[filmscanners] Re: HP PhotsSmart - questions

["Arthur Entlich" <artistik@shaw.ca>]

The native optical resolution of this scanner varies dependent upon the
size of the image being scanned.  In the case of 35mm film, which is
just under 1" wide, the scanner sensor/CCD scans at 2400 ppi/dpi.
However, when switched to reflective mode, the scanner can scan up to 5
x 7" prints (I previously incorrectly noted 4x6").  In this mode the
maximum is 300 ppi/dpi (although the math implies it could scan up to
about 450 ppi/dpi) but who knows what kind of optical light path bending
they had to do to accomplish that.

Art

Laurie Solomon wrote:

> I looked at the web site you gave the link for; it was not clear from its
> contents as to what the unit's native optical resolution is.  If the native
> optical resolution is 150 dpi and the other resolutions are all
> interpolations, that might account for the reason that the 150 is sharper
> than the 300 dpi.  Moreover, the screen resolution might also enter into the
> equation since the screen rendering of the image will be such as to make the
> 300 dpi scan be rendered on the monitor at twice the size as the 150 dpi
> scan which can result it some apparent fuzziness with the smaller rendering
> appearing sharper even at lower resolutions.
>
> The standard rule of thumb sage advice is to scan at the scanners optical
> resolution and not at an interpolated resolution to get the maximum
> sharpness and the minimum flaws, artifacts, and noise.
>
> But you have me a little confused.  You speak of scanning a 3x5 print; but
> then you say you also had this negative roll scanned at Target.  Are we
> talking about positive paper prints or film negatives?  They are two very
> different things.
>
> Unless you will be enlarging a hard copy print to a print size larger then
> the original or a portion of a cropped print to the size of the entire
> original print or larger, a 300 dpi is sufficient since hard copy prints
> typically do not yield resolutions greater then 300 dpi since the
> information is not there in the original to support a higher resolution with
> actual original data.  To scan 35mm film, one will normally scan it at a
> resolution of around 4000 dpi since the frames will typically be enlarged to
> at least 3.5 X so as to produce a 3.5 X 5 image at around 300 dpi.  A 1200
> dpi scan of a 35mm film frame is a relatively low resolution to be scanning
> 35mm at and would require interpolation in the event that one wanted to
> enlarge the image in its entirety or in part.  Thus, Target is really not
> doing any better than your machine would do on a 35mm film frame. Moreover,
> we do not know if the 1200 dpi that Target scans at is real optical
> resolution or interpolated resolution.
>
>
>>-----Original Message-----
>>From: filmscanners_owner@halftone.co.uk
>>[mailto:filmscanners_owner@halftone.co.uk] On Behalf Of Rich Koziol
>>Sent: Saturday, August 06, 2005 1:01 PM
>>To: laurie@advancenet.net
>>Subject: [filmscanners] Re: HP PhotsSmart - questions
>>
>>On 6 Aug 2005 at 12:06, Laurie Solomon wrote:
>>
>>
>>>As for the question of " why 150 dpi appears sharper than
>>
>>300 dpi when
>>
>>>scanning a 3 x 5 color print," you did not tell us if the
>>
>>result you
>>
>>>speak of was on the monitor or on a hard copy print
>>
>>At this point I'm just looking at the results on a 19inch monitor.
>>Used the HP software to scan with.
>>
>>I also had this negative roll scanned at Target, for comparison.
>>Target offers 1200dpi scans for about $4/roll.  They just
>>started this service and are still somewhat sloppy with film handling.
>>
>>Rich
>>
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