Sir F. A. Rien:
The histogram doe snot show all the information.
It ‘disappears’ at about 5-10% of the levels. I
simply look at the image.
Such is the graphical histogram, but you will not
find any pixel with a value of 255 in any channel.
There are mounts made for scanning that include
the full frame and part of the biorder. In Weiss,
IIRC, they’re "K". I prefer to scan the chp unmounted.
I have a Nikon Coolscan IV film scanner (and am
dreaming of Coolscan 5000) which has two adapters:
ยท An adapter for un-mounted 6-frame film strips.
It work most of the time, but if the film is
badly curled (either laterally or longitudi-
ally) it does not allow for sharp scans because
it can’t hold such film sufficiently flat. And
both ends of the strip are especially difficult
to get flat (and therefore sharp).
For important frames, I usually forcus at sev-
eral points on the film and then manually set
the focus to a value in-between the maximum and
minimum of the measures.
Even for the 2900 dpi resolution the effects of
little focus deviation (present even on seem-
ingly flat film) are apparent. The scanner’s
lens seems to have a narrow depth of field.
ยท An adapter for mounted 6-frame film strips. The
mounting itself is a "frame" that helps to hold film flat by clamping the strip along the edges
and along the inter-frame spaces. Being so fee-
ble as to yield somewhat to strongly curled
film’s desire to spring back into a roll, it is
nevertheless better for scanning deformed film.
And there’s lots of it in my father’s ar-
chieves.
It also can accept single frames in the "stan-
dard" mount, like the slides here demostrated.
I don’t know if it is possible to use another
adapter with this scanner. A glass film holder would
be interesting to try for it would hold any film
perfectly flat…
Sorry, I didn’t understand what Weiss is in your
context.
That gives me the perforation holes as a reference
for ‘pure’ light.
It is a nice idea to use perforation holes for that.
More so it is in slides where one is never sure what
the minimal density is, because it appears on maxi-
mally exposed areas, while in negatives you always
have transparent film as reference point. Thank you
for the advice.
I’d not set individual channels at this point –
just the overall exposure and I’d extend the auto-
matic ‘white’ ‘black’ setting proposed.
I hadn’t done it before I ran into a film so bad
that the range of one channel was two or more times
narrower that the that of the others, like the red
channel on the slides. Manually setting the indivi-
dual exposure in the way I mentioned helps to use
the sensor’s dynamic range more effectively and to
get a better (with more correct levels and the white
point, and with more data) raw scan requiring less
tweaking in the postprocessing application.
Actually you want to maximize the signal to noise
ratio. The lower the ratio, the more noise.
Yes, but I was mentioning the noise-to-signal ratio
๐
When underexposed or when you set the histogram
too high for the blacks, they are compressed.
Let’s say from 0 to 16, is forced to 0. That then
drags down the other levels and makes the dark
areas ‘blocks’ rather than detail, even though
dark.
Hmmm. I wouldn’t call this compression. I’d call it
the clipping of blacks, or underexposure. If the
exposure is too low, densities from 0 to 16 are
"mapped" to, say, -20 to -4 on the censor that clips them all to zero. And with the clipping of whites
(overexposure) the situation is symmetric.
Compression is a non-linear operation, like a curve
to increase the contrast compresses blacks and
whites, while decompressing the mid-tones. The Lev-
els tool )(de)compresses the whole density range
uniformly. But neither happens with change of expo-
sure. That’s how I see it.
Just curious, from your rememberance, how close
was the coach?
I didn’t take this photos. They are older than I am
and originate from my friend’s collection. Also it
is not the original film (from the camera) but a
copy of it (which is probably the reason of the low
sharpness). In the Soviet times, such packs were
produced massively by Diafilm and sold at museums
e.t.c.
They also made "illustraded tales" based on anything from classics like "The Lost World" to Russian folk- lore. I have some of them too and am going to scan
them. They were in the half-frame format (24 x 18
mm), each frame consisting of a picture and several
lines of text.
Anton