On 1/4/2014 6:22 PM, Moose wrote:
> On 1/4/2014 7:07 AM, Chuck Norcutt wrote:
> So far I have
>> not experienced any focus problems that were claimed at one review site.
>> The film holders do have little feet that can be installed at two
>> different heights to adjust focus but I've not seen any need yet to use
>> them in other than the default configuration.
>
> I don't know how much is sample variation and how much compulsive pixel
> peeping. It has been a reported problem for more
> than one review site. I'm glad yours is good. In that case, I think the only
> advantage to the Canon is that it can scan
> 5 strips of film at once, instead of four.
Well, perhaps I should check focus more carefully. Maybe that's why I
didn't find more than 2400 dpi necessary. :-)
I have VueScan but haven't been able
>> to get it to work with film because it doesn't know the locations of the
>> negatives and slides in their film holders. There is a training process
>> one is supposed to use to teach it where the frames are but my one
>> attempt at using it didn't work. One of these days (when I get much
>> more serious about scanning the many thousands of film images I have)
>> I'll get back to it and figure out what I was doing wrong.
>
> Before going to all that trouble, you should try the latest update. If that
> doesn't work, drop Ed a line. The profiles
> for scanners are supposed to know where the film is in standard holders. He's
> always been very responsive when I've had
> trouble with VS.
Either the latest update or maybe just checking more carefully. I don't
recall any mention of film holder profiles for the V700. I didn't know
there was such a thing. I don't have the scanner with me but did just
search the user's manual for the term "multi crop" which is what is used
to describe multi-frame film holders. There's an "auto" setting. When
I selected auto it filled in some numbers for the little HP
print-scan-copy machine I have here and identified it as the scan
source. Maybe that's all I'll have to do when I get home and get the
V700 reattached. But that same menu selection area has the option for
custom building a multi-crop profile. That's exactly what I tried to do
so don't know why I missed the auto setting. Of course, what I was
running at the time was probably several versions back. Maybe it wasn't
there then for the V700. Anyhow I'll look harder when I get back home.
>
> A word about scanner resolution. The flatbeds designed for film scanning
> claim 4800 dpi resolution. And indeed, they put
> out 4800 dpi, but resolve no more detail than true film scanners of 4000 dpi.
> In personal comparisons of Canon 4000FS
> and 9950F, the lower speced film scanner resolved more detail on the same
> frames. From what I've read, that's generally
> true.
>
>> because there simply isn't that much true data in the image. Even excellent
>> 35mm images probably don't contain more than 8-9 MP of real data. 2400 dpi
>> will probably capture
>> all that's there on many if not most images. Certainly enough for an
>> 8x10 or 10x15 print and maybe even 11x14.
In a book I have at home called "Image Clarity" by John Williams
(published 1989/90 and 2012 in Kindle form)
<http://www.amazon.com/Image-Clarity-High-Resolution-John-Williams-ebook/dp/B008KL8J54/ref=sr_1_22?s=books&ie=UTF8&qid=1388951601&sr=1-22&keywords=image+sharpness#reader_B008KL8J54>
Williams spends many pages describing the maximum resolutions attainable
by amateur and professional photographers using unskilled and skilled
hand held methods and low to high resolution films on up to heavy studio
grade equipment with very high resolution B&W and extreme measures take
to prevent vibration. The average hand held photograph taken with
typical color films of the day fares poorly with resolutions ranging
from 20 lppm for the typical rank amateur to 30 lppm for the careful
amateur to 40 lppm for the very careful and meticulous processional.
It's actually rather disappointing since 40 lppm only translates to
(80x24) = 1920 pixels vertically and (80x36) = 2880 pixels horizontally
or about 5.5 megapixels for a 35mm film scan. Is this perhaps where the
5 MP resolution of the E-1 comes from as "good enough"? Of course, it
probably takes 4000 dpi to actually resolve that 1920 pixels vertically.
Of course, this is not tripod work (also covered) nor was IS known in
1989 but it does show the rather low resolutions we can reasonably
expect from many old and not so old photos. Also keep in mind that we
are dealing with "system resolution" where the resolution of the film is
a very limiting factor. Resolution of low contrast areas in typical
color films only ranges from about 50 to 80 lines/mm and perhaps double
that in high contrast areas. No matter how good and stable the lens the
end result can't be better than that and will likely be appreciably less.
Chuck Norcutt
>
> Well, yes and no. A carefully focused shot with a good lens at a good
> aperture on film from the last couple of decades,
> at least, does reveal significantly more detail at 4000 dpi than 2400. In
> fact, I've been able to slightly increase
> pixel level detail with multiple scan passes in VueScan. It's quite time
> consuming, although one may be elsewhere while
> it's happening. But if making a large print from a good frame, it could be
> worth it.
>
> I did a fair amount of careful testing, mostly on Portra 160, not the later
> couple of versions, which are said to be
> even better.
>
> Then again, what you say is also true, both of a great many images and of the
> needs of modest print sizes. Kodak 200
> film in an XA some years earlier had nothing extra at 4000 dpi.
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