at night. Useful advice for buying used
cars too! ;-)
