Re: [APML] 4x5 astrocamera (again?)

[Wei-Hao Wang <wang@IfA.Hawaii.Edu>]

Hi Dave,

E100SW has a warmer color because its blue density is suppressed.
In terms of red sensitivity, there is no difference between E100S
and E100SW.  The tech data for E100S/SW on kodak.com are incomplete.  
You can look at the tech data for E100G/GX.  They have identical 
spectral sensitivity and spectral dye density.  The only difference 
is their B HD curves.  However, the difference on actual slides 
is really small and should not be like what you described.  I never
had this when I used E100SW before.  I suppose there is something 
wrong with the film or development.

Loke made a good point about scan resolution.  2500 dpi sounds low
according to today's standard but is high enough for most astro work.
I'm not familiar with 4x5 lenses so cannot comment on this part.
If you are using a telescope (such as an APO + field flattener),
you can expect 30 to 40 um stellar size at the field center using 
E100S or Provia 100F.  This means 15 to 20 um pixles (1200 to 1600dpi) 
are enough even for the highest resolution region on your film.  This
should help to decrease your file size without losing details.  If you
compromise between the center and edge of the field, you can even 
use 1000 dpi.

My scanner can only do 1600 dpi.  The finest star I ever got with my
refractor is 30 um so 1600 dpi is enough for me.  On the other hand, 
Pentax 67 lenses produce stars smaller than 20um.  For these pictures,
I feel I need at least 2400 dpi.  If this is also the case for you, 
then you have to live with 750MB files.  My largest mosaic has about
this size.  You are not alone.

Cheers,

Wei-Hao


______________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

Address:                       Phone: 808-956-9867                  
2680 Woodlawn Drive            Personal Website:
Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
______________________________________________________________________



On Fri, 7 May 2004, D. Kodama wrote:

> 
> Wei-Hao,
> 
> Thanks for the info on 4x5 film choices.  I recently picked up my own
> combo 4x5" and 6x9cm setup (Mitsuboshi) so the info is appreciated.
> 
> Regarding E100SW, awhile back I tried it in 4x5 format but found that it
> had a tendency to go to yellow-green on long exposures.  I thought the "W"
> (warm) version of E100 would have better red response for nebulosity, but
> the green seems to overwhelm things.  I'd be interested in hearing if
> anyone has had a similar result.  I just shot a couple of test frames
> before becoming too busy to proceed further.
> 
> By the way, one of the "downsides" of 4x5" is the size of the digital
> files.  My scanner can only do 2500 DPI, but at that resolution a 48-bit
> TIFF file is 750,000,000 bytes!
> 
> Dave Kodama
> 
> 
> > Date: Thu, 6 May 2004 15:27:29 -1000 (HST)
> > From: Wei-Hao Wang <wang@IfA.Hawaii.Edu>
> > Subject: Re: [APML] 4x5 astrocamera (again?)
> > To: astro-photo@seds.org
> > Message-ID: <200405070133.i471Xml07592@galileo.ifa.hawaii.edu>
> > Content-Type: TEXT/plain; charset=us-ascii
> >
> > Hi Bobby,
> >
> > Yes, E100S is discontinued.  Now only 4x5 format (perhaps some
> > 120 format E100SW) is available.
> >
> > Wei-Hao
> 
> 
> 
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> 

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