[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [APML] The next great scanner?
I was speaking from memory. It is actually the "Auto Expose for slides"
setting that causes the ghosting. I suspect it overexposes the mostly
dark slide which then allows for internal reflections around the stars.
I just tested it again and this is the culprit. The auto expose setting
does do a nice job in bringing out nebulosity so its tempting to use
when you need to do a quick scan.
cheers
Duncan
Ray Butler wrote:
>
> Thanks for sharing your experience, Duncan.
>
>> I have a similar problem with ghosting around bright stars with my
>> Minolta dual scan 2. It goes away if I do a multi-pass scan and use a
>> more precise focus.
>
>
> I'm not quite sure how a multi-pass scan can help with a ghost image,
> like the type I get. Averaging multiple scans of the same thing can
> only reduce the random noise, whereas a bright ghost is systematic
> noise (it is _always_ +, not randomly + and -). Unless I have the
> wrong interpretation of "multi-scan"...
>
> Since you say that more precise focus also helps, I reckon that focus
> was probably the root of your problem. I've tested different focal
> heights on my flatbed and it doesn't make a difference to the
> ghosts/trails. That, plus the directionality of the ghosts, makes me
> convinced that my problem is sensor or illumination based, not focus
> based.
>
> So I guess that different types of scanners can present quite
> different problems, requiring quite different solutions.
>
> Ray "who can live with it, but would still like to know if anyone has
> sussed it" Butler.
>
>
>> cheers
>>
>>
>> Duncan
>>
>> Lane, Jason R wrote:
>>
>>> Hi guys,
>>>
>>> This exactly describes the issue I have with my HP Photosmart
>>> s20...little rainbow-like ghost reflection nearby. Uncoated optics,
>>> for sure.
>>>
>>> -----Original Message-----
>>> From: astro-photo-bounces@seds.org
>>> [mailto:astro-photo-bounces@seds.org]On Behalf Of Matthias Felsch
>>> Sent: Monday, October 04, 2004 6:34 AM
>>> To: Discussion of Film Astrophotography
>>> Subject: Re: [APML] The next great scanner?
>>>
>>>
>>>
>>> "Ray Butler" <ray.butler@nuigalway.ie> wrote:
>>>
>>>
>>>
>>>> When scanning slide films, whenever there is a star on a dark
>>>> background ("dark" meaning somewhere
>>>> at or above the rebate density, but somewhat less than the sky fog
>>>> limit), there is a faint little
>>>> 'trail' or 'ghost spot' left on both sides of the star image. .....
>>>> .......
>>>> Has anyone else noticed this effect?
>>>>
>>>
>>>
>>>
>>> I once tested a Minolta Multi Pro, which had similiar ghost effects,
>>> but
>>> I think they were stronger than the ones you describe.
>>> Each brighter star had a rainbow- like ghost reflection nearby.
>>> Minolta Japan did find out that the reason was a glass plate
>>> positioned in front of the ccd- sensor to protect it.
>>> This glass was NOT coated.... <g>
>>> When they modified this particular scanner with a coated glass, the
>>> ghosts were reduced by 95 %. The remaining 5% were tolerable in my
>>> opinion.
>>> Unfortunately the scanner had a second flaw, so it was returned...
>>>
>>> Regards
>>> Matthias
>>>
>>> www.mfelsch.de/astro/index.html
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>> Ray "who nonetheless considers the Epson 3200 to have been a great
>>>> buy at the time" Butler
>>>>
>>>>
>>>> Kevin McCarthy wrote:
>>>>
>>>>
>>>>
>>>>> Canon has just released their 9950F flatbed scanner, which will
>>>>> accept a whole roll of 35 mm, and
>>>>> two strips of 120 format. They claim that it is so good that they
>>>>> are discontinuing their line
>>>>> of dedicated film scanners. In the flatbed realm, the current
>>>>> best model seems to be the Epson
>>>>> 4870, which has been favorably compared to dedicated Nikon MF film
>>>>> scanners. I would like to
>>>>> hear any opinions as to how the new 9950F and year-old 4870
>>>>> compare. Curiously, Canon does not
>>>>> mention a Dmax value. An initial review of the 9950F is here,
>>>>> although he (Vincient Olivier)
>>>>> plans to follow up with an in-depth review shortly:
>>>>>
>>>>> http://www.photo-i.co.uk/News/Sept04/Canon%20scanner.htm
>>>>>
>>>>> He has an in depth review of the current champion Epson 4870 at:
>>>>>
>>>>> http://www.photo-i.co.uk/Reviews/interactive/Epson%204870/page_1.htm
>>>>>
>>>>> Here is some info from Canon:
>>>>>
>>>>> http://consumer.usa.canon.com/ir/controller?act=ModelDetailAct&fcategoryid=120&modelid=10446
>>>>> I
>>>>> did see some grousing on a German site that the Canon software is
>>>>> "too automatic", also some
>>>>> concern that third party software such as Digital Ice and
>>>>> SilverFast may take a while to be
>>>>> available for this scanner.
>>>>> It may still be too early to tell if this has a real performance
>>>>> edge over the 4870. Being in
>>>>> the market for a MF scanner, it caught my interest. On another
>>>>> note, Nikon LS-8000 can be had
>>>>> for ~ $1500 if you are willing to buy a refurb, more like ~2000
>>>>> otherwise. Opinions, anyone?
>>>>>
>>>>> Kevin McCarthy
>>>>>
>>>>> _______________________________________________
>>>>> Astro-Photo mailing list
>>>>> Astro-Photo@seds.org
>>>>> http://seds.org/mailman/listinfo/astro-photo
>>>>>
>>>>
>>>>
>>>> --
>>>> Dr. Ray Butler (ray.butler@nuigalway.ie || ray@physics.nuigalway.ie)
>>>> Lecturer, Dept. of Physics || Computational Astrophysics Laboratory
>>>> National University of Ireland, Galway, University Road, Galway,
>>>> Ireland.
>>>> Tel: +353-91-524411 ext. 3788 FAX: +353-91-525700
>>>>
>>>> _______________________________________________
>>>> Astro-Photo mailing list
>>>> Astro-Photo@seds.org
>>>> http://seds.org/mailman/listinfo/astro-photo
>>>>
>>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Astro-Photo mailing list
>>> Astro-Photo@seds.org
>>> http://seds.org/mailman/listinfo/astro-photo
>>> _______________________________________________
>>> Astro-Photo mailing list
>>> Astro-Photo@seds.org
>>> http://seds.org/mailman/listinfo/astro-photo
>>>
>>>
>>>
>>>
>>>
>>
>> _______________________________________________
>> Astro-Photo mailing list
>> Astro-Photo@seds.org
>> http://seds.org/mailman/listinfo/astro-photo
>
>
_______________________________________________
Astro-Photo mailing list
Astro-Photo@seds.org
http://seds.org/mailman/listinfo/astro-photo